paintbox画图

Question

在button的单击事件里:
with paintbox1 do
begin
canvas.MoveTo(left+width,top);
canvas.LineTo(left+width,top+height);
canvas.MoveTo(left,top+height);
canvas.LineTo(left+width,top+height);
end;运行单击button,在paintbox上并没有出现相应的图线
请大虾们帮忙看看为什么会这样

Answer 1

因为你的坐标已经起出了PaintBox的范围了,画布最大也就在Width-1那里加上Left就超出了,改成如下即可  with paintbox1 do
  begin
    canvas.MoveTo(left,top);
    canvas.LineTo(left,top+height);
    canvas.MoveTo(left,top);
    canvas.LineTo(left+width,top);
  end;

Answer 2

left+width已经超出了paintbox1 的画布范围,你得坐标取值有问题

Answer 3

设置笔宽能看到一点
Canvas.pen.width:=......

Answer 4

begin
  with Self.PaintBox1 do
  begin
    Canvas.Pen.Color := clRed;
    Canvas.Pen.Width := 5;
    canvas.MoveTo(width, 0);
    canvas.LineTo(width, height);
    canvas.MoveTo(0, height);
    canvas.LineTo(width, height);
  end;
end;你的已经越界了