目录
一、柱形图
1.示例源码
2.生成效果
二、折线图
1.示例源码
2.生成效果
三、饼形图
1.示例源码
2.生成效果
GDI+绘制的一些常用的图形，其中包括柱形图、折线图和饼形图。
一、柱形图
柱形图也称为条形图，是程序开发中比较常用的一种图表技术。柱形图是通过Graphics
类中的FillRectangle()方法实现的。
public void FillRectangle (Brush brush,int x,int y,int width,int height)| 参 数 | 说 明 |
| brush | 确定填充特性的Brush |
| X | 要填充矩形左上角的x坐标 |
| y | 要填充矩形左上角的y坐标 |
| width | 要填充矩形的宽度 |
| height | 要填充矩形的高度 |
1.示例源码
,NET 8.0的项目中需要使用NuGet程序包：system.data.sqlclient.4.8.5.nupkg。否则不能使用SqlClient的方法。
//Form1.cs
//投票窗口
using System.Data.SqlClient;
namespace _12
{
public partial class Form1 : Form
{
SqlConnection? conn;
public Form1()
{
InitializeComponent();
}
private void Form1_Load(object sender, EventArgs e)
{
ClientSize = new Size(292, 192); //设置Form1工作区域
StartPosition = FormStartPosition.CenterScreen;
radioButton1.Checked = false;
radioButton1.Text = "支付宝";
radioButton2.Text = "微信支付";
radioButton3.Text = "京东白条";
radioButton4.Text = "小度钱包";
button1.Text = "投一票吧";
button2.Text = "投票结果";
groupBox1.Text = "投票窗口";
radioButton1.Location = new Point(26, 37);
radioButton2.Location = new Point(26, 68);
radioButton3.Location = new Point(26, 101);
radioButton4.Location = new Point(26, 132);
radioButton1.Size = new Size(60, 16);
radioButton2.Size = new Size(60, 16);
radioButton3.Size = new Size(60, 16);
radioButton4.Size = new Size(60, 16);
button1.Location = new Point(195, 94);
button2.Location = new Point(195, 132);
button1.Size = new Size(75, 23);
button2.Size = new Size(75, 23);
}
private void Button1_Click(object sender, EventArgs e)
{
try
{
conn = new SqlConnection(@"server=DESKTOP-S11C97H\SQLEXPRESS;database=db_CSharp;integrated security = True");
string sqlstr = "";
if (radioButton1.Checked)
{
sqlstr = "update tb_vote set 票数=票数+1 where 选项='" + radioButton1.Text + "'";
}
if (radioButton2.Checked)
{
sqlstr = "update tb_vote set 票数=票数+1 where 选项='" + radioButton2.Text + "'";
}
if (radioButton3.Checked)
{
sqlstr = "update tb_vote set 票数=票数+1 where 选项='" + radioButton3.Text + "'";
}
if (radioButton4.Checked)
{
sqlstr = "update tb_vote set 票数=票数+1 where 选项='" + radioButton4.Text + "'";
}
conn.Open();
SqlCommand cmd = new(sqlstr, conn);
int i = cmd.ExecuteNonQuery();
conn.Close();
if (i > 0)
{
MessageBox.Show("投票成功");
}
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void Button2_Click(object sender, EventArgs e)
{
Form2 frm2 = new();
frm2.Show();
}
}
}
//Form2.cs
//根据选票数据库，绘制直方图
using System.Data;
using System.Data.SqlClient;
namespace _12
{
public partial class Form2 : Form
{
public Form2()
{
InitializeComponent();
}
private int Sum;
SqlConnection? conn;
private void CreateImage()
{
conn = new SqlConnection(@"server=DESKTOP-S11C97H\SQLEXPRESS;database=db_CSharp;integrated security = True");
conn.Open();
SqlCommand cmd = new("select sum(票数) from tb_vote", conn);
Sum = (int)cmd.ExecuteScalar();
SqlDataAdapter sda = new("select * from tb_vote", conn);
DataSet ds = new();
sda.Fill(ds);
