Question

I am new learner to WPF. here I got a question.
I have a image, width:360, height:360. Here I want to crop this image like below:

( 0,0 ) to (120,120) save to the first ImageSource object,

(120,0 ) to (240,120) save to the second ImageSource object,

(240,0 ) to (360,120) save to the third ImageSource object;,

……

pls see more details in below picture:

My code sample below:

    private void CutImage(string img)
    {
        int iLeft = 0;
        int iTop = 0;
        int count = 0;

        Image thisImg = new Image();
        BitmapImage src = new BitmapImage();
        src.BeginInit();
        src.UriSource = new Uri(img, UriKind.Relative);
        src.CacheOption = BitmapCacheOption.OnLoad;
        src.EndInit();
        thisImg.Source = src;

        for (int i = 0; i < 3; i++)
        {
            iTop = i * 120;
            for (int j = 0; j < 3; j++)
            {
                iLeft = j * 120;

                Canvas canvas = new Canvas();

                Rectangle destRect = new Rectangle();
                destRect.SetValue(Canvas.LeftProperty, (double)0);
                destRect.SetValue(Canvas.TopProperty,(double)0);
                destRect.Width = destRect.Height = 120;

                Rect srcRect = new Rect();
                srcRect.X = iLeft;
                srcRect.Y = iTop;
                srcRect.Width = srcRect.Height = 120;


                thisImg.Clip = new RectangleGeometry(srcRect);

                thisImg.Clip.SetValue(Canvas.TopProperty, (double)iTop);
                thisImg.Clip.SetValue(Canvas.LeftProperty, (double)iLeft);
                thisImg.Clip.SetValue(Canvas.WidthProperty, (double)120);
                thisImg.Clip.SetValue(Canvas.HeightProperty,(double)120);

                objImg[count++] = (ImageSource)thisImg.GetValue(Image.SourceProperty);
            }
        }
      }

but it doesn’t work as I expected, seems that all the ImageSource objects store the same image, not the corping part. Any one can help me ? thx.

Answer 1

Use CroppedBitmap to do this:

private void CutImage(string img)
{
    int count = 0;

    BitmapImage src = new BitmapImage();
    src.BeginInit();
    src.UriSource = new Uri(img, UriKind.Relative);
    src.CacheOption = BitmapCacheOption.OnLoad;
    src.EndInit();

    for (int i = 0; i < 3; i++)
        for (int j = 0; j < 3; j++)
            objImg[count++] = new CroppedBitmap(src, new Int32Rect(j * 120, i * 120, 120, 120));
}