Windows Store App - WriteableBitmap , blit method

Question

Alright , i am trying to merge two images(superimpose one image on top of another) using writeablebitmapex library's blit method. And after applying the blit all i am getting is a transparent image with no content.

I would like to superimpose the curtain image on top of the window image.

Source Code :

WriteableBitmap photoWriteableBitMap = await new WriteableBitmap(1,1).FromContent(new Uri("ms-appx:///Curtain1.jpg"));
WriteableBitmap frameWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Window1.jpg"));

var merge = new WriteableBitmap(750, 750);

merge.Blit(new Rect(0, 0, 100, 100), photoWriteableBitMap, new Rect(0, 0, photoWriteableBitMap.PixelWidth, photoWriteableBitMap.PixelHeight));
merge.Blit(new Rect(0, 0, 200, 200), frameWriteableBitMap, new Rect(0, 0, frameWriteableBitMap.PixelWidth, frameWriteableBitMap.PixelHeight));

// Assign the merged writeable bitmap to the image source.
imgMain.Source = merge; 

Expected Image :

Actual Image :

Please let me know what i am doing wrong.

Answer 1

I have found an answer to my solution in case anyone stumbles upon here.

First thing , I was unnecessarily trying to include an extra bitmap(merge) for the desired output.

All I had to do was apply the blit on the window image and set the source and the destination rectangles appropriately.

Below is the final code which works for me ,

WriteableBitmap photoWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Curtain1.jpg"));
WriteableBitmap frameWriteableBitMap = await new WriteableBitmap(1, 1).FromContent(new Uri("ms-appx:///Window1.jpg"));

frameWriteableBitMap.Blit(new Rect(300, 100, 250, 200), photoWriteableBitMap, new Rect(0, 0, photoWriteableBitMap.PixelWidth , photoWriteableBitMap.PixelHeight));

This is how my final image looks :