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feat(docs): proofread and edited docs (#7144)
This commit is contained in:
Victor Wheeler
GitHub
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@ -17,7 +17,7 @@ It's huge release with many interesting updates:
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- SDL renderer improvements (supporting all draw task types and improving speed)
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- Radial, Conic, and Skew `gradients supported <https://docs.lvgl.io/master/details/base-widget/styles/style.html#metallic-knob-with-conic-gradient>`__ by software rendering and VG-Lite
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- :ref:`qnx` and :ref:`mqx` support
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- :ref:`Mouse hover handling <styles_states>`
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- :ref:`Mouse hover handling <style_states>`
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- :ref:`lv_lottie` support
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- CI tests for UEFI builds
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@ -38,9 +38,9 @@ Units
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.. _coord_boxing_model:
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.. _boxing_model:
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Boxing model
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Boxing Model
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************
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LVGL follows CSS's `border-box <https://developer.mozilla.org/en-US/docs/Web/CSS/box-sizing>`__
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@ -164,11 +164,11 @@ Alignment
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Inside parent widget
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~~~~~~~~~~~~~~~~~~~~
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In many cases it is more convenient to tell LVGL to align your object relative to
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an "anchor point" in its parent *other* than its upper left corner. To establish
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that "anchor point", call :cpp:expr:`lv_obj_set_align(widget, LV_ALIGN_...)`. After
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that call, that "anchor point" will be remembered until another one is established.
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an "anchor" in its parent *other* than its upper left corner. To establish
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that "anchor", call :cpp:expr:`lv_obj_set_align(widget, LV_ALIGN_...)`. After
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that call, that "anchor" will be remembered until another one is established.
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In other words, every futire x and y setting for that Widget will be relative to the
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that "anchor point".
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that "anchor".
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Example: Position Widget (10,20) px relative to the center of its parent:
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@ -180,7 +180,7 @@ Example: Position Widget (10,20) px relative to the center of its parent:
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/* Or combine the above in one function... */
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lv_obj_align(widget, LV_ALIGN_CENTER, 10, 20);
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9 convenient "anchor points" can be used with these functions:
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9 convenient "anchors" can be used with these functions:
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- :cpp:enumerator:`LV_ALIGN_TOP_LEFT`
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- :cpp:enumerator:`LV_ALIGN_TOP_MID`
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@ -210,7 +210,7 @@ children is updated automatically.
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Relative to another Widget
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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Alternately, you can choose an "anchor point" on another Widget.
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Alternately, you can choose an "anchor" on another Widget.
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.. code-block:: c
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@ -238,10 +238,10 @@ Example: to horizontally center a label 10 pixels above a button:
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lv_obj_align_to(label, btn, LV_ALIGN_OUT_TOP_MID, 0, -10);
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Note that, unlike with :cpp:func:`lv_obj_align`, :cpp:func:`lv_obj_align_to`
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does not remember the "anchor point" used, and so will not automatically reposition
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does not remember the "anchor" used, and so will not automatically reposition
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the aligned widget if the reference widget later moves.
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The following illustration shows the meaning of each "anchor point" mentioned above.
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The following illustration shows the meaning of each "anchor" mentioned above.
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.. image:: /misc/align.png
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@ -4,39 +4,54 @@
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Flex
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====
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Overview
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********
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The Flexbox (or Flex for short) is a subset of `CSS Flexbox <https://css-tricks.com/snippets/css/a-guide-to-flexbox/>`__.
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The Flexbox (or Flex for short) is a subset of `CSS Flexbox`_ behaviors.
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It can arrange items into rows or columns (tracks), handle wrapping,
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adjust the spacing between the items and tracks, handle *grow* to make
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the item(s) fill the remaining space with respect to min/max width and
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It can arrange items (child Widgets) into rows or columns (tracks), handle wrapping,
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adjust the spacing between items and tracks, handle *grow* to make
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item(s) fill remaining space with respect to min/max width and
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height.
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To make a Widget flex container call
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To make a Widget a Flex container call
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:cpp:expr:`lv_obj_set_layout(widget, LV_LAYOUT_FLEX)`.
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Note that the flex layout feature of LVGL needs to be globally enabled
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Note that the Flex layout feature of LVGL needs to be globally enabled
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with :c:macro:`LV_USE_FLEX` in ``lv_conf.h``.
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Terms
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*****
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- **tracks**: the rows or columns
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- **main direction**: row or column, the direction in which the items are
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placed
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- **cross direction**: perpendicular to the main direction
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- **wrap**: if there is no more space in the track a new track is started
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- **grow**: if set on an item it will grow to fill the remaining space on
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- **tracks**: rows or columns
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- **main direction**: row or column, the direction in which multiple items are
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placed first
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- **cross direction**: the direction perpendicular to the **main direction**
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- **wrap**: if there is no more space in the track, a new track is started
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- **grow**: if set on an item it will "grow" to fill the remaining space in
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the track. The available space will be distributed among items
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respective to their grow value (larger value means more space)
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- **gap**: the space between the rows and columns or the items on a track
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- **gap**: the space between rows and columns or the items on a track
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Simple interface
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See `CSS Flexbox`_ for illustrations showing the meanings of these terms.
