From f142a7961e42d76bfde09ca20ee3b4e67366e9d6 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Mon, 14 Aug 2017 13:37:14 -0700
Subject: [PATCH] Fixed bug 2441 - SDL_DuplicateSurface

Rainer Deyke

I've written a small patch that adds a small SDL_DuplicateSurface function to SDL.  I've written the function as part of a larger (as yet unfinished) patch, but I think this function is useful enough that it merits inclusion in SDL on its own.
---
 include/SDL_surface.h             |  5 +++++
 src/dynapi/SDL_dynapi_overrides.h |  1 +
 src/dynapi/SDL_dynapi_procs.h     |  1 +
 src/video/SDL_surface.c           | 18 ++++++++++++++++++
 4 files changed, 25 insertions(+)

diff --git a/include/SDL_surface.h b/include/SDL_surface.h
index c3ea1d53292d9..510690c9cffe3 100644
--- a/include/SDL_surface.h
+++ b/include/SDL_surface.h
@@ -359,6 +359,11 @@ extern DECLSPEC SDL_bool SDLCALL SDL_SetClipRect(SDL_Surface * surface,
 extern DECLSPEC void SDLCALL SDL_GetClipRect(SDL_Surface * surface,
                                              SDL_Rect * rect);
 
+/*
+ * Creates a new surface identical to the existing surface
+ */
+extern DECLSPEC SDL_Surface *SDLCALL SDL_DuplicateSurface(SDL_Surface * surface);
+
 /**
  *  Creates a new surface of the specified format, and then copies and maps
  *  the given surface to it so the blit of the converted surface will be as
diff --git a/src/dynapi/SDL_dynapi_overrides.h b/src/dynapi/SDL_dynapi_overrides.h
index 7c3a8a06f4042..bb1f290caa57c 100644
--- a/src/dynapi/SDL_dynapi_overrides.h
+++ b/src/dynapi/SDL_dynapi_overrides.h
@@ -628,3 +628,4 @@
 #define SDL_LoadFile_RW SDL_LoadFile_RW_REAL
 #define SDL_wcscmp SDL_wcscmp_REAL
 #define SDL_ComposeCustomBlendMode SDL_ComposeCustomBlendMode_REAL
+#define SDL_DuplicateSurface SDL_DuplicateSurface_REAL
diff --git a/src/dynapi/SDL_dynapi_procs.h b/src/dynapi/SDL_dynapi_procs.h
index ed2c5e6e62835..a5aa6d94a9828 100644
--- a/src/dynapi/SDL_dynapi_procs.h
+++ b/src/dynapi/SDL_dynapi_procs.h
@@ -660,3 +660,4 @@ SDL_DYNAPI_PROC(size_t,SDL_utf8strlen,(const char *a),(a),return)
 SDL_DYNAPI_PROC(void*,SDL_LoadFile_RW,(SDL_RWops *a, size_t *b, int c),(a,b,c),return)
 SDL_DYNAPI_PROC(int,SDL_wcscmp,(const wchar_t *a, const wchar_t *b),(a,b),return)
 SDL_DYNAPI_PROC(SDL_BlendMode,SDL_ComposeCustomBlendMode,(SDL_BlendFactor a, SDL_BlendFactor b, SDL_BlendOperation c, SDL_BlendFactor d, SDL_BlendFactor e, SDL_BlendOperation f),(a,b,c,d,e,f),return)
+SDL_DYNAPI_PROC(SDL_Surface*,SDL_DuplicateSurface,(SDL_Surface *a),(a),return)
diff --git a/src/video/SDL_surface.c b/src/video/SDL_surface.c
index 19e1ab73e4e03..f4a014e85ae62 100644
--- a/src/video/SDL_surface.c
+++ b/src/video/SDL_surface.c
@@ -870,6 +870,15 @@ SDL_UnlockSurface(SDL_Surface * surface)
     }
 }
 
+/*
+ * Creates a new surface identical to the existing surface
+ */
+SDL_Surface *
+SDL_DuplicateSurface(SDL_Surface * surface)
+{
+    return SDL_ConvertSurface(surface, surface->format, surface->flags);
+}
+
 /*
  * Convert a surface into the specified pixel format.
  */
@@ -882,6 +891,15 @@ SDL_ConvertSurface(SDL_Surface * surface, const SDL_PixelFormat * format,
     SDL_Color copy_color;
     SDL_Rect bounds;
 
+    if (!surface) {
+        SDL_InvalidParamError("surface");
+        return NULL;
+    }
+    if (!format) {
+        SDL_InvalidParamError("format");
+        return NULL;
+    }
+
     /* Check for empty destination palette! (results in empty image) */
     if (format->palette != NULL) {
         int i;