裁剪图像通用应用程序 c#

Posted 2023-02-25

【中文标题】裁剪图像通用应用程序 c#

【英文标题】：cropping image universal app c#

【发布时间】：2015-04-13 11:29:10

【问题描述】：

我想在通用应用程序中用 x 和 y 裁剪图像， 我搜索了很多，没有发现任何有用的东西 我的想法是 我有一张图片，我想根据 start x ， y - end x 和 y 裁剪矩形

我试过了

BitmapImage img = new BitmapImage(new Uri(file.Path));
WriteableBitmap topLeft = img.Crop(0, 0, halfWidth, halfHeight);

它说 BitmapImage 不包含裁剪的定义

另一件事： 如何在通用应用程序中将 BitmapImage 转换为 WriteableBitmap ？

【参考方案1】：

您是否尝试过 BitmapEncoder/BitmapDecoder 类？查看MSDN code sample.

【参考方案2】：

  /// <summary>
        /// Gets the cropped bitmap asynchronously.
        /// </summary>
        /// <param name="originalImage">The original image.</param>
        /// <param name="startPoint">The start point.</param>
        /// <param name="cropSize">Size of the corp.</param>
        /// <param name="scale">The scale.</param>
        /// <returns>The cropped image.</returns>
        public static async Task<WriteableBitmap> GetCroppedBitmapAsync(IRandomAccessStream originalImage,
            Point startPoint, Size cropSize, double scale)
        
            if (double.IsNaN(scale) || double.IsInfinity(scale))
            
                scale = 1;
            

            // Convert start point and size to integer.
            var startPointX = (uint)Math.Floor(startPoint.X * scale);
            var startPointY = (uint)Math.Floor(startPoint.Y * scale);
            var height = (uint)Math.Floor(cropSize.Height * scale);
            var width = (uint)Math.Floor(cropSize.Width * scale);

            // Create a decoder from the stream. With the decoder, we can get 
            // the properties of the image.
            var decoder = await BitmapDecoder.CreateAsync(originalImage);

            // The scaledSize of original image.
            var scaledWidth = (uint)Math.Floor(decoder.PixelWidth * scale);
            var scaledHeight = (uint)Math.Floor(decoder.PixelHeight * scale);

            // Refine the start point and the size. 
            if (startPointX + width > scaledWidth)
            
                startPointX = scaledWidth - width;
            

            if (startPointY + height > scaledHeight)
            
                startPointY = scaledHeight - height;
            

            // Get the cropped pixels.
            var pixels = await GetPixelData(decoder, startPointX, startPointY, width, height,
                scaledWidth, scaledHeight);

            // Stream the bytes into a WriteableBitmap
            var cropBmp = new WriteableBitmap((int)width, (int)height);
            var pixStream = cropBmp.PixelBuffer.AsStream();
            pixStream.Write(pixels, 0, (int)(width * height * 4));

            return cropBmp;