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Simple Interface
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****************
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With the following functions you can set a Flex layout on any parent.
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Use the following functions to set and control the Flex layout on any parent Widget.
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.. note::
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The parent Widget must be a Flex container for these styles to take effect.
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The functions below cause the parent Widget to become a Flex container if it is
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not already.
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.. _flex_flow:
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@ -56,68 +71,83 @@ The possible values for ``flex_flow`` are:
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- :cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP_REVERSE`: Place the children in a row with wrapping but in reversed order
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- :cpp:enumerator:`LV_FLEX_FLOW_COLUMN_WRAP_REVERSE`: Place the children in a column with wrapping but in reversed order
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These values cause the Widget's layout behavior to model `CSS Flexbox`_ behavior
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by combining flex-direction_ and flex-wrap_ as defined under flex-flow_.
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.. _flex_align:
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Flex align
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----------
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To manage the placement of the children use
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To manage placement of children use
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:cpp:expr:`lv_obj_set_flex_align(widget, main_place, cross_place, track_cross_place)`
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which makes the parent Widget model the Flex-container behavior defined `here
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<justify-content_>`_.
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- ``main_place`` determines how to distribute the items in their track
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on the main axis. E.g. flush the items to the right on :cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP`. (It's called
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``justify-content`` in CSS)
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on the main axis. E.g. flush the items to the right on
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:cpp:enumerator:`LV_FLEX_FLOW_ROW_WRAP`. (It's called
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justify-content_ in CSS.)
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- ``cross_place`` determines how to distribute the items in their track
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on the cross axis. E.g. if the items have different height place them
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to the bottom of the track. (It's called ``align-items`` in CSS)
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on the cross axis. E.g. if the items have different height, align them
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against the bottom of the track. (It's called align-items_ in CSS.)
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- ``track_cross_place`` determines how to distribute the tracks (It's
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called ``align-content`` in CSS)
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called align-content_ in CSS.)
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The possible values are:
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- :cpp:enumerator:`LV_FLEX_ALIGN_START`: means left on a horizontally and top vertically (default)
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- :cpp:enumerator:`LV_FLEX_ALIGN_END`: means right on a horizontally and bottom vertically
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- :cpp:enumerator:`LV_FLEX_ALIGN_CENTER`: simply center
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- :cpp:enumerator:`LV_FLEX_ALIGN_START`: means left when direction is horizontal, top when vertical (default)
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- :cpp:enumerator:`LV_FLEX_ALIGN_END`: means right when direction is horizontal, bottom when vertical
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- :cpp:enumerator:`LV_FLEX_ALIGN_CENTER`: simply center with respect to direction
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- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_EVENLY`: items are distributed so
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that the spacing between any two items (and the space to the edges) is
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equal. Does not apply to ``track_cross_place``.
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- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_AROUND`: items are evenly
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distributed in the track with equal space around them. Note that
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visually the spaces aren't equal, since all the items have equal space
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on both sides. The first item will have one unit of space against the
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container edge, but two units of space between the next item because
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that next item has its own spacing that applies. Not applies to
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visually the spaces are not equal since all the items have equal space
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on both sides. This makes the space between items double the space
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between edge items and the container's edge. Does not apply to
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``track_cross_place``.
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- :cpp:enumerator:`LV_FLEX_ALIGN_SPACE_BETWEEN`: items are evenly distributed in
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the track: first item is on the start line, last item on the end line. Not applies to ``track_cross_place``.
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the track with no space before and after first and last items. Does not apply
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to ``track_cross_place``.
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See justify-content_, align-items_ and align-content_ for illustrations of these values.
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.. _flex_grow:
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Flex grow
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---------
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Flex grow can be used to make one or more children fill the available
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space on the track. When more children have grow parameters, the
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available space will be distributed proportionally to the grow values.
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For example, there is 400 px remaining space and 4 Widgets with grow:
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Flex grow can be used to make one or more children fill available space in the track.
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When more than one child Widget have non-zero grow values, all available space will
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be distributed in proportion to their respective grow values. For example, if there
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is 400 px space remaining and 3 child Widgets with non-zero grow values:
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- ``A`` with grow = 1
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- ``B`` with grow = 1
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- ``C`` with grow = 2
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``A`` and ``B`` will have 100 px size, and ``C`` will have 200 px size.
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``A`` and ``B`` will occupy 100 px, and ``C`` will occupy 200 px.
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Flex grow can be set on a child with
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:cpp:expr:`lv_obj_set_flex_grow(child, value)`. ``value`` needs to be >
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Flex grow can be set on a child Widget with
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:cpp:expr:`lv_obj_set_flex_grow(child, value)`. ``value`` needs to be >=
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1 or 0 to disable grow on the child.
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See flex-grow_ for an illustration of this behavior.
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.. _flex_style:
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Style interface
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Style Interface
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***************
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All the Flex-related values are style properties under the hood and you
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can use them similarly to any other style property.
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All Flex-related values are style properties under the hood so you
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can use them as you would any other style property.
