(Solved) selected area with rectangle

[xinyiman]

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]

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]

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]

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]

I solved in this mode

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