/****************************************************************************

**

** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).

** All rights reserved.

** Contact: Nokia Corporation (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 Technology Preview License Agreement accompanying

** this package.

**

** 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 1.1, included in the file LGPL_EXCEPTION.txt in this package.

**

** If you have questions regarding the use of this file, please contact

** Nokia at qt-info@nokia.com.

**

**

**

**

**

**

**

**

** $QT_END_LICENSE$

**

****************************************************************************/

static const int QGRAPHICSVIEW_REGION_RECT_THRESHOLD = 50;

static const int QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS = 503; // largest prime < 2^9

/*!

    \class QGraphicsView

    \brief The QGraphicsView class provides a widget for displaying the

    contents of a QGraphicsScene.

    \since 4.2

    \ingroup graphicsview-api

    QGraphicsView visualizes the contents of a QGraphicsScene in a scrollable

    viewport. To create a scene with geometrical items, see QGraphicsScene's

    documentation. QGraphicsView is part of the \l{Graphics View Framework}.

    To visualize a scene, you start by constructing a QGraphicsView object,

    passing the address of the scene you want to visualize to QGraphicsView's

    constructor. Alternatively, you can call setScene() to set the scene at a

    later point. After you call show(), the view will by default scroll to the

    center of the scene and display any items that are visible at this

    point. For example:

    \snippet doc/src/snippets/code/src_gui_graphicsview_qgraphicsview.cpp 0

    You can explicitly scroll to any position on the scene by using the

    scroll bars, or by calling centerOn(). By passing a point to centerOn(),

    QGraphicsView will scroll its viewport to ensure that the point is

    centered in the view. An overload is provided for scrolling to a

    QGraphicsItem, in which case QGraphicsView will see to that the center of

    the item is centered in the view. If all you want is to ensure that a

    certain area is visible, (but not necessarily centered,) you can call

    ensureVisible() instead.

    QGraphicsView can be used to visualize a whole scene, or only parts of it.

    The visualized area is by default detected automatically when the view is

    displayed for the first time (by calling

    QGraphicsScene::itemsBoundingRect()). To set the visualized area rectangle

    yourself, you can call setSceneRect(). This will adjust the scroll bars'

    ranges appropriately. Note that although the scene supports a virtually

    unlimited size, the range of the scroll bars will never exceed the range of

    an integer (INT_MIN, INT_MAX). When the scene is larger than the scroll

    bars' values, you can choose to use translate() to navigate the scene

    instead.

    QGraphicsView visualizes the scene by calling render(). By default, the

    items are drawn onto the viewport by using a regular QPainter, and using

    default render hints. To change the default render hints that

    QGraphicsView passes to QPainter when painting items, you can call

    setRenderHints().

    By default, QGraphicsView provides a regular QWidget for the viewport

    widget. You can access this widget by calling viewport(), or you can

    replace it by calling setViewport(). To render using OpenGL, simply call

    setViewport(new QGLWidget). QGraphicsView takes ownership of the viewport

    widget.

    QGraphicsView supports affine transformations, using QTransform. You can

    either pass a matrix to setTransform(), or you can call one of the

    convenience functions rotate(), scale(), translate() or shear(). The most

    two common transformations are scaling, which is used to implement

    zooming, and rotation. QGraphicsView keeps the center of the view fixed

    during a transformation.

    You can interact with the items on the scene by using the mouse and

    keyboard. QGraphicsView translates the mouse and key events into \e scene

    events, (events that inherit QGraphicsSceneEvent,), and forward them to

    the visualized scene. In the end, it's the individual item that handles

    the events and reacts to them. For example, if you click on a selectable

    item, the item will typically let the scene know that it has been

    selected, and it will also redraw itself to display a selection

    rectangle. Similiary, if you click and drag the mouse to move a movable

    item, it's the item that handles the mouse moves and moves itself.  Item

    interaction is enabled by default, and you can toggle it by calling

    setInteractive().