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The following flex related style properties exist:
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@ -133,18 +163,20 @@ Internal padding
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----------------
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To modify the minimum space flexbox inserts between Widgets, the
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following properties can be set on the flex container style:
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following functions can be used to set the flex container padding style:
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- ``pad_row`` Sets the padding between the rows.
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- :cpp:func:`lv_style_set_pad_row` sets padding between rows.
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- ``pad_column`` Sets the padding between the columns.
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- :cpp:func:`lv_style_set_pad_column` sets padding between columns.
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These can for example be used if you don't want any padding between your
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These can, for example, be used if you do not want any padding between
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Widgets: :cpp:expr:`lv_style_set_pad_column(&row_container_style, 0)`
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.. _flex_other:
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Other features
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Other Features
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**************
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RTL
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@ -165,13 +197,34 @@ New track
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You can force Flex to put an item into a new line with
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:cpp:expr:`lv_obj_add_flag(child, LV_OBJ_FLAG_FLEX_IN_NEW_TRACK)`.
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.. _flex_example:
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Example
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*******
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.. admonition:: Further Reading
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Learn more about `CSS Flexbox`_.
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.. _flex_examples:
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Examples
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********
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.. include:: ../../../examples/layouts/flex/index.rst
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.. Hyperlinks
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.. _css flexbox: https://css-tricks.com/snippets/css/a-guide-to-flexbox/
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.. _flex-direction: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-flex-direction
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.. _flex-wrap: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-flex-wrap
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.. _flex-flow: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-flex-flow
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.. _justify-content: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-justify-content
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.. _align-items: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-align-items
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.. _align-content: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-align-content
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.. _flex-grow: https://css-tricks.com/snippets/css/a-guide-to-flexbox/#aa-flex-grow
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.. _flex_api:
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API
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@ -4,35 +4,48 @@
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Grid
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====
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Overview
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********
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The Grid layout is a subset of `CSS Grid <https://css-tricks.com/snippets/css/complete-guide-grid/>`__.
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The Grid layout is a subset of `CSS Grid`_ layout.
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It can arrange items into a 2D "table" that has rows or columns
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(tracks). The item can span through multiple columns or rows. The
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track's size can be set in pixel, to the largest item
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(:c:macro:`LV_GRID_CONTENT`) or in "Free unit" (FR) to distribute the free
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space proportionally.
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It can arrange items (child Widgets) into a 2D "table" that has rows and columns
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(tracks). An item can span multiple columns or rows. The
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track's size can be set in pixels, to the largest item
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(:c:macro:`LV_GRID_CONTENT`), or to a fraction of the available free space
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(i.e. `Free [FR] Units <fr units_>`_) to distribute free space proportionally.
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To make a Widget a grid container call :cpp:expr:`lv_obj_set_layout(widget, LV_LAYOUT_GRID)`.
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To make a Widget a Grid container call :cpp:expr:`lv_obj_set_layout(widget, LV_LAYOUT_GRID)`.
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Note that the grid layout feature of LVGL needs to be globally enabled
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Note that the Grid layout feature of LVGL needs to be globally enabled
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with :c:macro:`LV_USE_GRID` in ``lv_conf.h``.
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Terms
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*****
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- **tracks**: the rows or columns
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- **free unit (FR)**: if set on track's size is set in ``FR`` it will grow
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to fill the remaining space on the parent.
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- **gap**: the space between the rows and columns or the items on a track
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- **tracks**: rows or columns
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- **free (FR) units**: if a track's size is set in ``FR units`` it will grow
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to fill the remaining space in the parent Widget (container), in proportion with
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other tracks that have non-zero FR-unit values.
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- **gap**: the space between rows and columns or the items on a track
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Simple interface
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Simple Interface
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****************
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With the following functions you can easily set a Grid layout on any
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parent.
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With the following functions you can cause any parent Widget to have Grid-layout behaviors.
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.. note::
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As with Flex containers, the parent Widget must be a Grid container for these
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styles to take effect. The functions below cause the parent Widget to become a
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Grid container if it is not already.
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.. _grid_descriptors:
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@ -47,62 +60,61 @@ For example:
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.. code-block:: c
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static int32_t column_dsc[] = {100, 400, LV_GRID_TEMPLATE_LAST}; /* 2 columns with 100 and 400 ps width */
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static int32_t row_dsc[] = {100, 100, 100, LV_GRID_TEMPLATE_LAST}; /* 3 100 px tall rows */
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static int32_t column_dsc[] = {100, 400, LV_GRID_TEMPLATE_LAST}; /* 2 columns with 100- and 400-px width */
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static int32_t row_dsc[] = {100, 100, 100, LV_GRID_TEMPLATE_LAST}; /* 3 100-px tall rows */
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To set the descriptors on a parent use
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:cpp:expr:`lv_obj_set_grid_dsc_array(widget, col_dsc, row_dsc)`.
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Besides simple settings the size in pixel you can use two special
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Besides settings the sizes in pixels, you can use two special
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values:
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- :c:macro:`LV_GRID_CONTENT` set the size to fit the largest child on this track
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- :cpp:expr:`LV_GRID_FR(X)` tell what portion of the remaining space
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should be used by this track. Larger value means larger space.
