- Re-added the SCI0 dithering code. Dithering is disabled by default. Added the 3 dithering modes as an enum (and reorganized them a bit)

- Added 3 config options for dithering in the ini file - mainly for purists (config option "dither_mode"): 0 - disabled, 1 - 16 color dithering (Sierra style) and 2 - 256 color dithering
- Dithering is now always applied depending on the screen scale (removed the relevant parameter)
- Removed the background picture buffering option, used to speed-up room changes. Room changing is quite fast (instantaneous), and the extra memory allocated is not worth the possible speed increase in small devices. Plus.... there is no reliable value to set this option to, so there is no point in letting the user decide what value to put there using guesswork

svn-id: r43915

5 files changed, 21 insertions, 62 deletions

diff --git a/engines/sci/gfx/gfx_options.h b/engines/sci/gfx/gfx_options.h
index 6060b30b4d..03b00ca616 100644
--- a/engines/sci/gfx/gfx_options.h
+++ b/engines/sci/gfx/gfx_options.h
@@ -47,15 +47,9 @@ namespace Sci {
  */
 struct gfx_options_t {
 #ifdef CUSTOM_GRAPHICS_OPTIONS
-	int buffer_pics_nr; /* Number of unused pics to buffer in LRU storage */
-
 	/* SCI0 pic resource options */
 	int pic0_unscaled; /* Don't draw scaled SCI0 pics */
-
-#if 0
-	int pic0_dither_mode; /* Mode to use for pic0 dithering, defined in gfx_resource.h */
-	int pic0_dither_pattern; /* Pattern to use for pic0 dithering, defined in gfx_resource.h */
-#endif
+	DitherMode pic0_dither_mode; /* Mode to use for pic0 dithering, defined in gfx_resource.h */
 
 	gfx_brush_mode_t pic0_brush_mode;
 	gfx_line_mode_t pic0_line_mode;
diff --git a/engines/sci/gfx/gfx_resmgr.cpp b/engines/sci/gfx/gfx_resmgr.cpp
index 0307fec026..9aa829c90c 100644
--- a/engines/sci/gfx/gfx_resmgr.cpp
+++ b/engines/sci/gfx/gfx_resmgr.cpp
@@ -119,12 +119,10 @@ int GfxResManager::calculatePic(gfxr_pic_t *scaled_pic, gfxr_pic_t *unscaled_pic
 
 		memcpy(scaled_pic->undithered_buffer, scaled_pic->visual_map->index_data, scaled_pic->undithered_buffer_size);
 
-#if 0
 #ifdef CUSTOM_GRAPHICS_OPTIONS
-		gfxr_dither_pic0(scaled_pic, _options->pic0_dither_mode, _options->pic0_dither_pattern);
+		gfxr_dither_pic0(scaled_pic, _options->pic0_dither_mode);
 #else
-		gfxr_dither_pic0(scaled_pic, GFXR_DITHER_MODE_D256, GFXR_DITHER_PATTERN_SCALED);
-#endif
+		gfxr_dither_pic0(scaled_pic, kDitherNone);
 #endif
 	}
 
@@ -152,22 +150,15 @@ int GfxResManager::getOptionsHash(gfx_resource_type_t type) {
 			return 10;
 		else
 			return (_options->pic0_unscaled) ? 0x10000 : 
-#if 0
 					 (_options->pic0_dither_mode << 12) |
-			         (_options->pic0_dither_pattern << 8) |
-#endif
 					 (_options->pic0_brush_mode << 4) |
 				     (_options->pic0_line_mode);
 #else
 		if (_resMan->isVGA())
 			return 10;
 		else
-#if 0
-			return 0x10000 | (GFXR_DITHER_PATTERN_SCALED << 8) | (GFX_BRUSH_MODE_RANDOM_ELLIPSES << 4) | GFX_LINE_MODE_CORRECT;
-#else
 			return 0x10000 | (GFX_BRUSH_MODE_RANDOM_ELLIPSES << 4) | GFX_LINE_MODE_CORRECT;
 #endif
-#endif
 
