[SDL] Surface getting munged

[Lilith Calbridge]

Just ran a test and it never hits the default case.

Lilith

>>> On 7/26/2006 at 10:54 PM, in message
<001e01c6b130$4f3b7100$6501a8c0 at ALAN>,
Atrix2 at cox.net wrote:
> Lilith, if you haven't tested this yet, in your default case for your
switch
> I'd make it log to a file that it hit the default just to see if it's
ever
> getting an invalid value for the "side" parameter.
> 
> -----Original Message-----
> From: sdl-bounces+atrix2=cox.net at libsdl.org 
> [mailto:sdl-bounces+atrix2=cox.net at libsdl.org] On Behalf Of Lilith
Calbridge
> Sent: Wednesday, July 26, 2006 8:48 PM
> To: sdl at libsdl.org 
> Subject: [SDL] Surface getting munged
> 
> This may not be the place to ask this but people on this list are
more
> apt to understand the SDL_Surface structure than other forums.  This
is
> probably more of a C/C++ behavior question but someone familiar with
the
> structures involved might give me a quicker answer.  Please feel free
to
> contact me off-list if necessary.
> 
> The problem popped us as logos I'd been blitting to my screen
surface
> quit showing up.  A debug session showed that the rectangles I was
using
> to tell it what portion of the screen to draw them were getting set
to
> zero, an indication that SDL_BlitSurface was having a problem with
it. 
> This meant something else was messing up other factors.  Here's my
> scenario and here's what I found...
> 
> SCR_Object is a class that has as a member SDL_Surface *image and
> SDL_Rect rect.  Everything's fine up to a point.  I wrote a function
> outside the class to position another surface against the first one
and
> centered on either top, bottom, left or right.  It looks like this:
> 
> void SCR_SetDishPos (SCR_Object *dish, SCR_Object companion, Uint8
> side)
> {
> 	SDL_Rect ctemp = companion.GetRect();
> 	SDL_Rect dtemp = dish->GetRect();
> 
> 	
> 	switch (side) {
> 	case right:
> 		ctemp.x += ctemp.w;
> 		ctemp.y += (ctemp.h - dtemp.h)/2;
> 		break;
> 	case top:
> 		ctemp.x += (ctemp.w - dtemp.w)/2;
> 		ctemp.y -= dtemp.h;
> 		break;
> 	case left:
> 		ctemp.x -= dtemp.w;
> 		ctemp.y += (ctemp.h - dtemp.h)/2;
> 		break;
> 	case bottom:
> 		ctemp.x += (ctemp.w - dtemp.w)/2;
> 		ctemp.y += ctemp.h;
> 		break;
> 	default:
> 		break;
> 	}		
> 	ctemp.h = dtemp.h;
> 	ctemp.w = dtemp.w;
> 	
> 	dish->SetRect(ctemp);
> }
> 
> And a call to the function looks like this:
> 
> 	SCR_SetDishPos (&CVCDish,  CVC,  right);	
> 
> The function calculates and (properly) sets the rectangle for
CVCDish
> to that it nests against the right side of the logo called CVC. 
> Everything about CVC is fine in the debug session up to the end of
the
> function.  But when I return from the function (which returns
nothing)
> EVERYTHING that CVC.image points to is set to 0xFEEE.  Every pair of
> bytes pointed to by image is FEEE.
> 
> There's nothing in the function or the call to the function that
> references image.  This happens with any "companion" object I pass
to
> the function.  I can see that even a copy of the object can allow a
> function to access the address of the image surface but there's
nothing
> in the code that even remotely does that.  I've checked the value of
> image for each object and it isn't that image, as a pointer, is
getting
> pointed elsewhere.  
> 
> I can certainly rewrite the code in at least two other ways but I'd
> rather try to nail this.
> 
>  Help?
> 
> Lilith
> 
> 
> 
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> 
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