SDL_Flip question about buffer contents

SDL Development
1

Hi folks,
If I’m exclusively dealing with software surfaces, do I have any sort of guarantee as to what is in the video buffer after a call to SDL_Flip(screen)? Will what was just drawn to screen still be there, or will it be gone/changed on some platforms? I use windows exclusively for now, but I’d also like to try some Linux programming soon, and maybe MacOS, too. I know that hardware screen surfaces can be a variety of things after being SDL_Flipped due to various driver implementations, but what about software? Anyone know for sure?
Thanks,
-Dave Olsen

2

When your screen is a software surface, SDL is shadowing it and
handles all scary details for you. Anything you put in screen->pixels
stays in screen->pixels and doesn’t get displayed until you UpdateRect
or Flip. Stuff that got UpdateRect’d or Flip’d onto the screen will
never be lost track of.
-:sigma.SBOn Wed, Apr 9, 2008 at 10:10 PM, David Olsen wrote:

If I’m exclusively dealing with software surfaces, do I have any sort of
guarantee as to what is in the video buffer after a call to
SDL_Flip(screen)?

3

Fantastic! I use to try and mess around with hardware surface, but they are
really just more trouble than they are worth, imo. And any faster blits are
negated by alpha-blending. Software for the win! Thanks for the info.
-Dave> ----- Original Message -----

From: sbizna@tejat.net (Solra Bizna)
To: "A list for developers using the SDL library. (includes SDL-announce)"

Sent: Friday, April 11, 2008 2:22 AM
Subject: Re: [SDL] SDL_Flip question about buffer contents

On Wed, Apr 9, 2008 at 10:10 PM, David Olsen <@David_Olsen> wrote:

If I’m exclusively dealing with software surfaces, do I have any sort of
guarantee as to what is in the video buffer after a call to
SDL_Flip(screen)?
When your screen is a software surface, SDL is shadowing it and
handles all scary details for you. Anything you put in screen->pixels
stays in screen->pixels and doesn’t get displayed until you UpdateRect
or Flip. Stuff that got UpdateRect’d or Flip’d onto the screen will
never be lost track of.
-:sigma.SB

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