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- :c:macro:`LV_GRID_CONTENT` sets size to fit the largest child on this track
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- :cpp:expr:`LV_GRID_FR(X)` determines what portion of the remaining space
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should be used by this track. Larger values means larger space.
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.. _grid_items:
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Grid items
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----------
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By default, the children are not added to the grid. They need to be
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By default, a Widget's children are not added to the grid. They need to be
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added manually to a cell.
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To do this call
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:cpp:expr:`lv_obj_set_grid_cell(child, column_align, column_pos, column_span, row_align, row_pos, row_span)`.
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``column_align`` and ``row_align`` determine how to align the children
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in its cell. The possible values are:
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``column_align`` and ``row_align`` determine how to align the child Widget
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in its cell. Possible values are:
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- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left on a horizontally and top vertically (default)
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- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right on a horizontally and bottom vertically
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- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left when direction is horizontal and top when vertical (default)
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- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right when direction is horizontal and bottom when vertical
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- :cpp:enumerator:`LV_GRID_ALIGN_CENTER`: simply center ``column_pos`` and ``row_pos``
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means the zero based index of the cell into the item should be placed.
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means the zero-based index of the cell in which the item should be placed.
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``column_span`` and ``row_span`` means how many tracks should the item
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involve from the start cell. Must be ``>= 1``.
|
||||
``column_span`` and ``row_span`` means how many tracks should be occupied
|
||||
from the start cell. Must be ``>= 1``.
|
||||
|
||||
.. _grid_align:
|
||||
|
||||
Grid align
|
||||
----------
|
||||
|
||||
If there are some empty space the track can be aligned several ways:
|
||||
If there is some empty space, items (Widgets) in Grid tracks can be aligned in several ways:
|
||||
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left on a horizontally and top vertically. (default)
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right on a horizontally and bottom vertically
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_START`: means left when direction is horizontal and top when vertical. (default)
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_END`: means right when direction is horizontal and bottom when vertical
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_CENTER`: simply center
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_EVENLY`: items are distributed so that the spacing
|
||||
between any two items (and the space to the edges) is equal. Not applies to ``track_cross_place``.
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_AROUND`: items are
|
||||
evenly distributed in the track with equal space around them. Note that
|
||||
visually the spaces aren't equal, since all the items have equal space
|
||||
on both sides. The first item will have one unit of space against the
|
||||
container edge, but two units of space between the next item because
|
||||
that next item has its own spacing that applies. Not applies to ``track_cross_place``.
|
||||
on both sides. This makes the space between items double the space
|
||||
between edge items and the container's edge. Does not apply to ``track_cross_place``.
|
||||
- :cpp:enumerator:`LV_GRID_ALIGN_SPACE_BETWEEN`: items are
|
||||
evenly distributed in the track: first item is on the start line, last
|
||||
item on the end line. Not applies to ``track_cross_place``.
|
||||
evenly distributed in the track with first and last items next to container's edges.
|
||||
Does not apply to ``track_cross_place``.
|
||||
|
||||
To set the track's alignment use
|
||||
:cpp:expr:`lv_obj_set_grid_align(widget, column_align, row_align)`.
|
||||
@ -112,28 +124,38 @@ To set the track's alignment use
|
||||
Sub grid
|
||||
--------
|
||||
|
||||
If you set the column and/or row grid descriptors of a widget to ``NULL`` it will use the grid descriptor(s) from it's parent.
|
||||
For example if you create a grid item on 2..6 columns and 1..3 rows of the parent,
|
||||
the grid item will see 5 columns and 4 rows with the corresponding track size from the parent.
|
||||
If you set the column and/or row grid descriptors of a widget to ``NULL`` it will use
|
||||
the grid descriptor(s) from it's parent.
|
||||
|
||||
This way even if a wrapper item is used on the grid and can be made "transparent" from the grid's point of view.
|
||||
For example if you create a grid item that spans columns 2..6 columns and rows 1..3
|
||||
of the grid, the grid item will occupy 5 columns and 4 rows with the corresponding
|
||||
track size from the parent Grid container.
|
||||
|
||||
This way even if a wrapper item is used in the grid, it can be made "transparent"
|
||||
from the grid's point of view.
|
||||
|
||||
Limitations:
|
||||
|
||||
- The sub grid is resolved only in one level depth. That is a grid can have a sub grid children, but a sub grid can't have another sub grid.
|
||||
- ``LV_GRID_CONTENT`` tracks on the are not handled in the sub grid, only in the its own grid.
|
||||
- The sub-grid is resolved only to a depth of 1 level. That is, a grid can have a
|
||||
sub-grid child, but that sub-grid cannot have another sub-grid.
|
||||
|
||||
- ``LV_GRID_CONTENT`` tracks on the grid are not handled in the sub-grid, only in its
|
||||
own grid.
|
||||
|
||||
The sub-grid feature works the same as in CSS. For further information, see
|
||||
`CSS Subgrid`_.
|
||||
|
||||
|
||||
The sub grid feature works the same as in CSS. For further reference see `this description <https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout/Subgrid>`__.
|
||||
|
||||
.. _grid_style:
|
||||
|
||||
Style interface
|
||||
Style Interface
|
||||
***************
|
||||
|
||||
All the Grid related values are style properties under the hood and you
|
||||
can use them similarly to any other style properties.
