From f9b5f6cc0f4d486ab960b582d3b9fa802cb72c5e Mon Sep 17 00:00:00 2001
From: Sylvain Becker <sylvain.becker@gmail.com>
Date: Sun, 27 Dec 2020 20:28:24 +0100
Subject: [PATCH] Forward scale mode to SW renderer (Bug 5313)

---
 src/render/SDL_sysrender.h          |  3 +++
 src/render/software/SDL_render_sw.c |  4 ++--
 src/video/SDL_surface.c             | 25 +++++++++++++++++++++++--
 3 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/src/render/SDL_sysrender.h b/src/render/SDL_sysrender.h
index 5bb98094e..0269a93ee 100644
--- a/src/render/SDL_sysrender.h
+++ b/src/render/SDL_sysrender.h
@@ -258,6 +258,9 @@ extern SDL_BlendOperation SDL_GetBlendModeAlphaOperation(SDL_BlendMode blendMode
    the next call, because it might be in an array that gets realloc()'d. */
 extern void *SDL_AllocateRenderVertices(SDL_Renderer *renderer, const size_t numbytes, const size_t alignment, size_t *offset);
 
+extern int SDL_PrivateLowerBlitScaled(SDL_Surface * src, SDL_Rect * srcrect, SDL_Surface * dst, SDL_Rect * dstrect, SDL_ScaleMode scaleMode);
+extern int SDL_PrivateUpperBlitScaled(SDL_Surface * src, const SDL_Rect * srcrect, SDL_Surface * dst, SDL_Rect * dstrect, SDL_ScaleMode scaleMode);
+
 #endif /* SDL_sysrender_h_ */
 
 /* vi: set ts=4 sw=4 expandtab: */
diff --git a/src/render/software/SDL_render_sw.c b/src/render/software/SDL_render_sw.c
index 18dc1808c..0f7ac57be 100644
--- a/src/render/software/SDL_render_sw.c
+++ b/src/render/software/SDL_render_sw.c
@@ -434,7 +434,7 @@ SW_RenderCopyEx(SDL_Renderer * renderer, SDL_Surface *surface, SDL_Texture * tex
             retval = -1;
         } else {
             SDL_SetSurfaceBlendMode(src_clone, SDL_BLENDMODE_NONE);
-            retval = SDL_BlitScaled(src_clone, srcrect, src_scaled, &scale_rect);
+            retval = SDL_PrivateUpperBlitScaled(src_clone, srcrect, src_scaled, &scale_rect, texture->scaleMode);
             SDL_FreeSurface(src_clone);
             src_clone = src_scaled;
             src_scaled = NULL;
@@ -720,7 +720,7 @@ SW_RunCommandQueue(SDL_Renderer * renderer, SDL_RenderCommand *cmd, void *vertic
                      * to avoid potentially frequent RLE encoding/decoding.
                      */
                     SDL_SetSurfaceRLE(surface, 0);
-                    SDL_BlitScaled(src, srcrect, surface, dstrect);
+                    SDL_PrivateUpperBlitScaled(src, srcrect, surface, dstrect, texture->scaleMode);
                 }
                 break;
             }
diff --git a/src/video/SDL_surface.c b/src/video/SDL_surface.c
index ade68bf34..dbb66aa88 100644
--- a/src/video/SDL_surface.c
+++ b/src/video/SDL_surface.c
@@ -26,6 +26,7 @@
 #include "SDL_RLEaccel_c.h"
 #include "SDL_pixels_c.h"
 #include "SDL_yuv_c.h"
+#include "../render/SDL_sysrender.h"
 
 
 /* Check to make sure we can safely check multiplication of surface w and pitch and it won't overflow size_t */
@@ -745,6 +746,14 @@ SDL_UpperBlit(SDL_Surface * src, const SDL_Rect * srcrect,
 int
 SDL_UpperBlitScaled(SDL_Surface * src, const SDL_Rect * srcrect,
               SDL_Surface * dst, SDL_Rect * dstrect)
+{
+    return SDL_PrivateUpperBlitScaled(src, srcrect, dst, dstrect, SDL_ScaleModeNearest);
+}
+
+
+int
+SDL_PrivateUpperBlitScaled(SDL_Surface * src, const SDL_Rect * srcrect,
+              SDL_Surface * dst, SDL_Rect * dstrect, SDL_ScaleMode scaleMode)
 {
     double src_x0, src_y0, src_x1, src_y1;
     double dst_x0, dst_y0, dst_x1, dst_y1;
@@ -889,7 +898,7 @@ SDL_UpperBlitScaled(SDL_Surface * src, const SDL_Rect * srcrect,
         return 0;
     }
 
-    return SDL_LowerBlitScaled(src, &final_src, dst, &final_dst);
+    return SDL_PrivateLowerBlitScaled(src, &final_src, dst, &final_dst, scaleMode);
 }
 
 /**
@@ -899,6 +908,13 @@ SDL_UpperBlitScaled(SDL_Surface * src, const SDL_Rect * srcrect,
 int
 SDL_LowerBlitScaled(SDL_Surface * src, SDL_Rect * srcrect,
                 SDL_Surface * dst, SDL_Rect * dstrect)
+{
+    return SDL_PrivateLowerBlitScaled(src, srcrect, dst, dstrect, SDL_ScaleModeNearest);
+}
+
+int
+SDL_PrivateLowerBlitScaled(SDL_Surface * src, SDL_Rect * srcrect,
+                SDL_Surface * dst, SDL_Rect * dstrect, SDL_ScaleMode scaleMode)
 {
     static const Uint32 complex_copy_flags = (
         SDL_COPY_MODULATE_COLOR | SDL_COPY_MODULATE_ALPHA |
@@ -914,7 +930,12 @@ SDL_LowerBlitScaled(SDL_Surface * src, SDL_Rect * srcrect,
     if ( !(src->map->info.flags & complex_copy_flags) &&
          src->format->format == dst->format->format &&
          !SDL_ISPIXELFORMAT_INDEXED(src->format->format) ) {
-        return SDL_SoftStretch( src, srcrect, dst, dstrect );
+
+        if (scaleMode != SDL_ScaleModeNearest && src->format->BytesPerPixel == 4 && src->format->format != SDL_PIXELFORMAT_ARGB2101010) {
+            return SDL_SoftStretchLinear(src, srcrect, dst, dstrect);
+        } else {
+            return SDL_SoftStretch( src, srcrect, dst, dstrect );
+        }
     } else {
         return SDL_LowerBlit( src, srcrect, dst, dstrect );
     }