Question

c#里面怎么使用gdi的库？

可以具体给个事例的话，追加分......

Answer 1

C#中使用GDI+实现饼状图和柱状图跟数据库联接显示数据的方法.(其实也就是饼图的制作原理之一)

using System;
using System.IO;//用于文件存取
using System.Data;//用于数据访问
using System.Drawing;//提供画GDI+图形的基本功能
using System.Drawing.Text;//提供画GDI+图形的高级功能
using System.Drawing.Drawing2D;//提供画高级二维，矢量图形功能
using System.Drawing.Imaging;//提供画GDI+图形的高级功能
namespace BaseLayer
{
public class PieChart
{
public PieChart()
{
}
//Render是图形大标题，图开小标题，图形宽度，图形长度，饼图的数据集和饼图的数据集要表示出来的数据
public Image Render(string title, string subTitle, int width, int height, DataSet chartData,int DataLine)
{
const int SIDE_LENGTH = 400;
const int PIE_DIAMETER = 200;
DataTable dt = chartData.Tables[0];

//通过输入参数，取得饼图中的总基数
float sumData = 0;
foreach(DataRow dr in dt.Rows)
{
sumData += Convert.ToSingle(dr[DataLine]);
}
//产生一个image对象，并由此产生一个Graphics对象
Bitmap bm = new Bitmap(width,height);
Graphics g = Graphics.FromImage(bm);
//设置对象g的属性
g.ScaleTransform((Convert.ToSingle(width))/SIDE_LENGTH,(Convert.ToSingle(height))/SIDE_LENGTH);
g.SmoothingMode = SmoothingMode.Default;
g.TextRenderingHint = TextRenderingHint.AntiAlias;

//画布和边的设定
g.Clear(Color.White);
g.DrawRectangle(Pens.Black,0,0,SIDE_LENGTH-1,SIDE_LENGTH-1);
//画饼图标题
g.DrawString(title,new Font("Tahoma",14),Brushes.Black,new PointF(5,5));
//画饼图的图例
g.DrawString(subTitle,new Font("Tahoma",12),Brushes.Black,new PointF(7,35));
//画饼图
float curAngle = 0;
float totalAngle = 0;
for(int i=0;i {
curAngle = Convert.ToSingle(dt.Rows[i][DataLine]) / sumData * 360;

g.FillPie(new SolidBrush(ChartUtil.GetChartItemColor(i)),100,65,PIE_DIAMETER,PIE_DIAMETER,totalAngle,curAngle);
g.DrawPie(Pens.Black,100,65,PIE_DIAMETER,PIE_DIAMETER,totalAngle,curAngle);
totalAngle += curAngle;
}
//画图例框及其文字
g.DrawRectangle(Pens.Black,200,300,199,99);
g.DrawString("图表说明",new Font("Tahoma",12,FontStyle.Bold),Brushes.Black,new PointF(200,300));

//画图例各项
PointF boxOrigin = new PointF(210,330);
PointF textOrigin = new PointF(235,326);
float percent = 0;
for(int i=0;i {
g.FillRectangle(new SolidBrush(ChartUtil.GetChartItemColor(i)),boxOrigin.X,boxOrigin.Y,20,10);
g.DrawRectangle(Pens.Black,boxOrigin.X,boxOrigin.Y,20,10);
percent = Convert.ToSingle(dt.Rows[i][DataLine]) / sumData * 100;
g.DrawString(dt.Rows[i][1].ToString() + " - " + dt.Rows[i][0].ToString() + " (" + percent.ToString("0") + "%)",new Font("Tahoma",10),Brushes.Black,textOrigin);
boxOrigin.Y += 15;
textOrigin.Y += 15;
}
//回收资源
g.Dispose();
return (Image) bm;

}
}

//画条形图
public class BarChart
{
public BarChart()
{
}
//Render是图形大标题，图开小标题，图形宽度，图形长度，饼图的数据集和饼图的数据集
public Image Render(string title, string subTitle, int width, int height, DataSet chartData)
{
const int SIDE_LENGTH = 400;
const int CHART_TOP = 75;
const int CHART_HEIGHT = 200;
const int CHART_LEFT = 50;
const int CHART_WIDTH = 300;
DataTable dt = chartData.Tables[0];