|
||||
All the Grid-related values are style properties under the hood so you
|
||||
can use them as you would any other style property.
|
||||
|
||||
The following Grid related style properties exist:
|
||||
The following Grid-related style properties exist:
|
||||
|
||||
- :cpp:enumerator:`GRID_COLUMN_DSC_ARRAY`
|
||||
- :cpp:enumerator:`GRID_ROW_DSC_ARRAY`
|
||||
@ -154,8 +176,11 @@ Internal padding
|
||||
To modify the minimum space Grid inserts between Widgets, the following
|
||||
properties can be set on the Grid container style:
|
||||
|
||||
- ``pad_row`` Sets the padding between the rows.
|
||||
- ``pad_column`` Sets the padding between the columns.
|
||||
- :cpp:func:`lv_style_set_pad_row` sets padding between rows.
|
||||
|
||||
- :cpp:func:`lv_style_set_pad_column` sets padding between columns.
|
||||
|
||||
|
||||
|
||||
.. _grid_other:
|
||||
|
||||
@ -171,6 +196,15 @@ swapped. I.e. ``START`` will mean right-most.
|
||||
|
||||
The columns will be placed from right to left.
|
||||
|
||||
|
||||
|
||||
.. admonition:: Further Reading
|
||||
|
||||
- Learn more about `CSS Grid`_ layout.
|
||||
- Learn more about `CSS Subgrid`_ layout.
|
||||
|
||||
|
||||
|
||||
.. _grid_examples:
|
||||
|
||||
Example
|
||||
@ -178,6 +212,15 @@ Example
|
||||
|
||||
.. include:: ../../../examples/layouts/grid/index.rst
|
||||
|
||||
|
||||
.. Hyperlinks
|
||||
|
||||
.. _css grid: https://css-tricks.com/snippets/css/complete-guide-grid/
|
||||
.. _fr units: https://css-tricks.com/introduction-fr-css-unit/
|
||||
.. _css subgrid: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_grid_layout/Subgrid
|
||||
|
||||
|
||||
|
||||
.. _grid_api:
|
||||
|
||||
API
|
||||
|
||||
@ -4,20 +4,20 @@
|
||||
Style Details
|
||||
=============
|
||||
|
||||
*Styles* are used to set the appearance of Widgets. Styles in lvgl are
|
||||
Styles are used to set the appearance of Widgets. Styles in lvgl are
|
||||
heavily inspired by CSS. The concept in a nutshell is that a
|
||||
style is an :cpp:type:`lv_style_t` variable which can hold properties like
|
||||
border width, font, text color and so on. It's similar to a ``class`` in CSS.
|
||||
|
||||
- Styles can be assigned to Widgets to change their appearance. Upon
|
||||
assignment, the target part (*pseudo-element* in CSS) and target state
|
||||
(*pseudo class*) can be specified. For example one can add
|
||||
assignment, the target part (pseudo-element_ in CSS) and target state
|
||||
(pseudo-class_ in CSS) can be specified. For example one can add
|
||||
``style_blue`` to the knob of a slider when it's in pressed state.
|
||||
- The same style can be used by any number of Widgets.
|
||||
- Styles can be cascaded which means multiple styles may be assigned to a Widget and
|
||||
each style can have different properties. Therefore, not all properties
|
||||
have to be specified in a style. LVGL will search for a property until a
|
||||
style defines it or use a default if it's not specified by any of the
|
||||
style defines it or use a default value if it's not specified by any of the
|
||||
styles. For example ``style_btn`` can result in a default gray button
|
||||
and ``style_btn_red`` can add only a ``background-color=red`` to
|
||||
overwrite the background color.
|
||||
@ -25,11 +25,13 @@ border width, font, text color and so on. It's similar to a ``class`` in CSS.
|
||||
is specified in two styles the newest style in the Widget will be used.
|
||||
- Some properties (e.g. text color) can be inherited from a parent(s) if it's not specified in a Widget.
|
||||
- Widgets can also have local styles with higher precedence than "normal" styles.
|
||||
- Unlike CSS (where pseudo-classes describe different states, e.g. ``:focus``),
|
||||
- Unlike CSS (where pseudo-classes_ describe different states, e.g. ``:focus``),
|
||||
in LVGL a property is assigned to a given state.
|
||||
- Transitions can be applied when the Widget changes state.
|
||||
|
||||
.. _styles_states:
|
||||
|
||||
|
||||
.. _style_states:
|
||||
|
||||
States
|
||||
******
|
||||
@ -60,8 +62,9 @@ property will be used. Typically this means the property with
|
||||
:cpp:enumerator:`LV_STATE_DEFAULT` is used.˛ If the property is not set even for the
|
||||
default state the default value will be used. (See later)
|
||||
|
||||
But what does the "best matching state's property" really mean? States
|
||||
have a precedence which is shown by their value (see in the above list).
|
||||
What does the "best matching state's property" mean?
|
||||
----------------------------------------------------
|
||||
States have a precedence which is shown by their value (see in the above list).
