FormatConvertedBitmap.BeginInit 方法

定義

命名空間:

System.Windows.Media.Imaging

組件:

PresentationCore.dll

表示 FormatConvertedBitmap 初始化開始。

public:
 virtual void BeginInit();

public void BeginInit ();

abstract member BeginInit : unit -> unit
override this.BeginInit : unit -> unit

Public Sub BeginInit ()

實作

BeginInit()

例外狀況

InvalidOperationException

FormatConvertedBitmap 目前正在起始。 已經呼叫 BeginInit()。

-或-

FormatConvertedBitmap 已經完成初始化。

範例

下列範例示範如何使用 和 EndInit 方法，以 BeginInit 一組屬性初始化 FormatConvertedBitmap 。

using System;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
using System.Windows.Media.Imaging;

namespace SDKSample
{
    public partial class FormatConvertedBitmapExample : Page
    {
        public FormatConvertedBitmapExample()
        {

            ///// 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 gray scale 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;

            // Set the new format to Gray32Float (grayscale).
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Gray32Float;
            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;
        }
    }
}

Imports System.Windows
Imports System.Windows.Controls
Imports System.Windows.Media
Imports System.Windows.Media.Imaging

Namespace SDKSample

    Class FormatConvertedBitmapExample
        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 gray scale 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

            ' Set the new format to Gray32Float (grayscale).
            newFormatedBitmapSource.DestinationFormat = PixelFormats.Gray32Float
            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
    End Class
End Namespace 'ImagingSnippetGallery

備註

必須在 和 EndInit 呼叫之間 BeginInit 完成屬性初始化。 FormatConvertedBitmap初始化 之後，會忽略屬性變更。

另請參閱

• EndInit()
• ISupportInitialize