Questions about using C # To draw function graphics

Reference http://www.cnblogs.com/zhangjun1130/archive/2010/01/04/1638874.html

C # program for drawing function graphics, and a pathological function (zz)

As mentioned in this article, you cannot use custom formulas. I use the COM control method, but the speed is relatively slow.

You need to add the Microsoft. scriptcontrol control. The formula can only be written in Javascript format.

 

Using system;
Using system. Collections. Generic;
Using system. Windows. forms;
Using system. drawing;

Namespace plotfunctionform
{
Static class Program
{

Sealed class plotform: Form
{

Static void main ()
{
Application. enablevisualstyles ();
Application. setcompatibletextrenderingdefault (false );
Application. Run (New plotform ());
}

// The function to be drawn. It is better to enter the function expression in textbox.
Double Function (Double X)
{

// Use the Microsoft scriptcontrol COM control
Msscriptcontrol. scriptcontrol SC = new msscriptcontrol. scriptcontrolclass ();
SC. Language = "JavaScript ";
String express = textbox1.text;
Express = Express. Replace ("X", X. tostring ());
Try
{
Double Y = double. parse (SC. eval (Express). tostring ());
Return y;
}
Catch (exception ex)
{MessageBox. Show (ex. Message); Return-1 ;}

// Double Z = math. Sin (X );
// Return Z;

// Return math. Sin (X );
// Double U = math. Pi-X;
// Double Pi2 = math. Pi * Math. Pi;
// Return 3 * x + math. Log (u * u)/Pi2/Pi2 + 1;
}

// Only used for display on the screen
String functionstring ()
{
Return textbox1.text;

// Return "f (x) = 3 * x ^ 2 + PI ^-4 * ln [(Pi-x) ^ 2] + 1 ";
}

Const int ybase = 24; // The height of the screen retaining Area

Textbox tbxx0, tbxx1; // value range of the function Independent Variable

Textbox textbox1;

Label label1 = new label ();
Label label2 = new label ();

Plotform ()
{
Suspendlayout ();

Button btnsubmit = new button ();
Btnsubmit. Text = "refresh ";
Btnsubmit. Location = new point (0, 0 );
Btnsubmit. size = new size (48, 24 );
Btnsubmit. Click + = new eventhandler (btnsubmit_click );

Label1.autosize = true;
Label1.location = new system. Drawing. Point (55, 7 );
Label1.name = "label1 ";
Label1.size = new system. Drawing. Size (40, 12 );
Label1.tabindex = 0;
Label1.text = "value range ";

Tbxx0 = new Textbox ();
Tbxx0.text = "-3 ";
Tbxx0.location = new point (110, 3 );
Tbxx0.size = new size (50, 20 );

Tbxx1 = new Textbox ();
Tbxx1.text = "3 ";
Tbxx1.location = new point (165, 3 );
Tbxx1.size = new size (50, 20 );

Label2.text = "formula ";
Label2.location = new point (220, 7 );
Label2.size = new size (30, 20 );

Textbox1 = new Textbox ();
Textbox1.text = "math. Sin (x )";
Textbox1.location = new point (255, 3 );
Textbox1.size = new size (200, 20 );

Controls. addrange (new control [] {btnsubmit, tbxx0, tbxx1, textbox1, label1, label2 });
TEXT = "plot ";
Backcolor = color. White;
Clientsize = new size (600,600 + ybase );
// Windowstate = formwindowstate. maximized;

Resumelayout (false );
}

Void btnsubmit_click (Object sender, eventargs E)
{
Invalidate ();
}

Protected override void onsizechanged (eventargs E)
{
Invalidate ();
Base. onsizechanged (E );
}

Protected override void onpaint (painteventargs E)
{
Double X0 = double. parse (tbxx0.text );
Double X1 = double. parse (tbxx1.text );
Graphics GC = E. graphics;
Size size = clientsize;
Int I0 = 0;
Int I1 = size. Width-1;
Int J0 = ybase;
Int J1 = size. Height-1;
Pen = new pen (color. Black, 1 );
GC. drawline (pen, I0, J0, i1, J0); // The boundary between the drawing area and the reserved area
Double RX = (x1-X0)/(I1-I0 );
Double Y0 = 0, Y1 = 1;
Getfunctionvaluerange (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, functionstring ());
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); // number of pixels for each unit value of the function Independent Variable
Out (GC, 5, "ry: {0}", 1/ry); // The number of pixels used to represent the function value per unit
Out (GC, 6, "R: {0}", Rx/ry); // if the value is smaller than 1, the image is squashed vertically, and vice versa.
Pen. Color = color. Green;
Int J = J1 + (INT) (Y0/ry );
If (j> = J0 & J <= J1) GC. drawline (pen, I0, J, i1, J); // X coordinate axis
Int I = I0-(INT) (x0/RX );
If (I> = I0 & I <= I1) GC. drawline (pen, I, J0, I, J1); // y axis
Pen. Color = color. Red;
For (I = I0; I <= I1; I ++)
{
Double X = x0 + (I-I0) * RX;
Double Y = function (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); // plot the function.
}
Base. onpaint (E );
}

// Function value range
Void getfunctionvaluerange (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 = function (X );
If (double. isinfinity (y) | double. isnan (y) continue;
If (y0> Y) Y0 = y;
If (Y1 <Y) Y1 = y;
}
}

// Write the string at the specified position
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 ));
}

}
}
}