|
||||
A higher value means higher precedence. To determine which state's
|
||||
property to use let's take an example. Imagine the background color is
|
||||
defined like this:
|
||||
@ -93,15 +96,15 @@ defined like this:
|
||||
Some practical notes:
|
||||
|
||||
- The precedence (value) of states is quite intuitive, and it's something the
|
||||
user would expect naturally. E.g. if a Widget has focus the user will still
|
||||
user would expect naturally. Example: if a Widget has focus the user will still
|
||||
want to see if it's pressed, therefore the pressed state has a higher
|
||||
precedence. If the focused state had a higher precedence it would overwrite
|
||||
the pressed color.
|
||||
- If you want to set a property for all states (e.g. red background color)
|
||||
just set it for the default state. If the Widget can't find a property
|
||||
for its current state it will fall back to the default state's property.
|
||||
- Use ORed states to describe the properties for complex cases. (E.g.
|
||||
pressed + checked + focused)
|
||||
- Use ORed states to describe the properties for complex cases (e.g.
|
||||
pressed + checked + focused).
|
||||
- It might be a good idea to use different
|
||||
style elements for different states. For example, finding background
|
||||
colors for released, pressed, checked + pressed, focused, focused +
|
||||
@ -109,9 +112,11 @@ Some practical notes:
|
||||
Instead, for example, use the background color for pressed and checked
|
||||
states and indicate the focused state with a different border color.
|
||||
|
||||
.. _styles_cascading:
|
||||
|
||||
Cascading styles
|
||||
|
||||
.. _style_cascading:
|
||||
|
||||
Cascading Styles
|
||||
****************
|
||||
|
||||
It's not required to set all the properties in one style. It's possible
|
||||
@ -138,7 +143,9 @@ style (red). When the button is pressed the light-gray color is a better
|
||||
match because it describes the current state perfectly, so the button
|
||||
will be light-gray.
|
||||
|
||||
.. _styles_inheritance:
|
||||
|
||||
|
||||
.. _style_inheritance:
|
||||
|
||||
Inheritance
|
||||
***********
|
||||
@ -147,12 +154,14 @@ Some properties (typically those related to text) can be inherited from
|
||||
the parent Widget's styles. Inheritance is applied only if the given
|
||||
property is not set in the Widget's styles (even in default state). In
|
||||
this case, if the property is inheritable, the property's value will be
|
||||
searched in the parents until a Widget specifies a value for the
|
||||
searched up the parent hierarchy until a Widget specifies a value for the
|
||||
property. The parents will use their own state to determine the value.
|
||||
So if a button is pressed, and the text color comes from here, the
|
||||
So if a button is pressed, and the text color comes from a parent, the
|
||||
pressed text color will be used.
|
||||
|
||||
.. _styles_parts:
|
||||
|
||||
|
||||
.. _style_parts:
|
||||
|
||||
Parts
|
||||
*****
|
||||
@ -172,16 +181,18 @@ The following predefined parts exist in LVGL:
|
||||
|
||||
For example a :ref:`Slider <lv_slider>` has three parts:
|
||||
|
||||
- Background
|
||||
- Main (background)
|
||||
- Indicator
|
||||
- Knob
|
||||
|
||||
This means all three parts of the slider can have their own styles. See
|
||||
later how to add styles to Widgets and parts.
|
||||
|
||||
.. _styles_initialize:
|
||||
|
||||
Initialize styles and set/get properties
|
||||
|
||||
.. _style_initialize:
|
||||
|
||||
Initialize Styles and Set/Get Properties
|
||||
****************************************
|
||||
|
||||
Styles are stored in :cpp:type:`lv_style_t` variables. Style variables should be
|
||||
@ -224,7 +235,8 @@ To get a property's value from a style:
|
||||
do_something(v.color);
|
||||
}
|
||||
|
||||
:cpp:union:`lv_style_value_t` has 3 fields:
|
||||
:cpp:union:`lv_style_value_t` has 3 fields, only one of which will apply, depending
|
||||
on the type of property it is applied to:
|
||||
|
||||
- :cpp:member:`num`: for integer, boolean and opacity properties
|
||||
- :cpp:member:`color`: for color properties
|
||||
@ -251,13 +263,15 @@ Styles can be built as ``const`` as well to save RAM:
|
||||
Later ``const`` style can be used like any other style but (obviously)
|
||||
new properties cannot be added.
|
||||
|
||||
.. _styles_add_remove:
|
||||
|
||||
|
||||
.. _style_add_remove:
|
||||
|
||||
Add and remove styles to a widget
|
||||
*********************************
|
||||
|
||||
A style on its own is not that useful. It must be assigned to a Widget
|
||||
to take effect.
|
||||
A style on its own has no effect until it is added (assigned) to a Widget.
