面是該程序的運(yùn)行效果:
可以看到,此程序不但要畫的函數(shù)的表達(dá)式可以由用戶動(dòng)態(tài)地輸入,而且函數(shù)自變量的范圍也可以是常量表達(dá)式。 下面就是源程序:
// plot.cs: 畫函數(shù)圖形, 編譯方法: csc /t:winexe plot.cs Expression.cs
using System;
using System.Drawing;
using System.Windows.Forms;
using Skyiv.Util;
namespace Skyiv.Ben.Plot
{
sealed class PlotForm : Form
{
const int yBase = 24; // 屏幕保留區(qū)域的高度
TextBox tbxX0, tbxX1; // 函數(shù)自變量的取值范圍
TextBox tbxExpression; // 函數(shù)的表達(dá)式
PlotForm()
{
SuspendLayout();
Button btnSubmit = new Button();
btnSubmit.Text = "刷新";
btnSubmit.Location = new Point(0, 0);
btnSubmit.Size = new Size(48, 24);
btnSubmit.Click += new EventHandler(BtnSubmit_Click);
tbxX0 = new TextBox();
tbxX0.Text = "-Math.PI";
tbxX0.Location = new Point(55, 3);
tbxX0.Size = new Size(100, 20);
tbxX1 = new TextBox();
tbxX1.Text = "Math.PI";
tbxX1.Location = new Point(160, 3);
tbxX1.Size = new Size(100, 20);
tbxExpression = new TextBox();
tbxExpression.Text = "Math.Sin(x)";
tbxExpression.Location = new Point(265, 3);
tbxExpression.Size = new Size(335, 20);
tbxExpression.Anchor = (AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right);
Controls.AddRange(new Control[]{btnSubmit, tbxX0, tbxX1, tbxExpression});
Text = "Plot";
BackColor = Color.White;
ClientSize = new Size(600, 600 + yBase);
// WindowState = FormWindowState.Maximized;
ResumeLayout(false);
}
// 點(diǎn)擊“刷新”按鈕時(shí)重繪程序主窗口
void BtnSubmit_Click(object sender, EventArgs e)
{
Invalidate();
}
/*
// 因?yàn)楸境绦蚴褂?nbsp;C# 的反射功能動(dòng)態(tài)生成數(shù)學(xué)表達(dá)式并計(jì)算其值
// 所以重畫時(shí)有點(diǎn)慢,如果你的計(jì)算機(jī)的速度不是非?斓,
// 就不要在窗口改變大小時(shí)強(qiáng)制重繪,而是通過(guò)點(diǎn)擊發(fā)“刷新”按鈕重繪。
protected override void OnSizeChanged(EventArgs e)
{
Invalidate();
base.OnSizeChanged(e);
}
*/
protected override void OnPaint(PaintEventArgs e)
{
Graphics gc = e.Graphics;
try
{
double x0 = new Expression(tbxX0.Text).Compute(0);
double x1 = new Expression(tbxX1.Text).Compute(0);
Size size = ClientSize;
int i0 = 0;
int i1 = size.Width - 1;
int j0 = yBase;
int j1 = size.Height - 1;
Pen pen = new Pen(Color.Black, 1);
gc.DrawLine(pen, i0, j0, i1, j0); // 畫圖區(qū)和保留區(qū)的分界線
double rx = (x1 - x0) / (i1 - i0);
double y0, y1;
Expression fx = new Expression(tbxExpression.Text);
GetFunctionValueRange(fx, x0, rx, i0, i1, out y0, out y1);
double ry = (y1 - y0) / (j1 - j0);
Out(gc, 0, "ClientSize: {0}x{1}", i1 - i0 + 1, j1 - j0 + 1);
Out(gc, 1, "f(x): " + tbxExpression.Text);
Out(gc, 2, "x:[{0}, {1}] range:{2}", x0, x1, x1 - x0);
Out(gc, 3, "y:[{0}, {1}] range:{2}", y0, y1, y1 - y0);
Out(gc, 4, "rx:{0}", 1 / rx); // 函數(shù)自變量每單位值用多少個(gè)象素表示
