QGraphicsAnchorLayout: Adding QGraphicsAnchorLayout public and private classes

This is a total re-written implementation of QGraphicsAnchorLayout using
a numerical approach. We use QGraph and QSimplex in order to achieve this.
This first commit gives us a just ready-to-use qgraphicslayout, but the
private class still need to inherit from qgraphicslayoutprivate. Optimizations
and documentation are all work in progress.

Signed-off-by: Anselmo Lacerda S. de Melo <anselmo.melo@openbossa.org>
Signed-off-by: Caio Marcelo de Oliveira Filho <caio.oliveira@openbossa.org>
Signed-off-by: Eduardo M. Fleury <eduardo.fleury@openbossa.org>
Signed-off-by: Jesus Sanchez-Palencia <jesus.palencia@openbossa.org>

1 files changed, 235 insertions, 0 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout.cpp b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
new file mode 100644
index 0000000..d737e36
--- /dev/null
+++ b/src/gui/graphicsview/qgraphicsanchorlayout.cpp
@@ -0,0 +1,235 @@
+/****************************************************************************
+**
+** Copyright (C) 2009 Nokia Corporation and/or its subsidiary(-ies).
+** Contact: Qt Software Information (qt-info@nokia.com)
+**
+** This file is part of the QtGui module of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the either Technology Preview License Agreement or the
+** Beta Release License Agreement.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain
+** additional rights. These rights are described in the Nokia Qt LGPL
+** Exception version 1.0, included in the file LGPL_EXCEPTION.txt in this
+** package.
+**
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 3.0 as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL included in the
+** packaging of this file.  Please review the following information to
+** ensure the GNU General Public License version 3.0 requirements will be
+** met: http://www.gnu.org/copyleft/gpl.html.
+**
+** If you are unsure which license is appropriate for your use, please
+** contact the sales department at qt-sales@nokia.com.
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "qgraphicsanchorlayout_p.h"
+
+QGraphicsAnchorLayout::QGraphicsAnchorLayout(QGraphicsLayoutItem *parent)
+    : QGraphicsLayout(parent), d_ptr(new QGraphicsAnchorLayoutPrivate())
+{
+    // ### REMOVE THAT
+    d_ptr->q_ptr = this;
+
+    d_ptr->createLayoutEdges();
+}
+
+QGraphicsAnchorLayout::~QGraphicsAnchorLayout()
+{
+    Q_D(QGraphicsAnchorLayout);
+
+    for (int i = count() - 1; i >= 0; --i) {
+        QGraphicsLayoutItem *item = d->items.at(i);
+        removeAt(i);
+        if (item) {
+            if (item->ownedByLayout())
+                delete item;
+        }
+    }
+}
+
+void QGraphicsAnchorLayout::anchor(QGraphicsLayoutItem *firstItem,
+                                   Edge firstEdge,
+                                   QGraphicsLayoutItem *secondItem,
+                                   Edge secondEdge, qreal spacing)
+{
+    Q_D(QGraphicsAnchorLayout);
+    if ((firstItem == 0) || (secondItem == 0)) {
+        qWarning("QGraphicsAnchorLayout::anchor: "
+                 "Cannot anchor NULL items");
+        return;
+    }
+
+    if (firstItem == secondItem) {
+        qWarning("QGraphicsAnchorLayout::anchor: "
+                 "Cannot anchor the item to itself");
+        return;
+    }
+
+    if (d->edgeOrientation(secondEdge) != d->edgeOrientation(firstEdge)) {
+        qWarning("QGraphicsAnchorLayout::anchor: "
+                 "Cannot anchor edges of different orientations");
+        return;
+    }
+
+    // In QGraphicsAnchorLayout, items are represented in its internal
+    // graph as four anchors that connect:
+    //  - Left -> HCenter
+    //  - HCenter-> Right
+    //  - Top -> VCenter
+    //  - VCenter -> Bottom
+
+    // Ensure that the internal anchors have been created for both items.
+    if (firstItem != this && !d->items.contains(firstItem)) {
+        d->createItemEdges(firstItem);
+        d->addChildItem(firstItem);
+    }
+    if (secondItem != this && !d->items.contains(secondItem)) {
+        d->createItemEdges(secondItem);
+        d->addChildItem(secondItem);
