OpenVG Scenegraph Adaptation

This is an OpenVG backend for the Qt Quick 2 scenegraph.

Should be feature complete now, but there are still some issues that
could be improved in future commits:

If Rectangle nodes are rendered with a non-affine transform, they will
be rendered incorrectly.  This is because paths expect affine
transformations.

The Glyph cache is a bit cheeky in that it's caching paths, but doing
so per font size.  It shoudln't need to, but right now I've not though
up a good way of getting the transform/scale needed when rendering yet.

Change-Id: Ie3c4f2df35d14279b0f9f55e0e10a873328c025b
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>

1 files changed, 283 insertions, 0 deletions

diff --git a/src/plugins/scenegraph/openvg/qsgopenvgnodevisitor.cpp b/src/plugins/scenegraph/openvg/qsgopenvgnodevisitor.cpp
new file mode 100644
index 0000000000..fc9f5eb57c
--- /dev/null
+++ b/src/plugins/scenegraph/openvg/qsgopenvgnodevisitor.cpp
@@ -0,0 +1,283 @@
+/****************************************************************************
+**
+** Copyright (C) 2016 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the QtQuick 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.
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qsgopenvgnodevisitor.h"
+#include "qsgopenvginternalrectanglenode.h"
+#include "qsgopenvginternalimagenode.h"
+#include "qsgopenvgpublicnodes.h"
+#include "qsgopenvgglyphnode_p.h"
+#include "qsgopenvgpainternode.h"
+#include "qsgopenvgspritenode.h"
+#include "qsgopenvgrenderable.h"
+
+#include "qopenvgcontext_p.h"
+
+#include <QtQuick/qsgsimplerectnode.h>
+#include <QtQuick/qsgsimpletexturenode.h>
+#include <QtQuick/qsgrendernode.h>
+
+QT_BEGIN_NAMESPACE
+
+QSGOpenVGNodeVisitor::QSGOpenVGNodeVisitor()
+{
+    //Store the current matrix state
+    QVector<VGfloat> matrix(9);
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_PATH_USER_TO_SURFACE);
+    vgGetMatrix(matrix.data());
+
+    m_transformStack.push(QOpenVGMatrix(matrix.constData()));
+
+    // Opacity
+    m_opacityState.push(1.0f);
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGTransformNode *node)
+{
+    const QVector<float> matrixData = { node->matrix().constData()[0], node->matrix().constData()[1], node->matrix().constData()[3],
+                                        node->matrix().constData()[4], node->matrix().constData()[5], node->matrix().constData()[7],
+                                        node->matrix().constData()[12], node->matrix().constData()[13], node->matrix().constData()[15] };
+    const QOpenVGMatrix matrix2d(matrixData.constData());
+
+    m_transformStack.push(m_transformStack.top() * matrix2d);
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGTransformNode *)
+{
+    m_transformStack.pop();
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGClipNode *node)
+{
+    VGMaskOperation maskOperation = VG_INTERSECT_MASK;
+    if (m_clipStack.count() == 0) {
+        vgSeti(VG_MASKING, VG_TRUE);
+        vgMask(0,VG_FILL_MASK, 0, 0, VG_MAXINT, VG_MAXINT);
+    }
+
+    // Render clip node geometry to mask
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_PATH_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    VGPath clipPath = generateClipPath(node->clipRect());
+    vgRenderToMask(clipPath, VG_FILL_PATH, maskOperation);
+
+    auto clipState = new ClipState(clipPath, m_transformStack.top());
+    m_clipStack.push(clipState);
+
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGClipNode *)
+{
+    // Remove clip node geometry from mask
+    auto clipState = m_clipStack.pop();
+    vgDestroyPath(clipState->path);
+
+    if (m_clipStack.count() == 0) {
+        vgSeti(VG_MASKING, VG_FALSE);
+    } else {
+        // Recreate the mask
+        vgMask(0,VG_FILL_MASK, 0, 0, VG_MAXINT, VG_MAXINT);
+        for (auto state : m_clipStack) {
+            vgSeti(VG_MATRIX_MODE, VG_MATRIX_PATH_USER_TO_SURFACE);
+            vgLoadMatrix(state->transform.constData());
+            vgRenderToMask(state->path, VG_FILL_PATH, VG_INTERSECT_MASK);
+        }
+    }
+
+    delete clipState;