|
||||
|
||||
|
||||
Add styles
|
||||
----------
|
||||
@ -287,8 +301,8 @@ To replace a specific style of a Widget use
|
||||
:cpp:expr:`lv_obj_replace_style(widget, old_style, new_style, selector)`. This
|
||||
function will only replace ``old_style`` with ``new_style`` if the
|
||||
``selector`` matches the ``selector`` used in ``lv_obj_add_style``. Both
|
||||
styles, i.e. ``old_style`` and ``new_style``, must not be ``NULL`` (for
|
||||
adding and removing separate functions exist). If the combination of
|
||||
``old_style`` and ``new_style`` must not be ``NULL``. Separate functions exist for
|
||||
adding and removing styles. If the combination of
|
||||
``old_style`` and ``selector`` exists multiple times in ``obj``\ 's
|
||||
styles, all occurrences will be replaced. The return value of the
|
||||
function indicates whether at least one successful replacement took
|
||||
@ -314,8 +328,8 @@ To remove specific styles use
|
||||
the :cpp:enumerator:`LV_STATE_ANY` and :cpp:enumerator:`LV_PART_ANY` values to remove the style from
|
||||
any state or part.
|
||||
|
||||
Report style changes
|
||||
--------------------
|
||||
Reporting style changes
|
||||
-----------------------
|
||||
|
||||
If a style which is already assigned to a Widget changes (i.e. a
|
||||
property is added or changed), the Widgets using that style should be
|
||||
@ -331,23 +345,28 @@ notified. There are 3 options to do this:
|
||||
when needed, call :cpp:expr:`lv_obj_report_style_change(&style)`. If ``style``
|
||||
is ``NULL`` all Widgets will be notified about a style change.
|
||||
|
||||
Get a property's value on a Widget
|
||||
-----------------------------------
|
||||
Get a style property's value on a Widget
|
||||
----------------------------------------
|
||||
|
||||
To get a final value of property
|
||||
To get the final value of a style's property considering
|
||||
|
||||
- considering cascading, inheritance, local styles and transitions (see below)
|
||||
- property get functions like this can be used: ``lv_obj_get_style_<property_name>(widget, <part>)``.
|
||||
These functions use the Widget's current state and if no better candidate exists they return a default value.
|
||||
- cascading,
|
||||
- inheritance,
|
||||
- local styles and transitions (see below)
|
||||
|
||||
property "get" functions like this can be used: ``lv_obj_get_style_<property_name>(widget, <part>)``.
|
||||
These functions use the Widget's current state and if no better candidate exists they return the default value.
|
||||
For example:
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
lv_color_t color = lv_obj_get_style_bg_color(btn, LV_PART_MAIN);
|
||||
|
||||
.. _styles_local:
|
||||
|
||||
Local styles
|
||||
|
||||
.. _style_local:
|
||||
|
||||
Local Styles
|
||||
************
|
||||
|
||||
In addition to "normal" styles, Widgets can also store local styles.
|
||||
@ -360,7 +379,7 @@ freed when the Widget is deleted. They are useful to add local
|
||||
customization to a Widget.
|
||||
|
||||
Unlike in CSS, LVGL local styles can be assigned to states
|
||||
(*pseudo-classes*) and parts (*pseudo-elements*).
|
||||
(pseudo-classes_) and parts (pseudo-elements_).
|
||||
|
||||
To set a local property use functions like
|
||||
``lv_obj_set_style_<property_name>(widget, <value>, <selector>);`` For example:
|
||||
@ -370,6 +389,7 @@ To set a local property use functions like
|
||||
lv_obj_set_style_bg_color(slider, lv_color_red(), LV_PART_INDICATOR | LV_STATE_FOCUSED);
|
||||
|
||||
|
||||
|
||||
.. _style_properties_overview:
|
||||
|
||||
Style Properties Overview
|
||||
@ -381,9 +401,9 @@ For the full list of style properties click :ref:`here <style_properties>`.
|
||||
Typical background properties
|
||||
-----------------------------
|
||||
|
||||
In the documentation of the widgets you will see sentences like "The
|
||||
In documentation of widgets you will see sentences like "The
|
||||
widget uses the typical background properties". These "typical
|
||||
background properties" are the ones related to:
|
||||
background properties" are the properties being referred to:
|
||||
|
||||
- Background
|
||||
- Border
|
||||
@ -393,7 +413,11 @@ background properties" are the ones related to:
|
||||
- Width and height transformation
|
||||
- X and Y translation
|
||||
|
||||
.. _styles_transitions:
|
||||
See :ref:`boxing_model` for the meanings of these terms.
|
||||
|
||||
|
||||
|
||||
.. _style_transitions:
|
||||
|
||||
Transitions
|
||||
***********
|
||||
@ -436,14 +460,16 @@ initialized and added to a style:
|
||||
|
||||
lv_style_set_transition(&style1, &trans1);
|
||||
|
||||
.. _styles_opacity_blend_modes_transformations:
|
||||
|
||||
Opacity, Blend modes and Transformations
|
||||
|
||||
.. _style_opacity_blend_modes_transformations:
|
||||
|
||||
Opacity, Blend Modes and Transformations
|
||||
****************************************
|
||||
|
||||
If the ``opa``, ``blend_mode``, ``transform_angle``, or
|
||||
``transform_zoom`` properties are set to their non-default value LVGL
|
||||
creates a snapshot about the widget and all its children in order to
|
||||
``transform_zoom`` properties are set to a non-default value LVGL
|
||||
creates a snapshot of the widget and its children in order to
|
||||
blend the whole widget with the set opacity, blend mode and
|
||||
transformation properties.
