'''' This code is part of Document Solutions for Imaging demos.'' Copyright (c) MESCIUS inc. All rights reserved.''Imports System.IOImports System.DrawingImports System.Collections.GenericImports System.LinqImports System.NumericsImports GrapeCity.Documents.DrawingImports GrapeCity.Documents.Imaging
'' This sample demonstrates how to swap color channels on an image'' using pixel access. Here we swap red and blue channels to'' change the way the image looks.Public Class SwapColors    Function GenerateImage(        ByVal pixelSize As Size,        ByVal dpi As Single,        ByVal opaque As Boolean,        Optional ByVal sampleParams As String() = Nothing) As GcBitmap
        Dim bmp = New GcBitmap(pixelSize.Width, pixelSize.Height, opaque, dpi, dpi)        Using bmpSrc = New GcBitmap(Path.Combine("Resources", "ImagesBis", "alpamayo-sq.jpg"))            '' BitBlt requires the opacity of both images to be the same:            bmpSrc.Opaque = opaque            '' Render source image onto the target bitmap            '' (generally we might want to resize the source image first,            '' but in this case we just know that the source image has            '' the same size as the target, so skip this step):            bmp.BitBlt(bmpSrc, 0, 0)
            Using g = bmp.CreateGraphics()                For i = 0 To bmp.PixelWidth - 1                    For j = 0 To bmp.PixelHeight - 1                        Dim px = bmp(i, j)                        px = ((px And &HFFUI) << 16) Or ((px And &HFF0000UI) >> 16) Or (px And &HFF00FF00UI)                        bmp(i, j) = px                    Next                Next                '' Draw the original image in the bottom right corner for reference:                Dim sx = pixelSize.Width / 3, sy = pixelSize.Height / 3                g.DrawImage(bmpSrc, New RectangleF(sx * 2, sy * 2, sx, sy), Nothing, ImageAlign.StretchImage)            End Using        End Using        Return bmp    End FunctionEnd Class