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Package aldrin :: Module canvas :: Class CanvasBase |
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Canvas
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ScrolledCanvas
A canvas class for arbitrary drawing.
The Canvas class implements a window that allows for drawing arbitrary graphics. It implements a double buffer scheme and blits the off-screen buffer to the window during paint calls by the windowing system for speed.
Some other methods for determining the canvas colour and size are also provided.Method Summary | |
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Creates a canvas instance and initializes the off-screen buffer. | |
_finalize_canvas_init(self)
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Performs the blit of the buffer contents on-screen. | |
Actual drawing function for drawing into the off-screen buffer. | |
Returns a tuple that contains the co-ordinates of the top-left and bottom-right corners of the canvas. | |
MakeNewBuffer(self)
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onEraseBackground(self,
event)
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Renders the off-screen buffer on-screen. | |
onPostPaint(self,
dc)
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Perform actual redraw to off-screen buffer only when the size of the canvas has changed. | |
Explicitly tells the canvas to redraw it's contents. | |
Refresh(self)
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Class Variable Summary | |
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bool |
doublebuffered = True
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Method Details |
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__init__(self,
*args,
**kargs)
Creates a canvas instance and initializes the off-screen buffer.
Also sets the handler for rendering the canvas automatically via size
and paint calls from the windowing system.
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Blit(self, dc)Performs the blit of the buffer contents on-screen. |
DrawBuffer(self, *args, **kargs)Actual drawing function for drawing into the off-screen buffer. To be overrideen in the implementing class. Do nothing by default. |
GetBoundingRect(self)Returns a tuple that contains the co-ordinates of the top-left and bottom-right corners of the canvas. |
onPaint(self, event)Renders the off-screen buffer on-screen. |
onSize(self, event)Perform actual redraw to off-screen buffer only when the size of the canvas has changed. This saves a lot of computation since the same image can be re-used, provided the canvas size hasn't changed. |
ReDraw(self, *args, **kargs)Explicitly tells the canvas to redraw it's contents. |
Class Variable Details |
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doublebuffered
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