上面的代码不能吗?
delphi的实例:
procedure TForm1.FormPaint(Sender: TObject);
begin
with Canvas do
begin
MoveTo(0, 0);
LineTo(ClientWidth, ClientHeight);
MoveTo(0, ClientHeight);
LineTo(ClientWidth, 0);
end;
end;
我用的下面的(win32api):
var
h: hdc;
h := getdc(panel1.Handle);
MoveToEx(h, x, y, nil);
LineTo(h, x, y);
自己设置x,y
form1
..........
private
oldP,newP:TPoint;
......
procedre form1.onmousedown()...
begin
oldP:=Point(X,Y);
end;
procedure form1.onmouseMOVE()..
var
tempp:TPoint;
begin
tempP:=Point(X,Y);
with form1.canvas do begin
pen.mode;=ps_not;//这个自己看书,忘记是什么了.就是用反色笔画;
moveto(oldp);
lineto(tempp);//抹去旧的线;
pen.mode;=ps_not;//这个自己看书,忘记是什么了.就是用反色笔画;
moveto(oldp);
lineto(tempp);//这个是新的线;
end;
end;
procedure form1.onmouseup...
begin
newp:=point(x,y);
with form1.canvas do begin
pen.color:=youColor;
moveto(oldp);
lineTo(newP);
end;
end;