vhaudiquet/u-boot-krane
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

expo: Support object alignment

Browse Source 
Add support for left, right and centred alignment for text, in the
horizontal dimension.

Also support top, bottom and centred in the vertical dimension, for the
text object as a whole.

Alignment is not yet implemented for images. It has no meaning for
menus. A textline object uses a text object internally, so alignment
is supported there.

Provide some documentation to explain how objects are positioned.

Signed-off-by: Simon Glass <sjg@chromium.org>
This commit is contained in:
Simon Glass
2025-05-30 09:49:32 +01:00
parent 0635004e22
commit 09f6f915fe
4 changed files with 216 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files
doc/develop/expo.rst
+31
View File
@@ -107,6 +107,37 @@ refer to objects which have been created. So a menu item is just a collection
of IDs of text and image objects. When adding a menu item you must create these
objects first, then create the menu item, passing in the relevant IDs.
Position and alignment
~~~~~~~~~~~~~~~~~~~~~~
Objects are typically positioned automatically, when scene_arrange() is called.
However it is possible to position objects manually. The scene_obj_set_pos()
sets the coordinates of the top left of the object.
All objects have a bounding box. Typically this is calculated by looking at the
object contents, in `scene_calc_arrange()`. The calculated dimensions of each
object are stored in the object's `dims` field.
It is possible to adjust the size of an object with `scene_obj_set_size()` or
even set the bounding box, with `scene_obj_set_bbox()`. The `SCENEOF_SIZE_VALID`
flag tracks whether the width/height should be maintained when the position
changes.
If the bounding box is larger than the object needs, the object can be aligned
to different edges within the box. Objects can be left- or right-aligned,
or centred. For text objects this applies to each line of text. Normally objects
are drawn starting at the top of their bounding box, but they can be aligned
vertically to the bottom, or centred vertically within the box.
Where the width of a text object's bounding box is smaller than the space needed
to show the next, the text is word-wrapped onto multiple lines, assuming there
is enough vertical space. Newline characters in the next cause a new line to be
started. The measurement information is created by the Truetype console driver
and stored in an alist in `struct scene_txt_generic`.
When the object is drawn the `ofs` field indicates the x and y offset to use,
from the top left of the bounding box. These values are affected by alignment.
Creating an expo
----------------