[Glamor] [PATCH 4/7] Fix the problem of set the same stop several times

[junyan.he at linux.intel.com]

From: Junyan He <junyan.he at linux.intel.com>

 Some gradient set the stops at the same position, for
 example: firstly 0.5 to red color and then set 0.5 to
 blue. This kind of setting will cause the shader work
 not correctly because the percentage caculating need to
 use the stop[i] - stop[i-1] as dividend. The previous
 patch we just kill some stop if the distance between
 them is 0. But this cause the problem that the color
 for next stop is wrong. We now modify to handle it in
 the shader to avoid the 0 as dividend.


Signed-off-by: Junyan He <junyan.he at linux.intel.com>
---
 src/glamor_gradient.c |   25 ++++++++-----------------
 1 files changed, 8 insertions(+), 17 deletions(-)

diff --git a/src/glamor_gradient.c b/src/glamor_gradient.c
index a519b34..7263c2b 100644
--- a/src/glamor_gradient.c
+++ b/src/glamor_gradient.c
@@ -67,9 +67,12 @@ _glamor_create_getcolor_fs_program(ScreenPtr screen, int stops_count, int use_ar
 	    "            break; \n"
 	    "    }\n"
 	    "    \n"
-	    "    percentage = (stop_len - stops[i-1])/(stops[i] - stops[i-1]);\n"
 	    "    if(stops[i] - stops[i-1] > 2.0)\n"
 	    "        percentage = 0.0;\n" //For comply with pixman, walker->stepper overflow.
+	    "    else if(stops[i] - stops[i-1] < 0.000001)\n"
+	    "        percentage = 0.0;\n"
+	    "    else \n"
+	    "        percentage = (stop_len - stops[i-1])/(stops[i] - stops[i-1]);\n"
 	    "    new_alpha = percentage * stop_colors[i].a + \n"
 	    "                       (1.0-percentage) * stop_colors[i-1].a; \n"
 	    "    gradient_color = vec4((percentage * stop_colors[i].rgb \n"
@@ -116,58 +119,53 @@ _glamor_create_getcolor_fs_program(ScreenPtr screen, int stops_count, int use_ar
 	    "        stop_color_after = stop_color0;\n"
 	    "        stop_after = stop0;\n"
 	    "        stop_before = stop0;\n"
-	    "        percentage = 0.0;\n"
 	    "    } else if((stop_len < stop1) && (n_stop >= 2)) {\n"
 	    "        stop_color_before = stop_color0;\n"
 	    "        stop_color_after = stop_color1;\n"
 	    "        stop_after = stop1;\n"
 	    "        stop_before = stop0;\n"
-	    "        percentage = (stop_len - stop0)/(stop1 - stop0);\n"
 	    "    } else if((stop_len < stop2) && (n_stop >= 3)) {\n"
 	    "        stop_color_before = stop_color1;\n"
 	    "        stop_color_after = stop_color2;\n"
 	    "        stop_after = stop2;\n"
 	    "        stop_before = stop1;\n"
-	    "        percentage = (stop_len - stop1)/(stop2 - stop1);\n"
 	    "    } else if((stop_len < stop3) && (n_stop >= 4)){\n"
 	    "        stop_color_before = stop_color2;\n"
 	    "        stop_color_after = stop_color3;\n"
 	    "        stop_after = stop3;\n"
 	    "        stop_before = stop2;\n"
-	    "        percentage = (stop_len - stop2)/(stop3 - stop2);\n"
 	    "    } else if((stop_len < stop4) && (n_stop >= 5)){\n"
 	    "        stop_color_before = stop_color3;\n"
 	    "        stop_color_after = stop_color4;\n"
 	    "        stop_after = stop4;\n"
 	    "        stop_before = stop3;\n"
-	    "        percentage = (stop_len - stop3)/(stop4 - stop3);\n"
 	    "    } else if((stop_len < stop5) && (n_stop >= 6)){\n"
 	    "        stop_color_before = stop_color4;\n"
 	    "        stop_color_after = stop_color5;\n"
 	    "        stop_after = stop5;\n"
 	    "        stop_before = stop4;\n"
-	    "        percentage = (stop_len - stop4)/(stop5 - stop4);\n"
 	    "    } else if((stop_len < stop6) && (n_stop >= 7)){\n"
 	    "        stop_color_before = stop_color5;\n"
 	    "        stop_color_after = stop_color6;\n"
 	    "        stop_after = stop6;\n"
 	    "        stop_before = stop5;\n"
-	    "        percentage = (stop_len - stop5)/(stop6 - stop5);\n"
 	    "    } else if((stop_len < stop7) && (n_stop >= 8)){\n"
 	    "        stop_color_before = stop_color6;\n"
 	    "        stop_color_after = stop_color7;\n"
 	    "        stop_after = stop7;\n"
 	    "        stop_before = stop6;\n"
-	    "        percentage = (stop_len - stop6)/(stop7 - stop6);\n"
 	    "    } else {\n"
 	    "        stop_color_before = stop_color7;\n"
 	    "        stop_color_after = stop_color7;\n"
 	    "        stop_after = stop7;\n"
 	    "        stop_before = stop7;\n"
-	    "        percentage = 0.0;\n"
 	    "    }\n"
 	    "    if(stop_after - stop_before > 2.0)\n"
 	    "        percentage = 0.0;\n"//For comply with pixman, walker->stepper overflow.
+	    "    else if(stop_after - stop_before < 0.000001)\n"
+	    "        percentage = 0.0;\n"
+	    "    else \n"
+	    "        percentage = (stop_len - stop_before)/(stop_after - stop_before);\n"
 	    "    new_alpha = percentage * stop_color_after.a + \n"
 	    "                       (1.0-percentage) * stop_color_before.a; \n"
 	    "    gradient_color = vec4((percentage * stop_color_after.rgb \n"
@@ -883,13 +881,6 @@ _glamor_gradient_set_stops(PicturePtr src_picture, PictGradient * pgradient,
 	int count = 1;
 
 	for (i = 0; i < pgradient->nstops; i++) {
-		/* We find some gradient picture set the stops at the same percentage, which
-		   will cause the shader problem because the (stops[i] - stops[i-1]) will
-		   be used as divisor. We just keep the later one if stops[i] == stops[i-1] */
-		if (i < pgradient->nstops - 1
-		         && pgradient->stops[i].x == pgradient->stops[i+1].x)
-			continue;
-
 		stop_colors[count*4] = pixman_fixed_to_double(
 		                                pgradient->stops[i].color.red);
 		stop_colors[count*4+1] = pixman_fixed_to_double(
-- 
1.7.7.6