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Shahram Shafieha · Guest

Hi all,
1. I draw an image by LEADTools function on a form.
2. In MouseMove event, redraw image and, draw a rectangle around the mouse
pointer. So the old rectangle will be cleared. Position of the new rectanlge
depends on the position of the mouse.
3. By ClipRect API, define an area that mouse can not go out of this area.
This area fits the image.
4. When I move mouse slowly, always mouse will be inside of the rectangle,
and everything is ok. But if I move mouse fast, the pointer will go out of
the rectangle. Why?

Can anybody help me?

Kursat · Guest

How do you draw the rectangle? How do you calculate coordinates? Can you
post rectangle-drawing part of your code?

"Shahram Shafieha" <shshafieha (AT) yahoo (DOT) com> wrote

Shahram Shafieha · Guest

How do you draw the rectangle?
I draw rectangle by Rectangle API function as
Rectangle(Canvas.Handle, redRect.Left, redRect.Top, redRect.Right,
redRect.Bottom);
Canvas.Handle is the canvas of the form, and redRect is a TRect that
containt coordinates of the form.

How do you calculate coordinates?
On the FormShow I wrote:
redRect.Left := Round(a * MainImageRect.Left + rcDst.Left);
redRect.Top := Round(a * MainImageRect.Top + rcDst.Top);
redRect.Right := Round(a * MainImageRect.Right + rcDst.Left);
redRect.Bottom := Round(a * MainImageRect.Bottom + rcDst.Top);
a is a coefficient for changing coordinates, its formula is something like
this :
a := ClientWidth / (Bitmap1.Width * ZoomLevel);

Can you post rectangle-drawing part of your code?
Actually I send a part of it.

Dale Peyser · Guest

I don't know what the "ClipRect" you refer to is. The only symbol in the Delphi runtime I can find with that name is the ClipRect on a Canvas which corresponds to the GDI Region that needs repainting. It wouldn't prevent the mouse from doing anything.

But anyhow, when you have SetCapture on a window, it only changes the routing of Mouse Messages within that window's thread. If there was code somewhere that looked for the mousepointer to be outside of a particular rectangle, then forced it back in it would work if the mouse moved slowly but if it moved fast, it could get outside all the thread's window's rectangles before that code could trigger. Then it wouldn't know that the mouse was gone and sending its messages somewhere else (i.e. to the desktop or some other thread)

I don't think there is any way to control the mousepointer at the OS level apart from writing your own mouse driver.

You might want to reconsider your design and change it so you don't have to limit mouse movement.

Shahram Shafieha · Guest

I think about your suggestion, Thankyou
"Dale Peyser" <dalep (AT) pizer (DOT) removeme.com> wrote