使用GDI+绘制高质量图和字体

对于GDI+,在正常的操作,Bitmap-- Graphcis -- DrawImage或者DrawString ,生成图片的话,会产生很多杂点,或者是图片质量不稳定..尤其是在读取图片后,生成缩略图之后,文件会被压缩而失真..

主要原因是因为没有重新设置Graphics的几个属性..

1.Graphics.SmoothingMode属性: 例如SmoothingMode.HighQuality可以产生高质量图片,但是效率低.

2.Graphics.CompositingQuality 属性: 例如:CompositingQuality.HighQuality也是产生高质量图,效率低下.

3.Graphics.InterpolationMode 属性,例如:InterpolationMode.HighQualityBicubic与前两个也是同样的效果.

这三个属性的值都是enum,具体的enum参数可以查看MSDN的说明..在这里就我不赘述..
如果是对图片进行放大,缩小,可以调整Graphics.CompositingQuality 和Graphics.InterpolationMode 两个属性..如果是图片生成,则可以调整Graphics.SmoothingMode属性..

另外一个问题就是关于文字生成的..按照正常的模式生成的文字,可以很明显的看到文字带有锯齿..解决的办法也是需要修改Graphics的一个属性: Graphics.TextRenderingHint...注意一点,修改TextRenderingHint的话,需要引入System.Drawing.Text,例如:Graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;

经过对这四个属性的修改,操作大部分的图片之后,产生的结果都是比较让人满意的..

在这里提供一个简单的例子..是生成印章签名的效果..提供四种字体选择..并产生一个图片..如果你的机器中没有安装指定的几种字体,你需要把字体修改一下...直接把代码拷贝..就可以看到效果...

ASPX页面:

<%@ Page language="c#" Codebehind="underWrite.aspx.cs" AutoEventWireup="false" Inherits="testItem.movie.underWrite" %>
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
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<HTML>
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<HEAD>
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<title>underWrite</title>
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</HEAD>
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<body MS_POSITIONING="GridLayout">
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<form id="Form1" method="post" runat="server">
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<asp:Image id="Image1" style="Z-INDEX: 101; LEFT: 208px; POSITION: absolute; TOP: 360px" runat="server"></asp:Image>
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<asp:HyperLink id="HyperLink1" style="Z-INDEX: 105; LEFT: 304px; POSITION: absolute; TOP: 312px"
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runat="server" NavigateUrl="../mv/index.html">大头帖</asp:HyperLink>
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<asp:TextBox id="name" style="Z-INDEX: 104; LEFT: 208px; POSITION: absolute; TOP: 144px" runat="server"
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MaxLength="4"></asp:TextBox>
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<asp:RadioButtonList id="fontType" style="Z-INDEX: 103; LEFT: 208px; POSITION: absolute; TOP: 184px"
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runat="server" Width="240px">
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<asp:ListItem Value="方正黄草简体" Selected="True">方正黄草简体</asp:ListItem>
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<asp:ListItem Value="汉鼎繁淡古">汉鼎繁淡古</asp:ListItem>
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<asp:ListItem Value="汉鼎繁印篆">汉鼎繁印篆</asp:ListItem>
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<asp:ListItem Value="经典繁桟亭">经典繁桟亭</asp:ListItem>
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</asp:RadioButtonList>
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<asp:Button id="bu" style="Z-INDEX: 102; LEFT: 208px; POSITION: absolute; TOP: 312px" runat="server"
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Text=" 刻字 "></asp:Button>
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</form>
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</body>
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</HTML>
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CS文件:

using System;
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using System.Collections;
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using System.ComponentModel;
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using System.Data;
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using System.Drawing;
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using System.Drawing.Drawing2D;
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using System.IO;
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using System.Web;
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using System.Web.SessionState;
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using System.Web.UI;
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using System.Web.UI.WebControls;
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using System.Web.UI.HtmlControls;
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namespace testItem.movie
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{
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/// <summary>
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/// 生成印章签名
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/// </summary>
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public class underWrite : System.Web.UI.Page
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{
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protected System.Web.UI.WebControls.Image Image1;
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protected System.Web.UI.WebControls.RadioButtonList fontType;
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protected System.Web.UI.WebControls.HyperLink HyperLink1;
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protected System.Web.UI.WebControls.Button bu;
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protected System.Web.UI.WebControls.TextBox name;
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private void Page_Load(object sender, System.EventArgs e)
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{
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Image1.Visible = false;
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}
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Web 窗体设计器生成的代码
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private void Button1_Click(object sender, System.EventArgs e)
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{
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string Name = name.Text;
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if ( Name.Length < 4 ) {
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Response.Write( "请输入最少4个字符!" );
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return;
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}
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string FontName = fontType.SelectedValue;
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int fontSize = 36;
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int x = 10;
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int y = 10;
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switch( FontName ) {
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case "方正黄草简体":
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x = -8;
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y = -2;
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fontSize = 42;
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break;
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case "汉鼎繁淡古":
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x = -10;
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y = -2;
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break;
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case "汉鼎繁印篆":
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x = -15;
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y = -2;
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break;
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case "经典繁桟亭":
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fontSize = 34;
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x = -10;
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y = -3;
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break;
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}
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Bitmap bm = new Bitmap(110,100,System.Drawing.Imaging.PixelFormat.Format32bppArgb);
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Font font = new Font(FontName,fontSize,FontStyle.Bold);
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Graphics g = Graphics.FromImage( bm );
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g.TextRenderingHint = System.Drawing.Text.TextRenderingHint.ClearTypeGridFit;
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/* 这里的三个属性可以根据情况开放.
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*
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//g.CompositingQuality = CompositingQuality.HighQuality;
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//g.SmoothingMode = SmoothingMode.HighQuality;
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//g.InterpolationMode = InterpolationMode.HighQualityBicubic;
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*/
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g.Clear(Color.Red); //赋予图像一个背景色
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g.DrawString( Name.Substring(2,1),font,new SolidBrush(Color.White),0,2 );
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g.DrawString( Name.Substring(3,1),font,new SolidBrush(Color.White),0,45-y );
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g.DrawString( Name.Substring(0,1),font,new SolidBrush(Color.White),35-x,2 );
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g.DrawString( Name.Substring(1,1),font,new SolidBrush(Color.White),35-x,45-y );
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g.Dispose();
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//设置保存路径
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bm.Save( Server.MapPath("../upload/c.jpg"),System.Drawing.Imaging.ImageFormat.Jpeg );
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bm.Dispose();
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//显示产生的图片
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Image1.ImageUrl = Server.MapPath("../upload/c.jpg") ;
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Image1.Visible = true;
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}
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}
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}
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效果:

来源：https://www.cnblogs.com/lixianhuei/archive/2006/01/18/319670.html

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asp

system