[Mono-dev] Bitmap manipulation - am I doing it right?

[Stifu]

Thanks for your answer.

1) I'm not sure how that would work... Not saying it's not possible or
anything, I just have no idea. By the way, the size and the color of the
rectangle can vary, and it can also be semi-transparent (in case that's a
problem).
2) How would you do this, technically? Because the only solution that comes
to my mind is to clone a little part of my Bitmap to create the temporary
copy... and making a sub-sized clone of a Bitmap is actually much slower
than making a full clone. So it'd be actually slower than my current
implementation.


Andreas Nahr wrote:
> 
> What you are doing is very inefficient.
> Two ideas:
> 1) Don't directly draw onto the image if you are only want so show
> something
> to the user and not really want to manipulate the image. You could easily
> use a rectangle control and show that above the image control.
> 2) Before you paint the rectangle copy the overpainted area into a
> temporary
> image. Then draw the rectangle. To (re)move the rectangle copy the data
> back
> from the temporary image (do not copy the entire image or create a new
> one)
> 
> Andreas
> 
> -----Ursprüngliche Nachricht-----
> Von: mono-devel-list-bounces at lists.ximian.com
> [mailto:mono-devel-list-bounces at lists.ximian.com] Im Auftrag von Stifu
> Gesendet: Dienstag, 31. März 2009 10:10
> An: mono-devel-list at lists.ximian.com
> Betreff: [Mono-dev] Bitmap manipulation - am I doing it right?
> 
> 
> Hello,
> 
> I have an application that displays graphics, stored in a Bitmap.
> When you hover the concerned Panel, a square shows what tile you're
> currently highlighting. So if you move your cursor, the square moves too.
> 
> What I'm doing is, each time I repaint my Panel, clone the Bitmap then
> draw
> the rectangle (square) on it. If I didn't clone it first and worked
> directly
> with the original Bitmap, then the squares would never go away, and keep
> on
> multiplying as you move your cursor over the Panel.
> So I'm just wondering: is cloning the right thing to do here? Or is there
> a
> better / more efficient way to achieve the same results, like some kind of
> temporary modifications to a Bitmap or whatever? (I'm using double
> buffering, so everything has to be on the same Bitmap)
> 
> I already implemented clipping to improve performances, but I wanted to
> know
> if there was anything else I could do... Thanks.
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