Question

The following code should rotate an image 90 degrees, but it isn’t working. Instead, all i get on my screen after running is grey pixels and one line of the original pixels at the bottom. Any ideas about what I have done wrong in this code?

  void rotate90(Image& image)
    {
        Pixel * tempPixel = new Pixel[(image.infoHeader.biWidth * image.infoHeader.biHeight)];
        int tempWidth = image.infoHeader.biWidth;
        for(int r = 0; r < image.infoHeader.biHeight; r ++)
        {
            for(int c = 0; c < image.infoHeader.biWidth; c++)
            {

                int f = c+(r*image.infoHeader.biWidth);
                int t = (image.infoHeader.biHeight - r) + (image.infoHeader.biWidth-1);
                tempPixel[t] = image.pixels[f];
            }
        }

        delete[] image.pixels;
        image.pixels=tempPixel ;
    }

My updated code as of by comment below

void rotate90(Image& image)
{
    Pixel * tempPixel = new Pixel[(image.infoHeader.biWidth * image.infoHeader.biHeight)];
    int tempWidth = image.infoHeader.biWidth;
    image.infoHeader.biWidth = image.infoHeader.biHeight;
    image.infoHeader.biHeight = tempWidth;
    for(int r = 0; r < image.infoHeader.biHeight; r ++)
    {
        for(int c = 0; c < image.infoHeader.biWidth; c++)
        {

            int f = c+(r*image.infoHeader.biWidth);
            int t = (image.infoHeader.biHeight-r-1) +(image.infoHeader.biWidth * ((4 * image.infoHeader.biWidth * image.infoHeader.biHeight) % 4));
            tempPixel[t] = image.pixels[f];
        }
    }

    delete[] image.pixels;
    image.pixels=tempPixel ;
}

Answer 1

You are not using c in the calculation of the new position t. It should be multiplying the width I guess