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 <QFontMetrics>
  30 #include <QGraphicsScene>
  31 #include <QGraphicsView>
  32 #include <QScrollBar>
  33 #include <QStyleOption>
  34
  35 /**
  36  * Replaces the default viewport of KItemListContainer by a
  37  * non-scrollable viewport. The scrolling is done in an optimized
  38  * way by KItemListView internally.
  39  */
  40 class KItemListContainerViewport : public QGraphicsView
  41 {
  42     Q_OBJECT
  43
  44 public:
  45     KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent);
  46 protected:
  47     void wheelEvent(QWheelEvent* event) override;
  48 };
  49
  50 KItemListContainerViewport::KItemListContainerViewport(QGraphicsScene* scene, QWidget* parent) :
  51     QGraphicsView(scene, parent)
  52 {
  53     setHorizontalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  54     setVerticalScrollBarPolicy(Qt::ScrollBarAlwaysOff);
  55     setViewportMargins(0, 0, 0, 0);
  56     setFrameShape(QFrame::NoFrame);
  57 }
  58
  59 void KItemListContainerViewport::wheelEvent(QWheelEvent* event)
  60 {
  61     // Assure that the wheel-event gets forwarded to the parent
  62     // and not handled at all by QGraphicsView.
  63     event->ignore();
  64 }
  65
  66 KItemListContainer::KItemListContainer(KItemListController* controller, QWidget* parent) :
  67     QAbstractScrollArea(parent),
  68     m_controller(controller),
  69     m_horizontalSmoothScroller(nullptr),
  70     m_verticalSmoothScroller(nullptr)
  71 {
  72     Q_ASSERT(controller);
  73     controller->setParent(this);
  74
  75     QGraphicsView* graphicsView = new KItemListContainerViewport(new QGraphicsScene(this), this);
  76     setViewport(graphicsView);
  77
  78     m_horizontalSmoothScroller = new KItemListSmoothScroller(horizontalScrollBar(), this);
  79     m_verticalSmoothScroller = new KItemListSmoothScroller(verticalScrollBar(), this);
  80
  81     if (controller->model()) {
  82         slotModelChanged(controller->model(), nullptr);
  83     }
  84     if (controller->view()) {
  85         slotViewChanged(controller->view(), nullptr);
  86     }
  87
  88     connect(controller, &KItemListController::modelChanged,
  89             this, &KItemListContainer::slotModelChanged);
  90     connect(controller, &KItemListController::viewChanged,
  91             this, &KItemListContainer::slotViewChanged);
  92 }
  93
  94 KItemListContainer::~KItemListContainer()
  95 {
  96     // Don't rely on the QObject-order to delete the controller, otherwise
  97     // the QGraphicsScene might get deleted before the view.
  98     delete m_controller;
  99     m_controller = nullptr;
 100 }
 101
 102 KItemListController* KItemListContainer::controller() const
 103 {
 104     return m_controller;
 105 }
 106
 107 void KItemListContainer::setEnabledFrame(bool enable)
 108 {
 109     QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 110     if (enable) {
 111         setFrameShape(QFrame::StyledPanel);
 112         graphicsView->setPalette(palette());
 113         graphicsView->viewport()->setAutoFillBackground(true);
 114     } else {
 115         setFrameShape(QFrame::NoFrame);
 116         // Make the background of the container transparent and apply the window-text color
 117         // to the text color, so that enough contrast is given for all color
 118         // schemes
 119         QPalette p = graphicsView->palette();
 120         p.setColor(QPalette::Active,   QPalette::Text, p.color(QPalette::Active,   QPalette::WindowText));
 121         p.setColor(QPalette::Inactive, QPalette::Text, p.color(QPalette::Inactive, QPalette::WindowText));
 122         p.setColor(QPalette::Disabled, QPalette::Text, p.color(QPalette::Disabled, QPalette::WindowText));
 123         graphicsView->setPalette(p);
 124         graphicsView->viewport()->setAutoFillBackground(false);
 125     }
 126 }
 127
 128 bool KItemListContainer::enabledFrame() const
 129 {
 130     const QGraphicsView* graphicsView = qobject_cast<QGraphicsView*>(viewport());
 131     return graphicsView->autoFillBackground();
 132 }
 133
 134 void KItemListContainer::keyPressEvent(QKeyEvent* event)
 135 {
 136     // TODO: We should find a better way to handle the key press events in the view.