Out(gc, 5, "ry:{0}", 1 / ry); // 函數(shù)的值每單位值用多少個(gè)象素表示
Out(gc, 6, "r :{0}", rx / ry); // 該值如果小于1表示圖形縱向被壓扁,反之則被拉伸
pen.Color = Color.Green;
int j = j1 + (int)(y0 / ry);
if (j >= j0 && j <= j1) gc.DrawLine(pen, i0, j, i1, j); // x坐標(biāo)軸
int i = i0 - (int)(x0 / rx);
if (i >= i0 && i <= i1) gc.DrawLine(pen, i, j0, i, j1); // y坐標(biāo)軸
pen.Color = Color.Red;
for (i = i0; i <= i1; i++)
{
double x = x0 + (i - i0) * rx;
double y = fx.Compute(x);
if (double.IsInfinity(y) || double.IsNaN(y)) continue;
j = j1 - (int)((y - y0) / ry);
if (j > j1 || j < j0) continue;
gc.DrawLine(pen, i, j, i + 1, j); // 畫函數(shù)的圖形
}
}
catch (Exception ex)
{
Out(gc, 0, ex.Message);
}
base.OnPaint(e);
}
// 函數(shù)值的取值范圍
void GetFunctionValueRange(Expression fx, double x0, double rx, int i0, int i1, out double y0, out double y1)
{
y0 = double.MaxValue;
y1 = double.MinValue;
for (int i = i0; i <= i1; i++)
{
double x = x0 + (i - i0) * rx;
double y = fx.Compute(x);
if (double.IsInfinity(y) || double.IsNaN(y)) continue;
if (y0 > y) y0 = y;
if (y1 < y) y1 = y;
}
}
// 在指定的位置寫字符串
void Out(Graphics gc, int line, string fmt, params object [] args)
{
gc.DrawString(string.Format(fmt, args), new Font("Courier New", 10), Brushes.Blue, new PointF(5, yBase + 15 * line));
}
static void Main()
{
Application.Run(new PlotForm());
}
}
}
using System;
using System.Drawing;
using System.Windows.Forms;
using Skyiv.Util;
namespace Skyiv.Ben.Plot
{
sealed class PlotForm : Form
{
const int yBase = 24; // 屏幕保留區(qū)域的高度
TextBox tbxX0, tbxX1; // 函數(shù)自變量的取值范圍
TextBox tbxExpression; // 函數(shù)的表達(dá)式
PlotForm()
{
SuspendLayout();
Button btnSubmit = new Button();
btnSubmit.Text = "刷新";
btnSubmit.Location = new Point(0, 0);
btnSubmit.Size = new Size(48, 24);
btnSubmit.Click += new EventHandler(BtnSubmit_Click);
tbxX0 = new TextBox();
tbxX0.Text = "-Math.PI";
tbxX0.Location = new Point(55, 3);
tbxX0.Size = new Size(100, 20);
tbxX1 = new TextBox();
tbxX1.Text = "Math.PI";
tbxX1.Location = new Point(160, 3);
tbxX1.Size = new Size(100, 20);
tbxExpression = new TextBox();
tbxExpression.Text = "Math.Sin(x)";
tbxExpression.Location = new Point(265, 3);
tbxExpression.Size = new Size(335, 20);
tbxExpression.Anchor = (AnchorStyles.Top | AnchorStyles.Left | AnchorStyles.Right);
Controls.AddRange(new Control[]{btnSubmit, tbxX0, tbxX1, tbxExpression});
Text = "Plot";
BackColor = Color.White;
ClientSize = new Size(600, 600 + yBase);
// WindowState = FormWindowState.Maximized;
ResumeLayout(false);
}
// 點(diǎn)擊“刷新”按鈕時(shí)重繪程序主窗口
void BtnSubmit_Click(object sender, EventArgs e)
