# HG changeset patch
# User Sam Lantinga <slouken@libsdl.org>
# Date 1103005249 0
# Node ID f14e3059e138bba200d62208b59a47d4b910983c
# Parent  4095d9ca23f28727ab66add02eab92087eb7a9d2
Date: Mon, 13 Dec 2004 21:28:18 -0500
From: Jonathan Atkins
Subject: [SDL] SDL_SaveBMP width bugfix

this fixes the pitch versus width difference that can happen
(especially for 8bit and 24bit (with the exact RGBAmasks) surfaces)
when you use SDL_SaveBMP.  The problem was the pitch was used
instead of the width, which in some cases is much wider than the
screen area you really want to save...making for ugly crud on the
saved image borders.
This code has been tested with & without pitch overhangs...and
with the right masks for 24 bit surfaces.
I tested 8,15,16,24,32-0RGB,32-RGBA(with no SDL_SRCALPHA flag).

diff -r 4095d9ca23f2 -r f14e3059e138 src/video/SDL_bmp.c
--- a/src/video/SDL_bmp.c	Mon Dec 13 08:49:17 2004 +0000
+++ b/src/video/SDL_bmp.c	Tue Dec 14 06:20:49 2004 +0000
@@ -413,6 +413,8 @@
 	}
 
 	if ( surface && (SDL_LockSurface(surface) == 0) ) {
+		const int bw = surface->w*surface->format->BytesPerPixel;
+
 		/* Set the BMP file header values */
 		bfSize = 0;		 /* We'll write this when we're done */
 		bfReserved1 = 0;
@@ -485,11 +487,10 @@
 
 		/* Write the bitmap image upside down */
 		bits = (Uint8 *)surface->pixels+(surface->h*surface->pitch);
-		pad  = ((surface->pitch%4) ? (4-(surface->pitch%4)) : 0);
+		pad  = ((bw%4) ? (4-(bw%4)) : 0);
 		while ( bits > (Uint8 *)surface->pixels ) {
 			bits -= surface->pitch;
-			if ( SDL_RWwrite(dst, bits, 1, surface->pitch)
-							!= surface->pitch) {
+			if ( SDL_RWwrite(dst, bits, 1, bw) != bw) {
 				SDL_Error(SDL_EFWRITE);
 				break;
 			}