src/kitemviews/kitemlistcontainer.cpp

   1 /***************************************************************************
   2  *   Copyright (C) 2011 by Peter Penz <peter.penz19@gmail.com>             *
   3  *                                                                         *
   4  *   Based on the Itemviews NG project from Trolltech Labs:                *
   5  *   http://qt.gitorious.org/qt-labs/itemviews-ng                          *
   6  *                                                                         *
   7  *   This program is free software; you can redistribute it and/or modify  *
   8  *   it under the terms of the GNU General Public License as published by  *
   9  *   the Free Software Foundation; either version 2 of the License, or     *
  10  *   (at your option) any later version.                                   *
  11  *                                                                         *
  12  *   This program is distributed in the hope that it will be useful,       *
  13  *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
  14  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
  15  *   GNU General Public License for more details.                          *
  16  *                                                                         *
  17  *   You should have received a copy of the GNU General Public License     *
  18  *   along with this program; if not, write to the                         *
  19  *   Free Software Foundation, Inc.,                                       *
  20  *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA            *
  21  ***************************************************************************/
  22
  23 #include "kitemlistcontainer.h"
  24
  25 #include "kitemlistcontroller.h"
  26 #include "kitemlistview.h"
  27 #include "kitemmodelbase.h"
  28
  29 #include "private/kitemlistsmoothscroller.h"
  30
  31 #include <QApplication>
  32 #include <QGraphicsScene>
  33 #include <QGraphicsView>
  34 #include <QScrollBar>
  35 #include <QStyle>
  36 #include <QStyleOption>
  37
  38 /**
  39  * Replaces the default viewport of KItemListContainer by a
  40  * non-scrollable viewport. The scrolling is done in an optimized
  41  * way by KItemListView internally.
  42  */
  43 class KItemListContainerViewport : public QGraphicsView
  44 {
  45     Q_OBJECT
  46
  47 public:
  48     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  49 protected:
  50     void wheelEvent(QWheelEvent* event) override;
  51 };
  52
  53 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  54     QGraphicsView(scene, parent)
  55 {
  56     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  57     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  58     setViewportMargins(0, 0, 0, 0);
  59     setFrameShape(QFrame::NoFrame);
  60 }
  61
  62 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  63 {
  64     // Assure that the wheel-event gets forwarded to the parent
  65     // and not handled at all by QGraphicsView.
  66     event->ignore();
  67 }
  68
  69 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  70     QAbstractScrollArea(parent),
  71     m_controller(controller),
  72     m_horizontalSmoothScroller(nullptr),
  73     m_verticalSmoothScroller(nullptr)
  74 {
  75     Q_ASSERT(controller);
  76     controller->setParent(this);
  77
  78     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  79     setViewport(graphicsView);
  80
  81     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  82     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  83
  84     if (controller->model()) {
  85         slotModelChanged(controller->model(), nullptr);
  86     }
  87     if (controller->view()) {
  88         slotViewChanged(controller->view(), nullptr);
  89     }
  90
  91     connect(controller, &KItemListController::modelChanged,
  92             this, &KItemListContainer::slotModelChanged);
  93     connect(controller, &KItemListController::viewChanged,
  94             this, &KItemListContainer::slotViewChanged);
  95 }
  96
  97 KItemListContainer::~KItemListContainer()
  98 {
  99     // Don't rely on the QObject-order to delete the controller, otherwise
 100     // the QGraphicsScene might get deleted before the view.
 101     delete m_controller;
 102     m_controller = nullptr;
 103 }
 104
 105 KItemListController* KItemListContainer::controller() const
 106 {
 107     return m_controller;
 108 }
 109
 110 void KItemListContainer::setEnabledFrame(bool enable)
 111 {
 112     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 113     if (enable) {
 114         setFrameShape(QFrame::StyledPanel);
 115         graphicsView->setPalette(palette());
 116         graphicsView->viewport()->setAutoFillBackground(true);
 117     } else {
 118         setFrameShape(QFrame::NoFrame);
 119         // Make the background of the container transparent and apply the window-text color
 120         // to the text color, so that enough contrast is given for all color
 121         // schemes
 122         QPalette p = graphicsView->palette();
 123         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 124         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 125         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 126         graphicsView->setPalette(p);
 127         graphicsView->viewport()->setAutoFillBackground(false);
 128     }
 129 }
 130
 131 bool KItemListContainer::enabledFrame() const
 132 {
 133     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 134     return graphicsView->autoFillBackground();
 135 }
 136
 137 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 138 {
 139     // TODO: We should find a better way to handle the key press events in the view.
