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Added warning about graphics and widget movements

This commit is contained in:
Richard Larkin 2013-07-16 23:19:11 +02:00
parent 3cbf10b0e6
commit 3ef08c468b
2 changed files with 17 additions and 5 deletions
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2
doc/sources/guide/widgets.rst
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@ -307,6 +307,8 @@ This gives us:
As with |size_hint|, you should experiment with |pos_hint| to
understand the effect it has on the widget positions.
.. _adding_widget_background:
Adding a Background to a Layout
-------------------------------

20
kivy/graphics/__init__.py
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@ -2,8 +2,9 @@
Graphics
========
This package assemble all low level function to draw object. The whole graphics
package is compatible OpenGL ES 2.0, and have a lot of rendering optimizations.
This package assembles many low level functions used for drawing. The whole
graphics package is compatible with OpenGL ES 2.0 and has many rendering
optimizations.
The basics
----------
@ -13,8 +14,9 @@ For drawing on a screen, you will need :
1. a :class:`~kivy.graphics.instructions.Canvas` object.
2. :class:`~kivy.graphics.instructions.Instruction` objects.
Each widget in Kivy already have by default their :class:`Canvas`. When you are
creating a widget, you can create all the instructions needed for drawing. If
Each :class:`~kivy.uix.widget.Widget`
in Kivy already has a :class:`Canvas` by default. When you create
a widget, you can create all the instructions needed for drawing. If
`self` is your current widget, you can do::
from kivy.graphics import *
@ -26,7 +28,15 @@ creating a widget, you can create all the instructions needed for drawing. If
Rectangle(pos=(10, 10), size=(500, 500))
The instructions :class:`Color` and :class:`Rectangle` are automaticly added to
the canvas object, and will be used when the window drawing will happen.
the canvas object and will be used when the window is drawn.
.. note::
Drawing instructions are rendered directly by the OpenGL layer,
which means they do not automatically redraw when your widget moves. In
order to achieve this, the instructions need either to be declared in the
:mod:`KvLang <kivy.lang>` or bound to pos and size changes. Please see
:ref:`adding_widget_background` for more detail.
GL Reloading mechanism
----------------------