| 发表于：2007-02-08 17:51:465楼 得分:0 |
msdn上的示例代码：
// the following three methods will draw a rectangle and allow
// the user to use the mouse to resize the rectangle. if the
// rectangle intersects a control 's client rectangle, the
// control 's color will change.
bool isdrag = false;
rectangle therectangle = new rectangle
（new point（0, 0), new size（0, 0));
point startpoint;
private void form1_mousedown（object sender,
system.windows.forms.mouseeventargs e)
{
// set the isdrag variable to true and get the starting point
// by using the pointtoscreen method to convert form
// coordinates to screen coordinates.
if （e.button==mousebuttons.left)
{
isdrag = true;
}
control control = （control) sender;
// calculate the startpoint by using the pointtoscreen
// method.
startpoint = control.pointtoscreen（new point（e.x, e.y));
}
private void form1_mousemove（object sender,
system.windows.forms.mouseeventargs e)
{
// if the mouse is being dragged,
// undraw and redraw the rectangle as the mouse moves.
if （isdrag)
// hide the previous rectangle by calling the
// drawreversibleframe method with the same parameters.
{
controlpaint.drawreversibleframe（therectangle,
this.backcolor, framestyle.dashed);
// calculate the endpoint and dimensions for the new
// rectangle, again using the pointtoscreen method.
point endpoint = this.pointtoscreen（new point（e.x, e.y));
int width = endpoint.x-startpoint.x;
int height = endpoint.y-startpoint.y;
therectangle = new rectangle（startpoint.x,
startpoint.y, width, height);
// draw the new rectangle by calling drawreversibleframe
// again.
controlpaint.drawreversibleframe（therectangle,
this.backcolor, framestyle.dashed);
}
}
private void form1_mouseup（object sender,
system.windows.forms.mouseeventargs e)
{
// if the mouseup event occurs, the user is not dragging.
isdrag = false;
// draw the rectangle to be evaluated. set a dashed frame style
// using the framestyle enumeration.
controlpaint.drawreversibleframe（therectangle,
this.backcolor, framestyle.dashed);
// find out which controls intersect the rectangle and
// change their color. the method uses the rectangletoscreen
// method to convert the control 's client coordinates
// to screen coordinates.
rectangle controlrectangle;
for（int i = 0; i < controls.count; i++)
{
controlrectangle = controls[i].rectangletoscreen
（controls[i].clientrectangle);
if （controlrectangle.intersectswith（therectangle))
{
controls[i].backcolor = color.burlywood;
}
}
// reset the rectangle.
therectangle = new rectangle（0, 0, 0, 0);
}
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