 140     // The reasons why we need this hack are:
 141     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 142     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 143     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 144     //    does not work.
 145     KItemListView* view = m_controller->view();
 146     if (view) {
 147         QApplication::sendEvent(view, event);
 148     }
 149 }
 150
 151 void KItemListContainer::showEvent(QShowEvent* event)
 152 {
 153     QAbstractScrollArea::showEvent(event);
 154     updateGeometries();
 155 }
 156
 157 void KItemListContainer::resizeEvent(QResizeEvent* event)
 158 {
 159     QAbstractScrollArea::resizeEvent(event);
 160     updateGeometries();
 161 }
 162
 163 void KItemListContainer::scrollContentsBy(int dx, int dy)
 164 {
 165     m_horizontalSmoothScroller->scrollContentsBy(dx);
 166     m_verticalSmoothScroller->scrollContentsBy(dy);
 167 }
 168
 169 void KItemListContainer::wheelEvent(QWheelEvent* event)
 170 {
 171     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 172         event->ignore();
 173         return;
 174     }
 175
 176     KItemListView* view = m_controller->view();
 177     if (!view) {
 178         event->ignore();
 179         return;
 180     }
 181
 182     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 183                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 184     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 185                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 186
 187     smoothScroller->handleWheelEvent(event);
 188 }
 189
 190 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 191 {
 192     Q_UNUSED(previous);
 193     updateSmoothScrollers(current);
 194 }
 195
 196 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 197 {
 198     Q_UNUSED(current);
 199     Q_UNUSED(previous);
 200 }
 201
 202 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 203 {
 204     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 205     if (previous) {
 206         scene->removeItem(previous);
 207         disconnect(previous, &KItemListView::scrollOrientationChanged,
 208                    this, &KItemListContainer::slotScrollOrientationChanged);
 209         disconnect(previous, &KItemListView::scrollOffsetChanged,
 210                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 211         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 212                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 213         disconnect(previous, &KItemListView::itemOffsetChanged,
 214                    this, &KItemListContainer::updateItemOffsetScrollBar);
 215         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 216                    this, &KItemListContainer::updateItemOffsetScrollBar);
 217         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 218         m_horizontalSmoothScroller->setTargetObject(nullptr);
 219         m_verticalSmoothScroller->setTargetObject(nullptr);
 220     }
 221     if (current) {
 222         scene->addItem(current);
 223         connect(current, &KItemListView::scrollOrientationChanged,
 224                 this, &KItemListContainer::slotScrollOrientationChanged);
 225         connect(current, &KItemListView::scrollOffsetChanged,
 226                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 227         connect(current, &KItemListView::maximumScrollOffsetChanged,
 228                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 229         connect(current, &KItemListView::itemOffsetChanged,
 230                 this, &KItemListContainer::updateItemOffsetScrollBar);
 231         connect(current, &KItemListView::maximumItemOffsetChanged,
 232                 this, &KItemListContainer::updateItemOffsetScrollBar);
 233         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 234         m_horizontalSmoothScroller->setTargetObject(current);
 235         m_verticalSmoothScroller->setTargetObject(current);
 236         updateSmoothScrollers(current->scrollOrientation());
 237     }
 238 }
 239
 240 void KItemListContainer::scrollTo(qreal offset)
 241 {
 242     const KItemListView* view = m_controller->view();
 243     if (view) {
 244         if (view->scrollOrientation() == Qt::Vertical) {
 245             m_verticalSmoothScroller->scrollTo(offset);
 246         } else {
 247             m_horizontalSmoothScroller->scrollTo(offset);
 248         }
 249     }
 250 }
 251
 252 void KItemListContainer::updateScrollOffsetScrollBar()
 253 {
 254     const KItemListView* view = m_controller->view();
 255     if (!view) {
 256         return;
 257     }
 258
 259     KItemListSmoothScroller* smoothScroller = nullptr;
 260     QScrollBar* scrollOffsetScrollBar = nullptr;
 261     int singleStep = 0;
 262     int pageStep = 0;
 263     int maximum = 0;
 264     if (view->scrollOrientation() == Qt::Vertical) {
 265         smoothScroller = m_verticalSmoothScroller;
 266         scrollOffsetScrollBar = verticalScrollBar();
 267         singleStep = view->itemSizeHint().height();
 268         // We cannot use view->size().height() because this height might
 269         // include the header widget, which is not part of the scrolled area.