int TP1 = Convert.ToInt32(ds.Tables[0].Rows[0][2].ToString());//第一个选项的票数
int TP2 = Convert.ToInt32(ds.Tables[0].Rows[1][2].ToString());//第二个选项的票数
int TP3 = Convert.ToInt32(ds.Tables[0].Rows[2][2].ToString());//第三个选项的票数
int TP4 = Convert.ToInt32(ds.Tables[0].Rows[3][2].ToString());//第四个选项的票数
float tp1 = Convert.ToSingle(Convert.ToSingle(TP1) * 100 / Convert.ToSingle(Sum));
float tp2 = Convert.ToSingle(Convert.ToSingle(TP2) * 100 / Convert.ToSingle(Sum));
float tp3 = Convert.ToSingle(Convert.ToSingle(TP3) * 100 / Convert.ToSingle(Sum));
float tp4 = Convert.ToSingle(Convert.ToSingle(TP4) * 100 / Convert.ToSingle(Sum));
int width = 300, height = 300;
Bitmap bitmap = new(width, height);
Graphics g = Graphics.FromImage(bitmap);
try
{
g.Clear(Color.White);
Brush brush1 = new SolidBrush(Color.LightGray);
Brush brush2 = new SolidBrush(Color.Black);
Brush brush3 = new SolidBrush(Color.Red);
Brush brush4 = new SolidBrush(Color.Green);
Brush brush5 = new SolidBrush(Color.Orange);
Brush brush6 = new SolidBrush(Color.DarkBlue);
Font font1 = new("Courier New", 16, FontStyle.Bold);
Font font2 = new("Courier New", 8);
g.FillRectangle(brush1, 0, 0, width, height); //绘制背景浅灰色
g.DrawString("投票结果", font1, brush2, new Point(90, 20));
Point p1 = new(70, 50);
Point p2 = new(230, 50);
g.DrawLine(new Pen(Color.Black), p1, p2);
//绘制文字
g.DrawString("支付宝：", font2, brush2, new Point(45, 80));
g.DrawString("微信支付：", font2, brush2, new Point(32, 110));
g.DrawString("京东白条：", font2, brush2, new Point(32, 140));
g.DrawString("小度钱包：", font2, brush2, new Point(32, 170));
//绘制柱形图
g.FillRectangle(brush3, 95, 80, tp1, 17);
g.FillRectangle(brush4, 95, 110, tp2, 17);
g.FillRectangle(brush5, 95, 140, tp3, 17);
g.FillRectangle(brush6, 95, 170, tp4, 17);
//绘制所有选项的票数显示
g.DrawRectangle(new Pen(Color.Green), 10, 210, 280, 80); //绘制范围框
g.DrawString("支付宝：" + TP1.ToString() + "票", font2, brush2, new Point(15, 220));
g.DrawString("微信支付：" + TP2.ToString() + "票", font2, brush2, new Point(150, 220));
g.DrawString("京东白条：" + TP3.ToString() + "票", font2, brush2, new Point(15, 260));
g.DrawString("小度钱包：" + TP4.ToString() + "票", font2, brush2, new Point(150, 260));
pictureBox1.Image = bitmap;
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
}
private void Form2_Paint(object sender, PaintEventArgs e)
{
CreateImage();
}
/// <summary>
/// 设置窗体工作区大小，设置绘图板工作区，默认边距=8mm
/// </summary>
private void Form2_Load(object sender, EventArgs e)
{
ClientSize = new Size(324, 324); //Form2工作区域大小
StartPosition = FormStartPosition.CenterScreen;
pictureBox1.Size = new Size(300, 300); //pictureBox1尺寸，边距8mm
}
}
}
2.生成效果
二、折线图
折线图可以很直观地反映出相关数据的变化趋势，折线图主要是通过绘制点和折线实现的。绘制点是通过Graphics类中的FillEllipse()方法实现的。绘制折线是通过Graphics类中的DrawLine()方法实现的。
用DrawString()方法绘制文本时，文本的长度必须在所绘制的矩形区域内，如果超出区域，必须用format参数指定截断方式，否则将在最近的单词处截断。
1.示例源码
//折线图、趋势图
namespace _11
{
public partial class Form1 : Form
{
public Form1()
{
InitializeComponent();
