Submitted By: Ben Swartzlander (ben at swartzlander dot org)
Date: 2008-09-07
Initial Package Version: 1.6.0
Description: Change cursor emulation to make XOR cursors stand out better on black backgrounds (similar to WINE implementation)

diff -Naur rdesktop-1.6.0.orig/xwin.c rdesktop-1.6.0/xwin.c
--- rdesktop-1.6.0.orig/xwin.c	2008-09-06 00:43:49.000000000 -0400
+++ rdesktop-1.6.0/xwin.c	2008-09-06 22:30:29.000000000 -0400
@@ -2770,28 +2770,66 @@
 	XFreePixmap(g_display, (Pixmap) glyph);
 }
 
-RD_HCURSOR
-ui_create_cursor(unsigned int x, unsigned int y, int width, int height,
-		 uint8 * andmask, uint8 * xormask)
+static int
+ui_get_cursor_bit(uint8 * buffer, int stride, int x, int y)
 {
-	RD_HGLYPH maskglyph, cursorglyph;
-	XColor bg, fg;
-	Cursor xcursor;
-	uint8 *cursor, *pcursor;
-	uint8 *mask, *pmask;
+	return 0 != (buffer[stride * y + (x >> 3)] & (0x80 >> (x & 7)));
+}
+
+static void
+ui_set_cursor_bit(uint8 * buffer, int stride, int x, int y)
+{
+	buffer[stride * y + (x >> 3)] |= 0x80 >> (x & 7);
+}
+
+static void
+ui_add_xor_cursor_shadow(uint8 * cursor, uint8 * mask, int width, int scanline,
+	int height, uint8 * andmask, uint8 * xormask)
+{
+	int x, x2, y, y2;
+	uint8 * xorptr;
+
+	cursor += (height - 1) * scanline;
+	mask += (height - 1) * scanline;
+
+	/*
+	 *  For every pixel in the cursor that should be color-inverting
+	 *  (andmask == 0 && xormask != 0) we look one pixel down and one
+	 *  to the right and make that pixel white if it was previously
+	 *  transparent. This creates a white shadow effect under the black
+	 *  cursor that makes the cursor much more visible against dark
+	 *  backgrounds without affecting the cursor appearance on lighter
+	 *  backgrounds. This is the best we can do given the limitations of
+	 *  X cursors.
+	 */
+	for (y = 1; y < height; y++) {
+		y2 = y - 1;
+		xormask += 24 * scanline;
+		for (x = 0; x < width - 1; x++) {
+			x2 = x + 1;
+			xorptr = xormask + 3 * x;
+			if ((xorptr[0] || xorptr[1] || xorptr[2]) &&
+					ui_get_cursor_bit(andmask, scanline, x, y) &&
+					! ui_get_cursor_bit(mask, -scanline, x2, y2)) {
+				ui_set_cursor_bit(cursor, -scanline, x2, y2);
+				ui_set_cursor_bit(mask, -scanline, x2, y2);
+			}
+		}
+	}
+}
+
+static void
+ui_convert_cursor(uint8 * cursor, uint8 * mask, int scanline, int height,
+	uint8 * andmask, uint8 * xormask)
+{
+	uint8 * pcursor;
+	uint8 * pmask;
 	uint8 nextbit;
-	int scanline, offset;
 	int i, j;
+	int offset;
 
-	scanline = (width + 7) / 8;
 	offset = scanline * height;
 
-	cursor = (uint8 *) xmalloc(offset);
-	memset(cursor, 0, offset);
-
-	mask = (uint8 *) xmalloc(offset);
-	memset(mask, 0, offset);
-
 	/* approximate AND and XOR masks with a monochrome X pointer */
 	for (i = 0; i < height; i++)
 	{
@@ -2822,6 +2860,34 @@
 			pmask++;
 		}
 	}
+}
+
+RD_HCURSOR
+ui_create_cursor(unsigned int x, unsigned int y, int width, int height,
+		 uint8 * andmask, uint8 * xormask)
+{
+	RD_HGLYPH maskglyph, cursorglyph;
+	XColor bg, fg;
+	Cursor xcursor;
+	uint8 * cursor;
+	uint8 * mask;
+	int scanline, offset;
+
+	scanline = (width + 7) / 8;
+	offset = scanline * height;
+
+	cursor = (uint8 *) xmalloc(offset);
+	memset(cursor, 0, offset);
+
+	mask = (uint8 *) xmalloc(offset);
+	memset(mask, 0, offset);
+
+	/* original cursor conversion code */
+	ui_convert_cursor(cursor, mask, scanline, height, andmask, xormask);
+
+	/* code to add a "shadow" to XOR cursors for improved visibility */
+	ui_add_xor_cursor_shadow(cursor, mask, width, scanline, height,
+		andmask, xormask);
 
 	fg.red = fg.blue = fg.green = 0xffff;
 	bg.red = bg.blue = bg.green = 0x0000;