Initial commit

engines/m4/graphics/gr_line.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 "m4/graphics/gr_line.h"
+#include "m4/vars.h"
+
+namespace M4 {
+
+void gr_vline_xor(Buffer *buf, int32 x, int32 y1, int32 y2) {
+	if (y1 > y2) {
+		SWAP(y1, y2);
+	}
+
+	if ((x > buf->w) || (y1 > buf->h))
+		return;
+
+	if (y2 > buf->h)
+		y2 = buf->h;	// Don't draw past bottom
+
+	byte *start = buf->data + x;
+
+	for (int32 i = y1; i < y2; i++, start += buf->stride)
+		*start ^= 0xff;
+}
+
+void gr_hline_xor(Buffer *buf, int32 x1, int32 x2, int32 y) {
+	if (x1 > x2) {
+		SWAP(x1, x2);
+	}
+
+	if ((y > buf->h) || (x1 > buf->w))
+		return;
+
+	byte *start = gr_buffer_pointer(buf, x1, y);
+
+	for (int32 i = x1; i < x2; i++, start++)
+		*start ^= 0xff;
+}
+
+void gr_vline(Buffer *buf, int32 x, int32 y1, int32 y2) {
+	if (y1 > y2) {
+		SWAP(y1, y2);
+	}
+
+	if ((x > buf->w) || (y1 > buf->h))
+		return;
+
+	y2++;
+	if (y2 > buf->h)
+		y2 = buf->h;	// don't draw past bottom
+
+	byte *start = gr_buffer_pointer(buf, x, y1);
+
+	for (int32 i = y1; i < y2; i++, start += buf->stride)
+		*start = _G(color);
+}
+
+void gr_hline(Buffer *buf, int32 x1, int32 x2, int32 y) {
+	if (x1 > x2) {
+		SWAP(x1, x2);
+	}
+
+	if ((y > buf->h) || (x1 > buf->w))
+		return;
+
+	byte *start = gr_buffer_pointer(buf, x1, y);
+
+	x2++;
+	if (x2 > buf->w)
+		x2 = buf->w;
+
+	for (int32 i = x1; i < x2; i++, start++)
+		*start = _G(color);
+}
+
+void gr_line(int32 x1, int32 y1, int32 x2, int32 y2, int32 color, Buffer *screen) {
+	byte *myData = (byte *)screen->data;
+	int32 y_unit, x_unit; 							// Variables for amount of change in x and y
+
+	int32 offset = y1 * screen->stride + x1;		// Calculate offset into video RAM
+
+	int32 ydiff = y2 - y1; 							// Calculate difference between y coordinates
+	if (ydiff < 0) { 								// If the line moves in the negative direction
+		ydiff = -ydiff; 	 						// ...get absolute value of difference
+		y_unit = -screen->stride;					// ...and set negative unit in y dimension
+	} else y_unit = screen->stride;					// Else set positive unit in y dimension
+
+	int32 xdiff = x2 - x1;							// Calculate difference between x coordinates
+	if (xdiff < 0) {								// If the line moves in the negative direction
+		xdiff = -xdiff;								// ...get absolute value of difference
+		x_unit = -1;								// ...and set negative unit in x dimension
+	} else x_unit = 1;				 				// Else set positive unit in y dimension
+
+	int32 error_term = 0;							// Initialize error term
+	if (xdiff > ydiff) {								// If difference is bigger in x dimension
+		const int32 length = xdiff + 1;					// ...prepare to count off in x direction
+		for (int32 i = 0; i < length; i++) {				// Loop through points in x direction
+			myData[offset] = (char)color;			// Set the next pixel in the line to COLOR
+			offset += x_unit;						// Move offset to next pixel in x direction
+			error_term += ydiff;					// Check to see if move required in y direction
+			if (error_term > xdiff) {				// If so...
+				error_term -= xdiff;				// ...reset error term
+				offset += y_unit;					// ...and move offset to next pixel in y dir.
+			}
+		}
+	} else {										// If difference is bigger in y dimension
+		const int32 length = ydiff + 1;					// ...prepare to count off in y direction
+		for (int32 i = 0; i < length; i++) {		// Loop through points in y direction
+			myData[offset] = (char)color;			// Set the next pixel in the line to COLOR
+			offset += y_unit;						// Move offset to next pixel in y direction
+			error_term += xdiff; 		 			// Check to see if move required in x direction
+			if (error_term > 0) {					// If so...
+				error_term -= ydiff;				// ...reset error term
+				offset += x_unit;					// ...and move offset to next pixel in x dir.
+			}
+		}
+	}
+}
+
+} // namespace M4