//计算最高的点
float highPoint = 0;
foreach(DataRow dr in dt.Rows)
{
if(highPoint {
highPoint = Convert.ToSingle(dr[0]);
}
}
//建立一个Graphics对象实例
Bitmap bm = new Bitmap(width,height);
try
{
Graphics g = Graphics.FromImage(bm);
//设置条图图形和文字属性
g.ScaleTransform((Convert.ToSingle(width))/SIDE_LENGTH,(Convert.ToSingle(height))/SIDE_LENGTH);
g.SmoothingMode = SmoothingMode.Default;
g.TextRenderingHint = TextRenderingHint.AntiAlias;

//设定画布和边
g.Clear(Color.White);
g.DrawRectangle(Pens.Black,0,0,SIDE_LENGTH-1,SIDE_LENGTH-1);
//画大标题
g.DrawString(title,new Font("Tahoma",14),Brushes.Black,new PointF(5,5));
//画小标题
g.DrawString(subTitle,new Font("Tahoma",12),Brushes.Black,new PointF(7,35));
//画条形图
float barWidth = CHART_WIDTH / (dt.Rows.Count * 2);
PointF barOrigin = new PointF(CHART_LEFT + (barWidth / 2),0);
float barHeight = dt.Rows.Count;
for(int i=0;i {
barHeight = Convert.ToSingle(dt.Rows[i][0]) * 200 / highPoint * 1;
barOrigin.Y = CHART_TOP + CHART_HEIGHT - barHeight;
g.FillRectangle(new SolidBrush(ChartUtil.GetChartItemColor(i)),barOrigin.X,barOrigin.Y,barWidth,barHeight);
barOrigin.X = barOrigin.X + (barWidth * 2);
}
//设置边
g.DrawLine(new Pen(Color.Black,2),new Point(CHART_LEFT,CHART_TOP),new Point(CHART_LEFT,CHART_TOP + CHART_HEIGHT));
g.DrawLine(new Pen(Color.Black,2),new Point(CHART_LEFT,CHART_TOP + CHART_HEIGHT),new Point(CHART_LEFT + CHART_WIDTH,CHART_TOP + CHART_HEIGHT));
//画图例框和文字
g.DrawRectangle(new Pen(Color.Black,1),200,300,199,99);
g.DrawString("图表说明",new Font("Tahoma",12,FontStyle.Bold),Brushes.Black,new PointF(200,300));

//画图例
PointF boxOrigin = new PointF(210,330);
PointF textOrigin = new PointF(235,326);
for(int i=0;i {
g.FillRectangle(new SolidBrush(ChartUtil.GetChartItemColor(i)),boxOrigin.X,boxOrigin.Y,20,10);
g.DrawRectangle(Pens.Black,boxOrigin.X,boxOrigin.Y,20,10);
g.DrawString(dt.Rows[i][1].ToString() + " - " + dt.Rows[i][0].ToString(),new Font("Tahoma",10),Brushes.Black,textOrigin);
boxOrigin.Y += 15;
textOrigin.Y += 15;
}
//输出图形
g.Dispose();
return bm;
}
catch
{
return bm;
}
}
}
public class ChartUtil
{
public ChartUtil()
{
}
public static Color GetChartItemColor(int itemIndex)
{
Color selectedColor;
switch(itemIndex)
{
case 0:
selectedColor = Color.Blue;
break;
case 1:
selectedColor = Color.Red;
break;
case 2:
selectedColor = Color.Yellow;
break;
case 3:
selectedColor = Color.Purple;
break;
default:
selectedColor = Color.Green;
break;
}
return selectedColor;
}
}
}

Answer 2

不知道你说的GDI算不算GDI+。

这样说吧
======调用GDI+
很简单，System.Drawing命名空间就是为GDI+而设计的，用Graphics类进行Draw/Fill函数，就是调用GDI+

======调用GDI
NET中绘图多是GDI+的，但也有托管下的GDI函数，比如TextRender类就是GDI的，（因为GDI+的DrawString绘图不精准，因此NET 2.0引入了GDI的TextRender）

也可以直接调用Windows API中的GDI，用DllImport链接gdi32.dll，调用里面的函数就可以了。

Answer 3

关注中……