'''' This code is part of Document Solutions for Imaging demos.'' Copyright (c) MESCIUS inc. All rights reserved.''Imports System.IOImports System.DrawingImports GrapeCity.Documents.DrawingImports GrapeCity.Documents.TextImports GrapeCity.Documents.ImagingImports GCTEXT = GrapeCity.Documents.TextImports GCDRAW = GrapeCity.Documents.Drawing
'' This sample demonstrates how convert full color RGB'' to 4 BPP and 8 BPP indexed images.Public Class Indexing    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 origBmp = New GcBitmap()            '' Load a sample photo:            Dim imagePath = Path.Combine("Resources", "Images", "maple.jpg")            Using stm = New FileStream(imagePath, FileMode.Open, FileAccess.Read, FileShare.Read, 4096, FileOptions.RandomAccess)                origBmp.Load(stm)            End Using
            origBmp.SetAlphaTo255()            origBmp.Opaque = opaque
            '' Resize the original photo so we can place 4 samples of it            '' on the resulting bitmap:            Dim w = pixelSize.Width / 2            Dim h = pixelSize.Height / 2            Using sizedBmp = origBmp.Resize(w, h, InterpolationMode.Cubic),                ib4bpp = sizedBmp.ToIndexed4bppBitmap(DitheringMethod.JarvisJudiceNinke),                ib8bpp = sizedBmp.ToIndexed8bppBitmap(DitheringMethod.JarvisJudiceNinke),                b4bpp = ib4bpp.ToGcBitmap(),                b8bpp = ib8bpp.ToGcBitmap()                '' Copy the original And indexed images into 4 quadrants of the resulting bitmap:                bmp.BitBlt(sizedBmp, 0, 0)                b4bpp.Opaque = opaque                bmp.BitBlt(b4bpp, w, 0)                b8bpp.Opaque = opaque                bmp.BitBlt(b8bpp, 0, h)                bmp.BitBlt(sizedBmp, w, h)            End Using
            '' Add borders between the quadrants, And captions for each:            Dim lineh = 2            Using g = bmp.CreateGraphics(Nothing)                Dim foreColor = Color.Yellow                Dim backColor = Color.Blue                Dim fnt = GCTEXT.Font.FromFile(Path.Combine("Resources", "Fonts", "FreeMono.ttf"))                g.DrawLine(w, 0, w, h * 2, New GCDRAW.Pen(foreColor, lineh * 2))                g.DrawLine(0, h, w * 2, h, New GCDRAW.Pen(foreColor, lineh * 2))                Dim tf = New TextFormat() With {.Font = fnt, .FontSize = 18, .ForeColor = foreColor, .BackColor = backColor, .FontBold = True}                g.DrawString(" Original image ", tf, New PointF(0, 0))                g.DrawString(" Indexed 4 bits per pixel ", tf, New PointF(w + lineh, 0))                g.DrawString(" Indexed 8 bits per pixel ", tf, New PointF(0, h + lineh))                g.DrawString(" Original image ", tf, New PointF(w + lineh, h + lineh))            End Using            Return bmp        End Using    End FunctionEnd Class