Add another color correction mode

Cocoa/Preferences.xib

@@ -152,6 +152,7 @@
                                 <menuItem title="Correct color curves" id="B3Q-x1-VRl"/>
                                 <menuItem title="Emulate hardware" id="XBL-hS-7ke"/>
                                 <menuItem title="Preserve brightness" id="tlx-WB-Bkw"/>
+                                <menuItem title="Reduce contrast" id="wuO-Xv-0mQ"/>
                             </items>
                         </menu>
                     </popUpButtonCell>
@@ -203,7 +204,7 @@
                     <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                     <popUpButtonCell key="cell" type="push" title="Never" bezelStyle="rounded" alignment="left" lineBreakMode="truncatingTail" state="on" borderStyle="borderAndBezel" tag="1" imageScaling="proportionallyDown" inset="2" selectedItem="heL-AV-0az" id="DY9-2D-h1L">
                         <behavior key="behavior" lightByBackground="YES" lightByGray="YES"/>
-                        <font key="font" metaFont="system"/>
+                        <font key="font" metaFont="menu"/>
                         <menu key="menu" id="Rgf-mF-K9q">
                             <items>
                                 <menuItem title="Never" state="on" tag="1" id="heL-AV-0az">
@@ -459,7 +460,7 @@
                     <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                     <clipView key="contentView" focusRingType="none" ambiguous="YES" drawsBackground="NO" id="AMs-PO-nid">
                         <rect key="frame" x="1" y="1" width="238" height="209"/>
-                        <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
+                        <autoresizingMask key="autoresizingMask"/>
                         <subviews>
                             <tableView focusRingType="none" appearanceType="vibrantLight" verticalHuggingPriority="750" allowsExpansionToolTips="YES" columnAutoresizingStyle="lastColumnOnly" columnReordering="NO" columnResizing="NO" multipleSelection="NO" emptySelection="NO" autosaveColumns="NO" typeSelect="NO" id="UDd-IJ-fxX">
                                 <rect key="frame" x="0.0" y="0.0" width="238" height="209"/>

Core/display.c

@@ -133,7 +133,7 @@ static void display_vblank(GB_gameboy_t *gb)
         if (!GB_is_sgb(gb)) {
             uint32_t color = 0;
             if (GB_is_cgb(gb)) {
-                color = gb->rgb_encode_callback(gb, 0xFF, 0xFF, 0xFF);
+                color = GB_convert_rgb15(gb, 0x7FFF, false);
             }
             else {
                 color = is_ppu_stopped ?
@@ -261,7 +261,21 @@ uint32_t GB_convert_rgb15(GB_gameboy_t *gb, uint16_t color, bool for_border)
             }
             new_r = r;
             new_b = b;
-            if (gb->color_correction_mode == GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS) {
+            if (gb->color_correction_mode == GB_COLOR_CORRECTION_REDUCE_CONTRAST) {
+                r = new_r;
+                g = new_r;
+                b = new_r;
+                
+                new_r = new_r * 7 / 8 + (    g + b) / 16;
+                new_g = new_g * 7 / 8 + (r   +   b) / 16;
+                new_b = new_b * 7 / 8 + (r + g    ) / 16;
+
+                
+                new_r = new_r * (224 - 32) / 255 + 32;
+                new_g = new_g * (220 - 36) / 255 + 36;
+                new_b = new_b * (216 - 40) / 255 + 40;
+            }
+            else if (gb->color_correction_mode == GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS) {
                 uint8_t old_max = MAX(r, MAX(g, b));
                 uint8_t new_max = MAX(new_r, MAX(new_g, new_b));
                 

Core/display.h

@@ -50,6 +50,7 @@ typedef enum {
     GB_COLOR_CORRECTION_CORRECT_CURVES,
     GB_COLOR_CORRECTION_EMULATE_HARDWARE,
     GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS,
+    GB_COLOR_CORRECTION_REDUCE_CONTRAST,
 } GB_color_correction_mode_t;
 
 void GB_draw_tileset(GB_gameboy_t *gb, uint32_t *dest, GB_palette_type_t palette_type, uint8_t palette_index);

SDL/gui.c

@@ -422,7 +422,7 @@ const char *current_scaling_mode(unsigned index)
 
 const char *current_color_correction_mode(unsigned index)
 {
-    return (const char *[]){"Disabled", "Correct Color Curves", "Emulate Hardware", "Preserve Brightness"}
+    return (const char *[]){"Disabled", "Correct Color Curves", "Emulate Hardware", "Preserve Brightness", "Reduce Contrast"}
         [configuration.color_correction_mode];
 }
 
@@ -462,7 +462,7 @@ void cycle_scaling_backwards(unsigned index)
 
 static void cycle_color_correction(unsigned index)
 {
-    if (configuration.color_correction_mode == GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS) {
+    if (configuration.color_correction_mode == GB_COLOR_CORRECTION_REDUCE_CONTRAST) {
         configuration.color_correction_mode = GB_COLOR_CORRECTION_DISABLED;
     }
     else {
@@ -473,7 +473,7 @@ static void cycle_color_correction(unsigned index)
 static void cycle_color_correction_backwards(unsigned index)
 {
     if (configuration.color_correction_mode == GB_COLOR_CORRECTION_DISABLED) {
-        configuration.color_correction_mode = GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS;
+        configuration.color_correction_mode = GB_COLOR_CORRECTION_REDUCE_CONTRAST;
     }
     else {
         configuration.color_correction_mode--;

libretro/libretro.c

@@ -202,7 +202,7 @@ static retro_environment_t environ_cb;
 
 /* variables for single cart mode */
 static const struct retro_variable vars_single[] = {
-    { "sameboy_color_correction_mode", "Color correction; off|correct curves|emulate hardware|preserve brightness" },
+    { "sameboy_color_correction_mode", "Color correction; off|correct curves|emulate hardware|preserve brightness|reduce contrast" },
     { "sameboy_high_pass_filter_mode", "High-pass filter; off|accurate|remove dc offset" },
     { "sameboy_model", "Emulated model; Auto|Game Boy|Game Boy Color|Game Boy Advance|Super Game Boy|Super Game Boy 2" },
     { "sameboy_border", "Super Game Boy border; enabled|disabled" },
@@ -497,6 +497,8 @@ static void check_variables()
                 GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
             else if (strcmp(var.value, "preserve brightness") == 0)
                 GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
+            else if (strcmp(var.value, "reduce_contrast") == 0)
+                GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_REDUCE_CONTRAST);
         }
 
         var.key = "sameboy_high_pass_filter_mode";
@@ -561,6 +563,8 @@ static void check_variables()
                 GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
             else if (strcmp(var.value, "preserve brightness") == 0)
                 GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
+            else if (strcmp(var.value, "reduce_contrast") == 0)
+                GB_set_color_correction_mode(&gameboy[0], GB_COLOR_CORRECTION_REDUCE_CONTRAST);
         }
 
         var.key = "sameboy_color_correction_mode_2";
@@ -575,6 +579,9 @@ static void check_variables()
                 GB_set_color_correction_mode(&gameboy[1], GB_COLOR_CORRECTION_EMULATE_HARDWARE);
             else if (strcmp(var.value, "preserve brightness") == 0)
                 GB_set_color_correction_mode(&gameboy[1], GB_COLOR_CORRECTION_PRESERVE_BRIGHTNESS);
+            else if (strcmp(var.value, "reduce_contrast") == 0)
+                GB_set_color_correction_mode(&gameboy[1], GB_COLOR_CORRECTION_REDUCE_CONTRAST);
+
         }
 
         var.key = "sameboy_high_pass_filter_mode_1";