Program pozwala rysować linie w kontrolce Panel (panel1). Przycisk button1 pozwala czyścić narysowane linie, a przycisk button2 pozwala zmieniać kolor linii. hScrollBar1 i label pozwala zmieniać i wyświetlać szerokość pędzla.
namespace Drawing
{
public partial class Form1 : Form
{
Graphics gr;
Pen pen;
bool isPainting;
Point startPos;
Point endPos;
ColorDialog colorDialog;
int penDefWidth = 6;
public Form1()
{
InitializeComponent();
gr = panel1.CreateGraphics();
pen = new Pen(Color.Black, penDefWidth);
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
colorDialog = new();
hScrollBar1.Value = penDefWidth;
penWidthLabel.Text = hScrollBar1.Value.ToString();
}
private void panel1_MouseDown(object sender, MouseEventArgs e)
{
isPainting = true;
startPos = new Point(e.X, e.Y);
}
private void panel1_MouseUp(object sender, MouseEventArgs e)
{
isPainting = false;
}
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
if (isPainting)
{
endPos = new Point(e.X, e.Y);
gr.DrawLine(pen, startPos, endPos);
startPos = endPos;
}
}
private void button1_Click(object sender, EventArgs e)
{
panel1.Invalidate();
//gr.Clear(Color.White);
}
private void button2_Click(object sender, EventArgs e)
{
if (colorDialog.ShowDialog() == DialogResult.OK)
{
pen.Color = colorDialog.Color;
}
}
private void hScrollBar1_ValueChanged(object sender, EventArgs e)
{
pen.Width = hScrollBar1.Value;
penWidthLabel.Text = hScrollBar1.Value.ToString();
}
}
}
Event Paint w WinForms wywołuje się zawsze kiedy wygląd kontrolki musi zostać narysowany ponownie (zmieni się grafika, tekst, itd)
W WinForms można rysować kształty za pomocą wbudowanych metod, np:
using System;
using System.Drawing;
using System.Windows.Forms;
namespace Test
{
public partial class Form1 : Form
{
Graphics gr;
Pen pen;
public Form1()
{
InitializeComponent();
gr = panel1.CreateGraphics();
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
pen = new Pen(Color.Black, 5);
}
private void button1_Click(object sender, EventArgs e)
{
//gr.Clear(Color.White);
panel1.Invalidate();
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
gr.DrawRectangle(pen, 100, 100, 100, 100);
gr.DrawPie(pen, 300, 100, 100, 100, -90, 120);
gr.DrawArc(pen, 500, 100, 100, 100, 0, 90);
}
}
}
Rysowanie wypełnionych kształtów polygon z obrysem
private void panel1_Paint(object sender, PaintEventArgs e)
{
DrawM();
}
void DrawM()
{
Point[] p = new Point[]{
new Point(0, 0),
new Point(50, 25),
new Point(100, 0),
new Point(100, 50),
new Point(0, 50),
new Point(0, 0),
};
System.Drawing.Drawing2D.GraphicsPath gp = new System.Drawing.Drawing2D.GraphicsPath();
gp.AddPolygon(p);
Region r = new Region(gp);
Graphics gr = panel1.CreateGraphics();
gr.FillRegion(Brushes.BlueViolet, r);
Pen outlinePen = new Pen(Color.Red, 4);
gr.DrawPath(outlinePen, gp);
}Rysowanie kształtów za pomocą myszy
namespace HelloTemp1
{
public partial class Form1 : Form
{
Graphics gr;
Pen pen;
int penDefWidth = 6;
Point startPos;
Point endPos;
Rectangle rect;
bool isDrawing;
public Form1()
{
InitializeComponent();
gr = panel1.CreateGraphics();
pen = new Pen(Color.Black, penDefWidth);
gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.AntiAlias;
}
private void panel1_MouseDown(object sender, MouseEventArgs e)
{
isDrawing = true;
startPos = new Point(e.X, e.Y);
}
private void panel1_MouseUp(object sender, MouseEventArgs e)
{
isDrawing = false;
}
private void panel1_Paint(object sender, PaintEventArgs e)
{
gr.DrawRectangle(pen, GetRect());
}
private void panel1_MouseMove(object sender, MouseEventArgs e)
{
if(isDrawing)
{
panel1.Invalidate();
endPos = new Point(e.X, e.Y);
}
}
Rectangle GetRect()
{
rect = new Rectangle();
rect.X = Math.Min(startPos.X, endPos.X);
rect.Y = Math.Min(startPos.Y, endPos.Y);
rect.Width = Math.Abs(endPos.X - startPos.X);
rect.Height = Math.Abs(endPos.Y - startPos.Y);
return rect;
}
}
}