C#无损压缩图片
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2023-01-07 11:31:14
话不多说,请看代码:
///
/// 根据指定尺寸得到按比例缩放的尺寸,返回true表示以更改尺寸
/// &...
话不多说,请看代码:
/// <summary> /// 根据指定尺寸得到按比例缩放的尺寸,返回true表示以更改尺寸 /// </summary> /// <param name="picwidth">图片宽度</param> /// <param name="picheight">图片高度</param> /// <param name="specifiedwidth">指定宽度</param> /// /// <param name="specifiedheight">指定高度</param> /// <returns>返回true表示以更改尺寸</returns> private bool getpiczoomsize(ref int picwidth, ref int picheight, int specifiedwidth, int specifiedheight) { int sw = 0, sh = 0; boolean iszoomsize = false; //按比例缩放 size tem_size = new size(picwidth, picheight); if (tem_size.width > specifiedwidth || tem_size.height > specifiedheight) //将**改成c#中的或者操作符号 { if ((tem_size.width * specifiedheight) > (tem_size.height * specifiedwidth)) { sw = specifiedwidth; sh = (specifiedwidth * tem_size.height) / tem_size.width; } else { sh = specifiedheight; sw = (tem_size.width * specifiedheight) / tem_size.height; } iszoomsize = true; } else { sw = tem_size.width; sh = tem_size.height; } picheight = sh; picwidth = sw; return iszoomsize; } /// <summary> /// 无损压缩图片 /// </summary> /// <param name="sfile">原图片</param> /// <param name="dfile">压缩后保存位置</param> /// <param name="dheight">高度</param> /// <param name="dwidth">宽度</param> /// <param name="flag">压缩质量 1-100</param> /// <returns></returns> public bool getpicthumbnail(string sfile, string dfile, int dheight, int dwidth, int flag) { system.drawing.image isource = system.drawing.image.fromfile(sfile); imageformat tformat = isource.rawformat; int sw = isource.width, sh = isource.height; getpiczoomsize(ref sw, ref sh, dwidth, dheight); bitmap ob = new bitmap(dwidth, dheight); graphics g = graphics.fromimage(ob); g.clear(color.whitesmoke); g.compositingquality = compositingquality.highquality; g.smoothingmode = smoothingmode.highquality; g.interpolationmode = interpolationmode.highqualitybicubic; g.drawimage(isource, new rectangle((dwidth - sw) / 2, (dheight - sh) / 2, sw, sh), 0, 0, isource.width, isource.height, graphicsunit.pixel); g.dispose(); //以下代码为保存图片时,设置压缩质量 encoderparameters ep = new encoderparameters(); long[] qy = new long[1]; qy[0] = flag;//设置压缩的比例1-100 encoderparameter eparam = new encoderparameter(system.drawing.imaging.encoder.quality, qy); ep.param[0] = eparam; try { imagecodecinfo[] arrayici = imagecodecinfo.getimageencoders(); imagecodecinfo jpegiciinfo = null; for (int x = 0; x < arrayici.length; x++) { if (arrayici[x].formatdescription.equals("jpeg")) { jpegiciinfo = arrayici[x]; break; } } if (jpegiciinfo != null) { ob.save(dfile, jpegiciinfo, ep);//dfile是压缩后的新路径 } else { ob.save(dfile, tformat); } return true; } catch { return false; } finally { isource.dispose(); ob.dispose(); } }
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