wxPython/wx/lib/colourchooser/canvas.py

   1 """
   2 wxPyColourChooser
   3 Copyright (C) 2002 Michael Gilfix <mgilfix@eecs.tufts.edu>
   4
   5 This file is part of wxPyColourChooser.
   6
   7 This version of wxPyColourChooser is open source; you can redistribute it
   8 and/or modify it under the licensed terms.
   9
  10 This program is distributed in the hope that it will be useful,
  11 but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  13 """
  14
  15 # 12/14/2003 - Jeff Grimmett (grimmtooth@softhome.net)
  16 #
  17 # o 2.5 compatability update.
  18 #
  19
  20 import  wx
  21
  22 class BitmapBuffer(wx.MemoryDC):
  23     """A screen buffer class.
  24
  25     This class implements a screen output buffer. Data is meant to
  26     be drawn in the buffer class and then blitted directly to the
  27     output device, or on-screen window.
  28     """
  29     def __init__(self, width, height, colour):
  30         """Initialize the empty buffer object."""
  31         wx.MemoryDC.__init__(self)
  32
  33         self.width = width
  34         self.height = height
  35         self.colour = colour
  36
  37         self.bitmap = wx.EmptyBitmap(self.width, self.height)
  38         self.SelectObject(self.bitmap)
  39
  40         # Initialize the buffer to the background colour
  41         self.SetBackground(wx.Brush(self.colour, wx.SOLID))
  42         self.Clear()
  43
  44         # Make each logical unit of the buffer equal to 1 pixel
  45         self.SetMapMode(wx.MM_TEXT)
  46
  47     def GetBitmap(self):
  48         """Returns the internal bitmap for direct drawing."""
  49         return self.bitmap
  50
  51 class Canvas(wx.Window):
  52     """A canvas class for arbitrary drawing.
  53
  54     The Canvas class implements a window that allows for drawing
  55     arbitrary graphics. It implements a double buffer scheme and
  56     blits the off-screen buffer to the window during paint calls
  57     by the windowing system for speed.
  58
  59     Some other methods for determining the canvas colour and size
  60     are also provided.
  61     """
  62     def __init__(self, parent, id,
  63                  pos=wx.DefaultPosition,
  64                  size=wx.DefaultSize,
  65                  style=wx.SIMPLE_BORDER):
  66         """Creates a canvas instance and initializes the off-screen
  67         buffer. Also sets the handler for rendering the canvas
  68         automatically via size and paint calls from the windowing
  69         system."""
  70         wx.Window.__init__(self, parent, id, pos, size, style)
  71
  72         # Perform an intial sizing
  73         self.ReDraw()
  74
  75         # Register event handlers
  76         self.Bind(wx.EVT_SIZE, self.onSize)
  77         self.Bind(wx.EVT_PAINT, self.onPaint)
  78
  79     def MakeNewBuffer(self):
  80         size = self.GetSize()
  81         self.buffer = BitmapBuffer(size[0], size[1],
  82                                    self.GetBackgroundColour())
  83
  84     def onSize(self, event):
  85         """Perform actual redraw to off-screen buffer only when the
  86         size of the canvas has changed. This saves a lot of computation
  87         since the same image can be re-used, provided the canvas size
  88         hasn't changed."""
  89         self.MakeNewBuffer()
  90         self.DrawBuffer()
  91         self.Refresh()
  92
  93     def ReDraw(self):
  94         """Explicitly tells the canvas to redraw it's contents."""
  95         self.onSize(None)
  96
  97     def Refresh(self):
  98         """Re-draws the buffer contents on-screen."""
  99         dc = wx.ClientDC(self)
 100         self.Blit(dc)
 101
 102     def onPaint(self, event):
 103         """Renders the off-screen buffer on-screen."""
 104         dc = wx.PaintDC(self)
 105         self.Blit(dc)
 106
 107     def Blit(self, dc):
 108         """Performs the blit of the buffer contents on-screen."""
 109         width, height = self.buffer.GetSize()
 110         dc.BeginDrawing()
 111         dc.Blit((0, 0), (width, height), self.buffer, (0, 0))
 112         dc.EndDrawing()
 113
 114     def GetBoundingRect(self):
 115         """Returns a tuple that contains the co-ordinates of the
 116         top-left and bottom-right corners of the canvas."""
 117         x, y = self.GetPosition()
 118         w, h = self.GetSize()
 119         return(x, y + h, x + w, y)
 120
 121     def DrawBuffer(self):
 122         """Actual drawing function for drawing into the off-screen
 123         buffer. To be overrideen in the implementing class. Do nothing
 124         by default."""
 125         pass