Unflip wxImage loading

Question

I have the code here working fine except that all the non-power of 2 images are flipped in the y direction. In the wxImageLoader file there is this loop which I believe is the culprit:

 for(int y=0; y<newHeight; y++)
 {
  for(int x=0; x<newWidth; x++)
  {

   if( x<(*imageWidth) && y<(*imageHeight) ){
    imageData[(x+y*newWidth)*bytesPerPixel+0]=
    bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 0];

    imageData[(x+y*newWidth)*bytesPerPixel+1]=
     bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 1];

    imageData[(x+y*newWidth)*bytesPerPixel+2]=
     bitmapData[( x+(rev_val-y)*(*imageWidth))*old_bytesPerPixel + 2];

    if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3]=
     alphaData[ x+(rev_val-y)*(*imageWidth) ];

   }
   else
   {

    imageData[(x+y*newWidth)*bytesPerPixel+0] = 0;
    imageData[(x+y*newWidth)*bytesPerPixel+1] = 0;
    imageData[(x+y*newWidth)*bytesPerPixel+2] = 0;
    if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3] = 0;
   }

  }//next
 }//next

But I can't figure out how to un-flip the images.

Answer 1

In your loop you use (rev_val - y) for the index of the pixels of your "old" image. This will cause the image to flip. Try to find an alternative. From your code you posted it is difficult to know what the function of rev_val is.

Answer 2

The correct for loop is:

for(int y=0; y<newHeight; y++)
 {
  for(int x=0; x<newWidth; x++)
  {

   if( x<(*imageWidth) && y<(*imageHeight) ){
    imageData[(x+y*newWidth)*bytesPerPixel+0]=
    bitmapData[( x+y*(*imageWidth))*old_bytesPerPixel + 0];

    imageData[(x+y*newWidth)*bytesPerPixel+1]=
     bitmapData[( x+y*(*imageWidth))*old_bytesPerPixel + 1];

    imageData[(x+y*newWidth)*bytesPerPixel+2]=
     bitmapData[( x+y*(*imageWidth))*old_bytesPerPixel + 2];

    if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3]=
     alphaData[ x+y*(*imageWidth) ];

   }
   else
   {

    imageData[(x+y*newWidth)*bytesPerPixel+0] = 0;
    imageData[(x+y*newWidth)*bytesPerPixel+1] = 0;
    imageData[(x+y*newWidth)*bytesPerPixel+2] = 0;
    if(bytesPerPixel==4) imageData[(x+y*newWidth)*bytesPerPixel+3] = 0;
   }

  }//next
 }//next