view panner.cpp @ 203:c77c4d00a4fe

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/* -*- c-basic-offset: 4 indent-tabs-mode: nil -*-  vi:set ts=8 sts=4 sw=4: */

/*
    EasyMercurial

    Based on HgExplorer by Jari Korhonen
    Copyright (c) 2010 Jari Korhonen
    Copyright (c) 2010 Chris Cannam
    Copyright (c) 2010 Queen Mary, University of London
    
    This program is free software; you can redistribute it and/or
    modify it under the terms of the GNU General Public License as
    published by the Free Software Foundation; either version 2 of the
    License, or (at your option) any later version.  See the file
    COPYING included with this distribution for more information.
*/

#include "panner.h"
#include "panned.h"
#include "debug.h"

#include <QPolygon>
#include <QMouseEvent>
#include <QColor>

#include <iostream>

class PannerScene : public QGraphicsScene
{
public:
    friend class Panner;
};

Panner::Panner() :
    m_clicked(false)
{
    setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
    setOptimizationFlags(QGraphicsView::DontSavePainterState |
                         QGraphicsView::IndirectPainting);
    setMouseTracking(true);
    setInteractive(false);
}

void
Panner::fit(QRectF r)
{
    Qt::AspectRatioMode m = Qt::IgnoreAspectRatio;
    if (height() > width()) {
        // Our panner is vertical; if the source is not tall,
        // don't stretch it to fit in the height, it'd look weird
        if (r.height() < height() * 2) {
            m = Qt::KeepAspectRatio;
        }
    } else {
        // Similarly, but horizontal
        if (r.width() < width() * 2) {
            m = Qt::KeepAspectRatio;
        }
    }
    DEBUG << "Panner: fit mode " << m << endl;
    fitInView(r, m);
}

void
Panner::setScene(QGraphicsScene *s)
{
    if (scene()) {
        disconnect(scene(), SIGNAL(changed(const QList<QRectF> &)),
                   this, SLOT(slotSceneChanged(const QList<QRectF> &)));
        disconnect(scene(), SIGNAL(sceneRectChanged(const QRectF &)),
                   this, SLOT(slotSceneRectChanged(const QRectF &)));
    }
    QGraphicsView::setScene(s);
    m_cache = QPixmap();
    if (scene()) {
        QRectF r = sceneRect();
        DEBUG << "scene rect: " << r << ", my rect " << rect() << endl;
        fit(r);
        connect(scene(), SIGNAL(changed(const QList<QRectF> &)),
                this, SLOT(slotSceneChanged(const QList<QRectF> &)));
        connect(scene(), SIGNAL(sceneRectChanged(const QRectF &)),
                this, SLOT(slotSceneRectChanged(const QRectF &)));
    }
}

void
Panner::connectToPanned(Panned *p)
{
    connect(p, SIGNAL(pannedRectChanged(QRectF)),
            this, SLOT(slotSetPannedRect(QRectF)));

    connect(this, SIGNAL(pannedRectChanged(QRectF)),
            p, SLOT(slotSetPannedRect(QRectF)));

    connect(this, SIGNAL(zoomIn()),
            p, SLOT(zoomIn()));

    connect(this, SIGNAL(zoomOut()),
            p, SLOT(zoomOut()));
}

void
Panner::slotSetPannedRect(QRectF rect) 
{
    m_pannedRect = rect;
    viewport()->update();
}

void
Panner::resizeEvent(QResizeEvent *)
{
    if (scene()) fit(sceneRect());
    m_cache = QPixmap();
}

void
Panner::slotSceneRectChanged(const QRectF &newRect)
{
    if (!scene()) return; // spurious
    fit(newRect);
    m_cache = QPixmap();
    viewport()->update();
}

void
Panner::slotSceneChanged(const QList<QRectF> &)
{
    if (!scene()) return; // spurious
    m_cache = QPixmap();
    viewport()->update();
}

void
Panner::paintEvent(QPaintEvent *e)
{
    QPaintEvent *e2 = new QPaintEvent(e->region().boundingRect());
    QGraphicsView::paintEvent(e2);

