Comment : encoder et décoder une image PNG

Les exemples suivants montrent comment décoder et encoder une image PNG (Portable Network Graphics) à l’aide des objets et PngBitmapEncoder des objets spécifiquesPngBitmapDecoder.

Décoder une image PNG

Cet exemple montre comment décoder une image PNG à l’aide d’un PngBitmapDecoderFileStream.

// 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)

Encoder une image PNG

Cet exemple montre comment encoder un BitmapSource fichier dans une image PNG à l’aide d’un 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)

Voir aussi

• Vue d’ensemble de la création d’images