wxPython/wx/lib/colourchooser/canvas.py

   1 """
   2 PyColourChooser
   3 Copyright (C) 2002 Michael Gilfix <mgilfix@eecs.tufts.edu>
   4
   5 This file is part of PyColourChooser.
   6
   7 This version of PyColourChooser 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 # 12/21/2003 - Jeff Grimmett (grimmtooth@softhome.net)
  20 #
  21 # o wxPyColorChooser -> PyColorChooser
  22 # o wxPyColourChooser -> PyColourChooser
  23 #
  24
  25 import  wx
  26
  27 class BitmapBuffer(wx.MemoryDC):
  28     """A screen buffer class.
  29
  30     This class implements a screen output buffer. Data is meant to
  31     be drawn in the buffer class and then blitted directly to the
  32     output device, or on-screen window.
  33     """
  34     def __init__(self, width, height, colour):
  35         """Initialize the empty buffer object."""
  36         wx.MemoryDC.__init__(self)
  37
  38         self.width = width
  39         self.height = height
  40         self.colour = colour
  41
  42         self.bitmap = wx.EmptyBitmap(self.width, self.height)
  43         self.SelectObject(self.bitmap)
  44
  45         # Initialize the buffer to the background colour
  46         self.SetBackground(wx.Brush(self.colour, wx.SOLID))
  47         self.Clear()
  48
  49         # Make each logical unit of the buffer equal to 1 pixel
  50         self.SetMapMode(wx.MM_TEXT)
  51
  52     def GetBitmap(self):
  53         """Returns the internal bitmap for direct drawing."""
  54         return self.bitmap
  55
  56 class Canvas(wx.Window):
  57     """A canvas class for arbitrary drawing.
  58
  59     The Canvas class implements a window that allows for drawing
  60     arbitrary graphics. It implements a double buffer scheme and
  61     blits the off-screen buffer to the window during paint calls
  62     by the windowing system for speed.
  63
  64     Some other methods for determining the canvas colour and size
  65     are also provided.
  66     """
  67     def __init__(self, parent, id,
  68                  pos=wx.DefaultPosition,
  69                  size=wx.DefaultSize,
  70                  style=wx.SIMPLE_BORDER):
  71         """Creates a canvas instance and initializes the off-screen
  72         buffer. Also sets the handler for rendering the canvas
  73         automatically via size and paint calls from the windowing
  74         system."""
  75         wx.Window.__init__(self, parent, id, pos, size, style)
  76
  77         # Perform an intial sizing
  78         self.ReDraw()
  79
  80         # Register event handlers
  81         self.Bind(wx.EVT_SIZE, self.onSize)
  82         self.Bind(wx.EVT_PAINT, self.onPaint)
  83
  84     def MakeNewBuffer(self):
  85         size = self.GetSize()
  86         self.buffer = BitmapBuffer(size[0], size[1],
  87                                    self.GetBackgroundColour())
  88
  89     def onSize(self, event):
  90         """Perform actual redraw to off-screen buffer only when the
  91         size of the canvas has changed. This saves a lot of computation
  92         since the same image can be re-used, provided the canvas size
  93         hasn't changed."""
  94         self.MakeNewBuffer()
  95         self.DrawBuffer()
  96         self.Refresh()
  97
  98     def ReDraw(self):
  99         """Explicitly tells the canvas to redraw it's contents."""
 100         self.onSize(None)
 101
 102     def Refresh(self):
 103         """Re-draws the buffer contents on-screen."""
 104         dc = wx.ClientDC(self)
 105         self.Blit(dc)
 106
 107     def onPaint(self, event):
 108         """Renders the off-screen buffer on-screen."""
 109         dc = wx.PaintDC(self)
 110         self.Blit(dc)
 111
 112     def Blit(self, dc):
 113         """Performs the blit of the buffer contents on-screen."""
 114         width, height = self.buffer.GetSize()
 115         dc.BeginDrawing()
 116         dc.Blit(0, 0, width, height, self.buffer, 0, 0)
 117         dc.EndDrawing()
 118
 119     def GetBoundingRect(self):
 120         """Returns a tuple that contains the co-ordinates of the
 121         top-left and bottom-right corners of the canvas."""
 122         x, y = self.GetPosition()
 123         w, h = self.GetSize()
 124         return(x, y + h, x + w, y)
 125
 126     def DrawBuffer(self):
 127         """Actual drawing function for drawing into the off-screen
 128         buffer. To be overrideen in the implementing class. Do nothing
 129         by default."""
 130         pass