裁剪位圖克隆與pictureBox sizeMode是放大

Question

我發現這個功能在互聯網上裁剪圖像，它做得很好，如果pictureBox源sizeMode是正常的。但是當pictureBox sizeMode縮放時，它仍然像正常sizeMode一樣被克隆。

如何克隆相同的縮放pictureBox？不是原始正常位圖的大小？

public static Bitmap CropBitmap(Bitmap bitmap, int x, int y, int w, int h) 
{ 
    Rectangle rect = new Rectangle(x, y, w, h); 
    Bitmap cropped = bitmap.Clone(rect, bitmap.PixelFormat); 
    return cropped; 
} 

像這樣

pictureBox2.Image = CropBitmap((Bitmap)pictureBox1.Image.Clone(), 35, 0, 110, 150); 

Answer 1

最簡單的方法採用的是用DrawToBitmap方法從不管SizeMode的圖片框的產量，然後裁剪該輸出是這樣的：

public static Bitmap Crop(PictureBox pb, int x, int y, int w, int h) 
{ 
    var rect = pb.ClientRectangle; 
    using (var output = new Bitmap(rect.Width, rect.Height, pb.Image.PixelFormat)) 
    { 
     pb.DrawToBitmap(output, rect); 
     return output.Clone(new Rectangle(x, y, w, h), output.PixelFormat); 
    } 
} 

但是，上述方法的缺點是它真的會裁剪潛在縮放的圖像。

如果您確實想裁剪原始圖像，則需要將傳遞的矩形（我假設它在圖片框客戶端座標中）映射到原始圖像座標。

如果圖片框提供了一種方法ClientToImage（類似於ClientToScreen），但它沒有這將是很好的，所以我們需要從Reference Source提取SizeMode邏輯。

新的方法是這樣的：

public static class ImageUtils 
{ 
    public static Bitmap CropImage(this PictureBox pb, int x, int y, int w, int h) 
    { 
     var imageRect = pb.GetImageRectangle(); 
     var image = pb.Image; 
     float scaleX = (float)image.Width/imageRect.Width; 
     float scaleY = (float)image.Height/imageRect.Height; 
     var cropRect = new Rectangle(); 
     cropRect.X = Scale(x - imageRect.X, scaleX, image.Width); 
     cropRect.Y = Scale(y - imageRect.Y, scaleY, image.Height); 
     cropRect.Width = Scale(w, scaleX, image.Width - cropRect.X); 
     cropRect.Height = Scale(h, scaleY, image.Height - cropRect.Y); 
     var result = new Bitmap(cropRect.Width, cropRect.Height, image.PixelFormat); 
     using (var g = Graphics.FromImage(result)) 
      g.DrawImage(image, new Rectangle(new Point(0, 0), cropRect.Size), cropRect, GraphicsUnit.Pixel); 
     return result; 
    } 

    static int Scale(int value, float scale, int maxValue) 
    { 
     int result = (int)(value * scale); 
     return result < 0 ? 0 : result > maxValue ? maxValue : result; 
    } 

    public static Rectangle GetImageRectangle(this PictureBox pb) 
    { 
     var rect = pb.ClientRectangle; 
     var padding = pb.Padding; 
     rect.X += padding.Left; 
     rect.Y += padding.Top; 
     rect.Width -= padding.Horizontal; 
     rect.Height -= padding.Vertical; 
     var image = pb.Image; 
     var sizeMode = pb.SizeMode; 
     if (sizeMode == PictureBoxSizeMode.Normal || sizeMode == PictureBoxSizeMode.AutoSize) 
      rect.Size = image.Size; 
     else if (sizeMode == PictureBoxSizeMode.CenterImage) 
     { 
      rect.X += (rect.Width - image.Width)/2; 
      rect.Y += (rect.Height - image.Height)/2; 
      rect.Size = image.Size; 
     } 
     else if (sizeMode == PictureBoxSizeMode.Zoom) 
     { 
      var imageSize = image.Size; 
      var zoomSize = pb.ClientSize; 
      float ratio = Math.Min((float)zoomSize.Width/imageSize.Width, (float)zoomSize.Height/imageSize.Height); 
      rect.Width = (int)(imageSize.Width * ratio); 
      rect.Height = (int)(imageSize.Height * ratio); 
      rect.X = (pb.ClientRectangle.Width - rect.Width)/2; 
      rect.Y = (pb.ClientRectangle.Height - rect.Height)/2; 
     } 
     return rect; 
    } 
}