图片裁剪和旋转处理 （unity适用）

        unity实现旋转和裁剪需要在图片导入的时候设置好属性为可读写，但是对于一些动态加载来的图片设置的话要using UnityEditor了，这样打包的时候又会有问题。网上还有一些直接截屏的方法，个人认为不是很好，尤其是屏幕上有其他界面会出现遮挡或特效遮挡界面的时候，我目前想到的方法就是如下啦~~~

 //裁剪
    public static string CutImage(string filePath, int beginX, int beginY, int lenth, int height, string fileName,
      string savePath,
      string fileExtension)
    {
        Bitmap bitmap = new Bitmap(filePath);

        if (((beginX + lenth) <= bitmap.Width) && ((beginY + height) <= bitmap.Height))
        {
            Bitmap destBitmap = new Bitmap(lenth, height);
            Rectangle destRect = new Rectangle(0, 0, lenth, height);
            Rectangle srcRect = new Rectangle(beginX, beginY, lenth, height);
            //bitmap.RotateFlip(flipType);
            System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBitmap);
            graph.DrawImage(bitmap, destRect, srcRect, GraphicsUnit.Pixel);

            ImageFormat format = ImageFormat.Png;//建议用png，jpg会导致纹理被压缩变的越来越模糊。
            switch (fileExtension.ToLower())
            {
                case "png":
                    format = ImageFormat.Png;
                    break;
                case "bmp":
                    format = ImageFormat.Bmp;
                    break;
                case "gif":
                    format = ImageFormat.Gif;
                    break;
                case "jpeg":
                case "jpg":
                    format = ImageFormat.Jpeg;
                    break;
            }
            if (!Directory.Exists(savePath))
            {
                Directory.CreateDirectory(savePath);
            }
            string path = savePath + "/" + fileName.Split('.')[0] + "." + fileExtension;
            destBitmap.Save(path, format);

            destBitmap.Dispose();//要释放掉资源
            bitmap.Dispose();//要释放掉资源
            return path;

        }
        bitmap.Dispose();

        Debug.Log("截取范围超出图片范围");
        return null;

    }

  //旋转
    public static string RotateImage(string filePath, string fileName, string savePath, string fileExtension, RotateFlipType flipType)
    {
        Bitmap bitmap = new Bitmap(filePath);
        Bitmap destBitmap = new Bitmap(bitmap.Height, bitmap.Width);
        Rectangle destRect = new Rectangle(0, 0, bitmap.Height, bitmap.Width);

        bitmap.RotateFlip(flipType);
        System.Drawing.Graphics graph = System.Drawing.Graphics.FromImage(destBitmap);
        graph.DrawImage(bitmap, destRect);

        ImageFormat format = ImageFormat.Png;
        switch (fileExtension.ToLower())
        {
            case "png":
                format = ImageFormat.Png;
                break;
            case "bmp":
                format = ImageFormat.Bmp;
                break;
            case "gif":
                format = ImageFormat.Gif;
                break;
            case "jpeg":
            case "jpg":
                format = ImageFormat.Jpeg;
                break;
        }
        if (!Directory.Exists(savePath))
        {
            Directory.CreateDirectory(savePath);
        }
        string path = savePath + "/" + fileName.Split('.')[0] + "." + fileExtension;
        destBitmap.Save(path, format);

        destBitmap.Dispose();//要释放掉资源
        bitmap.Dispose();  //要释放掉资源
        return path;

    }