LoadFile( bHeaderOnly ): only load image dimensions

caching TM4: 37 secs -> 28 secs
only implemented for PNG; 90% of song images are PNG anyway

stepmania/src/RageSurface_Load.cpp

@@ -6,14 +6,14 @@
 #include "RageUtil.h"
 #include "RageFile.h"
 
-SDL_Surface *RageSurface::LoadFile( const CString &sPath )
+SDL_Surface *RageSurface::LoadFile( const CString &sPath, bool bHeaderOnly )
 {
 	const CString ext = GetExtension( sPath );
 
 	CString error;
 	SDL_Surface *ret = NULL;
 	if( !ext.CompareNoCase("png") )
-		ret = RageSurface_Load_PNG( sPath, error );
+		ret = RageSurface_Load_PNG( sPath, bHeaderOnly, error );
 	else if( !ext.CompareNoCase("gif") )
 		ret = RageSurface_Load_GIF( sPath, error );
 	else if( !ext.CompareNoCase("jpg") )

stepmania/src/RageSurface_Load.h

@@ -4,7 +4,9 @@
 struct SDL_Surface;
 namespace RageSurface
 {
-	SDL_Surface *LoadFile( const CString &sPath );
+	/* If bHeaderOnly is true, the loader is only required to return a surface
+	 * with the width and height set (but may return a complete surface). */
+	SDL_Surface *LoadFile( const CString &sPath, bool bHeaderOnly=false );
 }
 
 #endif

stepmania/src/RageSurface_Load_PNG.cpp

@@ -52,7 +52,7 @@ static void PNG_Warning( png_struct *png, const char *warning )
 
 /* Since libpng forces us to use longjmp (gross!), this function shouldn't create any C++
  * objects, and needs to watch out for memleaks. */
-static SDL_Surface *RageSurface_Load_PNG( RageFile *f, const char *fn, char errorbuf[1024] )
+static SDL_Surface *RageSurface_Load_PNG( RageFile *f, const char *fn, char errorbuf[1024], bool bHeaderOnly )
 {
 	error_info error;
 	error.err = errorbuf;
@@ -76,7 +76,7 @@ static SDL_Surface *RageSurface_Load_PNG( RageFile *f, const char *fn, char erro
 	SDL_Surface *volatile img = NULL;
 	if( setjmp(png_jmpbuf(png)) )
 	{
-		png_destroy_read_struct( &png, &info_ptr, png_infopp_NULL );
+		png_destroy_read_struct( &png, &info_ptr, NULL );
 		if( img )
 			SDL_FreeSurface( img );
 		return NULL;
@@ -90,6 +90,22 @@ static SDL_Surface *RageSurface_Load_PNG( RageFile *f, const char *fn, char erro
 	int bit_depth, color_type;
 	png_get_IHDR( png, info_ptr, &width, &height, &bit_depth, &color_type, NULL, NULL, NULL );
 
+	/* If bHeaderOnly is true, don't allocate the pixel storage space or decompress
+	 * the image.  Just return an empty surface with only the width and height set. */
+	if( bHeaderOnly )
+	{
+		img = SDL_CreateRGBSurfaceFrom( SDL_SWSURFACE, width, height, 32, 0, 0, 0, 0, NULL );
+		png_destroy_read_struct( &png, &info_ptr, NULL );
+		if( !img )
+		{
+			strcpy( errorbuf, SDL_GetError() );
+			return NULL;
+		}
+
+		return img;
+	}
+
+
 	png_set_strip_16(png); /* 16bit->8bit */
 	png_set_packing( png ); /* 1,2,4 bit->8 bit */
 
@@ -206,13 +222,13 @@ static SDL_Surface *RageSurface_Load_PNG( RageFile *f, const char *fn, char erro
 		png_read_row( png, pixels + img->pitch*y, NULL );
 
 	png_read_end( png, info_ptr );
-	png_destroy_read_struct( &png, &info_ptr, png_infopp_NULL );
+	png_destroy_read_struct( &png, &info_ptr, NULL );
 
 	return img;
 }
 
 
-SDL_Surface *RageSurface_Load_PNG( const CString &sPath, CString &error )
+SDL_Surface *RageSurface_Load_PNG( const CString &sPath, bool bHeaderOnly, CString &error )
 {
 	RageFile f;
 	if( !f.Open( sPath ) )
@@ -222,7 +238,7 @@ SDL_Surface *RageSurface_Load_PNG( const CString &sPath, CString &error )
 	}
 
 	char errorbuf[1024];
-	SDL_Surface *ret = RageSurface_Load_PNG( &f, sPath, errorbuf );
+	SDL_Surface *ret = RageSurface_Load_PNG( &f, sPath, errorbuf, bHeaderOnly );
 	if( ret == NULL )
 	{
 		error = errorbuf;

stepmania/src/RageSurface_Load_PNG.h

@@ -3,7 +3,7 @@
 
 #include "SDL_utils.h"
 
-SDL_Surface *RageSurface_Load_PNG( const CString &sPath, CString &error );
+SDL_Surface *RageSurface_Load_PNG( const CString &sPath, bool bHeaderOnly, CString &error );
 
 #endif
 

stepmania/src/Song.cpp

@@ -684,7 +684,8 @@ void Song::TidyUpData()
 			continue;	// skip
 
 		CString sPath = m_sSongDir + arrayImages[i];
-		SDL_Surface *img = RageSurface::LoadFile( sPath );
+		/* We only care about the dimensions. */
+		SDL_Surface *img = RageSurface::LoadFile( sPath, true );
 		if( !img )
 		{
 			LOG->Trace("Couldn't load '%s': %s", sPath.c_str(), SDL_GetError());