Move QPolygonClipper to XCB native painting

It is the only code using it.

Change-Id: I30060a63b6621ea94ae487ec93cd857117e12a46
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>

3 files changed, 318 insertions, 1 deletions

diff --git a/src/plugins/platforms/xcb/nativepainting/nativepainting.pri b/src/plugins/platforms/xcb/nativepainting/nativepainting.pri
index 78ed00843f..e1a47fb7d7 100644
--- a/src/plugins/platforms/xcb/nativepainting/nativepainting.pri
+++ b/src/plugins/platforms/xcb/nativepainting/nativepainting.pri
@@ -7,6 +7,7 @@ qtConfig(xcb-native-painting) {
         $$PWD/qtessellator_p.h \
         $$PWD/qpixmap_x11_p.h \
         $$PWD/qpaintengine_x11_p.h \
+        $$PWD/qpolygonclipper_p.h \
         $$PWD/qt_x11_p.h \
         $$PWD/qcolormap_x11_p.h \
         $$PWD/qbackingstore_x11_p.h \
diff --git a/src/plugins/platforms/xcb/nativepainting/qpaintengine_x11.cpp b/src/plugins/platforms/xcb/nativepainting/qpaintengine_x11.cpp
index 82900d4054..e69030ca97 100644
--- a/src/plugins/platforms/xcb/nativepainting/qpaintengine_x11.cpp
+++ b/src/plugins/platforms/xcb/nativepainting/qpaintengine_x11.cpp
@@ -41,7 +41,6 @@
 
 #include <private/qpixmapcache_p.h>
 #include <private/qpaintengine_p.h>
-#include <private/qpolygonclipper_p.h>
 #include <private/qpainterpath_p.h>
 #include <private/qdrawhelper_p.h>
 #include <private/qfontengineglyphcache_p.h>
@@ -51,6 +50,7 @@
 #endif
 
