c#图片处理之图片裁剪成不规则图形

为了让大家知道下面内容是否是自己想要的，我先发效果图。

好了，那就开始贴代码了

以下为一个按钮的事件，为裁剪准备图片、裁剪路径、保存路径

private void button1_click(object sender, eventargs e)
        {
            graphicspath path = new graphicspath();
            point[] p = {
                            new point(424,244),
                            new point(240,440),
                            new point(340,552),
                            new point(550,526),
                            new point(478,366),
                            new point(348,660),
                            new point(424,244)
                        };
            path.addlines(p);
            openfiledialog openfiledialog = new openfiledialog();

            openfiledialog.filter = @"bitmap文件(*.bmp)|*.bmp|jpeg文件(*.jpg)|*.jpg|所有合适文件(*.bmp,*.jpg)|*.bmp;*.jpg";

            openfiledialog.filterindex = 3;

            openfiledialog.restoredirectory = true;

            if (dialogresult.ok == openfiledialog.showdialog())
            {

                bitmap bit = (bitmap)bitmap.fromfile(openfiledialog.filename, false);

                bitmap newbit = null;
                bitmapcrop(bit, path, out newbit);
                newbit.save(@"c:\users\public\pictures\sample pictures\沙漠22.jpg");
            }
        }

以下为裁剪的关键代码

/// <summary>
        /// 图片截图
        /// </summary>
        /// <param name="bitmap">原图</param>
        /// <param name="path">裁剪路径</param>
        /// <param name="outputbitmap">输出图</param>
        /// <returns></returns>
        public static bitmap bitmapcrop(bitmap bitmap, graphicspath path, out bitmap outputbitmap)
        {
            rectanglef rect = path.getbounds();
            int left = (int)rect.left;
            int top = (int)rect.top;
            int width = (int)rect.width;
            int height = (int)rect.height;
            bitmap image = (bitmap)bitmap.clone();
            outputbitmap = new bitmap(width, height);
            for (int i = left; i < left + width; i++)
            {
                for (int j = top; j < top + height; j++)
                {
                    //判断坐标是否在路径中  
                    if (path.isvisible(i, j))
                    {
                        //复制原图区域的像素到输出图片  
                        outputbitmap.setpixel(i - left, j - top, image.getpixel(i, j));
                        //设置原图这部分区域为透明  
                        image.setpixel(i, j, color.fromargb(0, image.getpixel(i, j)));
                    }
                    else
                    {
                        outputbitmap.setpixel(i - left, j - top, color.fromargb(0, 255, 255, 255));
                    }
                }
            }
            bitmap.dispose();
            return image;
        }

有了这个前台只需要获取用户的鼠标路径传到后台就可以。