【借鉴】delphi paintbox 滚轮

1.在窗体的public里写procedure WmMouseSheel(var msg:TWMMOUSEWHEEL);message WM_MOUSEWHEEL;函数。

具体的实现部分如下：

procedure TMapChildFrm.WmMouseSheel(var msg: TWMMOUSEWHEEL);

var

pt: TPoint;

begin

GetCursorPos(pt); //{这是获取的相对于屏幕的坐标}

pt := ScreenToClient(pt); //{转换成本地坐标}

if (pt.X>ScrollBox1.Left)

and(pt.X<ScrollBox1.Left+paintbox1.Width)

and(pt.y>ScrollBox1.Top)

and(pt.y<ScrollBox1.Top+paintbox1.Height) then

begin

if msg.WheelDelta>0 then

begin

Zoom(@drawdata, 2);

AutoFillMap;

repaint;

end

else

begin

Zoom(@drawdata, 1 / 2);

AutoFillMap;

repaint;

end;

end;

end;(已实践)

2.继承paintbox，写个滚轮事件。(未实践);