picturebox控件中的图片如何放大缩小

[qq976542596]

picturebox控件中的图片如何放大缩小

[本拉灯]

这个要自定义控件，重截PictureBox

[娃都会打酱油了]

等比放大缩小么？第一部分代码就是等比例 http://blog.csdn.net/starfd/article/details/44850449

[qq976542596]

引用 2 楼 starfd 的回复:

等比放大缩小么？第一部分代码就是等比例 http://blog.csdn.net/starfd/article/details/44850449

             Point point = new Point(0, 0);  
            Point point2 = new Point(width, 0);  
            Point point3 = new Point(0, height);  
           Point[] destPoints = new Point[] { point, point2, point3 };  
           Rectangle rect = GetImageRectangle(fromImage);  
           graphics.DrawImage(fromImage, destPoints, rect, GraphicsUnit.Pixel);  

这里什么意思？

[娃都会打酱油了]

设置起点，然后矩形的两个位置，你F12看DrawImage对应的参数描述就有了解了

[qq976542596]

还有其他方法吗？

[娃都会打酱油了]

DrawImage你F12就知道了啊，好几个方法的

[a1295962107]

学习收藏了。

[-小蕾-]

第一种方法：

/// <summary>
        /// 图片等比例缩放
        /// </summary>
        /// <param name="b"></param>
        /// <param name="destHeight"></param>
        /// <param name="destWidth"></param>
        /// <returns></returns>
        public static Bitmap GetThumbnail(Bitmap b, int destHeight, int destWidth)
        {
            System.Drawing.Image imgSource = b;
            System.Drawing.Imaging.ImageFormat thisFormat = imgSource.RawFormat;
            int sW = 0, sH = 0;
            // 按比例缩放           
            int sWidth = imgSource.Width;
            int sHeight = imgSource.Height;
            if (sHeight > destHeight || sWidth > destWidth)
            {
                if ((sWidth * destHeight) > (sHeight * destWidth))
                {
                    sW = destWidth;
                    sH = (destWidth * sHeight) / sWidth;
                }
                else
                {
                    sH = destHeight;
                    sW = (sWidth * destHeight) / sHeight;
                }
            }
            else
            {
                sW = sWidth;
                sH = sHeight;
            }
            Bitmap outBmp = new Bitmap(destWidth, destHeight);
            Graphics g = Graphics.FromImage(outBmp);
            g.Clear(Color.Transparent);
            // 设置画布的描绘质量         
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;
            g.DrawImage(imgSource, new Rectangle((destWidth - sW) / 2, (destHeight - sH) / 2, sW, sH), 0, 0, imgSource.Width, imgSource.Height, GraphicsUnit.Pixel);
            g.Dispose();
            // 以下代码为保存图片时，设置压缩质量     
            EncoderParameters encoderParams = new EncoderParameters();
            long[] quality = new long[1];
            quality[0] = 100;
            EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
            encoderParams.Param[0] = encoderParam;
            imgSource.Dispose();
            return outBmp;
        }

第二种方法：

/// <summary>  
        ///  Resize图片   
        /// </summary>  
        /// <param name="bmp">原始Bitmap </param>  
        /// <param name="newW">新的宽度</param>  
        /// <param name="newH">新的高度</param>  
        /// <returns>处理以后的图片</returns>  
        public static Bitmap ResizeImage(Bitmap bmp, int newW, int newH)
        {
            try
            {
                Bitmap b = new Bitmap(newW, newH);
                Graphics g = Graphics.FromImage(b);
                // 插值算法的质量   
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.DrawImage(bmp, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, bmp.Width, bmp.Height), GraphicsUnit.Pixel);
                g.Dispose();
                return b;
            }
            catch
            {
                return null;
            }
        }