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engines/ultima/nuvie/screen/dither.cpp

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+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include "ultima/nuvie/core/nuvie_defs.h"
+#include "ultima/nuvie/files/nuvie_io_file.h"
+#include "ultima/nuvie/misc/u6_misc.h"
+#include "ultima/nuvie/conf/configuration.h"
+#include "ultima/nuvie/screen/dither.h"
+
+namespace Ultima {
+namespace Nuvie {
+
+//dither EGA to CGA
+static const uint8 dither_cga_tbl[0x10] =   {0, 3, 3, 3, 13, 13, 13, 3, 3, 13, 15, 3, 13, 13, 15, 15};
+//static const uint8 dither_cga_tbl[0x10] = {0,1,1,1,2 ,2 ,2 ,1,1,2 ,3 ,1,2 ,2 ,3, 3};
+
+Dither::Dither(const Configuration *cfg) : config(cfg), dither(nullptr), mode(DITHER_NONE) {
+	set_mode();
+
+	if (mode != DITHER_NONE)
+		load_data();
+}
+
+Dither::~Dither() {
+	if (dither)
+		free(dither);
+}
+
+bool Dither::load_data() {
+	Common::Path path;
+	NuvieIOFileRead file;
+
+	config_get_path(config, "dither", path);
+	if (file.open(path) == false)
+		return false;//fixme better error handling
+
+	dither = (uint8 *)malloc(0x200);
+	if (dither == nullptr)
+		return false;
+
+	file.readToBuf(dither, 0x200);
+
+	file.close();
+
+	return true;
+}
+
+void Dither::set_mode() {
+	Std::string str_dither_mode;
+
+	config->value("config/general/dither_mode", str_dither_mode);
+
+	if (str_dither_mode == "none")
+		mode = DITHER_NONE;
+	else if (str_dither_mode == "cga") {
+		mode = DITHER_CGA;
+	} else if (str_dither_mode == "ega") {
+		mode = DITHER_EGA;
+	} else
+		mode = DITHER_NONE;
+
+	return;
+}
+
+bool Dither::dither_bitmap(unsigned char *src_buf, uint16 src_w, uint16 src_h, bool has_transparency) {
+	if (!dither || mode == DITHER_NONE)
+		return false;
+
+	for (int y = 0; y < src_h; y++) {
+		for (int x = 0; x < src_w; x++) {
+			uint8 pixel = src_buf[y * src_w + x];
+
+			if (has_transparency && pixel == 0xff)
+				continue;
+
+			if (pixel >= 0xe0 && pixel != 0xff)
+				pixel &= 0xf;
+
+			if (((x & 1) ^ (y & 1)) == 0)
+				pixel = dither[0x100 + pixel];
+			else
+				pixel = dither[pixel];
+
+			if (mode == DITHER_CGA)
+				pixel = dither_cga_tbl[pixel];
+
+			src_buf[y * src_w + x] = pixel;
+		}
+	}
+
+	return true;
+}
+
+} // End of namespace Nuvie
+} // End of namespace Ultima