|
||||
|
||||
@ -459,32 +485,36 @@ configured by the following properties in ``lv_conf.h``:
|
||||
- :cpp:enumerator:`LV_LAYER_SIMPLE_FALLBACK_BUF_SIZE`: [bytes] used if :cpp:enumerator:`LV_LAYER_SIMPLE_BUF_SIZE` couldn't be allocated.
|
||||
|
||||
If transformation properties were also used the layer cannot be
|
||||
rendered in chunks, but one larger memory needs to be allocated. The
|
||||
rendered in chunks, but one larger memory block needs to be allocated. The
|
||||
required memory depends on the angle, zoom and pivot parameters, and the
|
||||
size of the area to redraw, but it's never larger than the size of the
|
||||
widget (including the extra draw size used for shadow, outline, etc).
|
||||
|
||||
If the widget can fully cover the area to redraw, LVGL creates an RGB
|
||||
layer (which is faster to render and uses less memory). If the opposite
|
||||
case ARGB rendering needs to be used. A widget might not cover its area
|
||||
if it has radius, ``bg_opa != 255``, has shadow, outline, etc.
|
||||
case ARGB rendering needs to be used, a widget might not cover its area
|
||||
if it has radius, ``bg_opa < 255``, has shadow, outline, etc.
|
||||
|
||||
The click area of the widget is also transformed accordingly.
|
||||
|
||||
.. _styles_color_filter:
|
||||
|
||||
Color filter
|
||||
|
||||
.. _style_color_filter:
|
||||
|
||||
Color Filter
|
||||
************
|
||||
|
||||
TODO
|
||||
|
||||
.. _styles_themes:
|
||||
|
||||
|
||||
.. _style_themes:
|
||||
|
||||
Themes
|
||||
******
|
||||
|
||||
Themes are a collection of styles. If there is an active theme LVGL
|
||||
applies it on every created widget. This will give a default appearance
|
||||
applies it to every newly-created widget. This will give a default appearance
|
||||
to the UI which can then be modified by adding further styles.
|
||||
|
||||
Every display can have a different theme. For example, you could have a
|
||||
@ -501,12 +531,15 @@ example shows how to set the "default" theme:
|
||||
|
||||
.. code-block:: c
|
||||
|
||||
lv_theme_t * th = lv_theme_default_init(display, /* Use the DPI, size, etc from this display */
|
||||
LV_COLOR_PALETTE_BLUE, LV_COLOR_PALETTE_CYAN, /* Primary and secondary palette */
|
||||
false, /* Light or dark mode */
|
||||
&lv_font_montserrat_10, &lv_font_montserrat_14, &lv_font_montserrat_18); /* Small, normal, large fonts */
|
||||
lv_theme_t * th = lv_theme_default_init(display, /* Use DPI, size, etc. from this display */
|
||||
LV_COLOR_PALETTE_BLUE, /* Primary and secondary palette */
|
||||
LV_COLOR_PALETTE_CYAN,
|
||||
false, /* Dark theme? False = light theme. */
|
||||
&lv_font_montserrat_10, /* Small, normal, large fonts */
|
||||
&lv_font_montserrat_14,
|
||||
&lv_font_montserrat_18);
|
||||
|
||||
lv_display_set_theme(display, th); /* Assign the theme to the display */
|
||||
lv_display_set_theme(display, th); /* Assign theme to display */
|
||||
|
||||
The included themes are enabled in ``lv_conf.h``. If the default theme
|
||||
is enabled by :c:macro:`LV_USE_THEME_DEFAULT` LVGL automatically initializes
|
||||
@ -523,7 +556,7 @@ E.g. default theme -> custom theme -> dark theme.
|
||||
:cpp:expr:`lv_theme_set_parent(new_theme, base_theme)` extends the
|
||||
``base_theme`` with the ``new_theme``.
|
||||
|
||||
There is an example for it below.
|
||||
There is an example of this below.
|
||||
|
||||
.. _styles_example:
|
||||
|
||||
@ -532,6 +565,18 @@ Examples
|
||||
|
||||
.. include:: ../../../examples/styles/index.rst
|
||||
|
||||
|
||||
|
||||
.. Hyperlinks
|
||||
|
||||
.. _pseudo-elements:
|
||||
.. _pseudo-element: https://developer.mozilla.org/en-US/docs/Learn/CSS/Building_blocks/Selectors#pseudo-classes_and_pseudo-elements
|
||||
.. _pseudo-classes:
|
||||
.. _pseudo-class: https://developer.mozilla.org/en-US/docs/Glossary/Pseudo-class
|
||||
|
||||
|
||||
|
||||
|
||||
.. _styles_api:
|
||||
|
||||
API
|
||||
|
||||
@ -144,7 +144,7 @@ the original, non-zoomed coordinates.
|
||||
|
||||
**IMPORTANT** The transformation of the image is independent of the
|
||||
transformation properties coming from styles. (See
|
||||
:ref:`here <styles_opacity_blend_modes_transformations>`). The main
|
||||
:ref:`here <style_opacity_blend_modes_transformations>`). The main
|
||||
differences are that pure image widget transformation
|
||||
|
||||
- doesn't transform the children of the image widget
|
||||
|
||||
Loading…
Reference in New Issue
Block a user