如何改变图像的大小

我从CameraCaptureTask获取图像，我希望能够在保存之前使图像更小。 宽度和高度自动设置为最高分辨率，远远超过我的需要。 虽然我遇到了错误，但我一直试图获取图像，更改尺寸，然后尝试保存。

原版的

MainPage.xaml.cs中

private void cameraTask_Completed(object sender, PhotoResult e) { if (e.TaskResult == TaskResult.OK) { BitmapImage bmi = new BitmapImage(); bmi.SetSource(e.ChosenPhoto); //MessageBox.Show(bmi.PixelWidth.ToString() + "x" + bmi.PixelHeight.ToString()); var gcd = GCD(bmi.PixelWidth, bmi.PixelHeight); var result = string.Format("{0}:{1}", bmi.PixelWidth / gcd, bmi.PixelHeight / gcd); WriteableBitmap wb; Stream stream; switch (result) { case "3:4": wb = new WriteableBitmap(480,640); break; case "4:3": wb = new WriteableBitmap(640,480); break; case "9:16": wb = new WriteableBitmap(448, 800); break; case "16:9": wb = new WriteableBitmap(800, 448); break; default: wb = null; return; } //Set the wb to the original stream? wb.SetSource(e.ChosenPhoto); //Convert the wb to a stream for saving stream = new MemoryStream(wb.ToByteArray()); //Need to replace the following line with the new image stream for saving? //var capturedPicture = new CapturedPicture(e.OriginalFileName, e.ChosenPhoto); var capturedPicture = new CapturedPicture(e.OriginalFileName, stream); } } public int GCD(int a, int b) { while (a != 0 && b != 0) { if (a > b) a %= b; else b %= a; } if (a == 0) return b; else return a; } 

编辑：新的实施

 private void cameraTask_Completed(object sender, PhotoResult e) { if (e.TaskResult == TaskResult.OK) { BitmapImage bmi = new BitmapImage(); bmi.SetSource(e.ChosenPhoto); var gcd = GCD(bmi.PixelWidth, bmi.PixelHeight); var result = string.Format("{0}:{1}", bmi.PixelWidth / gcd, bmi.PixelHeight / gcd); WriteableBitmap wb = new WriteableBitmap(bmi); Stream stream = new MemoryStream(); switch (result) { case "3:4": wb.SaveJpeg(stream, 480, 640, 0, 100); break; case "4:3": wb.SaveJpeg(stream, 640, 480, 0, 100); break; case "9:16": wb.SaveJpeg(stream, 448, 800, 0, 100); break; case "16:9": wb.SaveJpeg(stream, 800, 448, 0, 100); break; default: wb = null; return; } stream.Seek(0, SeekOrigin.Begin); //var capturedPicture = new CapturedPicture(e.OriginalFileName, e.ChosenPhoto); var capturedPicture = new CapturedPicture(e.OriginalFileName, stream); 

Answer 1

使用重载的Bitmap构造函数来创建一个重新resize的图像，你唯一缺少的是回转到Image数据类型：

 public static Image resizeImage(Image imgToResize, Size size) { return (Image)(new Bitmap(imgToResize, size)); } yourImage = resizeImage(yourImage, new Size(50,50));