HOW TO：將 BitmapSource 轉換為索引像素格式

更新：2007 年 11 月

本範例說明如何將 BitmapSource 轉換成索引像素格式。

範例

Imports System
Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Media.Imaging
Imports System.Collections.Generic

Namespace SDKSample

    Class FormatConvertedBitmapExample2
        Inherits Page

        Public Sub New()

            '/// Create a BitmapImage and set it's DecodePixelWidth to 200. Use  /////
            '/// this BitmapImage as a source for other BitmapSource objects.    /////
            Dim myBitmapImage As New BitmapImage()

            ' BitmapSource objects like BitmapImage can only have their properties
            ' changed within a BeginInit/EndInit block.
            myBitmapImage.BeginInit()
            myBitmapImage.UriSource = New Uri("sampleImages/WaterLilies.jpg", UriKind.Relative)

            ' To save significant application memory, set the DecodePixelWidth or  
            ' DecodePixelHeight of the BitmapImage value of the image source to the desired 
            ' height or width of the rendered image. If you don't do this, the application will 
            ' cache the image as though it were rendered as its normal size rather then just 
            ' the size that is displayed.
            ' Note: In order to preserve aspect ratio, set DecodePixelWidth
            ' or DecodePixelHeight but not both.
            myBitmapImage.DecodePixelWidth = 200
            myBitmapImage.EndInit()

            '//////// Convert the BitmapSource to a new format ////////////
            ' Use the BitmapImage created above as the source for a new BitmapSource object
            ' which is set to a two color pixel format using the FormatConvertedBitmap BitmapSource.                                               
            ' Note: New BitmapSource does not cache. It is always pulled when required.
            Dim newFormatedBitmapSource As New FormatConvertedBitmap()

            ' BitmapSource objects like FormatConvertedBitmap can only have their properties
            ' changed within a BeginInit/EndInit block.
            newFormatedBitmapSource.BeginInit()

            ' Use the BitmapSource object defined above as the source for this new 
            ' BitmapSource (chain the BitmapSource objects together).
            newFormatedBitmapSource.Source = myBitmapImage

            ' Because the DestinationFormat for the FormatConvertedBitmap will be an
            ' indexed pixel format (Indexed1),a DestinationPalette also needs to be specified.
            ' Below, create a custom two color palette to be used for the DestinationPalette.
            Dim colors As New List(Of Color)
            colors.Add(System.Windows.Media.Colors.Red)
            colors.Add(System.Windows.Media.Colors.Blue)
            Dim myPalette As New BitmapPalette(colors)

            ' Set the DestinationPalette property to the custom palette created above.
            newFormatedBitmapSource.DestinationPalette = myPalette

            ' Set the DestinationFormat to the palletized pixel format of Indexed1.
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Indexed1
            newFormatedBitmapSource.EndInit()

            ' Create Image Element
            Dim myImage As New Image()
            myImage.Width = 200
            'set image source
            myImage.Source = newFormatedBitmapSource

            ' Add Image to the UI
            Dim myStackPanel As New StackPanel()
            myStackPanel.Children.Add(myImage)
            Me.Content = myStackPanel

        End Sub 'New
    End Class 'FormatConvertedBitmapExample2
End Namespace 'ImagingSnippetGallery

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Collections.Generic;
namespace SDKSample
{
    public partial class FormatConvertedBitmapExample2 : Page
    {
        public FormatConvertedBitmapExample2()
        {

            ///// Create a BitmapImage and set it's DecodePixelWidth to 200. Use  /////
            ///// this BitmapImage as a source for other BitmapSource objects.    /////

            BitmapImage myBitmapImage = new BitmapImage();

            // BitmapSource objects like BitmapImage can only have their properties
            // changed within a BeginInit/EndInit block.
            myBitmapImage.BeginInit();
            myBitmapImage.UriSource = new Uri(@"sampleImages/WaterLilies.jpg",UriKind.Relative);

            // To save significant application memory, set the DecodePixelWidth or  
            // DecodePixelHeight of the BitmapImage value of the image source to the desired 
            // height or width of the rendered image. If you don't do this, the application will 
            // cache the image as though it were rendered as its normal size rather then just 
            // the size that is displayed.
            // Note: In order to preserve aspect ratio, set DecodePixelWidth
            // or DecodePixelHeight but not both.
            myBitmapImage.DecodePixelWidth = 200;
            myBitmapImage.EndInit();

            ////////// Convert the BitmapSource to a new format ////////////
            // Use the BitmapImage created above as the source for a new BitmapSource object
            // which is set to a two color pixel format using the FormatConvertedBitmap BitmapSource.                                               
            // Note: New BitmapSource does not cache. It is always pulled when required.

            FormatConvertedBitmap newFormatedBitmapSource = new FormatConvertedBitmap();

            // BitmapSource objects like FormatConvertedBitmap can only have their properties
            // changed within a BeginInit/EndInit block.
            newFormatedBitmapSource.BeginInit();

            // Use the BitmapSource object defined above as the source for this new 
            // BitmapSource (chain the BitmapSource objects together).
            newFormatedBitmapSource.Source = myBitmapImage;

            // Because the DestinationFormat for the FormatConvertedBitmap will be an
            // indexed pixel format (Indexed1),a DestinationPalette also needs to be specified.
            // Below, create a custom two color palette to be used for the DestinationPalette.
            List<System.Windows.Media.Color> colors = new List<System.Windows.Media.Color>();
            colors.Add(System.Windows.Media.Colors.Red);
            colors.Add(System.Windows.Media.Colors.Blue);
            BitmapPalette myPalette = new BitmapPalette(colors);

            // Set the DestinationPalette property to the custom palette created above.
            newFormatedBitmapSource.DestinationPalette = myPalette;

            // Set the DestinationFormat to the palletized pixel format of Indexed1.
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Indexed1;
            newFormatedBitmapSource.EndInit();

            // Create Image Element
            Image myImage = new Image();
            myImage.Width = 200;
            //set image source
            myImage.Source = newFormatedBitmapSource;

            // Add Image to the UI
            StackPanel myStackPanel = new StackPanel();
            myStackPanel.Children.Add(myImage);
            this.Content = myStackPanel;
        }
    }
}