'''' 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.TextImports GrapeCity.Documents.ImagingImports GCTEXT = GrapeCity.Documents.Text
'' This sample takes a color JPEG, And creates bilevel bitmaps from it'' using all available dithering methods. The resulting b/w images'' are added as frames to a multi-frame TIFF.'' The original color image Is added as the last page.Public Class DitheringInTiff    Function GenerateImageStream(                ByVal targetMime As String,                ByVal pixelSize As Size,                ByVal dpi As Single,                ByVal opaque As Boolean,                Optional sampleParams As String() = Nothing) As Stream
        If Not targetMime = MimeTypes.TIFF Then            Throw New Exception("This sample only supports TIFF output format.")        End If
        Dim pth = Path.Combine("Resources", "Images", "minerva.jpg")        Dim fnt = GCTEXT.Font.FromFile(Path.Combine("Resources", "Fonts", "FreeMono.ttf"))        Dim ms = New MemoryStream()        Using tw = New GcTiffWriter(ms), bmp = New GcBitmap(pth)            '' Create text layout for labels:            Dim tl = New TextLayout(bmp.DpiX)            tl.DefaultFormat.Font = fnt            tl.DefaultFormat.FontSize = 16            tl.DefaultFormat.BackColor = Color.White            '' Loop through all dithering methods (starting with no dithering):            Dim methods = GetType(DitheringMethod).GetEnumValues()            For Each method As DitheringMethod In methods                Using tbmp = bmp.Clone()                    '' Apply dithering:                    tbmp.ApplyEffect(DitheringEffect.Get(method))                    '' Draw label:                    tl.Clear()                    tl.Append(method.ToString())                    tl.PerformLayout(True)                    Using g = tbmp.CreateGraphics()                        g.DrawTextLayout(tl, New PointF(0, tbmp.Height - tl.ContentHeight))                    End Using                    '' Convert to bilevel bitmap                    Using f = tbmp.ToBilevelBitmap()                        tw.AppendFrame(f)                    End Using                End Using            Next            '' Add original image:            tw.AppendFrame(bmp)        End Using        ms.Seek(0, SeekOrigin.Begin)        Return ms    End Function
    Public ReadOnly Property DefaultMime() As String        Get            Return MimeTypes.TIFF        End Get    End PropertyEnd Class