aboutsummaryrefslogtreecommitdiffstats
path: root/meta/recipes-qt/qt4/qt4-4.8.5/0022-Fix-drawing-of-0-width-polylines-from-outside-the-de.patch
blob: ad45dd0511b3ecf1c3737cfaeb5aa6714fd6177b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
From b7029fbd12c32e851ed7d81b692197176eb71d9e Mon Sep 17 00:00:00 2001
From: Gunnar Sletta <gunnar.sletta@digia.com>
Date: Thu, 4 Jul 2013 16:20:40 +1000
Subject: [PATCH] Fix drawing of 0-width polylines from outside the devicerect.

This was broken by a previous fix which aimed to fix gaps in
polylines with tiny line segments. The result was that we
skipped updating the origin point when stroke() didn't produce
pixels which accidentally included the case of the line
being completely outside the deviceRect. I fixed this
by returning the value of clipLine in drawLine to the caller
so we could still update the origin for this case.

Upstream-Status: Accepted [https://codereview.qt-project.org/#change,60427]
Signed-off-by: Jonathan Liu <net147@gmail.com>

Task-number: QTBUG-31579
Change-Id: Iac29436f042da7658bbeaf9370351dc6f2c95065
(cherry picked from qtbase/900cccfd459fcbdbc4aa3d313afe12cfbf68fd87)
---
 src/gui/painting/qcosmeticstroker.cpp | 42 ++++++++++++++++++++++-------------
 src/gui/painting/qcosmeticstroker_p.h |  2 +-
 2 files changed, 27 insertions(+), 17 deletions(-)

diff --git a/src/gui/painting/qcosmeticstroker.cpp b/src/gui/painting/qcosmeticstroker.cpp
index 0061ecb..4413170 100644
--- a/src/gui/painting/qcosmeticstroker.cpp
+++ b/src/gui/painting/qcosmeticstroker.cpp
@@ -133,10 +133,15 @@ struct NoDasher {
 
 };
 
+/*
+ * The return value is the result of the clipLine() call performed at the start
+ * of each of the two functions, aka "false" means completely outside the devices
+ * rect.
+ */
 template<DrawPixel drawPixel, class Dasher>
-static void drawLine(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+static bool drawLine(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
 template<DrawPixel drawPixel, class Dasher>
-static void drawLineAA(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+static bool drawLineAA(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
 
 inline void drawPixel(QCosmeticStroker *stroker, int x, int y, int coverage)
 {
@@ -602,17 +607,20 @@ void QCosmeticStroker::drawPath(const QVectorPath &path)
                 caps |= CapEnd;
 
             QCosmeticStroker::Point last = this->lastPixel;
-            stroke(this, p.x(), p.y(), p2.x(), p2.y(), caps);
+            bool unclipped = stroke(this, p.x(), p.y(), p2.x(), p2.y(), caps);
 
             /* fix for gaps in polylines with fastpen and aliased in a sequence
                of points with small distances: if current point p2 has been dropped
-               out, keep last non dropped point p. */
-            if (fastPenAliased) {
-                if (last.x != lastPixel.x || last.y != lastPixel.y ||
-                    points == begin + 2 || points == end - 2 ) {
-                    {
-                        p = p2;
-                    }
+               out, keep last non dropped point p.
+
+               However, if the line was completely outside the devicerect, we
+               still need to update p to avoid drawing the line after this one from
+               a bad starting position.
+            */
+            if (fastPenAliased && unclipped) {
+                if (last.x != lastPixel.x || last.y != lastPixel.y
+                    || points == begin + 2 || points == end - 2) {
+                    p = p2;
                 }
             } else {
                 p = p2;
@@ -720,10 +728,10 @@ static inline void capAdjust(int caps, int &x1, int &x2, int &y, int yinc)
   the drawing shifts from horizontal to vertical or back.
   */
 template<DrawPixel drawPixel, class Dasher>
-static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
+static bool drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
 {
     if (stroker->clipLine(rx1, ry1, rx2, ry2))
-        return;
+        return false;
 
     static const int half = 31;
     int x1 = toF26Dot6(rx1) + half;
@@ -813,7 +821,7 @@ static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2,
     } else {
         // horizontal
         if (!dx)
-            return;
+            return true;
 
         QCosmeticStroker::Direction dir = QCosmeticStroker::LeftToRight;
 
@@ -886,14 +894,15 @@ static void drawLine(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2,
         }
     }
     stroker->lastPixel = last;
+    return true;
 }
 
 
 template<DrawPixel drawPixel, class Dasher>
-static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
+static bool drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx2, qreal ry2, int caps)
 {
     if (stroker->clipLine(rx1, ry1, rx2, ry2))
-        return;
+        return false;
 
     int x1 = toF26Dot6(rx1);
     int y1 = toF26Dot6(ry1);
@@ -967,7 +976,7 @@ static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx
     } else {
         // horizontal
         if (!dx)
-            return;
+            return true;
 
         int yinc = F16Dot16FixedDiv(dy, dx);
 
@@ -1029,6 +1038,7 @@ static void drawLineAA(QCosmeticStroker *stroker, qreal rx1, qreal ry1, qreal rx
             drawPixel(stroker, x, (y>>16) + 1, alpha * alphaEnd >> 6);
         }
     }
+    return true;
 }
 
 QT_END_NAMESPACE
diff --git a/src/gui/painting/qcosmeticstroker_p.h b/src/gui/painting/qcosmeticstroker_p.h
index 870738b..3216856 100644
--- a/src/gui/painting/qcosmeticstroker_p.h
+++ b/src/gui/painting/qcosmeticstroker_p.h
@@ -56,7 +56,7 @@ QT_MODULE(Gui)
 class QCosmeticStroker;
 
 
-typedef void (*StrokeLine)(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
+typedef bool (*StrokeLine)(QCosmeticStroker *stroker, qreal x1, qreal y1, qreal x2, qreal y2, int caps);
 
 class QCosmeticStroker
 {
-- 
1.8.3.2