C#鼠标拖动控件改变位置并绘制虚框

最新推荐文章于 2019-11-11 11:03:55 发布

转载最新推荐文章于 2019-11-11 11:03:55 发布 · 821 阅读

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本文介绍了一种在PictureBox上实现鼠标拖拽选择区域的方法。通过监听MouseDown、MouseMove及MouseUp事件，绘制一个可随鼠标移动调整大小的选择框。该方法适用于Windows Forms应用中需要用户自由选择图片区域的场景。

private Point downPoint;
private Rectangle downRectangle;
private Rectangle lastRectangle;

private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
downPoint = e.Location;
downRectangle =
new Rectangle(0, 0, ((Control)sender).Width, pictureBox1.Height);
downRectangle.Offset(((Control)sender).PointToScreen(new Point(0, 0)));
ControlPaint.DrawReversibleFrame(
downRectangle, Color.White, FrameStyle.Thick);
lastRectangle = downRectangle;
}

private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
ControlPaint.DrawReversibleFrame(
lastRectangle, Color.White, FrameStyle.Thick);

Rectangle rectangle = downRectangle;
rectangle.Offset(e.X - downPoint.X, e.Y - downPoint.Y);
ControlPaint.DrawReversibleFrame(
rectangle, Color.White, FrameStyle.Thick);
lastRectangle = rectangle;
}

private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
{
if (e.Button != MouseButtons.Left) return;
ControlPaint.DrawReversibleFrame(
lastRectangle, Color.White, FrameStyle.Thick);

pictureBox1.Location = new Point(
((Control)sender).Location.X + e.X - downPoint.X,
((Control)sender).Location.Y + e.Y - downPoint.Y);
}