BitmapImage.BeginInit 方法

定义

命名空间:

System.Windows.Media.Imaging

程序集:

PresentationCore.dll

用信号通知 BitmapImage 初始化开始。

public:
 virtual void BeginInit();

public void BeginInit ();

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

Public Sub BeginInit ()

实现

BeginInit()

例外

InvalidOperationException

BitmapImage 当前正被初始化。 已调用 BeginInit()。

• 或 - BitmapImage 已初始化。

示例

以下示例演示如何使用BeginInit和EndInit方法初始化BitmapImage一组属性。

// Define a BitmapImage.
Image myImage = new Image();
BitmapImage bi = new BitmapImage();

// Begin initialization.
bi.BeginInit();

// Set properties.
bi.CacheOption = BitmapCacheOption.OnDemand;
bi.CreateOptions = BitmapCreateOptions.DelayCreation;
bi.DecodePixelHeight = 125;
bi.DecodePixelWidth = 125;
bi.Rotation = Rotation.Rotate90;
MessageBox.Show(bi.IsDownloading.ToString());
bi.UriSource = new Uri("smiley.png", UriKind.Relative);

// End initialization.
bi.EndInit();
myImage.Source = bi;
myImage.Stretch = Stretch.None;
myImage.Margin = new Thickness(5);

' Define a BitmapImage.
Dim myImage As New Image()
Dim bi As New BitmapImage()

' Begin initialization.
bi.BeginInit()

' Set properties.
bi.CacheOption = BitmapCacheOption.OnDemand
bi.CreateOptions = BitmapCreateOptions.DelayCreation
bi.DecodePixelHeight = 125
bi.DecodePixelWidth = 125
bi.Rotation = Rotation.Rotate90
MessageBox.Show(bi.IsDownloading.ToString())
bi.UriSource = New Uri("smiley.png", UriKind.Relative)

' End initialization.
bi.EndInit()
myImage.Source = bi
myImage.Stretch = Stretch.None
myImage.Margin = New Thickness(5)

注解

必须在调用EndInit之间BeginInit完成属性初始化。 BitmapImage初始化属性后，将忽略属性更改。

另请参阅

• EndInit()
• ISupportInitialize