"""
Overlay a simple grid on a bitmap derived from image file using a PaintDC.

Ray Pasco
pascor(at)verizon(dot)net
2011-04-12-Tue__PM-01-55-16__April

"""

import wx

#----------------------------------------------------------

class MainFrame( wx.Frame ):

    def __init__( self, parent=None, id=-1, title='wx.PaintDC Test' ):
    
        wx.Frame.__init__( self, parent=parent, id=id, title=title,
                           size=(300, 300), pos=(100, 50) )
        
        frmPanel = wx.Panel( self )
        
        # Read the image file into a bitmap.
        graphicFilename = 'GuidoInTheComfyChair.PNG'
        self.imgBmap = wx.Image( graphicFilename, wx.BITMAP_TYPE_ANY ).ConvertToBitmap()
        bmapSize = self.imgBmap.GetSize()
        bmapSizeX, bmapSizeY = bmapSize
        
        self.imgMargin = 25
        self.imgPanel = wx.Panel( frmPanel, size=bmapSize, pos=(self.imgMargin, self.imgMargin) )
        # Calc and set the Frame interior size so to allow the bitmap to be centered
        #   with a border around it.
        self.ClientSize = (2*self.imgMargin+bmapSizeX, 2*self.imgMargin+bmapSizeY)
        
        #-----
        
        # Keep track of OnPaint handler calls just for DEBUG info gathering purposes.
        self.paintCtr = 0
        
        wx.EVT_PAINT( self.imgPanel, self.OnPaint )
        
    #end def __init__
    
    #-----
        
    def OnPaint( self, event ):
        
        self.paintCtr += 1;  print '----  OnPaint() ', self.paintCtr
        
        panelDC = wx.PaintDC( self.imgPanel )
        
        # Copy (blit, "Block Level Transfer") a portion of the screen bitmap 
        #   into the returned capture bitmap.
        # The bitmap associated with memDC (captureBmap) is the blit destination.
        #                                                   # Blit (copy) parameter(s):
        imgPos = (0, 0)
        panelDC.DrawBitmapPoint( self.imgBmap, imgPos )
        
        # Once the BG mode is set to wx.Transparent it cannot be reset to wx.SOLID.
        #panelDC.SetBackgroundMode( wx.TRANSPARENT )     # wx.SOLID or wx.TRANSPARENT
        panelDC.SetBackgroundMode( wx.SOLID )           # wx.SOLID or wx.TRANSPARENT
        panelDC.SetTextForeground( wx.WHITE )
        panelDC.SetTextBackground( wx.BLUE )    # has no effect id bg mode is wx.TRANSPARENT
        panelDC.DrawText( ' AB CDEF GHIJ ', 25, 35 )
        
        # Draw a NxM grid pattern - (n+1)+(m+1) lines.
        # Drawing thicker lines would be a bit trickier.
        numRows, numCols = 3, 3
        gridWid, gridHgt = panelDC.GetSizeTuple()
        cellWid = float( gridWid - 1) / numRows
        cellHgt = float( gridHgt - 1) / numCols

        panelDC.SetBrush( wx.Brush( wx.WHITE, wx.TRANSPARENT) )
        panelDC.SetPen( wx.Pen( wx.WHITE, 1, wx.SOLID) )
        panelDC.DrawRectangle( 0, 0, gridWid, gridHgt )

        panelDC.SetPen( wx.Pen( wx.BLUE, 1, wx.SOLID) )
        for rowNum in xrange( numRows + 1) :
            panelDC.DrawLine( 0, rowNum*cellHgt, gridWid, rowNum*cellHgt )

        for colNum in xrange( numCols + 1 ) :
            panelDC.DrawLine( colNum*cellWid, 0, colNum*cellWid, gridHgt )
        
        
        
        event.Skip()    # Very important to let all higher level handlers be called.
        
    #end def OnPaint
    
#end  MainFrame class

#----------------------------------------------------------

if __name__ == '__main__' :
    
    myApp = wx.App( False )   # Send errors to command window, not a pop-up.
    appFrame = MainFrame()
    appFrame.Show()
    myApp.MainLoop()

#end if