Add integer scaling option (#2)

This patch adds option ‚3‘ integer scaling. dst_rect is an integral multiple of src_rect. Should prevent scaling artifacts.
spurious · Nov 18, 2016 · 9d9af1f · 9d9af1f
1 parent 5bd7159
commit 9d9af1f
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diff --git a/include/SDL_hints.h b/include/SDL_hints.h
@@ -671,11 +671,15 @@ extern "C" {
  *   "1"       - Requested video resolution will be scaled to desktop resolution.
  *               Aspect ratio of requested video resolution will be respected.
  *   "2"       - Requested video resolution will be scaled to desktop resolution.
+ *   "3"       - Requested video resolution will be scaled to desktop resolution.
+ *               Aspect ratio of requested video resolution will be respected.
+ *               If possible output resolution will be integral multiple of video
+ *               resolution.
  */
 #define SDL_HINT_VIDEO_RPI_SCALE_MODE    "SDL_VIDEO_RPI_SCALE_MODE"
 
 /**
- *  \brief Tell dispmanx to set an specific aspect ratio.
+ *  \brief Tell dispmanx to set a specific aspect ratio.
  *
  * This hint only applies to the rpi video driver.
  *

diff --git a/src/video/raspberry/SDL_rpivideo.c b/src/video/raspberry/SDL_rpivideo.c
@@ -244,12 +244,33 @@ RPI_CreateWindow(_THIS, SDL_Window * window)
 
     float srcAspect = 1; 
     float dstAspect = 1;
+    int factor_x = 0;
+    int factor_y = 0;
 
     if (hintScale != NULL)
         scalemode = *hintScale;
 
     /* Create a dispman element and associate a window to it */
     switch(scalemode) {
+        case '3':
+            /* Pixel perfect scaling mode. */
+            factor_x = (display->desktop_mode.w / window->w);
+            factor_y = (display->desktop_mode.h / window->h);
+            if ((factor_x != 0) && (factor_y != 0)) {
+                if (factor_x >= factor_y) {
+                    dst_rect.width = window->w * factor_y;
+                    dst_rect.height = window->h * factor_y;
+                }
+                else {
+                    dst_rect.width = window->w * factor_x;
+                    dst_rect.height = window->h * factor_x;
+                }
+                /* Center window. */
+                dst_rect.x = (display->desktop_mode.w - dst_rect.width) / 2;
+                dst_rect.y = (display->desktop_mode.h - dst_rect.height) / 2;
+                break;
+            }
+            /* If integer scale is not possible fallback to mode 1. */
         case '1':
             /* Fullscreen mode. */
             /* Calculate source and destination aspect ratios. */