{
Invalidate();
}
/*
// 因?yàn)楸境绦蚴褂?nbsp;C# 的反射功能動(dòng)態(tài)生成數(shù)學(xué)表達(dá)式并計(jì)算其值
// 所以重畫時(shí)有點(diǎn)慢,如果你的計(jì)算機(jī)的速度不是非?斓,
// 就不要在窗口改變大小時(shí)強(qiáng)制重繪,而是通過(guò)點(diǎn)擊發(fā)“刷新”按鈕重繪。
protected override void OnSizeChanged(EventArgs e)
{
Invalidate();
base.OnSizeChanged(e);
}
*/
protected override void OnPaint(PaintEventArgs e)
{
Graphics gc = e.Graphics;
try
{
double x0 = new Expression(tbxX0.Text).Compute(0);
double x1 = new Expression(tbxX1.Text).Compute(0);
Size size = ClientSize;
int i0 = 0;
int i1 = size.Width - 1;
int j0 = yBase;
int j1 = size.Height - 1;
Pen pen = new Pen(Color.Black, 1);
gc.DrawLine(pen, i0, j0, i1, j0); // 畫圖區(qū)和保留區(qū)的分界線
double rx = (x1 - x0) / (i1 - i0);
double y0, y1;
Expression fx = new Expression(tbxExpression.Text);
GetFunctionValueRange(fx, x0, rx, i0, i1, out y0, out y1);
double ry = (y1 - y0) / (j1 - j0);
Out(gc, 0, "ClientSize: {0}x{1}", i1 - i0 + 1, j1 - j0 + 1);
Out(gc, 1, "f(x): " + tbxExpression.Text);
Out(gc, 2, "x:[{0}, {1}] range:{2}", x0, x1, x1 - x0);
Out(gc, 3, "y:[{0}, {1}] range:{2}", y0, y1, y1 - y0);
Out(gc, 4, "rx:{0}", 1 / rx); // 函數(shù)自變量每單位值用多少個(gè)象素表示
Out(gc, 5, "ry:{0}", 1 / ry); // 函數(shù)的值每單位值用多少個(gè)象素表示
Out(gc, 6, "r :{0}", rx / ry); // 該值如果小于1表示圖形縱向被壓扁,反之則被拉伸
pen.Color = Color.Green;
int j = j1 + (int)(y0 / ry);
if (j >= j0 && j <= j1) gc.DrawLine(pen, i0, j, i1, j); // x坐標(biāo)軸
int i = i0 - (int)(x0 / rx);
if (i >= i0 && i <= i1) gc.DrawLine(pen, i, j0, i, j1); // y坐標(biāo)軸
pen.Color = Color.Red;
for (i = i0; i <= i1; i++)
{
double x = x0 + (i - i0) * rx;
double y = fx.Compute(x);
if (double.IsInfinity(y) || double.IsNaN(y)) continue;
j = j1 - (int)((y - y0) / ry);
if (j > j1 || j < j0) continue;
gc.DrawLine(pen, i, j, i + 1, j); // 畫函數(shù)的圖形
}
}
catch (Exception ex)
{
Out(gc, 0, ex.Message);
}
base.OnPaint(e);
}
// 函數(shù)值的取值范圍
void GetFunctionValueRange(Expression fx, double x0, double rx, int i0, int i1, out double y0, out double y1)
{
y0 = double.MaxValue;
y1 = double.MinValue;
for (int i = i0; i <= i1; i++)
{
double x = x0 + (i - i0) * rx;
double y = fx.Compute(x);
if (double.IsInfinity(y) || double.IsNaN(y)) continue;
if (y0 > y) y0 = y;
if (y1 < y) y1 = y;
}
}
// 在指定的位置寫字符串
void Out(Graphics gc, int line, string fmt, params object [] args)
{
gc.DrawString(string.Format(fmt, args), new Font("Courier New", 10), Brushes.Blue, new PointF(5, yBase + 15 * line));
}
static void Main()
{
Application.Run(new PlotForm());
}
}
}
原文:http://skyivben.cnblogs.com/archive/2005/11/01/266649.html