Procedura: codificare e decodificare un'immagine PNGHow to: Encode and Decode a PNG Image

Nell'esempio seguente viene illustrato come decodificare e codificare un Portable Network Graphics (PNG)Portable Network Graphics (PNG) immagine usando la specifica PngBitmapDecoder e PngBitmapEncoder oggetti.The following examples show how to decode and encode a Portable Network Graphics (PNG)Portable Network Graphics (PNG) image using the specific PngBitmapDecoder and PngBitmapEncoder objects.

EsempioExample

In questo esempio viene illustrato come decodificare un PNGPNG immagine usando un PngBitmapDecoder da un FileStream.This example demonstrates how to decode a PNGPNG image using a PngBitmapDecoder from a FileStream.


// Open a Stream and decode a PNG image
Stream^ imageStreamSource = gcnew FileStream("smiley.png", FileMode::Open, FileAccess::Read, FileShare::Read);
PngBitmapDecoder^ decoder = gcnew PngBitmapDecoder(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 PNG image
Stream imageStreamSource = new FileStream("smiley.png", FileMode.Open, FileAccess.Read, FileShare.Read);
PngBitmapDecoder decoder = new PngBitmapDecoder(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 PNG image
Dim imageStreamSource As New FileStream("smiley.png", FileMode.Open, FileAccess.Read, FileShare.Read)
Dim decoder As New PngBitmapDecoder(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)

EsempioExample

In questo esempio viene illustrato come codificare un BitmapSource in un PNGPNG immagine usando un PngBitmapEncoder.This example demonstrates how to encode a BitmapSource into a PNGPNG image using a PngBitmapEncoder.

int width = 128;
int height = 128;
int stride = width;
array<System::Byte>^ pixels = gcnew array<System::Byte>(height * stride);

// Define the image palette
BitmapPalette^ myPalette = BitmapPalettes::Halftone256;

// Creates a new empty image with the pre-defined palette

BitmapSource^ image = BitmapSource::Create(width,
   height,
   96,
   96,
   PixelFormats::Indexed8,
   myPalette,
   pixels,
   stride);

FileStream^ stream = gcnew FileStream("new.png", FileMode::Create);
PngBitmapEncoder^ encoder = gcnew PngBitmapEncoder();
TextBlock^ myTextBlock = gcnew TextBlock();
myTextBlock->Text = "Codec Author is: " + encoder->CodecInfo->Author->ToString();
encoder->Interlace = PngInterlaceOption::On;
encoder->Frames->Add(BitmapFrame::Create(image));
encoder->Save(stream);

int width = 128;
int height = 128;
int stride = width;
byte[] pixels = new byte[height * stride];

// Define the image palette
BitmapPalette myPalette = BitmapPalettes.Halftone256;

// Creates a new empty image with the pre-defined palette

BitmapSource image = BitmapSource.Create(
    width,
    height,
    96,
    96,
    PixelFormats.Indexed8,
    myPalette,
    pixels,
    stride);

FileStream stream = new FileStream("new.png", FileMode.Create);
PngBitmapEncoder encoder = new PngBitmapEncoder();
TextBlock myTextBlock = new TextBlock();
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString();
encoder.Interlace = PngInterlaceOption.On;
encoder.Frames.Add(BitmapFrame.Create(image));
encoder.Save(stream);

Dim width As Integer = 128
Dim height As Integer = 128
Dim stride As Integer = width
Dim pixels(height * stride) As Byte

' Define the image palette
Dim myPalette As BitmapPalette = BitmapPalettes.Halftone256

' Creates a new empty image with the pre-defined palette
Dim image As BitmapSource = System.Windows.Media.Imaging.BitmapSource.Create( _
    width, height, 96, 96, PixelFormats.Indexed8, myPalette, pixels, stride)
Dim stream As New FileStream("new.png", FileMode.Create)
Dim encoder As New PngBitmapEncoder()
Dim myTextBlock As New TextBlock()
myTextBlock.Text = "Codec Author is: " + encoder.CodecInfo.Author.ToString()
encoder.Interlace = PngInterlaceOption.On
encoder.Frames.Add(BitmapFrame.Create(image))
encoder.Save(stream)

Vedere ancheSee Also

Cenni preliminari sulla creazione dell'immagineImaging Overview