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 from wxPython.wx import *
  16
  17 class BitmapBuffer(wxMemoryDC):
  18     """A screen buffer class.
  19
  20     This class implements a screen output buffer. Data is meant to
  21     be drawn in the buffer class and then blitted directly to the
  22     output device, or on-screen window.
  23     """
  24     def __init__(self, width, height, colour):
  25         """Initialize the empty buffer object."""
  26         wxMemoryDC.__init__(self)
  27
  28         self.width = width
  29         self.height = height
  30         self.colour = colour
  31
  32         self.bitmap = wxEmptyBitmap(self.width, self.height)
  33         self.SelectObject(self.bitmap)
  34
  35         # Initialize the buffer to the background colour
  36         self.SetBackground(wxBrush(self.colour, wxSOLID))
  37         self.Clear()
  38
  39         # Make each logical unit of the buffer equal to 1 pixel
  40         self.SetMapMode(wxMM_TEXT)
  41
  42     def GetBitmap(self):
  43         """Returns the internal bitmap for direct drawing."""
  44         return self.bitmap
  45
  46 class Canvas(wxWindow):
  47     """A canvas class for arbitrary drawing.
  48
  49     The Canvas class implements a window that allows for drawing
  50     arbitrary graphics. It implements a double buffer scheme and
  51     blits the off-screen buffer to the window during paint calls
  52     by the windowing system for speed.
  53
  54     Some other methods for determining the canvas colour and size
  55     are also provided.
  56     """
  57     def __init__(self, parent, id,
  58                  pos=wxDefaultPosition,
  59                  size=wxDefaultSize,
  60                  style=wxSIMPLE_BORDER):
  61         """Creates a canvas instance and initializes the off-screen
  62         buffer. Also sets the handler for rendering the canvas
  63         automatically via size and paint calls from the windowing
  64         system."""
  65         wxWindow.__init__(self, parent, id, pos, size, style)
  66
  67         # Perform an intial sizing
  68         self.ReDraw()
  69
  70         # Register event handlers
  71         EVT_SIZE(self, self.onSize)
  72         EVT_PAINT(self, self.onPaint)
  73
  74     def MakeNewBuffer(self):
  75         size = self.GetSizeTuple()
  76         self.buffer = BitmapBuffer(size[0], size[1],
  77                                    self.GetBackgroundColour())
  78
  79     def onSize(self, event):
  80         """Perform actual redraw to off-screen buffer only when the
  81         size of the canvas has changed. This saves a lot of computation
  82         since the same image can be re-used, provided the canvas size
  83         hasn't changed."""
  84         self.MakeNewBuffer()
  85         self.DrawBuffer()
  86         self.Refresh()
  87
  88     def ReDraw(self):
  89         """Explicitly tells the canvas to redraw it's contents."""
  90         self.onSize(None)
  91
  92     def Refresh(self):
  93         """Re-draws the buffer contents on-screen."""
  94         dc = wxClientDC(self)
  95         self.Blit(dc)
  96
  97     def onPaint(self, event):
  98         """Renders the off-screen buffer on-screen."""
  99         dc = wxPaintDC(self)
 100         self.Blit(dc)
 101
 102     def Blit(self, dc):
 103         """Performs the blit of the buffer contents on-screen."""
 104         width, height = self.buffer.GetSize()
 105         dc.BeginDrawing()
 106         dc.Blit((0, 0), (width, height), self.buffer, (0, 0))
 107         dc.EndDrawing()
 108
 109     def GetBoundingRect(self):
 110         """Returns a tuple that contains the co-ordinates of the
 111         top-left and bottom-right corners of the canvas."""
 112         x, y = self.GetPositionTuple()
 113         w, h = self.GetSize()
 114         return(x, y + h, x + w, y)
 115
 116     def DrawBuffer(self):
 117         """Actual drawing function for drawing into the off-screen
 118         buffer. To be overrideen in the implementing class. Do nothing
 119         by default."""
 120         pass