 	case GFX_RESOURCE_TYPE_FONT:
 	case GFX_RESOURCE_TYPE_CURSOR:
@@ -384,11 +375,7 @@ gfxr_pic_t *GfxResManager::getPic(int num, int maps, int flags, int default_pale
 		if (!res) {
 			res = (gfx_resource_t *)malloc(sizeof(gfx_resource_t));
 			res->ID = GFXR_RES_ID(GFX_RESOURCE_TYPE_PIC, num);
-#ifdef CUSTOM_GRAPHICS_OPTIONS
-			res->lock_sequence_nr = _options->buffer_pics_nr;
-#else
 			res->lock_sequence_nr = 0;
-#endif
 			resMap[num] = res;
 		} else {
 			gfxr_free_pic(res->scaled_data.pic);
@@ -400,11 +387,7 @@ gfxr_pic_t *GfxResManager::getPic(int num, int maps, int flags, int default_pale
 		res->scaled_data.pic = pic;
 		res->unscaled_data.pic = unscaled_pic;
 	} else {
-#ifdef CUSTOM_GRAPHICS_OPTIONS
-		res->lock_sequence_nr = _options->buffer_pics_nr; // Update lock counter
-#else
 		res->lock_sequence_nr = 0;
-#endif
 	}
 
 #ifdef CUSTOM_GRAPHICS_OPTIONS
@@ -496,11 +479,7 @@ gfxr_pic_t *GfxResManager::addToPic(int old_nr, int new_nr, int flags, int old_d
 		_gfxr_unscale_pixmap_index_data(res->scaled_data.pic->priority_map, _driver->getMode());
 
 	// The following two operations are needed when returning scaled maps (which is always the case here)
-#ifdef CUSTOM_GRAPHICS_OPTIONS
-	res->lock_sequence_nr = _options->buffer_pics_nr;
-#else
 	res->lock_sequence_nr = 0;
-#endif
 	calculatePic(res->scaled_data.pic, need_unscaled ? res->unscaled_data.pic : NULL,
 		                               flags | DRAWPIC01_FLAG_OVERLAID_PIC, default_palette, new_nr);
 
diff --git a/engines/sci/gfx/gfx_resource.h b/engines/sci/gfx/gfx_resource.h
index 79fa955666..5fcf67e3fa 100644
--- a/engines/sci/gfx/gfx_resource.h
+++ b/engines/sci/gfx/gfx_resource.h
@@ -42,17 +42,12 @@ namespace Common {
 namespace Sci {
 
 /*** Styles for pic0 drawing ***/
-// These are used for the now-disabled dithering code. Is it even used anywhere?
-#if 0
-/* Dithering modes */
-#define GFXR_DITHER_MODE_D16 0  /* Sierra SCI style */
-#define GFXR_DITHER_MODE_F256 1 /* Flat color interpolation */
-#define GFXR_DITHER_MODE_D256 2 /* 256 color dithering */
-
-/* Dithering patterns */
-#define GFXR_DITHER_PATTERN_SCALED 0 /* Dither per pixel on the 320x200 grid */
-#define GFXR_DITHER_PATTERN_1 1      /* Dither per pixel on the target */
-#endif
+/* Dithering modes for SCI0 games */
+enum DitherMode {
+	kDitherNone = 0,         // No dithering
+	kDither16Colors = 1,     // Sierra SCI style
+	kDither256Colors = 2     // Enhanced style
+};
 
 #define SCI_TITLEBAR_SIZE 10
 
@@ -247,16 +242,13 @@ void gfxr_draw_pic11(gfxr_pic_t *pic, int fill_normally,
  */
 void gfxr_remove_artifacts_pic0(gfxr_pic_t *dest, gfxr_pic_t *src);
 
-#if 0
 /**
  * Dithers a gfxr_visual_map.
  *
- * @param[in] pic		The pic to dither
- * @param[in] mode		One of GFXR_DITHER_MODE
- * @param[in] pattern	One of GFXR_DITHER_PATTERN
+ * @param[in] pic		        The pic to dither
+ * @param[DitherMode] mode		The dithering mode to use
  */
-void gfxr_dither_pic0(gfxr_pic_t *pic, int mode, int pattern);
-#endif
+void gfxr_dither_pic0(gfxr_pic_t *pic, DitherMode mode);
 