    You can also provide your own custom scene interaction, by creating a

    subclass of QGraphicsView, and reimplementing the mouse and key event

    handlers. To simplify how you programmatically interact with items in the

    view, QGraphicsView provides the mapping functions mapToScene() and

    mapFromScene(), and the item accessors items() and itemAt(). These

    functions allow you to map points, rectangles, polygons and paths between

    view coordinates and scene coordinates, and to find items on the scene

    using view coordinates.

    \img graphicsview-view.png

    \sa QGraphicsScene, QGraphicsItem, QGraphicsSceneEvent

*/

/*!

    \enum QGraphicsView::ViewportAnchor

    This enums describe the possible anchors that QGraphicsView can

    use when the user resizes the view or when the view is

    transformed.

    \value NoAnchor No anchor, i.e. the view leaves the scene's

                    position unchanged.

    \value AnchorViewCenter The scene point at the center of the view

                            is used as the anchor.

    \value AnchorUnderMouse The point under the mouse is used as the anchor.

    \sa resizeAnchor, transformationAnchor

*/

/*!

    \enum QGraphicsView::ViewportUpdateMode

    \since 4.3

    This enum describes how QGraphicsView updates its viewport when the scene

    contents change or are exposed.

    \value FullViewportUpdate When any visible part of the scene changes or is

    reexposed, QGraphicsView will update the entire viewport. This approach is

    fastest when QGraphicsView spends more time figuring out what to draw than

    it would spend drawing (e.g., when very many small items are repeatedly

    updated). This is the preferred update mode for viewports that do not

    support partial updates, such as QGLWidget, and for viewports that need to

    disable scroll optimization.

    \value MinimalViewportUpdate QGraphicsView will determine the minimal

    viewport region that requires a redraw, minimizing the time spent drawing

    by avoiding a redraw of areas that have not changed. This is

    QGraphicsView's default mode. Although this approach provides the best

    performance in general, if there are many small visible changes on the

    scene, QGraphicsView might end up spending more time finding the minimal

    approach than it will spend drawing.

    \value SmartViewportUpdate QGraphicsView will attempt to find an optimal

    update mode by analyzing the areas that require a redraw.

    \value BoundingRectViewportUpdate The bounding rectangle of all changes in

    the viewport will be redrawn. This mode has the advantage that

    QGraphicsView searches only one region for changes, minimizing time spent

    determining what needs redrawing. The disadvantage is that areas that have

    not changed also need to be redrawn.

    \value NoViewportUpdate QGraphicsView will never update its viewport when

    the scene changes; the user is expected to control all updates. This mode

    disables all (potentially slow) item visibility testing in QGraphicsView,

    and is suitable for scenes that either require a fixed frame rate, or where

    the viewport is otherwise updated externally.

    \sa viewportUpdateMode

*/

/*!

    \enum QGraphicsView::OptimizationFlag

    \since 4.3

    This enum describes flags that you can enable to improve rendering

    performance in QGraphicsView. By default, none of these flags are set.

    Note that setting a flag usually imposes a side effect, and this effect

    can vary between paint devices and platforms.

    \value DontClipPainter This value is obsolete and has no effect.

    \value DontSavePainterState When rendering, QGraphicsView protects the

    painter state (see QPainter::save()) when rendering the background or

    foreground, and when rendering each item. This allows you to leave the

    painter in an altered state (i.e., you can call QPainter::setPen() or

    QPainter::setBrush() without restoring the state after painting). However,

    if the items consistently do restore the state, you should enable this

    flag to prevent QGraphicsView from doing the same.

    \value DontAdjustForAntialiasing Disables QGraphicsView's antialiasing

    auto-adjustment of exposed areas. Items that render antialiased lines on

    the boundaries of their QGraphicsItem::boundingRect() can end up rendering

    parts of the line outside. To prevent rendering artifacts, QGraphicsView

    expands all exposed regions by 2 pixels in all directions. If you enable

    this flag, QGraphicsView will no longer perform these adjustments,

    minimizing the areas that require redrawing, which improves performance. A

    common side effect is that items that do draw with antialiasing can leave

    painting traces behind on the scene as they are moved.