 270         pageStep = view->verticalPageStep();
 271
 272         // However, the total height of the view must be considered for the
 273         // maximum value of the scroll bar. Note that the view's scrollOffset()
 274         // refers to the offset of the top part of the view, which might be
 275         // hidden behind the header.
 276         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 277     } else {
 278         smoothScroller = m_horizontalSmoothScroller;
 279         scrollOffsetScrollBar = horizontalScrollBar();
 280         singleStep = view->itemSize().width();
 281         pageStep = view->size().width();
 282         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 283     }
 284
 285     const int value = view->scrollOffset();
 286     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 287         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 288                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 289
 290         scrollOffsetScrollBar->setSingleStep(singleStep);
 291         scrollOffsetScrollBar->setPageStep(pageStep);
 292         scrollOffsetScrollBar->setMinimum(0);
 293         scrollOffsetScrollBar->setMaximum(maximum);
 294         scrollOffsetScrollBar->setValue(value);
 295
 296         if (updatePolicy) {
 297             // Prevent a potential endless layout loop (see bug #293318).
 298             updateScrollOffsetScrollBarPolicy();
 299         }
 300     }
 301 }
 302
 303 void KItemListContainer::updateItemOffsetScrollBar()
 304 {
 305     const KItemListView* view = m_controller->view();
 306     if (!view) {
 307         return;
 308     }
 309
 310     KItemListSmoothScroller* smoothScroller = nullptr;
 311     QScrollBar* itemOffsetScrollBar = nullptr;
 312     int singleStep = 0;
 313     int pageStep = 0;
 314     if (view->scrollOrientation() == Qt::Vertical) {
 315         smoothScroller = m_horizontalSmoothScroller;
 316         itemOffsetScrollBar = horizontalScrollBar();
 317         singleStep = view->size().width() / 10;
 318         pageStep = view->size().width();
 319     } else {
 320         smoothScroller = m_verticalSmoothScroller;
 321         itemOffsetScrollBar = verticalScrollBar();
 322         singleStep = view->size().height() / 10;
 323         pageStep = view->size().height();
 324     }
 325
 326     const int value = view->itemOffset();
 327     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 328     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 329         itemOffsetScrollBar->setSingleStep(singleStep);
 330         itemOffsetScrollBar->setPageStep(pageStep);
 331         itemOffsetScrollBar->setMinimum(0);
 332         itemOffsetScrollBar->setMaximum(maximum);
 333         itemOffsetScrollBar->setValue(value);
 334     }
 335 }
 336
 337 void KItemListContainer::updateGeometries()
 338 {
 339     QRect rect = geometry();
 340
 341     int extra = frameWidth() * 2;
 342     QStyleOption option;
 343     option.initFrom(this);
 344     int scrollbarSpacing = 0;
 345     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 346         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 347     }
 348
 349     const int widthDec = verticalScrollBar()->isVisible()
 350                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 351                          : extra;
 352
 353     const int heightDec = horizontalScrollBar()->isVisible()
 354                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 355                           : extra;
 356
 357     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 358                              rect.height() - heightDec);
 359     if (m_controller->view()->geometry() != newGeometry) {
 360         m_controller->view()->setGeometry(newGeometry);
 361
 362         // Get the real geometry of the view again since the scrollbars
 363         // visibilities and the view geometry may have changed in re-layout.
 364         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 365         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 366
 367         updateScrollOffsetScrollBar();
 368         updateItemOffsetScrollBar();
 369     }
 370 }
 371
 372 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 373 {
 374     if (orientation == Qt::Vertical) {
 375         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 376         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 377     } else {
 378         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 379         m_verticalSmoothScroller->setPropertyName("itemOffset");
 380     }
 381 }
 382
 383 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 384 {
 385     const KItemListView* view = m_controller->view();
 386     Q_ASSERT(view);
 387     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 388
 389     QStyleOption option;
 390     option.initFrom(this);
 391     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 392
 393     QSizeF newViewSize = m_controller->view()->size();
 394     if (vertical) {
 395         newViewSize.rwidth() += scrollBarInc;
 396     } else {
 397         newViewSize.rheight() += scrollBarInc;
 398     }
 399
 400     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 401                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 402     if (vertical) {
 403         setVerticalScrollBarPolicy(policy);
 404     } else {
 405         setHorizontalScrollBarPolicy(policy);
 406     }
 407 }
 408
 409 #include "kitemlistcontainer.moc"