Use SDL_StretchSurface() to implement SDL_SoftStretch() and SDL_SoftStretchLinear()

Fixes #251

Author: slouken

src/sdl2_compat.c

@@ -398,7 +398,7 @@ static char loaderror[256];
 #endif
 
 #ifndef SDL3_REQUIRED_VER
-#define SDL3_REQUIRED_VER SDL_VERSIONNUM(3,2,0)
+#define SDL3_REQUIRED_VER SDL_VERSIONNUM(3,2,4)
 #endif
 
 #ifndef DIRSEP
@@ -3635,13 +3635,13 @@ SDL_LowerBlitScaled(SDL2_Surface *src2, SDL_Rect *srcrect, SDL2_Surface *dst2, S
 SDL_DECLSPEC int SDLCALL
 SDL_SoftStretch(SDL2_Surface *src, const SDL_Rect *srcrect, SDL2_Surface *dst, const SDL_Rect *dstrect)
 {
-    return SDL3_BlitSurfaceScaled(Surface2to3(src), srcrect, Surface2to3(dst), dstrect, SDL_SCALEMODE_NEAREST) ? 0 : -1;
+    return SDL3_StretchSurface(Surface2to3(src), srcrect, Surface2to3(dst), dstrect, SDL_SCALEMODE_NEAREST) ? 0 : -1;
 }
 
 SDL_DECLSPEC int SDLCALL
 SDL_SoftStretchLinear(SDL2_Surface *src, const SDL_Rect *srcrect, SDL2_Surface *dst, const SDL_Rect *dstrect)
 {
-    return SDL3_BlitSurfaceScaled(Surface2to3(src), srcrect, Surface2to3(dst), dstrect, SDL_SCALEMODE_LINEAR) ? 0 : -1;
+    return SDL3_StretchSurface(Surface2to3(src), srcrect, Surface2to3(dst), dstrect, SDL_SCALEMODE_LINEAR) ? 0 : -1;
 }
 
 /* SDL_GetTicks is 64-bit in SDL3. Clamp it for SDL2. */

src/sdl3_include_wrapper.h

@@ -1273,8 +1273,8 @@
 #define __BUILDING_SDL2_COMPAT__ 1
 
 #include <SDL3/SDL.h>
-#if !SDL_VERSION_ATLEAST(3,2,0)
-#error You need to compile against SDL >= 3.2.0 headers
+#if !SDL_VERSION_ATLEAST(3,2,4)
+#error You need to compile against SDL >= 3.2.4 headers
 #endif
 
 #define SDL_MAIN_HANDLED 1

src/sdl3_syms.h

@@ -676,6 +676,7 @@ SDL3_SYM(void,SignalSemaphore,(SDL_Semaphore *a),(a),return)
 SDL3_SYM(bool,StartTextInput,(SDL_Window *a),(a),return)
 SDL3_SYM(bool,StartTextInputWithProperties,(SDL_Window *a, SDL_PropertiesID b),(a,b),return)
 SDL3_SYM(bool,StopTextInput,(SDL_Window *a),(a),return)
+SDL3_SYM(bool,StretchSurface,(SDL_Surface *a, const SDL_Rect *b, SDL_Surface *c, const SDL_Rect *d, SDL_ScaleMode e),(a,b,c,d,e),return)
 SDL3_SYM(bool,SurfaceHasColorKey,(SDL_Surface *a),(a),return)
 SDL3_SYM(bool,SurfaceHasRLE,(SDL_Surface *a),(a),return)
 SDL3_SYM_RENAMED(void,TLSCleanup,CleanupTLS,(void),(),)