    \value IndirectPainting Since Qt 4.6, restore the old painting algorithm

    that calls QGraphicsView::drawItems() and QGraphicsScene::drawItems().

    To be used only for compatibility with old code.

*/

/*!

    \enum QGraphicsView::CacheModeFlag

    This enum describes the flags that you can set for a QGraphicsView's cache

    mode.

    \value CacheNone All painting is done directly onto the viewport.

    \value CacheBackground The background is cached. This affects both custom

    backgrounds, and backgrounds based on the backgroundBrush property. When

    this flag is enabled, QGraphicsView will allocate one pixmap with the full

    size of the viewport.

    \sa cacheMode

*/

/*!

    \enum QGraphicsView::DragMode

    This enum describes the default action for the view when pressing and

    dragging the mouse over the viewport.

    \value NoDrag Nothing happens; the mouse event is ignored.

    \value ScrollHandDrag The cursor changes into a pointing hand, and

    dragging the mouse around will scroll the scrolbars. This mode works both

    in \l{QGraphicsView::interactive}{interactive} and non-interactive mode.

    \value RubberBandDrag A rubber band will appear. Dragging the mouse will

    set the rubber band geometry, and all items covered by the rubber band are

    selected. This mode is disabled for non-interactive views.

    \sa dragMode, QGraphicsScene::setSelectionArea()

*/

#include "qgraphicsview.h"

#include "qgraphicsview_p.h"

#ifndef QT_NO_GRAPHICSVIEW

#include "qgraphicsitem.h"

#include "qgraphicsitem_p.h"

#include "qgraphicsscene.h"

#include "qgraphicsscene_p.h"

#include "qgraphicssceneevent.h"

#include "qgraphicswidget.h"

#include <QtCore/qdatetime.h>

#include <QtCore/qdebug.h>

#include <QtCore/qmath.h>

#include <QtGui/qapplication.h>

#include <QtGui/qdesktopwidget.h>

#include <QtGui/qevent.h>

#include <QtGui/qlayout.h>

#include <QtGui/qtransform.h>

#include <QtGui/qmatrix.h>

#include <QtGui/qpainter.h>

#include <QtGui/qscrollbar.h>

#include <QtGui/qstyleoption.h>

#include <QtGui/qinputcontext.h>

#ifdef Q_WS_X11

#include <QtGui/qpaintengine.h>

#include <private/qt_x11_p.h>

#endif

#include <private/qevent_p.h>

QT_BEGIN_NAMESPACE

bool qt_sendSpontaneousEvent(QObject *receiver, QEvent *event);

inline int q_round_bound(qreal d) //### (int)(qreal) INT_MAX != INT_MAX for single precision

{

    if (d <= (qreal) INT_MIN)

        return INT_MIN;

    else if (d >= (qreal) INT_MAX)

        return INT_MAX;

    return d >= 0.0 ? int(d + 0.5) : int(d - int(d-1) + 0.5) + int(d-1);

}

void QGraphicsViewPrivate::translateTouchEvent(QGraphicsViewPrivate *d, QTouchEvent *touchEvent)

{

    QList<QTouchEvent::TouchPoint> touchPoints = touchEvent->touchPoints();

    for (int i = 0; i < touchPoints.count(); ++i) {

        QTouchEvent::TouchPoint &touchPoint = touchPoints[i];

        // the scene will set the item local pos, startPos, lastPos, and rect before delivering to

        // an item, but for now those functions are returning the view's local coordinates

        touchPoint.setSceneRect(d->mapToScene(touchPoint.rect()));

        touchPoint.setStartScenePos(d->mapToScene(touchPoint.startPos()));

        touchPoint.setLastScenePos(d->mapToScene(touchPoint.lastPos()));

        // screenPos, startScreenPos, lastScreenPos, and screenRect are already set

    }

    touchEvent->setTouchPoints(touchPoints);

}

/*!

