Introduce SVGPathQuery to hold SVG path query methods

third_party/WebKit/Source/core/svg/SVGPathQuery.cpp

+/*
+ * Copyright (C) 2004, 2005, 2006, 2007, 2008 Nikolas Zimmermann <zimmermann@kde.org>
+ * Copyright (C) 2004, 2005 Rob Buis <buis@kde.org>
+ * Copyright (C) 2007 Eric Seidel <eric@webkit.org>
+ * Copyright (C) Research In Motion Limited 2010. All rights reserved.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public License
+ * along with this library; see the file COPYING.LIB.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#include "config.h"
+#include "core/svg/SVGPathQuery.h"
+
+#include "core/svg/SVGPathByteStreamSource.h"
+#include "core/svg/SVGPathConsumer.h"
+#include "core/svg/SVGPathData.h"
+#include "core/svg/SVGPathParser.h"
+#include "platform/graphics/PathTraversalState.h"
+
+namespace blink {
+
+namespace {
+
+class SVGPathTraversalState final : public SVGPathConsumer {
+public:
+    SVGPathTraversalState(PathTraversalState::PathTraversalAction traversalAction, float desiredLength = 0)
+        : m_traversalState(traversalAction)
+        , m_segmentIndex(0)
+    {
+        m_traversalState.m_desiredLength = desiredLength;
+    }
+
+    unsigned segmentIndex() const { return m_segmentIndex; }
+    float totalLength() const { return m_traversalState.m_totalLength; }
+    FloatPoint computedPoint() const { return m_traversalState.m_current; }
+
+    void consumedSegment() { m_segmentIndex++; }
+
+    bool processSegment()
+    {
+        m_traversalState.processSegment();
+        return m_traversalState.m_success;
+    }
+
+private:
+    void emitSegment(const PathSegmentData&) override;
+
+    PathTraversalState m_traversalState;
+    unsigned m_segmentIndex;
+};
+
+void SVGPathTraversalState::emitSegment(const PathSegmentData& segment)
+{
+    switch (segment.command) {
+    case PathSegMoveToAbs:
+        m_traversalState.m_totalLength += m_traversalState.moveTo(segment.targetPoint);
+        break;
+    case PathSegLineToAbs:
+        m_traversalState.m_totalLength += m_traversalState.lineTo(segment.targetPoint);
+        break;
+    case PathSegClosePath:
+        m_traversalState.m_totalLength += m_traversalState.closeSubpath();
+        break;
+    case PathSegCurveToCubicAbs:
+        m_traversalState.m_totalLength += m_traversalState.cubicBezierTo(segment.point1, segment.point2, segment.targetPoint);
+        break;
+    default:
+        ASSERT_NOT_REACHED();
+    }
+}
+
+void executeQuery(const SVGPathByteStream& pathByteStream, SVGPathTraversalState& traversalState)
+{
+    SVGPathByteStreamSource source(pathByteStream);
+    SVGPathNormalizer normalizer(&traversalState);
+
+    bool hasMoreData = source.hasMoreData();
+    while (hasMoreData) {
+        PathSegmentData segment = source.parseSegment();
+        ASSERT(segment.command != PathSegUnknown);
+
+        normalizer.emitSegment(segment);
+
+        if (traversalState.processSegment())
+            return;
+
+        hasMoreData = source.hasMoreData();
+        if (hasMoreData)
+            traversalState.consumedSegment();

[f(malita), 2015/11/24 14:22:40]

Could we get rid of consumedSegment by folding its logic into processSegment
(pass an hasMoreData arg, or indiscriminately inc the segment index)?

[fs, 2015/11/24 14:51:46]

Done (the former, the latter would change semantics.)

+    }
+}
+
+}
+
+SVGPathQuery::SVGPathQuery(const SVGPathByteStream& pathByteStream)
+    : m_pathByteStream(pathByteStream)
+{
+}
+
+unsigned SVGPathQuery::getPathSegIndexAtLength(float length) const
+{
+    SVGPathTraversalState traversalState(PathTraversalState::TraversalSegmentAtLength, length);
+    executeQuery(m_pathByteStream, traversalState);
+    return traversalState.segmentIndex();
+}
+
+float SVGPathQuery::getTotalLength() const
+{
+    SVGPathTraversalState traversalState(PathTraversalState::TraversalTotalLength);
+    executeQuery(m_pathByteStream, traversalState);
+    return traversalState.totalLength();
+}
+
+FloatPoint SVGPathQuery::getPointAtLength(float length) const
+{
+    SVGPathTraversalState traversalState(PathTraversalState::TraversalPointAtLength, length);
+    executeQuery(m_pathByteStream, traversalState);
+    return traversalState.computedPoint();
+}
+
+}