Question

I have raw data in a custom image format (canot be changed) that is stored in column major order (after some binary header data). I read the file into a Byte[] called “imageDataBytes”.

int XSize = 1280; // Really the height of the image
int YSize = 2048; // Really the width of the image
WriteableBitMap myImage = new WritableBitmap(XSize, YSize, 96, 96, PixelFormats.Gray16, null)
System.Windows.Int32Rect rect = new System.Windows.Int32Rect(0, 0, XSize , YSize);
myImage.WritePixels(rect, customImage.imageDataBytes, stride, customImage.imageOffset);

Now, I show this in XAML with

    <Image Grid.Column="0" Grid.Row="1" Cursor="Cursor1.cur"Source="{Binding myImage}" Stretch="None"/>

I need to get the image rotated (to correct for the column major order in the bytestream but I can’t find array transformations for the Byte[] similar to IPPs in C# (and I don’t have IPP available here). And The rotation of the image from xaml moves the image all over the place (rather than rotating around the center).

<Image ... // From above>
    <Image.RenderTransform>
        <RotateTransform CenterX="0.5" CenterY="0.5" Angle="-90"/>
    </Image.RenderTransform>
</Image>

What can I do? Am I missing the transforms on the byte[] somewhere? Why is the RotateTransform moving the image when the center is set to 0.5?

Note that this must be as fast as possible, it is clearly a large image and I am trying to render at 10Hz+, this is why the nieve for-loop Byte array transformation is excluded from the realm of possible.

Thanks as always

~TMII

Answer 1

That’s because you are not rotating about the object’s center but about the point (0.5, 0.5).
See http://msdn.microsoft.com/en-us/library/system.windows.media.rotatetransform.centerx.aspx

If you have access to the image in the code behind, set the RenderTransform manually, and specify the CenterX and CenterY as Image.Width/2.0 and Image.Height/2.0.
You only need to do this when the image changes.