[英]Delphi 7:Attach Image to Mouse
I want a derivate of TImage follow the Cursor when it has been clicked and stop following when it gets clicked again. 我希望TImage的衍生版本在单击时跟随Cursor,并在再次单击时停止跟随。 For this, I created a pointer, named 'Attached', that points to a TImage or a derivate.
为此,我创建了一个名为'Attached'的指针,指向TImage或衍生物。
var Attached: ^TImage;
I also set the derivate of Timage to call the procedure ChangeAttachState when its clicked. 我还设置了Timage的派生,在单击时调用过程ChangeAttachState。
Now, in the ChangeAttachState procedure I want to change the pointer that it points on the clicked Image or point to nil when an Image was already attached. 现在,在ChangeAttachState过程中,我想更改它指向所单击图像的指针,或者在已附加图像时指向nil。 In Code:
在代码中:
procedure TForm1.ChangeAttachState(Sender:TObject);
begin
if Attached = nil then
Attached := @Sender
else
Attached := nil;
end;
However, the line 'Attached := @Sender' does not seem to work, causing an Access violation when I want to use the pointer to ie move the Image to the Right. 但是,“Attached:= @Sender”这一行似乎不起作用,当我想使用指针即将图像向右移动时,会导致访问冲突。
I think the pointer points at a wrong location. 我认为指针指向错误的位置。 How can I make the pointer point at the correct save adress or make the clicked Image follow the mouse with other methods?
如何使指针指向正确的保存地址,或者使用其他方法使点击的图像跟随鼠标?
(I hope I used the right technical terms, as English is not my native language) (我希望我使用正确的技术术语,因为英语不是我的母语)
An object is already a pointer, declare your Attached
a TImage
(as opposed to ^TImage
) and you can assign to it like Attached := Sender as TImage
in 'ChangeAttachedState' (as opposed to Attached := @Sender
). 一个对象已经是一个指针,声明你的
Attached
了一个TImage
(而不是^TImage
),你可以像在'ChangeAttachedState'中那样将Attached := Sender as TImage
(与Attached := @Sender
)。
You can then attach a mouse move handler on the form like so: 然后,您可以在窗体上附加鼠标移动处理程序,如下所示:
procedure TForm1.FormMouseMove(Sender: TObject; Shift: TShiftState; X,
Y: Integer);
begin
if Assigned(Attached) then begin
Attached.Left := X;
Attached.Top := Y;
end;
end;
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