JpegBitmapDecoder 构造函数

定义

命名空间:
System.Windows.Media.Imaging
程序集:
PresentationCore.dll

初始化 JpegBitmapDecoder 类的新实例。

重载

JpegBitmapDecoder(Stream, BitmapCreateOptions, BitmapCacheOption)

JpegBitmapDecoder使用指定的createOptions和 cacheOption。

public:
 JpegBitmapDecoder(System::IO::Stream ^ bitmapStream, System::Windows::Media::Imaging::BitmapCreateOptions createOptions, System::Windows::Media::Imaging::BitmapCacheOption cacheOption);
[System.Security.SecurityCritical]
public JpegBitmapDecoder(System.IO.Stream bitmapStream, System.Windows.Media.Imaging.BitmapCreateOptions createOptions, System.Windows.Media.Imaging.BitmapCacheOption cacheOption);
public JpegBitmapDecoder(System.IO.Stream bitmapStream, System.Windows.Media.Imaging.BitmapCreateOptions createOptions, System.Windows.Media.Imaging.BitmapCacheOption cacheOption);
[<System.Security.SecurityCritical>]
new System.Windows.Media.Imaging.JpegBitmapDecoder : System.IO.Stream * System.Windows.Media.Imaging.BitmapCreateOptions * System.Windows.Media.Imaging.BitmapCacheOption -> System.Windows.Media.Imaging.JpegBitmapDecoder
new System.Windows.Media.Imaging.JpegBitmapDecoder : System.IO.Stream * System.Windows.Media.Imaging.BitmapCreateOptions * System.Windows.Media.Imaging.BitmapCacheOption -> System.Windows.Media.Imaging.JpegBitmapDecoder
Public Sub New (bitmapStream As Stream, createOptions As BitmapCreateOptions, cacheOption As BitmapCacheOption)

参数

bitmapStream
Stream

要解码的位图流。

createOptions
BitmapCreateOptions

位图图像的初始化选项。

cacheOption
BitmapCacheOption

用于位图图像的缓存方法。

属性
SecurityCriticalAttribute

例外

ArgumentNullException

值为 bitmapStreamnull.

FileFormatException

这不是 bitmapStream 联合摄影专家组（JPEG）编码的图像。

示例

下面的代码示例演示如何创建文件流中的实例并使用 JpegBitmapDecoder 实例。 解码的图像用作控件的 Image 源。

// Open a Stream and decode a JPEG image
Stream^ imageStreamSource = gcnew FileStream("tulipfarm.jpg", FileMode::Open, FileAccess::Read, FileShare::Read);
JpegBitmapDecoder^ decoder = gcnew JpegBitmapDecoder(imageStreamSource, BitmapCreateOptions::PreservePixelFormat, BitmapCacheOption::Default);
BitmapSource^ bitmapSource = decoder->Frames[0];

// Draw the Image
Image^ myImage = gcnew Image();
myImage->Source = bitmapSource;
myImage->Stretch = Stretch::None;
myImage->Margin = System::Windows::Thickness(20);


// Open a Stream and decode a JPEG image
Stream imageStreamSource = new FileStream("tulipfarm.jpg", FileMode.Open, FileAccess.Read, FileShare.Read);
JpegBitmapDecoder decoder = new JpegBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapSource bitmapSource = decoder.Frames[0];

// Draw the Image
Image myImage = new Image();
myImage.Source = bitmapSource;
myImage.Stretch = Stretch.None;
myImage.Margin = new Thickness(20);

' Open a Stream and decode a JPEG image
Dim imageStreamSource As New FileStream("tulipfarm.jpg", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim decoder As New JpegBitmapDecoder(imageStreamSource, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)
Dim bitmapSource As BitmapSource = decoder.Frames(0)

' Draw the Image
Dim myImage As New Image()
myImage.Source = bitmapSource
myImage.Stretch = Stretch.None
myImage.Margin = New Thickness(20)