    \internal

*/

QGraphicsViewPrivate::QGraphicsViewPrivate()

    : renderHints(QPainter::TextAntialiasing),

      dragMode(QGraphicsView::NoDrag),

      sceneInteractionAllowed(true), hasSceneRect(false),

      connectedToScene(false),

      useLastMouseEvent(false),

      identityMatrix(true),

      dirtyScroll(true),

      accelerateScrolling(true),

      keepLastCenterPoint(true),

      transforming(false),

      handScrolling(false),

      mustAllocateStyleOptions(false),

      mustResizeBackgroundPixmap(true),

      fullUpdatePending(true),

      hasUpdateClip(false),

      mousePressButton(Qt::NoButton),

      leftIndent(0), topIndent(0),

      lastMouseEvent(QEvent::None, QPoint(), Qt::NoButton, 0, 0),

      alignment(Qt::AlignCenter),

      transformationAnchor(QGraphicsView::AnchorViewCenter), resizeAnchor(QGraphicsView::NoAnchor),

      viewportUpdateMode(QGraphicsView::MinimalViewportUpdate),

      optimizationFlags(0),

      scene(0),

#ifndef QT_NO_RUBBERBAND

      rubberBanding(false),

      rubberBandSelectionMode(Qt::IntersectsItemShape),

#endif

      handScrollMotions(0), cacheMode(0),

#ifndef QT_NO_CURSOR

      hasStoredOriginalCursor(false),

#endif

      lastDragDropEvent(0),

      updateSceneSlotReimplementedChecked(false)

{

    styleOptions.reserve(QGRAPHICSVIEW_PREALLOC_STYLE_OPTIONS);

}

/*!

    \internal

*/

void QGraphicsViewPrivate::recalculateContentSize()

{

    Q_Q(QGraphicsView);

    QSize maxSize = q->maximumViewportSize();

    int width = maxSize.width();

    int height = maxSize.height();

    QRectF viewRect = matrix.mapRect(q->sceneRect());

    bool frameOnlyAround = (q->style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, 0, q));

    if (frameOnlyAround) {

        if (hbarpolicy == Qt::ScrollBarAlwaysOn)

            height -= frameWidth * 2;

        if (vbarpolicy == Qt::ScrollBarAlwaysOn)

            width -= frameWidth * 2;

    }

    // Adjust the maximum width and height of the viewport based on the width

    // of visible scroll bars.

    int scrollBarExtent = q->style()->pixelMetric(QStyle::PM_ScrollBarExtent, 0, q);

    if (frameOnlyAround)

        scrollBarExtent += frameWidth * 2;

    bool useHorizontalScrollBar = (viewRect.width() > width) && hbarpolicy != Qt::ScrollBarAlwaysOff;

    bool useVerticalScrollBar = (viewRect.height() > height) && vbarpolicy != Qt::ScrollBarAlwaysOff;

    if (useHorizontalScrollBar && !useVerticalScrollBar) {

        if (viewRect.height() > height - scrollBarExtent)

            useVerticalScrollBar = true;

    }

    if (useVerticalScrollBar && !useHorizontalScrollBar) {

        if (viewRect.width() > width - scrollBarExtent)

            useHorizontalScrollBar = true;

    }

    if (useHorizontalScrollBar && hbarpolicy != Qt::ScrollBarAlwaysOn)

        height -= scrollBarExtent;

    if (useVerticalScrollBar && vbarpolicy != Qt::ScrollBarAlwaysOn)

        width -= scrollBarExtent;

    // Setting the ranges of these scroll bars can/will cause the values to

    // change, and scrollContentsBy() will be called correspondingly. This

    // will reset the last center point.