+    }
+
+    // Use heuristics to find out what the user meant with this anchor.
+    d->correctEdgeDirection(firstItem, firstEdge, secondItem, secondEdge);
+
+    // Create actual anchor between firstItem and secondItem.
+    AnchorData *data;
+    if (spacing >= 0) {
+        data = new AnchorData(spacing);
+        d->addAnchor(firstItem, firstEdge, secondItem, secondEdge, data);
+    } else {
+        data = new AnchorData(-spacing);
+        d->addAnchor(secondItem, secondEdge, firstItem, firstEdge, data);
+    }
+
+    invalidate();
+}
+
+void QGraphicsAnchorLayout::removeAnchor(QGraphicsLayoutItem *firstItem, Edge firstEdge,
+                                         QGraphicsLayoutItem *secondItem, Edge secondEdge)
+{
+    Q_D(QGraphicsAnchorLayout);
+    if ((firstItem == 0) || (secondItem == 0)) {
+        qWarning("QGraphicsAnchorLayout::removeAnchor: "
+                 "Cannot remove anchor between NULL items");
+        return;
+    }
+
+    if (firstItem == secondItem) {
+        qWarning("QGraphicsAnchorLayout::removeAnchor: "
+                 "Cannot remove anchor from the item to itself");
+        return;
+    }
+
+    if (d->edgeOrientation(secondEdge) != d->edgeOrientation(firstEdge)) {
+        qWarning("QGraphicsAnchorLayout::removeAnchor: "
+                 "Cannot remove anchor from edges of different orientations");
+        return;
+    }
+
+    d->removeAnchor(firstItem, firstEdge, secondItem, secondEdge);
+
+    invalidate();
+}
+
+void QGraphicsAnchorLayout::setGeometry(const QRectF &geom)
+{
+    Q_D(QGraphicsAnchorLayout);
+    QGraphicsLayout::setGeometry(geom);
+    d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Horizontal);
+    d->calculateVertexPositions(QGraphicsAnchorLayoutPrivate::Vertical);
+    d->setItemsGeometries();
+}
+
+void QGraphicsAnchorLayout::removeAt(int index)
+{
+    Q_D(QGraphicsAnchorLayout);
+    QGraphicsLayoutItem *item = d->items.value(index);
+
+    if (item) {
+        d->items.remove(index);
+        d->removeAnchors(item);
+        item->setParentLayoutItem(0);
+    }
+}
+
+int QGraphicsAnchorLayout::count() const
+{
+    Q_D(const QGraphicsAnchorLayout);
+    return d->items.size();
+}
+
+QGraphicsLayoutItem *QGraphicsAnchorLayout::itemAt(int index) const
+{
+    Q_D(const QGraphicsAnchorLayout);
+    return d->items.value(index);
+}
+
+void QGraphicsAnchorLayout::invalidate()
+{
+    Q_D(QGraphicsAnchorLayout);
+    QGraphicsLayout::invalidate();
+    d->calculateGraphCacheDirty = 1;
+}
+
+QSizeF QGraphicsAnchorLayout::sizeHint(Qt::SizeHint which, const QSizeF &constraint) const
+{
+    Q_UNUSED(which);
+    Q_UNUSED(constraint);
+    Q_D(const QGraphicsAnchorLayout);
+
+    // Some setup calculations are delayed until the information is
+    // actually needed, avoiding unnecessary recalculations when
+    // adding multiple anchors.
+
+    // sizeHint() / effectiveSizeHint() already have a cache
+    // mechanism, using invalidate() to force recalculation. However
+    // sizeHint() is called three times after invalidation (for max,
+    // min and pref), but we just need do our setup once.
+
+    const_cast<QGraphicsAnchorLayoutPrivate *>(d)->calculateGraphs();
+
+    // ### apply constraint!
+    QSizeF engineSizeHint(
+        d->sizeHints[QGraphicsAnchorLayoutPrivate::Horizontal][which],
+        d->sizeHints[QGraphicsAnchorLayoutPrivate::Vertical][which]);
+
+    qreal left, top, right, bottom;
+    getContentsMargins(&left, &top, &right, &bottom);
+
+    return engineSizeHint + QSizeF(left + right, top + bottom);
+}
+
+//////// DEBUG /////////
+#include <QFile>
+void QGraphicsAnchorLayout::dumpGraph()
+{
+    Q_D(QGraphicsAnchorLayout);
+
+    QFile file(QString::fromAscii("anchorlayout.dot"));
+    if (!file.open(QIODevice::WriteOnly | QIODevice::Text | QIODevice::Truncate))
+        qWarning("Could not write to %s", file.fileName().toLocal8Bit().constData());
+
+    QString dotContents = d->graph[0].serializeToDot();
+    file.write(dotContents.toLocal8Bit());
+    dotContents = d->graph[1].serializeToDot();
+    file.write(dotContents.toLocal8Bit());
+
+    file.close();
+}