Can not create Bitmap from byte?

Question

I have byte arrary of bitmap which is created by c++ BITMAPFILEHEADER and BitmapInfo

in .net I want to create it to bitmap or image.

in winui3.0 I tried

CanvasBitmap.CreateFromBytes

but I do not know what format it is.

in wpf I tried

WriteableBitmap 

but can not too.

I can use

System.IO.WriteAllBytes("d:\\1.jpeg",my_bytes) 

to write the byte to jpeg in my disk.

and If I read it by BitmapImage in wpf the format is Bgr32

BitmapSource.Create(176, 144, 0, 0, PixelFormats.Bgr32, null,data 176*3);

can not create it too.Value does not fall within the expected

how to do it ?

and I will change the image very frequently so I can not create a new one but change its pixels.

Answer 1

It works with a WriteableBitmap

I used it for example in WinUI 3 in this test : CMediaEngine.cs

(function GetCaptureWriteableBitmap where I get a byte array (pPixels) from a Win32 hBitmap

then WriteableBitmap.PixelBuffer.AsStream().WriteAsync to write the byte array into the WriteableBitmap)

Answer 2

Hi,@mc. Welcome Microsoft Q&A. Here are some solutions that may work for you in WPF.

You could load the byte array into a MemoryStream and then create a BitmapImage from that MemoryStream. This approach should work with various common image formats.

Load the byte array into a MemoryStream.

public BitmapImage ToImage(byte[] array)
{
    using (var ms = new System.IO.MemoryStream(array))
    {
        var image = new BitmapImage();
        image.BeginInit();
        image.CacheOption = BitmapCacheOption.OnLoad; // here
        image.StreamSource = ms;
        image.EndInit();
        return image;
    }
}

From the Remarks section in BitmapImage.StreamSource:

Set the CacheOption property to BitmapCacheOption.OnLoad if you wish to close the stream after the BitmapImage is created.

Besides that, you can also use built-in type conversion to convert from type byte[] to type ImageSource (or the derived BitmapSource):

var bitmap = (BitmapSource)new ImageSourceConverter().ConvertFrom(array);

Method that uses the ImageConverter object in .Net Framework to convert a byte array, presumably containing a JPEG or PNG file image, into a Bitmap object, which can also be used as an Image object.

  /// <param name="byteArray">byte array containing JPEG or PNG file image or similar</param>

  public static Bitmap GetImageFromByteArray(byte[] byteArray)
  {
     Bitmap bm = (Bitmap)_imageConverter.ConvertFrom(byteArray);

     if (bm != null && (bm.HorizontalResolution != (int)bm.HorizontalResolution ||
                        bm.VerticalResolution != (int)bm.VerticalResolution))
     {
        // Correct a strange glitch that has been observed in the test program when converting 
        //  from a PNG file image created by CopyImageToByteArray() - the dpi value "drifts" 
        //  slightly away from the nominal integer value
        bm.SetResolution((int)(bm.HorizontalResolution + 0.5f), 
                         (int)(bm.VerticalResolution + 0.5f));
     }

     return bm;
  }

Or you can refer to the solution here to see if it is helpful to you.

If you still have questions, please feel free to let me know.

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