淺談C#使用GDI+

C#使用GDI+

當我們的軟體需要各種餅狀圖和柱狀圖來表示資料時，我們或許會想到用Offices中的圖形控製或是第三方控制項，但現在的第三方控制項大都需要註冊，有些免費的控制會有開發商的標記等。而對於使用Offices的圖形控制來說，並不能在程式中得良好控制，其使用的簡易程度也較低，所以在這我給出在C#使用GDI+實現餅狀圖和柱狀圖跟資料庫聯接顯示資料的方法。

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<dt.Rows.Count;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<dt.Rows.Count;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<Convert.ToSingle(dr[0]))  
{  
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<dt.Rows.Count;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);  
barOriginbarOrigin.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<dt.Rows.Count;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;  
}  
}  
}

以上是一個完整的WinForm中製作餅狀圖和柱狀圖源程序，大家可以透過以上程序的更改，做出能滿足自己程序的需要。 C#使用GDI+實現餅狀圖和長條圖跟資料庫聯接顯示資料的方法。

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