幕布斯7119047
这是一个旧线程，还有其他几个有关C＃WinForms图像旋转的线程，但是现在我想出了解决方案，我认为这是发布它的好地方。 /// <summary> /// Method to rotate an Image object. The result can be one of three cases: /// - upsizeOk = true: output image will be larger than the input, and no clipping occurs /// - upsizeOk = false & clipOk = true: output same size as input, clipping occurs /// - upsizeOk = false & clipOk = false: output same size as input, image reduced, no clipping /// /// A background color must be specified, and this color will fill the edges that are not /// occupied by the rotated image. If color = transparent the output image will be 32-bit, /// otherwise the output image will be 24-bit. /// /// Note that this method always returns a new Bitmap object, even if rotation is zero - in /// which case the returned object is a clone of the input object. /// </summary> /// <param name="inputImage">input Image object, is not modified</param> /// <param name="angleDegrees">angle of rotation, in degrees</param> /// <param name="upsizeOk">see comments above</param> /// <param name="clipOk">see comments above, not used if upsizeOk = true</param> /// <param name="backgroundColor">color to fill exposed parts of the background</param> /// <returns>new Bitmap object, may be larger than input image</returns> public static Bitmap RotateImage(Image inputImage, float angleDegrees, bool upsizeOk, bool clipOk, Color backgroundColor) { // Test for zero rotation and return a clone of the input image if (angleDegrees == 0f) return (Bitmap)inputImage.Clone(); // Set up old and new image dimensions, assuming upsizing not wanted and clipping OK int oldWidth = inputImage.Width; int oldHeight = inputImage.Height; int newWidth = oldWidth; int newHeight = oldHeight; float scaleFactor = 1f; // If upsizing wanted or clipping not OK calculate the size of the resulting bitmap if (upsizeOk || !clipOk) { double angleRadians = angleDegrees * Math.PI / 180d; double cos = Math.Abs(Math.Cos(angleRadians)); double sin = Math.Abs(Math.Sin(angleRadians)); newWidth = (int)Math.Round(oldWidth * cos + oldHeight * sin); newHeight = (int)Math.Round(oldWidth * sin + oldHeight * cos); } // If upsizing not wanted and clipping not OK need a scaling factor if (!upsizeOk && !clipOk) { scaleFactor = Math.Min((float)oldWidth / newWidth, (float)oldHeight / newHeight); newWidth = oldWidth; newHeight = oldHeight; } // Create the new bitmap object. If background color is transparent it must be 32-bit, // otherwise 24-bit is good enough. Bitmap newBitmap = new Bitmap(newWidth, newHeight, backgroundColor == Color.Transparent ? PixelFormat.Format32bppArgb : PixelFormat.Format24bppRgb); newBitmap.SetResolution(inputImage.HorizontalResolution, inputImage.VerticalResolution); // Create the Graphics object that does the work using (Graphics graphicsObject = Graphics.FromImage(newBitmap)) { graphicsObject.InterpolationMode = InterpolationMode.HighQualityBicubic; graphicsObject.PixelOffsetMode = PixelOffsetMode.HighQuality; graphicsObject.SmoothingMode = SmoothingMode.HighQuality; // Fill in the specified background color if necessary if (backgroundColor != Color.Transparent) graphicsObject.Clear(backgroundColor); // Set up the built-in transformation matrix to do the rotation and maybe scaling graphicsObject.TranslateTransform(newWidth / 2f, newHeight / 2f); if (scaleFactor != 1f) graphicsObject.ScaleTransform(scaleFactor, scaleFactor); graphicsObject.RotateTransform(angleDegrees); graphicsObject.TranslateTransform(-oldWidth / 2f, -oldHeight / 2f); // Draw the result graphicsObject.DrawImage(inputImage, 0, 0); } return newBitmap; }这是从StackOverflow和其他地方获得许多灵感的结果。Naveen在此线程上的回答特别有用。