(Solved) selected area with rectangle
lazarus / 39-Graphics

----------------------------------------------------------------------
xinyiman · 2012-07-23 14:09

Who tells me how do I create a rectangle (with dotted lines) on a
TImage when I select a part of? And how do I determine the coordinates
of the selected area?

----------------------------------------------------------------------
KpjComp · 2012-07-23 14:17

So that you don't modify the TImage itself, what you can do is place a
TPaintBox over the top of the TImage.  And then draw you dotted lines
on the TPaintBox OnPaint event.

To make it so the user can move/size the rectangle you could place
even more TPaintBox's or TShape's for the Handles, and the use the
following technique to do the moving. ->
http://www.lazarus.freepascal.org/index.php?topic=17356.0

----------------------------------------------------------------------
xinyiman · 2012-07-27 08:23

Ok, doing a bit of evidence I think I have figured out how. I only
have a doubt! How do I clean the TPaintBox riseleziono when another
part of the object?!

So how can I delete the rectangles already created in TPaintBox?!

----------------------------------------------------------------------
xinyiman · 2012-07-27 09:08

I understand that you have to use the property invalidated. Except
that when I use it and then drawing a rectangle in succession I do not
keep! I delete it. How can I do?!

----------------------------------------------------------------------
xinyiman · 2012-07-27 09:30

I solved in this mode

          PaintBox1.Invalidate;
          PaintBox1.Refresh;
          PaintBox1.Canvas.Rectangle(x_SelIniz,y_SelIniz,x,y);