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