From 4f6d27a8f4a98d558d436acfee1bdf91fb2b03bb Mon Sep 17 00:00:00 2001
From: OBattler <oubattler@gmail.com>
Date: Wed, 22 Jan 2020 05:24:44 +0100
Subject: [PATCH] Integer scale is now actually integer scale (but might still
 be blurred by the host hardware if using the SDL (Hardware) renderer, so use
 SDL (Software) if you don't want the blur).

---
 src/win/win_sdl.c | 82 +++++++++++++++++++++++++++--------------------
 1 file changed, 48 insertions(+), 34 deletions(-)

diff --git a/src/win/win_sdl.c b/src/win/win_sdl.c
index 762f4c5db..77b5c8a2f 100644
--- a/src/win/win_sdl.c
+++ b/src/win/win_sdl.c
@@ -12,13 +12,13 @@
  *		we will not use that, but, instead, use a new window which
  *		coverrs the entire desktop.
  *
- * Version:	@(#)win_sdl.c  	1.0.10	2019/12/06
+ * Version:	@(#)win_sdl.c  	1.0.11	2020/01/22
  *
  * Authors:	Fred N. van Kempen, <decwiz@yahoo.com>
  *		Michael Drüing, <michael@drueing.de>
  *
- *		Copyright 2018,2019 Fred N. van Kempen.
- *		Copyright 2018,2019 Michael Drüing.
+ *		Copyright 2018-2020 Fred N. van Kempen.
+ *		Copyright 2018-2020 Michael Drüing.
  *
  *		Redistribution and  use  in source  and binary forms, with
  *		or  without modification, are permitted  provided that the
@@ -108,10 +108,31 @@ sdl_log(const char *fmt, ...)
 #endif
 
 
+static void
+sdl_integer_scale(double *d, double *g)
+{
+    double ratio;
+
+    if (*d > *g) {
+	ratio = floor(*d / *g);
+	*d = *g * ratio;
+    } else {
+	ratio = ceil(*d / *g);
+	*d = *g / ratio;
+    }
+}
+
+
 static void
 sdl_stretch(int *w, int *h, int *x, int *y)
 {
-    double dw, dh, dx, dy, temp, temp2, ratio_w, ratio_h, gsr, hsr;
+    double hw, gw, hh, gh, dx, dy, dw, dh, gsr, hsr;
+
+    hw = (double) sdl_w;
+    hh = (double) sdl_h;
+    gw = (double) *w;
+    gh = (double) *h;
+    hsr = hw / hh;
 
     switch (video_fullscreen_scale) {
 	case FULLSCR_SCALE_FULL:
@@ -122,44 +143,37 @@ sdl_stretch(int *w, int *h, int *x, int *y)
 		break;
 	case FULLSCR_SCALE_43:
 	case FULLSCR_SCALE_KEEPRATIO:
-		dw = (double) sdl_w;
-		dh = (double) sdl_h;
-		hsr = dw / dh;
 		if (video_fullscreen_scale == FULLSCR_SCALE_43)
 			gsr = 4.0 / 3.0;
 		else
-			gsr = ((double) *w) / ((double) *h);
+			gsr = gw / gh;
 		if (gsr <= hsr) {
-			temp = dh * gsr;
-			dx = (dw - temp) / 2.0;
-			dw = temp;
-			*w = (int) dw;
-			*h = (int) dh;
-			*x = (int) dx;
-			*y = 0;
+			dw = hh * gsr;
+			dh = hh;
 		} else {
-			temp = dw / gsr;
-			dy = (dh - temp) / 2.0;
-			dh = temp;
-			*w = (int) dw;
-			*h = (int) dh;
-			*x = 0;
-			*y = (int) dy;
+			dw = hw;
+			dh = hw / gsr;
 		}
+		dx = (hw - dw) / 2.0;
+		dy = (hh - dh) / 2.0;
+		*w = (int) hw;
+		*h = (int) hh;
+		*x = (int) dx;
+		*y = (int) dy;
 		break;
 	case FULLSCR_SCALE_INT:
-		dw = (double) sdl_w;
-		dh = (double) sdl_h;
-		temp = ((double) *w);
-		temp2 = ((double) *h);
-		ratio_w = dw / ((double) *w);
-		ratio_h = dh / ((double) *h);
-		if (ratio_h < ratio_w)
-			ratio_w = ratio_h;
-		dx = (dw / 2.0) - ((temp * ratio_w) / 2.0);
-		dy = (dh / 2.0) - ((temp2 * ratio_h) / 2.0);
-		dw -= (dx * 2.0);
-		dh -= (dy * 2.0);
+		gsr = gw / gh;
+		if (gsr <= hsr) {
+			dw = hh * gsr;
+			dh = hh;
+		} else {
+			dw = hw;
+			dh = hw / gsr;
+		}
+		sdl_integer_scale(&dw, &gw);
+		sdl_integer_scale(&dh, &gh);
+		dx = (hw - dw) / 2.0;
+		dy = (hh - dh) / 2.0;
 		*w = (int) dw;
 		*h = (int) dh;
 		*x = (int) dx;