界面:
感觉没有什么地方需要解释。
核心代码:
bool isDrag = false;
Rectangle theRectangle = new Rectangle(new Point(0, 0), new Size(0, 0));
Point startPoint, oldPoint;
private Graphics ig;
private void button1_Click(object sender, EventArgs e)
{
openFileDialog1.Filter = "*.jpg,*.jpeg,*.bmp,*.gif,*.ico,*.png,*.tif,*.wmf|*.jpg;*.jpeg;*.bmp;*.gif;*.ico;*.png;*.tif;*.wmf";
openFileDialog1.ShowDialog();
Image myImage = System.Drawing.Image.FromFile(openFileDialog1.FileName);
pictureBox1.Image = myImage;
}
private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button == MouseButtons.Left)
{
//如果开始绘制,则开始记录鼠标位置
if ((isDrag = !isDrag) == true)
{
startPoint = new Point(e.X, e.Y);
oldPoint = new Point(e.X, e.Y);
}
}
}
private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
isDrag = false;
ig = pictureBox1.CreateGraphics();
ig.DrawRectangle(new Pen(Color.Black, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
theRectangle = new Rectangle(startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
}
private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
Graphics g = this.CreateGraphics();
if (isDrag)
{
g.DrawRectangle(new Pen(Color.Black, 1), startPoint.X, startPoint.Y, e.X - startPoint.X, e.Y - startPoint.Y);
}
}
private void Form1_MouseClick(object sender, MouseEventArgs e)
{
try
{
Graphics graphics = this.CreateGraphics();
Bitmap bitmap = new Bitmap(pictureBox1.Image);
Bitmap cloneBitmap = bitmap.Clone(theRectangle, PixelFormat.DontCare);
graphics.DrawImage(cloneBitmap, e.X, e.Y);
Graphics g = pictureBox1.CreateGraphics();
SolidBrush myBrush = new SolidBrush(Color.White);
g.FillRectangle(myBrush, theRectangle);
}
catch
{ }
}