···canvas的一个问题！(10分)

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• 2006-08-22

• #1

procedure TForm1.Button1Click(Sender: TObject);
begin
with panel1 do
begin
panel1.canvas.Pen.Width:=1;
panel1.canvas.Pen.Color:=clblue;
panel1.canvas.MoveTo(0,0);
panel1.canvas.LineTo(panel1.Width,panel1.Height);
end;
end;
我想在panel1上画一条直线，但是以上代码不能编译，请问错在哪儿？
编译时报错：[Pascal Error] Unit1.pas(32): E2362 Cannot access protected symbol TCustomControl.Canvas

 

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• 2006-08-22

• #2

怎么没人会阿？

 

W

weichao9999

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• 2006-08-22

• #3

procedure TForm1.Button1Click(Sender: TObject);
begin
with panel1 do
begin
canvas.Pen.Width:=1;
canvas.Pen.Color:=clblue;
canvas.MoveTo(0,0);
canvas.LineTo(panel1.Width,panel1.Height);
end;
end;
最起码应该这样写

 

心

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• 2006-08-22

• #4

这样写就划线到form1上了！

 

Z

zywcd

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• 2006-08-22

• #5

你把panel1改成image吧。

 

心

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• 2006-08-22

• #6

好，我试试！

 

心

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• 2006-08-22

• #7

procedure TForm1.Button1Click(Sender: TObject);
begin
with image1 do
begin
canvas.Pen.Width:=1;
canvas.Pen.Color:=clblue;
canvas.MoveTo(0,0);
canvas.LineTo(image1.Width,image1.Height);
end;
end;
这回OK了，不过用panel为什么不对呢？

 

Z

zbr

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• 2006-08-22

• #8

panel 没有canvas属性

 

Z

zywcd

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• 2006-08-22

• #9

我刚才测试panel不能使用canvas，
版本的d7

 

T

tonmy

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• 2006-08-22

• #10

最好用TPaintBox来作画图载体
with PaintBox1 do
begin
canvas.Pen.Width:=1;
canvas.Pen.Color:=clblue;
canvas.MoveTo(0,0);
canvas.LineTo(PaintBox1.Width,PaintBox1.Height);
end;

 

云

云影

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• 2006-08-24

• #11

procedure TForm1.Button1Click(Sender: TObject);
var
c:TcontrolCanvas;
begin
c:=TcontrolCanvas.create;
c.control:=panel1;
with c do
begin
Pen.Width:=1;
Pen.Color:=clblue;
MoveTo(0,0);
LineTo(panel1.Width,panel1.Height);
end;
end;
试一下看行不
qq:494558048

 

云

云影

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• 2006-08-24

• #12

上面c，记住不用了要free

 

D

delphfans

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• 2006-08-25

• #13

panel 没有canvas属性 也可以画 你取 他的hdc然后用api 画就可以panel 有canvas 只是delphi 没有透出来给我们使用 或者你改下组建 不过很麻烦 分数有点少 呵呵

 

Q

ql

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• 2006-08-25

• #14

type
TMYPanel=class(TPanel)
public
property Canvas;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
TMYPanel(Panel1).Canvas.Pen.Color := clblack;
TMYPanel(Panel1).Canvas.Pen.Width := 3;
TMYPanel(Panel1).Canvas.MoveTo(0,0);
TMYPanel(Panel1).Canvas.LineTo(panel1.Width,panel1.Height);
end;

 

D

delphfans

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• 2006-08-25

• #15

ql 能流下qq 吗 ?向你学习 或者你加我 qq: 439661788