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGGeometryNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_PATH_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_IMAGE_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    if (QSGSimpleRectNode *rectNode = dynamic_cast<QSGSimpleRectNode *>(node)) {
+        // TODO: Try and render the QSGSimpleRectNode
+        Q_UNUSED(rectNode)
+        return false;
+    } else if (QSGSimpleTextureNode *tn = dynamic_cast<QSGSimpleTextureNode *>(node)) {
+        // TODO: Try and render the QSGSimpleTextureNode
+        Q_UNUSED(tn)
+        return false;
+    } else if (QSGOpenVGNinePatchNode *nn = dynamic_cast<QSGOpenVGNinePatchNode *>(node)) {
+        renderRenderableNode(nn);
+    } else if (QSGOpenVGRectangleNode *rn = dynamic_cast<QSGOpenVGRectangleNode *>(node)) {
+        renderRenderableNode(rn);
+    } else if (QSGOpenVGImageNode *n = dynamic_cast<QSGOpenVGImageNode *>(node)) {
+        renderRenderableNode(n);
+    } else {
+        // We dont know, so skip
+        return false;
+    }
+
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGGeometryNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGOpacityNode *node)
+{
+    m_opacityState.push(m_opacityState.top() * node->opacity());
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGOpacityNode *)
+{
+    m_opacityState.pop();
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGInternalImageNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_IMAGE_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    renderRenderableNode(static_cast<QSGOpenVGInternalImageNode*>(node));
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGInternalImageNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGPainterNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_IMAGE_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    renderRenderableNode(static_cast<QSGOpenVGPainterNode*>(node));
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGPainterNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGInternalRectangleNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_PATH_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    renderRenderableNode(static_cast<QSGOpenVGInternalRectangleNode*>(node));
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGInternalRectangleNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGGlyphNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_GLYPH_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    renderRenderableNode(static_cast<QSGOpenVGGlyphNode*>(node));
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGGlyphNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGRootNode *)
+{
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGRootNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGSpriteNode *node)
+{
+    vgSeti(VG_MATRIX_MODE, VG_MATRIX_IMAGE_USER_TO_SURFACE);
+    vgLoadMatrix(m_transformStack.top().constData());
+    renderRenderableNode(static_cast<QSGOpenVGSpriteNode*>(node));
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGSpriteNode *)
+{
+}
+
+bool QSGOpenVGNodeVisitor::visit(QSGRenderNode *)
+{
+    return true;
+}
+
+void QSGOpenVGNodeVisitor::endVisit(QSGRenderNode *)
+{
+}
+
+VGPath QSGOpenVGNodeVisitor::generateClipPath(const QRectF &rect) const
+{
+    VGPath clipPath = vgCreatePath(VG_PATH_FORMAT_STANDARD, VG_PATH_DATATYPE_F, 1, 0, 0, 0,
+                                   VG_PATH_CAPABILITY_APPEND_TO);
+
+    // Create command list
+    static const VGubyte rectCommands[] = {
+        VG_MOVE_TO_ABS,
+        VG_HLINE_TO_REL,
+        VG_VLINE_TO_REL,
+        VG_HLINE_TO_REL,
+        VG_CLOSE_PATH
+    };
+
+    // Create command data
+    QVector<VGfloat> coordinates(5);
+    coordinates[0] = rect.x();
+    coordinates[1] = rect.y();
+    coordinates[2] = rect.width();
+    coordinates[3] = rect.height();
+    coordinates[4] = -rect.width();
+
+    vgAppendPathData(clipPath, 5, rectCommands, coordinates.constData());
+    return clipPath;
+}
+
+void QSGOpenVGNodeVisitor::renderRenderableNode(QSGOpenVGRenderable *node)
+{
+    if (!node)
+        return;
+
+    node->setOpacity(m_opacityState.top());
+    node->render();
+}
+
+QT_END_NAMESPACE