Fix very slow stroking of paths in X11 paint engine.

Use QStroker::setRect() to avoid dashing parts of the path that are
outside the device rect.

Task-number: 246573
Reviewed-by: Trond

4 files changed, 24 insertions, 14 deletions

diff --git a/src/gui/painting/qpaintengine_x11.cpp b/src/gui/painting/qpaintengine_x11.cpp
index 32cb63d..d931f55 100644
--- a/src/gui/painting/qpaintengine_x11.cpp
+++ b/src/gui/painting/qpaintengine_x11.cpp
@@ -62,6 +62,7 @@
 #include <private/qpaintengine_x11_p.h>
 #include <private/qfontengine_x11_p.h>
 #include <private/qwidget_p.h>
+#include <private/qpainterpath_p.h>
 
 #include "qpen.h"
 #include "qcolor.h"
@@ -1756,9 +1757,11 @@ void QX11PaintEngine::drawPath(const QPainterPath &path)
         QPainterPath stroke;
         qreal width = d->cpen.widthF();
         QPolygonF poly;
+        QRectF deviceRect(0, 0, d->pdev->width(), d->pdev->height());
         // necessary to get aliased alphablended primitives to be drawn correctly
         if (d->cpen.isCosmetic() || d->has_scaling_xform) {
             stroker.setWidth(width == 0 ? 1 : width * d->xform_scale);
+            stroker.d_ptr->stroker.setClipRect(deviceRect);
             stroke = stroker.createStroke(path * d->matrix);
             if (stroke.isEmpty())
                 return;
@@ -1766,6 +1769,7 @@ void QX11PaintEngine::drawPath(const QPainterPath &path)
             d->fillPath(stroke, QX11PaintEnginePrivate::PenGC, false);
         } else {
             stroker.setWidth(width);
+            stroker.d_ptr->stroker.setClipRect(d->matrix.inverted().mapRect(deviceRect));
             stroke = stroker.createStroke(path);
             if (stroke.isEmpty())
                 return;
diff --git a/src/gui/painting/qpainterpath.cpp b/src/gui/painting/qpainterpath.cpp
index bb07f81..70036e1 100644
--- a/src/gui/painting/qpainterpath.cpp
+++ b/src/gui/painting/qpainterpath.cpp
@@ -2387,21 +2387,13 @@ void qt_path_stroke_cubic_to(qfixed c1x, qfixed c1y,
     \sa QPen, QBrush
 */
 
-class QPainterPathStrokerPrivate
+QPainterPathStrokerPrivate::QPainterPathStrokerPrivate()
+    : dashOffset(0)
 {
-public:
-    QPainterPathStrokerPrivate()
-        : dashOffset(0)
-    {
-        stroker.setMoveToHook(qt_path_stroke_move_to);
-        stroker.setLineToHook(qt_path_stroke_line_to);
-        stroker.setCubicToHook(qt_path_stroke_cubic_to);
-    }
-
-    QStroker stroker;
-    QVector<qfixed> dashPattern;
-    qreal dashOffset;
-};
+    stroker.setMoveToHook(qt_path_stroke_move_to);
+    stroker.setLineToHook(qt_path_stroke_line_to);
+    stroker.setCubicToHook(qt_path_stroke_cubic_to);
+}
 
 /*!
    Creates a new stroker.
@@ -2445,6 +2437,7 @@ QPainterPath QPainterPathStroker::createStroke(const QPainterPath &path) const
         QDashStroker dashStroker(&d->stroker);
         dashStroker.setDashPattern(d->dashPattern);
         dashStroker.setDashOffset(d->dashOffset);
+        dashStroker.setClipRect(d->stroker.clipRect());
         dashStroker.strokePath(path, &stroke, QTransform());
     }
     stroke.setFillRule(Qt::WindingFill);
diff --git a/src/gui/painting/qpainterpath.h b/src/gui/painting/qpainterpath.h
index 88fb19d..6cd2af8 100644
--- a/src/gui/painting/qpainterpath.h
+++ b/src/gui/painting/qpainterpath.h
@@ -277,6 +277,8 @@ public:
     QPainterPath createStroke(const QPainterPath &path) const;
 
 private:
+    friend class QX11PaintEngine;
+
     QPainterPathStrokerPrivate *d_ptr;
 };
 
diff --git a/src/gui/painting/qpainterpath_p.h b/src/gui/painting/qpainterpath_p.h
index 93f9704..29c48df 100644
--- a/src/gui/painting/qpainterpath_p.h
+++ b/src/gui/painting/qpainterpath_p.h
@@ -61,9 +61,20 @@
 #include <qdebug.h>
 
 #include <private/qvectorpath_p.h>
+#include <private/qstroker_p.h>
 
 QT_BEGIN_NAMESPACE
 
+class QPainterPathStrokerPrivate
+{
+public:
+    QPainterPathStrokerPrivate();
+
+    QStroker stroker;
+    QVector<qfixed> dashPattern;
+    qreal dashOffset;
+};
+
 class QPolygonF;
 class QVectorPathConverter;