Pixel plot method errors out without error message.
- by sonny5
// The following method blows up (big red x on screen) without generating error info. Any // ideas why?
// MyPlot.PlotPixel(x, y, Color.BlueViolet, Grf); // runs if commented out
// My goal is to draw a pixel on a form. Is there a way to increase the pixel size also?
using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
public class Plot : System.Windows.Forms.Form
{
private Size _ClientArea; //keeps the pixels info
private double _Xspan;
private double _Yspan;
public Plot()
{
InitializeComponent();
}
public Size ClientArea { set { _ClientArea = value; } }
private void InitializeComponent()
{
this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
this.ClientSize = new System.Drawing.Size(400, 300);
this.Text="World Plot (world_plot.cs)";
this.Resize += new System.EventHandler(this.Form1_Resize);
this.Paint += new System.Windows.Forms.PaintEventHandler(this.doLine);
this.Paint += new System.Windows.Forms.PaintEventHandler(this.TransformPoints); // new
this.Paint += new System.Windows.Forms.PaintEventHandler(this.DrawRectangleFloat);
this.Paint += new System.Windows.Forms.PaintEventHandler(this.DrawWindow_Paint);
}
private void DrawWindow_Paint(object sender, PaintEventArgs e)
{
Graphics Grf = e.Graphics;
pixPlot(Grf);
}
static void Main()
{
Application.Run(new Plot());
}
private void doLine(object sender, System.Windows.Forms.PaintEventArgs e)
{
// no transforms done yet!!!
Graphics g = e.Graphics;
g.FillRectangle(Brushes.White, this.ClientRectangle);
Pen p = new Pen(Color.Black);
g.DrawLine(p, 0, 0, 100, 100); // draw DOWN in y, which is positive since no matrix called
p.Dispose();
}
public void PlotPixel(double X, double Y, Color C, Graphics G)
{
Bitmap bm = new Bitmap(1, 1);
bm.SetPixel(0, 0, C);
G.DrawImageUnscaled(bm, TX(X), TY(Y));
}
private int TX(double X) //transform real coordinates to pixels for the X-axis
{
double w;
w = _ClientArea.Width / _Xspan * X + _ClientArea.Width / 2;
return Convert.ToInt32(w);
}
private int TY(double Y) //transform real coordinates to pixels for the Y-axis
{
double w;
w = _ClientArea.Height / _Yspan * Y + _ClientArea.Height / 2;
return Convert.ToInt32(w);
}
private void pixPlot(Graphics Grf)
{
Plot MyPlot = new Plot();
double x = 12.0;
double y = 10.0;
MyPlot.ClientArea = this.ClientSize;
Console.WriteLine("x = {0}", x);
Console.WriteLine("y = {0}", y);
//MyPlot.PlotPixel(x, y, Color.BlueViolet, Grf); // blows up
}
private void DrawRectangleFloat(object sender, PaintEventArgs e)
{
// Create pen.
Pen penBlu = new Pen(Color.Blue, 2);
// Create location and size of rectangle.
float x = 0.0F;
float y = 0.0F;
float width = 200.0F;
float height = 200.0F; // translate DOWN by 200 pixels
// Draw rectangle to screen.
e.Graphics.DrawRectangle(penBlu, x, y, width, height);
}
private void TransformPoints(object sender, System.Windows.Forms.PaintEventArgs e)
{
// after transforms
Graphics g = this.CreateGraphics();
Pen penGrn = new Pen(Color.Green, 3);
Matrix myMatrix2 = new Matrix(1, 0, 0, -1, 0, 0); // flip Y axis with -1
g.Transform = myMatrix2;
g.TranslateTransform(0, 200, MatrixOrder.Append); // translate DOWN the same distance as the rectangle...
// ...so this will put it at lower left corner
g.DrawLine(penGrn, 0, 0, 100, 90); // notice that y 90 is going UP
}
private void Form1_Resize(object sender, System.EventArgs e)
{
Invalidate();
}
}