 #include "qpaintengine_x11_p.h"
+#include "qpolygonclipper_p.h"
 #include "qtessellator_p.h"
 #include "qpixmap_x11_p.h"
 #include "qcolormap_x11_p.h"
diff --git a/src/plugins/platforms/xcb/nativepainting/qpolygonclipper_p.h b/src/plugins/platforms/xcb/nativepainting/qpolygonclipper_p.h
new file mode 100644
index 0000000000..33499df6ed
--- /dev/null
+++ b/src/plugins/platforms/xcb/nativepainting/qpolygonclipper_p.h
@@ -0,0 +1,316 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef QPOLYGONCLIPPER_P_H
+#define QPOLYGONCLIPPER_P_H
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists for the convenience
+// of other Qt classes.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include <QtCore/qrect.h>
+#include <QtGui/private/qdatabuffer_p.h>
+
+QT_BEGIN_NAMESPACE
+
+/* based on sutherland-hodgman line-by-line clipping, as described in
+   Computer Graphics and Principles */
+template <typename InType, typename OutType, typename CastType> class QPolygonClipper
+{
+public:
+    QPolygonClipper() :
+        buffer1(0), buffer2(0)
+    {
+        x1 = y1 = x2 = y2 = 0;
+    }
+
+    ~QPolygonClipper()
+    {
+    }
+
+    void setBoundingRect(const QRect bounds)
+    {
+        x1 = bounds.x();
+        x2 = bounds.x() + bounds.width();
+        y1 = bounds.y();
+        y2 = bounds.y() + bounds.height();
+    }
+
+    QRect boundingRect()
+    {
+        return QRect(QPoint(x1, y1), QPoint(x2, y2));
+    }
+
+    inline OutType intersectLeft(const OutType &p1, const OutType &p2)
+    {
+        OutType t;
+        qreal dy = (p1.y - p2.y) / qreal(p1.x - p2.x);
+        t.x = x1;
+        t.y = static_cast<CastType>(p2.y + (x1 - p2.x) * dy);
+        return t;
+    }
+
+
+    inline OutType intersectRight(const OutType &p1, const OutType &p2)
+    {
+        OutType t;
+        qreal dy = (p1.y - p2.y) / qreal(p1.x - p2.x);
+        t.x = x2;
+        t.y = static_cast<CastType>(p2.y + (x2 - p2.x) * dy);
+        return t;
+    }
+
+
+    inline OutType intersectTop(const OutType &p1, const OutType &p2)
+    {
+        OutType t;
+        qreal dx = (p1.x - p2.x) / qreal(p1.y - p2.y);
+        t.x = static_cast<CastType>(p2.x + (y1 - p2.y) * dx);
+        t.y = y1;
+        return t;
+    }
+
+
+    inline OutType intersectBottom(const OutType &p1, const OutType &p2)
+    {
+        OutType t;
+        qreal dx = (p1.x - p2.x) / qreal(p1.y - p2.y);
+        t.x = static_cast<CastType>(p2.x + (y2 - p2.y) * dx);
+        t.y = y2;
+        return t;
+    }
+
+
+    void clipPolygon(const InType *inPoints, int inCount, OutType **outPoints, int *outCount,
+                     bool closePolygon = true)
+    {
+        Q_ASSERT(outPoints);
+        Q_ASSERT(outCount);
+
+        if (inCount < 2) {
+            *outCount = 0;
+            return;
+        }
+
+        buffer1.reset();
+        buffer2.reset();
+
+        QDataBuffer<OutType> *source = &buffer1;
+        QDataBuffer<OutType> *clipped = &buffer2;
+
+        // Gather some info since we are iterating through the points anyway..
+        bool doLeft = false, doRight = false, doTop = false, doBottom = false;
+        OutType ot;
+        for (int i=0; i<inCount; ++i) {
+            ot = inPoints[i];
+            clipped->add(ot);
+
+            if (ot.x < x1)
+                doLeft = true;
+            else if (ot.x > x2)
+                doRight = true;
+            if (ot.y < y1)
+                doTop = true;
+            else if (ot.y > y2)
+                doBottom = true;
+        }
+
+        if (doLeft && clipped->size() > 1) {
+            QDataBuffer<OutType> *tmp = source;
+            source = clipped;
+            clipped = tmp;
+            clipped->reset();
+            int lastPos, start;
+            if (closePolygon) {
+                lastPos = source->size() - 1;
+                start = 0;
+            } else {
+                lastPos = 0;
+                start = 1;
+                if (source->at(0).x >= x1)
+                    clipped->add(source->at(0));
+            }
+            for (int i=start; i<inCount; ++i) {
+                const OutType &cpt = source->at(i);
+                const OutType &ppt = source->at(lastPos);
+
+                if (cpt.x >= x1) {
+                    if (ppt.x >= x1) {
+                        clipped->add(cpt);
+                    } else {
+                        clipped->add(intersectLeft(cpt, ppt));
+                        clipped->add(cpt);
+                    }
+                } else if (ppt.x >= x1) {
+                    clipped->add(intersectLeft(cpt, ppt));
+                }
+                lastPos = i;
+            }
+        }
+
+        if (doRight && clipped->size() > 1) {
+            QDataBuffer<OutType> *tmp = source;
+            source = clipped;
+            clipped = tmp;
+            clipped->reset();
+            int lastPos, start;
+            if (closePolygon) {
+                lastPos = source->size() - 1;
+                start = 0;
+            } else {
+                lastPos = 0;
+                start = 1;
+                if (source->at(0).x <= x2)
+                    clipped->add(source->at(0));
+            }
+            for (int i=start; i<source->size(); ++i) {
+                const OutType &cpt = source->at(i);
+                const OutType &ppt = source->at(lastPos);
+
+                if (cpt.x <= x2) {
+                    if (ppt.x <= x2) {
+                        clipped->add(cpt);
+                    } else {
+                        clipped->add(intersectRight(cpt, ppt));
+                        clipped->add(cpt);
+                    }
+                } else if (ppt.x <= x2) {
+                    clipped->add(intersectRight(cpt, ppt));
+                }
+
+                lastPos = i;
+            }
+
+        }
+
+        if (doTop && clipped->size() > 1) {
+            QDataBuffer<OutType> *tmp = source;
+            source = clipped;
+            clipped = tmp;
+            clipped->reset();
+            int lastPos, start;
+            if (closePolygon) {
+                lastPos = source->size() - 1;
+                start = 0;
+            } else {
+                lastPos = 0;
+                start = 1;
+                if (source->at(0).y >= y1)
+                    clipped->add(source->at(0));
+            }
+            for (int i=start; i<source->size(); ++i) {
+                const OutType &cpt = source->at(i);
+                const OutType &ppt = source->at(lastPos);
+
+                if (cpt.y >= y1) {
+                    if (ppt.y >= y1) {
+                        clipped->add(cpt);
+                    } else {
+                        clipped->add(intersectTop(cpt, ppt));
+                        clipped->add(cpt);
+                    }
+                } else if (ppt.y >= y1) {
+                    clipped->add(intersectTop(cpt, ppt));
+                }
+
+                lastPos = i;
+            }
+        }
+
+        if (doBottom && clipped->size() > 1) {
+            QDataBuffer<OutType> *tmp = source;
+            source = clipped;
+            clipped = tmp;
+            clipped->reset();
+            int lastPos, start;
+            if (closePolygon) {
+                lastPos = source->size() - 1;
+                start = 0;
+            } else {
+                lastPos = 0;
+                start = 1;
+                if (source->at(0).y <= y2)
+                    clipped->add(source->at(0));
+            }
+            for (int i=start; i<source->size(); ++i) {
+                const OutType &cpt = source->at(i);
+                const OutType &ppt = source->at(lastPos);
+
+                if (cpt.y <= y2) {
+                    if (ppt.y <= y2) {
+                        clipped->add(cpt);
+                    } else {
+                        clipped->add(intersectBottom(cpt, ppt));
+                        clipped->add(cpt);
+                    }
+                } else if (ppt.y <= y2) {
+                    clipped->add(intersectBottom(cpt, ppt));
+                }
+                lastPos = i;
+            }
+        }
+
+        if (closePolygon && clipped->size() > 0) {
+            // close clipped polygon
+            if (clipped->at(0).x != clipped->at(clipped->size()-1).x ||
+                clipped->at(0).y != clipped->at(clipped->size()-1).y) {
+                OutType ot = clipped->at(0);
+                clipped->add(ot);
+            }
+        }
+        *outCount = clipped->size();
+        *outPoints = clipped->data();
+    }
+
+private:
+    int x1, x2, y1, y2;
+    QDataBuffer<OutType> buffer1;
+    QDataBuffer<OutType> buffer2;
+};
+
+QT_END_NAMESPACE
+
+#endif // QPOLYGONCLIPPER_P_H