请问如何将大图片缩小显示？
请问如何将大图片缩小显示？
我试过用<asp:Image>和<asp:ImageButton>，指定它的宽度和高度，但只要图片大小超过指定的宽高，都会显示成原始大上，把页面弄得混乱不堪。而且图片太多，不可能全部处理成指定大小，所以上来请教，谢谢!
[解决办法]
应该不会.
<asp:image style="width:100px;height:100px" 不管图片多大都会按指定大小显示
[解决办法]
1 直接使用缩略图
2 将图片转换成一定大小再显示（比例，固定高度和宽度等）
[解决办法]
- C# code
//代码摘自网络,自己定义个类，将相关代码放进去即可使用enum Dimensions { Width, Height } enum AnchorPosition { Top, Center, Bottom, Left, Right }static Image ScaleByPercent(Image imgPhoto, int Percent) { float nPercent = ((float)Percent/100); int sourceWidth = imgPhoto.Width; int sourceHeight = imgPhoto.Height; int sourceX = 0; int sourceY = 0; int destX = 0; int destY = 0; int destWidth = (int)(sourceWidth * nPercent); int destHeight = (int)(sourceHeight * nPercent); Bitmap bmPhoto = new Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb); bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); Graphics grPhoto = Graphics.FromImage(bmPhoto); grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; grPhoto.DrawImage(imgPhoto, new Rectangle(destX,destY,destWidth,destHeight), new Rectangle(sourceX,sourceY,sourceWidth,sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); return bmPhoto; } static Image ConstrainProportions(Image imgPhoto, int Size, Dimensions Dimension) { int sourceWidth = imgPhoto.Width; int sourceHeight = imgPhoto.Height; int sourceX = 0; int sourceY = 0; int destX = 0; int destY = 0; float nPercent = 0; switch(Dimension) { case Dimensions.Width: nPercent = ((float)Size/(float)sourceWidth); break; default: nPercent = ((float)Size/(float)sourceHeight); break; } int destWidth = (int)(sourceWidth * nPercent); int destHeight = (int)(sourceHeight * nPercent); Bitmap bmPhoto = new Bitmap(destWidth, destHeight, PixelFormat.Format24bppRgb); bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); Graphics grPhoto = Graphics.FromImage(bmPhoto); grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; grPhoto.DrawImage(imgPhoto, new Rectangle(destX,destY,destWidth,destHeight), new Rectangle(sourceX,sourceY,sourceWidth,sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); return bmPhoto; } static Image FixedSize(Image imgPhoto, int Width, int Height) { int sourceWidth = imgPhoto.Width; int sourceHeight = imgPhoto.Height; int sourceX = 0; int sourceY = 0; int destX = 0; int destY = 0; float nPercent = 0; float nPercentW = 0; float nPercentH = 0; nPercentW = ((float)Width/(float)sourceWidth); nPercentH = ((float)Height/(float)sourceHeight); //if we have to pad the height pad both the top and the bottom //with the difference between the scaled height and the desired height if(nPercentH < nPercentW) { nPercent = nPercentH; destX = (int)((Width - (sourceWidth * nPercent))/2); } else { nPercent = nPercentW; destY = (int)((Height - (sourceHeight * nPercent))/2); } int destWidth = (int)(sourceWidth * nPercent); int destHeight = (int)(sourceHeight * nPercent); Bitmap bmPhoto = new Bitmap(Width, Height, PixelFormat.Format24bppRgb); bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); Graphics grPhoto = Graphics.FromImage(bmPhoto); grPhoto.Clear(Color.Red); grPhoto.InterpolationMode = InterpolationMode.HighQualityBicubic; grPhoto.DrawImage(imgPhoto, new Rectangle(destX,destY,destWidth,destHeight), new Rectangle(sourceX,sourceY,sourceWidth,sourceHeight), GraphicsUnit.Pixel); grPhoto.Dispose(); return bmPhoto; }
[解决办法]
- C# code
using System.Drawing;using System.Drawing.Imaging;using System.Drawing.Drawing2D;
[解决办法]
生成缩略图就行了..
- C# code
using System;using System.Data;using System.Configuration;using System.Drawing;namespace MyClassLib{ /// <summary> /// MakeThumbnail 的摘要说明 /// </summary> public class MakeThumbnail { public MakeThumbnail() { // // TODO: 在此处添加构造函数逻辑 // } /// <summary> /// 生成缩略图 /// </summary> /// <param name=\"originalImagePath\">源图路径（物理路径）</param> /// <param name=\"thumbnailPath\">缩略图路径（物理路径）</param> /// <param name=\"width\">缩略图宽度</param> /// <param name=\"height\">缩略图高度</param> /// <param name=\"mode\">生成缩略图的方式</param> public static void Makethumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode) { System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath); int towidth = width; int toheight = height; int x = 0; int y = 0; int ow = originalImage.Width; int oh = originalImage.Height; switch (mode) { case "HW"://指定高宽缩放（可能变形） break; case "W"://指定宽，高按比例 toheight = originalImage.Height * width / originalImage.Width; break; case "H"://指定高，宽按比例 towidth = originalImage.Width * height / originalImage.Height; break; case "Cut"://指定高宽裁减（不变形） if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight) { oh = originalImage.Height; ow = originalImage.Height * towidth / toheight; y = 0; x = (originalImage.Width - ow) / 2; } else { ow = originalImage.Width; oh = originalImage.Width * height / towidth; x = 0; y = (originalImage.Height - oh) / 2; } break; default: break; } //新建一个bmp图片 System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight); //新建一个画板 System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap); //设置高质量插值法 g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; //设置高质量,低速度呈现平滑程度 g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //清空画布并以透明背景色填充 g.Clear(Color.Transparent); //在指定位置并且按指定大小绘制原图片的指定部分 g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight), new Rectangle(x, y, ow, oh), GraphicsUnit.Pixel); try { //以jpg格式保存缩略图 bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg); } catch (System.Exception e) { throw e; } finally { originalImage.Dispose(); bitmap.Dispose(); g.Dispose(); } } }}