WorkingWithImages

Formats and Conversions

• Conversions among wxImage, wxBitmap, wxCursor, wxIcon and DATA

  • wxImage to wxBitmap --  myWxImage.ConvertToBitmap() 

    wxImage to DATA --  myWxImage.GetData()  returning a string in width * height * 3 format

    DATA to wxImage --  image = wxImage(); image.SetData( data )  where data is a Python string of length width * height * 3. DATA to wxBitmap -- {{{ bitmap = wxBitmapFromData( data, DATA to wxIcon -- Should be possible, but I don't see an overloaded-constructor name for it.

Using dynamic bitmaps (wxBitmapFromData)

• Using PIL with wxPython Run-time generation of images Using device contexts to write into wxBitmaps

Examples

• This example shows the creation of a bitmap using a Numeric Python array as the data source for a wxImage/wxBitmap. Note that Numeric uses reversed column-row ordering compared to wxPython, so you'll need to make sure that you generate images using height, width, not width, height coordinates. Also note the user of the 'c' data type for image data.

        def GetBitmap( self, width=32, height=32, colour = (0,0,0) ):
                array = Numeric.zeros( (height, width, 3),'c')
                array[:,:,] = colour
                image = wxEmptyImage(width,height)
                image.SetData( array.tostring())
                return image.ConvertToBitmap()

• This example shows use of Numeric's (extended) slicing notation to alter the in-memory image. This slicing notation, for our purposes, goes as follows:

   [ rowStart: rowEnd, columnStart: columnEnd, colourPlanes ] 

  To assign a single colour to the entire image:  array[:,:] = (r,g,b)  . To assign a value to the entire red bit plane:  array[:,:,0] = 255  . To assign a colour to the first row:  array[ 0 ] = (r,g,b )  .

        def GetBitmap( self, width=32, height=32, colour = (128,128,128), border=5, borderColour=(255,255,255) ):
                array = Numeric.zeros( (height, width, 3),'c')
                array[border:-border,border:-border,:] = colour
                array[:border,:,:] = borderColour
                array[-border:,:,:] = borderColour
                array[:,:border,:] = borderColour
                array[:,-border:,:] = borderColour
                image = wxEmptyImage(width,height)
                image.SetData( array.tostring())
                return image.ConvertToBitmap()

Drawing Bitmaps to Screen/Printer Contexts

• This is basically covered in the demo, but it's part of the topic.

Masks and Transparency/Alpha

• Bitmap masks (from the demo) Alpha-blending (is this even possible?)