Package wx :: Package lib :: Package colourchooser :: Module canvas :: Class Canvas
[frames | no frames]

Type Canvas

object --+            
         |            
    Object --+        
             |        
    EvtHandler --+    
                 |    
            Window --+
                     |
                    Canvas

Known Subclasses:
PyColourSlider, PyPalette

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
  __init__(self, parent, id, pos, size, style)
Creates a canvas instance and initializes the off-screen buffer.
  Blit(self, dc)
Performs the blit of the buffer contents on-screen.
  DrawBuffer(self)
Actual drawing function for drawing into the off-screen buffer.
  GetBoundingRect(self)
Returns a tuple that contains the co-ordinates of the top-left and bottom-right corners of the canvas.
  MakeNewBuffer(self)
  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.
  ReDraw(self)
Explicitly tells the canvas to redraw it's contents.
  Refresh(self)
Re-draws the buffer contents on-screen.

Property Summary

Instance Method Details

__init__(self, parent, id, pos=wx.Point(-1, -1), size=wx.Size(-1, -1), style=33554432)
(Constructor)

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.

Overrides:
wx.Window.__init__

Blit(self, dc)

Performs the blit of the buffer contents on-screen.

DrawBuffer(self)

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)

Explicitly tells the canvas to redraw it's contents.

Refresh(self)

Re-draws the buffer contents on-screen.

Overrides:
wx.Window.Refresh

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