 /**
  * Calculates an EGA view.
diff --git a/engines/sci/gfx/res_pic.cpp b/engines/sci/gfx/res_pic.cpp
index 90f100a901..041a47119f 100644
--- a/engines/sci/gfx/res_pic.cpp
+++ b/engines/sci/gfx/res_pic.cpp
@@ -1684,36 +1684,34 @@ void gfxr_draw_pic11(gfxr_pic_t *pic, int flags, int default_palette, int size,
 	gfxr_draw_pic01(pic, flags, default_palette, size - vector_data_ptr, resource + vector_data_ptr, style, resid, kViewVga11, static_pal, portBounds);
 }
 
-#if 0
-void gfxr_dither_pic0(gfxr_pic_t *pic, int dmode, int pattern) {
+void gfxr_dither_pic0(gfxr_pic_t *pic, DitherMode dmode) {
 	int xl = pic->visual_map->index_width;
 	int yl = pic->visual_map->index_height;
-	int xfrob_max = (pattern == GFXR_DITHER_PATTERN_1) ? 1 : pic->mode->xfact;
-	int yfrob_max = (pattern == GFXR_DITHER_PATTERN_1) ? 1 : pic->mode->yfact;
+	int xfrob_max = pic->mode->xfact;
+	int yfrob_max = pic->mode->yfact;
 	int xfrobc = 0, yfrobc = 0;
 	int selection = 0;
 	int x, y;
 	byte *data = pic->visual_map->index_data;
 
-	if (dmode == GFXR_DITHER_MODE_F256)
+	if (dmode == kDitherNone)
 		return; // Nothing to do
 
-	if (dmode == GFXR_DITHER_MODE_D16) { // Limit to 16 colors
+	if (dmode == kDither16Colors)
 		pic->visual_map->palette = gfx_sci0_image_pal[sci0_palette]->getref();
-	}
 
 	for (y = 0; y < yl; y++) {
 		for (x = 0; x < xl; x++) {
 
 			switch (dmode) {
-			case GFXR_DITHER_MODE_D16:
+			case kDither16Colors:
 				if (selection)
 					*data = (*data & 0xf0) >> 4;
 				else
 					*data = (*data & 0xf);
 				break;
 
-			case GFXR_DITHER_MODE_D256:
+			case kDither256Colors:
 				if (selection)
 					*data = ((*data & 0xf) << 4) | ((*data & 0xf0) >> 4);
 				break;
@@ -1737,6 +1735,5 @@ void gfxr_dither_pic0(gfxr_pic_t *pic, int dmode, int pattern) {
 		}
 	}
 }
-#endif
 
 } // End of namespace Sci
diff --git a/engines/sci/sci.cpp b/engines/sci/sci.cpp
index 9abe01f483..c9e2c4ba3a 100644
--- a/engines/sci/sci.cpp
+++ b/engines/sci/sci.cpp
@@ -164,17 +164,14 @@ Common::Error SciEngine::run() {
 	ConfMan.registerDefault("view_filter", "0");
 	ConfMan.registerDefault("pic_filter", "0");
 	ConfMan.registerDefault("text_filter", "0");
+	ConfMan.registerDefault("dither_mode", "0");
 
 	// Default config:
 	gfx_options_t gfx_options;
 
 #ifdef CUSTOM_GRAPHICS_OPTIONS
-	gfx_options.buffer_pics_nr = 0;
 	gfx_options.pic0_unscaled = 1;
-#if 0
-	gfx_options.pic0_dither_mode = GFXR_DITHER_MODE_F256;
-	gfx_options.pic0_dither_pattern = GFXR_DITHER_PATTERN_SCALED;
-#endif
+	gfx_options.pic0_dither_mode = (DitherMode)ConfMan.getInt("dither_mode");
 	gfx_options.pic0_brush_mode = GFX_BRUSH_MODE_RANDOM_ELLIPSES;
 	gfx_options.pic0_line_mode = GFX_LINE_MODE_CORRECT;
 	gfx_options.cursor_xlate_filter = (gfx_xlate_filter_t)ConfMan.getInt("cursor_filter");