将字节转换为BitmapImage uwp C＃

Question

I try to convert a white bitmapImage to black. So i have a byte[] PixelArray, which is good but when i try to use this array to create my black image it doesn't work. Here is my code :

var stream = new InMemoryRandomAccessStream();
await stream.WriteAsync(byteArray.AsBuffer());
stream.Seek(0);
await image.SetSourceAsync(stream);

Thanks guys

Answer 1

As @Clemens said, we should be able to use WriteableBitmap . We can get the Width and the Height by BitmapDecoder.PixelWidth and BitmapDecoder.PixelHeight property. Then we can use WriteableBitmap.PixelBuffer to set the bytes Array to the WriteableBitmap .

PixelBuffer cannot be written to directly, however, you can use language-specific techniques to access the buffer and change its contents. To access the pixel content from C# or Microsoft Visual Basic, you can use the AsStream extension method to access the underlying buffer as a stream.

For more info, see Remarks of the WriteableBitmap.PixelBuffer .

For example:

IRandomAccessStream random = await RandomAccessStreamReference.CreateFromUri(ImageWhite.UriSour‌​ce).OpenReadAsync();
BitmapDecoder decoder = await BitmapDecoder.CreateAsync(random);
PixelDataProvider pixelData = await decoder.GetPixelDataAsync();
var PixelArray = pixelData.DetachPixelData();
WriteableBitmap bitmap = new WriteableBitmap((int)decoder.PixelWidth, (int)decoder.PixelHeight);
await bitmap.PixelBuffer.AsStream().WriteAsync(PixelArray, 0, PixelArray.Length);
MyImage.Source = bitmap;

Update:

To Convert the WriteableBitmap to BitmapImage , we should be able to encode the stream from WriteableBitmap .

For example:

InMemoryRandomAccessStream inMemoryRandomAccessStream = new InMemoryRandomAccessStream();
BitmapEncoder encoder = await BitmapEncoder.CreateAsync(BitmapEncoder.JpegEncoderId, inMemoryRandomAccessStream);
Stream pixelStream = bitmap.PixelBuffer.AsStream();
byte[] pixels = new byte[pixelStream.Length];
await pixelStream.ReadAsync(pixels, 0, pixels.Length);
encoder.SetPixelData(BitmapPixelFormat.Bgra8, BitmapAlphaMode.Ignore, (uint)bitmap.PixelWidth, (uint)bitmap.PixelHeight, 96.0, 96.0, pixels);
await encoder.FlushAsync();
BitmapImage bitmapImage = new BitmapImage();
bitmapImage.SetSource(inMemoryRandomAccessStream);
MyImage.Source = bitmapImage;