A brief discussion on using GDI+ in C#

C# uses GDI+

When our software requires various pie charts and bar charts to represent data, we may think of using graphic controls in Offices or third-party controls, but most of the current third-party controls require registration. Some free controls will have developer logos, etc. As for the graphical controls using Offices, they cannot be well controlled in the program, and their ease of use is also low, so here I will use GDI+ to connect pie charts and bar charts to the database in C#. Method to display data.

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;  
}  
}  
}

The above is a complete source program for making pie charts and bar charts in WinForm. You can make changes to the above program to meet the needs of your own program. C# uses GDI+ to realize the method of connecting pie charts and bar charts to the database to display data.

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