C#切割指定区域图片操作

使用winform制作了一个切割图片的功能，切一些固定大小的图片，比如头像。
界面如图：

打开本地图片

 OpenFileDialog opdialog = new OpenFileDialog();
            opdialog.InitialDirectory = @"C:";
            opdialog.FilterIndex = 1;
            opdialog.Filter = "Image   Files(*.BMP;*.JPG;*.PNG)|*.BMP;*.JPG;*.PNG";
            if (opdialog.ShowDialog() == System.Windows.Forms.DialogResult.OK)
                this.pb_photo_original.Image = Image.FromFile(opdialog.FileName);

拖动选择切割区域

if (e.Button != MouseButtons.Left)
                return;

            if (oldCutRect.Contains(e.Location))
            {
                this.newCutRect.Offset(e.Location.X - this.m_LastMSPoint.X, e.Location.Y - this.m_LastMSPoint.Y);
                if (newCutRect.Location.X < 0)
                    newCutRect.X = 0;
                if (newCutRect.Location.Y < 0)
                    newCutRect.Y = 0;
                if (newCutRect.Location.X + 128 > 300)
                    newCutRect.X = 300 - 128;
                if (newCutRect.Location.Y + 160 > 300)
                    newCutRect.Y = 300 - 160;

                this.panel_shade.Invalidate(oldCutRect, false);
                this.panel_shade.Invalidate(newCutRect, false);
                this.m_LastMSPoint = e.Location;
                oldCutRect = newCutRect;
            }

保存区域图片完成切割

Bitmap bitmap = new Bitmap(128, 160);        
            //创建作图区域   
            Graphics graphic = Graphics.FromImage(bitmap);
            Point p = this.pb_photo_original.PointToScreen(this.oldCutRect.Location);
            //截取原图相应区域写入作图区   
            //graphic.DrawImage(this.pb_photo_original.Image, new Rectangle(0, 0, 128, 160), oldCutRect, GraphicsUnit.Pixel);
            graphic.CopyFromScreen(p.X, p.Y, 0, 0, new Size(128, 160));

            Bitmap zoomBitmap = new Bitmap(bitmap, new Size(80, 100));
            this.pb_photo_cut.Image = zoomBitmap;

            //保存图象   
            zoomBitmap.Save(@"D:	est.jpg");

            bitmap.Dispose();
            graphic.Dispose();