    QPainter paint;
    paint.begin(viewport());
    paint.setClipRegion(e->region());

    QPainterPath path;
    path.addRect(rect());
    path.addPolygon(mapFromScene(m_pannedRect));

    QColor c(QColor::fromHsv(211, 194, 238));
    c.setAlpha(80);
    paint.setPen(Qt::NoPen);
    paint.setBrush(c);
    paint.drawPath(path);

    paint.setBrush(Qt::NoBrush);
    paint.setPen(QPen(QColor::fromHsv(211, 194, 238), 0));
    paint.drawConvexPolygon(mapFromScene(m_pannedRect));

    paint.end();

    emit pannerChanged(m_pannedRect);
}

void
Panner::updateScene(const QList<QRectF> &rects)
{
    if (!m_cache.isNull()) m_cache = QPixmap();
    QGraphicsView::updateScene(rects);
}

void
Panner::drawItems(QPainter *painter, int numItems,
                  QGraphicsItem *items[],
                  const QStyleOptionGraphicsItem options[])
{
    if (m_cache.size() != viewport()->size()) {

        DEBUG << "Panner: cache size " << m_cache.size() << " != viewport size " << viewport()->size() << ": recreating cache" << endl;

        QGraphicsScene *s = scene();
        if (!s) return;
        PannerScene *ps = static_cast<PannerScene *>(s);

        m_cache = QPixmap(viewport()->size());
        m_cache.fill(Qt::transparent);
        QPainter cachePainter;
        cachePainter.begin(&m_cache);
        cachePainter.setTransform(viewportTransform());
        ps->drawItems(&cachePainter, numItems, items, options);
        cachePainter.end();
    }

    painter->save();
    painter->setTransform(QTransform());
    painter->drawPixmap(0, 0, m_cache);
    painter->restore();
}
 
void
Panner::mousePressEvent(QMouseEvent *e)
{
    if (e->button() != Qt::LeftButton) {
        QGraphicsView::mouseDoubleClickEvent(e);
        return;
    }
    m_clicked = true;
    m_clickedRect = m_pannedRect;
    m_clickedPoint = e->pos();
}

void
Panner::mouseDoubleClickEvent(QMouseEvent *e)
{
    if (e->button() != Qt::LeftButton) {
        QGraphicsView::mouseDoubleClickEvent(e);
        return;
    }

    moveTo(e->pos());
}

void
Panner::mouseMoveEvent(QMouseEvent *e)
{
    if (!m_clicked) return;
    QPointF cp = mapToScene(m_clickedPoint);
    QPointF mp = mapToScene(e->pos());
    QPointF delta = mp - cp;
    QRectF nr = m_clickedRect;
    nr.translate(delta);
    m_pannedRect = nr;
    emit pannedRectChanged(m_pannedRect);
    viewport()->update();
}

void
Panner::mouseReleaseEvent(QMouseEvent *e)
{
    if (e->button() != Qt::LeftButton) {
        QGraphicsView::mouseDoubleClickEvent(e);
        return;
    }

    if (m_clicked) {
        mouseMoveEvent(e);
    }

    m_clicked = false;
    viewport()->update();
}

void
Panner::wheelEvent(QWheelEvent *e)
{
    int d = e->delta();
    if (d > 0) {
        while (d > 0) {
            emit zoomOut();
            d -= 120;
        }
    } else {
        while (d < 0) {
            emit zoomIn();
            d += 120;
        }
    }
}

void
Panner::moveTo(QPoint p)
{
    QPointF sp = mapToScene(p);
    QRectF nr = m_pannedRect;
    double d = sp.x() - nr.center().x();
    nr.translate(d, 0);
    slotSetPannedRect(nr);
    emit pannedRectChanged(m_pannedRect);
    viewport()->update();
}