注解

OnLoad如果要在创建解码器后关闭bitmapStream缓存选项。 默认 OnDemand 缓存选项将保留对流的访问，直到需要位图并由垃圾回收器处理清理。

适用于

JpegBitmapDecoder(Uri, BitmapCreateOptions, BitmapCacheOption)

JpegBitmapDecoder用指定的UricreateOptions和 cacheOption。

public:
 JpegBitmapDecoder(Uri ^ bitmapUri, System::Windows::Media::Imaging::BitmapCreateOptions createOptions, System::Windows::Media::Imaging::BitmapCacheOption cacheOption);
[System.Security.SecurityCritical]
public JpegBitmapDecoder(Uri bitmapUri, System.Windows.Media.Imaging.BitmapCreateOptions createOptions, System.Windows.Media.Imaging.BitmapCacheOption cacheOption);
public JpegBitmapDecoder(Uri bitmapUri, System.Windows.Media.Imaging.BitmapCreateOptions createOptions, System.Windows.Media.Imaging.BitmapCacheOption cacheOption);
[<System.Security.SecurityCritical>]
new System.Windows.Media.Imaging.JpegBitmapDecoder : Uri * System.Windows.Media.Imaging.BitmapCreateOptions * System.Windows.Media.Imaging.BitmapCacheOption -> System.Windows.Media.Imaging.JpegBitmapDecoder
new System.Windows.Media.Imaging.JpegBitmapDecoder : Uri * System.Windows.Media.Imaging.BitmapCreateOptions * System.Windows.Media.Imaging.BitmapCacheOption -> System.Windows.Media.Imaging.JpegBitmapDecoder
Public Sub New (bitmapUri As Uri, createOptions As BitmapCreateOptions, cacheOption As BitmapCacheOption)

参数

bitmapUri
Uri

用于 Uri 标识要解码的位图。

createOptions
BitmapCreateOptions

位图图像的初始化选项。

cacheOption
BitmapCacheOption

用于位图图像的缓存方法。

属性
SecurityCriticalAttribute

例外

ArgumentNullException

值为 bitmapUrinull.

FileFormatException

这不是 bitmapUri 联合摄影专家组（JPEG）编码的图像。

示例

下面的代码示例演示如何创建一个实例并使用 JpegBitmapDecoder a.Uri 解码的图像用作控件的 Image 源。

// Open a Uri and decode a JPEG image
System::Uri^ myUri = gcnew System::Uri("tulipfarm.jpg", UriKind::RelativeOrAbsolute);
JpegBitmapDecoder^ decoder2 = gcnew JpegBitmapDecoder(myUri, BitmapCreateOptions::PreservePixelFormat, BitmapCacheOption::Default);
BitmapSource^ bitmapSource2 = decoder2->Frames[0];

// Draw the Image
Image^ myImage2 = gcnew Image();
myImage2->Source = bitmapSource2;
myImage2->Stretch = Stretch::None;
myImage2->Margin = System::Windows::Thickness(20);


// Open a Uri and decode a JPEG image
Uri myUri = new Uri("tulipfarm.jpg", UriKind.RelativeOrAbsolute);
JpegBitmapDecoder decoder2 = new JpegBitmapDecoder(myUri, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default);
BitmapSource bitmapSource2 = decoder2.Frames[0];

// Draw the Image
Image myImage2 = new Image();
myImage2.Source = bitmapSource2;
myImage2.Stretch = Stretch.None;
myImage2.Margin = new Thickness(20);

' Open a Uri and decode a JPEG image
Dim myUri As New Uri("tulipfarm.jpg", UriKind.RelativeOrAbsolute)
Dim decoder2 As New JpegBitmapDecoder(myUri, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.Default)
Dim bitmapSource2 As BitmapSource = decoder2.Frames(0)

' Draw the Image
Dim myImage2 As New Image()
myImage2.Source = bitmapSource2
myImage2.Stretch = Stretch.None
myImage2.Margin = New Thickness(20)

注解

如果解码器无法加载指定的 bitmapUri值，将发生异常。

适用于