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Diffstat (limited to 'doc/python_api/rst/info_gotcha.rst')
| -rw-r--r-- | doc/python_api/rst/info_gotcha.rst | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/doc/python_api/rst/info_gotcha.rst b/doc/python_api/rst/info_gotcha.rst index d3067eb0518..2dd6c3c92b1 100644 --- a/doc/python_api/rst/info_gotcha.rst +++ b/doc/python_api/rst/info_gotcha.rst @@ -86,7 +86,8 @@ No updates after setting values Sometimes you want to modify values from Python and immediately access the updated values, e.g: Once changing the objects :class:`bpy.types.Object.location` you may want to access its transformation right after from :class:`bpy.types.Object.matrix_world`, -but this doesn't work as you might expect. +but this doesn't work as you might expect. There are similar issues with changes to the UI, that +are covered in the next section. Consider the calculations that might contribute to the object's final transformation, this includes: @@ -110,6 +111,35 @@ Now all dependent data (child objects, modifiers, drivers, etc.) have been recalculated and are available to the script within the active view layer. +No updates after changing UI context +------------------------------------ + +Similar to the previous issue, some changes to the UI may also not have an immediate effect. For example, setting +:class:`bpy.types.Window.workspace` doesn't seem to cause an observable effect in the immediately following code +(:class:`bpy.types.Window.workspace` is still the same), but the UI will in fact reflect the change. Some of the +properties that behave that way are: + +- :class:`bpy.types.Window.workspace` +- :class:`bpy.types.Window.screen` +- :class:`bpy.types.Window.scene` +- :class:`bpy.types.Area.type` +- :class:`bpy.types.Area.uitype` + +Such changes impact the UI, and with that the context (:class:`bpy.context`) quite drastically. This can break +Blender's context management. So Blender delays this change until after operators have run and just before the UI is +redrawn, making sure that context can be changed safely. + +If you rely on executing code with an updated context this can be worked around by executing the code in a delayed +fashion as well. Possible options include: + + - :ref:`Modal Operator <modal_operator>`. + - :class:`bpy.app.handlers`. + - :class:`bpy.app.timer`. + +It's also possible to depend on drawing callbacks although these should generally be avoided as failure to draw a +hidden panel, region, cursor, etc. could cause your script to be unreliable + + Can I redraw during script execution? ------------------------------------- |