}
private void Form1_Paint(object sender, PaintEventArgs e)
{
string[] month = ["一月", "二月", "三月", "四月", "五月", "六月", "七月", "八月", "九月", "十月", "十一月", "十二月"];
float[] d = [20.5F, 60, 10.8F, 15.6F, 30, 70.9F, 50.3F, 30.7F, 70, 50.4F, 30.8F, 20];
//画图初始化
Bitmap bMap = new(500, 500);
Graphics gph = Graphics.FromImage(bMap);
gph.Clear(Color.White);
PointF cPt = new(40, 420); //坐标原点
PointF[] xPt = [new PointF(cPt.Y + 15, cPt.Y), new PointF(cPt.Y, cPt.Y - 4), new PointF(cPt.Y, cPt.Y + 4)]; //X轴箭头点
PointF[] yPt = [new PointF(cPt.X, cPt.X - 15), new PointF(cPt.X - 4, cPt.X), new PointF(cPt.X + 4, cPt.X)]; //Y轴箭头点
gph.DrawString("产品月产量趋势图", new Font("宋体", 14), Brushes.Blue, new PointF(cPt.X + 60, cPt.X)); //图标题
//画X轴
gph.DrawLine(Pens.Green, cPt.X, cPt.Y, cPt.Y, cPt.Y); //X轴的长度=420= cPt.Y
gph.DrawPolygon(Pens.Black, xPt); //X轴箭头
gph.FillPolygon(new SolidBrush(Color.Pink), xPt);
gph.DrawString("月份", new Font("宋体", 12), Brushes.Black, new PointF(cPt.Y + 10, cPt.Y + 10));
//画Y轴
gph.DrawLine(Pens.Black, cPt.X, cPt.Y, cPt.X, cPt.X); //Y轴的长度=420-40=380
gph.DrawPolygon(Pens.Black, yPt); //Y轴箭头
gph.FillPolygon(new SolidBrush(Color.Black), yPt);
gph.DrawString("单位(万)", new Font("宋体", 12), Brushes.Black, new PointF(0, 7));
for (int i = 1; i <= 12; i++)
{
//画Y轴刻度
if (i < 11)
{
gph.DrawString((i * 10).ToString(), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X - 30, cPt.Y - i * 30 - 6)); //间隔30单位打一个标记，工程值和坐标值间有个3倍的关系
gph.DrawLine(Pens.Black, cPt.X - 3, cPt.Y - i * 30, cPt.X, cPt.Y - i * 30); //间隔30单位刻一条标尺
}
//画X轴项目
gph.DrawString(month[i - 1].AsSpan(0, 1), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30 - 5, cPt.Y + 5)); //间隔30单位打第一个字
gph.DrawString(month[i - 1].AsSpan(1, 1), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30 - 5, cPt.Y + 20)); //间隔30单位打第二个字
if (month[i - 1].Length > 2) gph.DrawString(month[i - 1].AsSpan(2, 1), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30 - 5, cPt.Y + 35)); //间隔30单位打第三个字
//画数据点
gph.DrawEllipse(Pens.Black, cPt.X + i * 30 - 1.5F, cPt.Y - d[i - 1] * 3 - 1.5F, 3, 3); //以下Y坐标都要乘以3倍
gph.FillEllipse(new SolidBrush(Color.Black), cPt.X + i * 30 - 1.5F, cPt.Y - d[i - 1] * 3 - 1.5F, 3, 3);
//画数据值
gph.DrawString(d[i - 1].ToString(), new Font("宋体", 11), Brushes.Black, new PointF(cPt.X + i * 30, cPt.Y - d[i - 1] * 3));
//画折线
if (i > 1) gph.DrawLine(Pens.Red, cPt.X + (i - 1) * 30, cPt.Y - d[i - 2] * 3, cPt.X + i * 30, cPt.Y - d[i - 1] * 3);
}
pictureBox1.Image = bMap;
}
}
}
2.生成效果
三、饼形图
饼形图可以很直观地查看不同数据所占的比例情况，通过Graphics类中的FillPie()方法，可以方便地绘制出饼形图。
public void FillPie (Brush brush,int x,int y,int width,int height,int startAngle,int sweepAngle)| 参 数 | 说 明 |
| brush | 确定填充特性的Brush |
| X | 边框左上角的x坐标，该边框定义扇形区所属的椭圆 |
| y | 边框左上角的y坐标，该边框定义扇形区所属的椭圆 |
| width | 边框的宽度，该边框定义扇形区所属的椭圆 |
| heigh | 边框的高度，该边框定义扇形区所属的椭圆 |
| startAngle | 从x轴沿顺时针方向旋转到扇形区第一个边所测得的角度(以度为单位) |
| sweepAngle | 从startAngle参数沿顺时针方向旋转到扇形区第二个边所测得的角度(以度为单位) |
