如何在Monououch中裁剪圖像Xamarin

Question

我在UIImageview中顯示圖像，我想剪裁圖像，以下是我的要求。

選擇裁剪圖標應顯示一個固定大小（600X600）的方形，該方形通過網格線固定在圖像上以協助校正圖像。將會有一個控件允許圖像在網格下轉動。

Answer 1

您可以嘗試製作一個覆蓋矩形來指定要裁剪的內容。提供一個x和y（如果你的圖像不在左上角，如果是，這些值都是0），寬度和高度（對於你的例子，它們都應該是600）。我不知道一種允許網格線拉直圖像的方法。我也不知道旋轉圖像的方法。但對於直線圖像，您可以使用如下所示的方法：

private UIImage Crop(UIImage image, int x, int y, int width, int height) 
{ 
    SizeF imgSize = image.Size; 

    UIGraphics.BeginImageContext(new SizeF(width, height)); 
    UIGraphics imgToCrop = UIGraphics.GetCurrentContext(); 

    RectangleF croppingRectangle = new RectangleF(0, 0, width, height); 
    imgToCrop.ClipToRect(croppingRectangle); 

    RectangleF drawRectangle = new RectangleF(-x, -y, imgSize.Width, imgSize.Height); 

    image.Draw(drawRectangle); 
    UIGraphics croppedImg = UIGraphics.GetImageFromCurrentImageContext(); 

    UIGraphics.EndImageContext(); 
    return croppedImg; 
} 

Answer 2

這就是我最終用來居中裁切圖像的方法。

//Crops an image to even width and height 
public UIImage CenterCrop(UIImage originalImage) 
{ 
    // Use smallest side length as crop square length 
    double squareLength = Math.Min(originalImage.Size.Width, originalImage.Size.Height); 

    nfloat x, y; 
    x = (nfloat)((originalImage.Size.Width - squareLength)/2.0); 
    y = (nfloat)((originalImage.Size.Height - squareLength)/2.0); 

    //This Rect defines the coordinates to be used for the crop 
    CGRect croppedRect = CGRect.FromLTRB(x, y, x + (nfloat)squareLength, y + (nfloat)squareLength); 

    // Center-Crop the image 
    UIGraphics.BeginImageContextWithOptions(croppedRect.Size, false, originalImage.CurrentScale); 
    originalImage.Draw(new CGPoint(-croppedRect.X, -croppedRect.Y)); 
    UIImage croppedImage = UIGraphics.GetImageFromCurrentImageContext(); 
    UIGraphics.EndImageContext(); 

    return croppedImage; 
}