Scribble with Bitmap
using System;
using System.Drawing;
using System.Windows.Forms;
class ScribbleWithBitmap: Form
{
bool bTracking;
Point ptLast;
Bitmap bitmap;
Graphics grfxBm;
public static void Main()
{
Application.Run(new ScribbleWithBitmap());
}
public ScribbleWithBitmap()
{
Size size = SystemInformation.PrimaryMonitorMaximizedWindowSize;
bitmap = new Bitmap(size.Width, size.Height);
grfxBm = Graphics.FromImage(bitmap);
grfxBm.Clear(BackColor);
}
protected override void OnMouseDown(MouseEventArgs mea)
{
if (mea.Button != MouseButtons.Left)
return;
ptLast = new Point(mea.X, mea.Y);
bTracking = true;
}
protected override void OnMouseMove(MouseEventArgs mea)
{
if (!bTracking)
return;
Point ptNew = new Point(mea.X, mea.Y);
Pen pen = new Pen(ForeColor);
Graphics grfx = CreateGraphics();
grfx.DrawLine(pen, ptLast, ptNew);
grfx.Dispose();
grfxBm.DrawLine(pen, ptLast, ptNew);
ptLast = ptNew;
}
protected override void OnMouseUp(MouseEventArgs mea)
{
bTracking = false;
}
protected override void OnPaint(PaintEventArgs pea)
{
Graphics grfx = pea.Graphics;
grfx.DrawImage(bitmap, 0, 0, bitmap.Width, bitmap.Height);
}
}
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