    QPointF savedLastCenterPoint = lastCenterPoint;

    // Remember the former indent settings

    qreal oldLeftIndent = leftIndent;

    qreal oldTopIndent = topIndent;

    // If the whole scene fits horizontally, we center the scene horizontally,

    // and ignore the horizontal scroll bars.

    int left =  q_round_bound(viewRect.left());

    int right = q_round_bound(viewRect.right() - width);

    if (left >= right) {

        hbar->setRange(0, 0);

        switch (alignment & Qt::AlignHorizontal_Mask) {

        case Qt::AlignLeft:

            leftIndent = -viewRect.left();

            break;

        case Qt::AlignRight:

            leftIndent = width - viewRect.width() - viewRect.left() - 1;

            break;

        case Qt::AlignHCenter:

        default:

            leftIndent = width / 2 - (viewRect.left() + viewRect.right()) / 2;

            break;

        }

    } else {

        hbar->setRange(left, right);

        hbar->setPageStep(width);

        hbar->setSingleStep(width / 20);

        leftIndent = 0;

    }

    // If the whole scene fits vertically, we center the scene vertically, and

    // ignore the vertical scroll bars.

    int top = q_round_bound(viewRect.top());

    int bottom = q_round_bound(viewRect.bottom()  - height);

    if (top >= bottom) {

        vbar->setRange(0, 0);

        switch (alignment & Qt::AlignVertical_Mask) {

        case Qt::AlignTop:

            topIndent = -viewRect.top();

            break;

        case Qt::AlignBottom:

            topIndent = height - viewRect.height() - viewRect.top() - 1;

            break;

        case Qt::AlignVCenter:

        default:

            topIndent = height / 2 - (viewRect.top() + viewRect.bottom()) / 2;

            break;

        }

    } else {

        vbar->setRange(top, bottom);

        vbar->setPageStep(height);

        vbar->setSingleStep(height / 20);

        topIndent = 0;

    }

    // Restorethe center point from before the ranges changed.

    lastCenterPoint = savedLastCenterPoint;

    // Issue a full update if the indents change.

    // ### If the transform is still the same, we can get away with just a

    // scroll instead.

    if (oldLeftIndent != leftIndent || oldTopIndent != topIndent) {

        dirtyScroll = true;

        updateAll();

    } else if (q->isRightToLeft() && !leftIndent) {

        // In reverse mode, the horizontal scroll always changes after the content

        // size has changed, as the scroll is calculated by summing the min and

        // max values of the range and subtracting the current value. In normal

        // mode the scroll remains unchanged unless the indent has changed.

        dirtyScroll = true;

    }

    if (cacheMode & QGraphicsView::CacheBackground) {

        // Invalidate the background pixmap

        mustResizeBackgroundPixmap = true;

    }

}

/*!

    \internal

*/

void QGraphicsViewPrivate::centerView(QGraphicsView::ViewportAnchor anchor)

{

    Q_Q(QGraphicsView);

    switch (anchor) {

    case QGraphicsView::AnchorUnderMouse: {

        if (q->underMouse()) {

            // Last scene pos: lastMouseMoveScenePoint

            // Current mouse pos:

            QPointF transformationDiff = q->mapToScene(viewport->rect().center())

                                         - q->mapToScene(viewport->mapFromGlobal(QCursor::pos()));

            q->centerOn(lastMouseMoveScenePoint + transformationDiff);

        } else {

            q->centerOn(lastCenterPoint);

        }

        break;

    }

    case QGraphicsView::AnchorViewCenter:

        q->centerOn(lastCenterPoint);

        break;

    case QGraphicsView::NoAnchor:

        break;

    }

}

/*!

    \internal

*/

void QGraphicsViewPrivate::updateLastCenterPoint()

{

    Q_Q(QGraphicsView);

    lastCenterPoint = q->mapToScene(viewport->rect().center());

}

/*!

    \internal