 137     // The reasons why we need this hack are:
 138     // 1. Without reimplementing keyPressEvent() here, the event would not reach the QGraphicsView.
 139     // 2. By default, the KItemListView does not have the keyboard focus in the QGraphicsScene, so
 140     //    simply sending the event to the QGraphicsView which is the KItemListContainer's viewport
 141     //    does not work.
 142     KItemListView* view = m_controller->view();
 143     if (view) {
 144         QApplication::sendEvent(view, event);
 145     }
 146 }
 147
 148 void KItemListContainer::showEvent(QShowEvent* event)
 149 {
 150     QAbstractScrollArea::showEvent(event);
 151     updateGeometries();
 152 }
 153
 154 void KItemListContainer::resizeEvent(QResizeEvent* event)
 155 {
 156     QAbstractScrollArea::resizeEvent(event);
 157     updateGeometries();
 158 }
 159
 160 void KItemListContainer::scrollContentsBy(int dx, int dy)
 161 {
 162     m_horizontalSmoothScroller->scrollContentsBy(dx);
 163     m_verticalSmoothScroller->scrollContentsBy(dy);
 164 }
 165
 166 void KItemListContainer::wheelEvent(QWheelEvent* event)
 167 {
 168     if (event->modifiers().testFlag(Qt::ControlModifier)) {
 169         event->ignore();
 170         return;
 171     }
 172
 173     KItemListView* view = m_controller->view();
 174     if (!view) {
 175         event->ignore();
 176         return;
 177     }
 178
 179     const bool scrollHorizontally = (event->orientation() == Qt::Horizontal) ||
 180                                     (event->orientation() == Qt::Vertical && !verticalScrollBar()->isVisible());
 181     KItemListSmoothScroller* smoothScroller = scrollHorizontally ?
 182                                               m_horizontalSmoothScroller : m_verticalSmoothScroller;
 183
 184     smoothScroller->handleWheelEvent(event);
 185 }
 186
 187 void KItemListContainer::slotScrollOrientationChanged(Qt::Orientation current, Qt::Orientation previous)
 188 {
 189     Q_UNUSED(previous)
 190     updateSmoothScrollers(current);
 191 }
 192
 193 void KItemListContainer::slotModelChanged(KItemModelBase* current, KItemModelBase* previous)
 194 {
 195     Q_UNUSED(current)
 196     Q_UNUSED(previous)
 197 }
 198
 199 void KItemListContainer::slotViewChanged(KItemListView* current, KItemListView* previous)
 200 {
 201     QGraphicsScene* scene = static_cast<QGraphicsView*>(viewport())->scene();
 202     if (previous) {
 203         scene->removeItem(previous);
 204         disconnect(previous, &KItemListView::scrollOrientationChanged,
 205                    this, &KItemListContainer::slotScrollOrientationChanged);
 206         disconnect(previous, &KItemListView::scrollOffsetChanged,
 207                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 208         disconnect(previous, &KItemListView::maximumScrollOffsetChanged,
 209                    this, &KItemListContainer::updateScrollOffsetScrollBar);
 210         disconnect(previous, &KItemListView::itemOffsetChanged,
 211                    this, &KItemListContainer::updateItemOffsetScrollBar);
 212         disconnect(previous, &KItemListView::maximumItemOffsetChanged,
 213                    this, &KItemListContainer::updateItemOffsetScrollBar);
 214         disconnect(previous, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 215         m_horizontalSmoothScroller->setTargetObject(nullptr);
 216         m_verticalSmoothScroller->setTargetObject(nullptr);
 217     }
 218     if (current) {
 219         scene->addItem(current);
 220         connect(current, &KItemListView::scrollOrientationChanged,
 221                 this, &KItemListContainer::slotScrollOrientationChanged);
 222         connect(current, &KItemListView::scrollOffsetChanged,
 223                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 224         connect(current, &KItemListView::maximumScrollOffsetChanged,
 225                 this, &KItemListContainer::updateScrollOffsetScrollBar);
 226         connect(current, &KItemListView::itemOffsetChanged,
 227                 this, &KItemListContainer::updateItemOffsetScrollBar);
 228         connect(current, &KItemListView::maximumItemOffsetChanged,
 229                 this, &KItemListContainer::updateItemOffsetScrollBar);
 230         connect(current, &KItemListView::scrollTo, this, &KItemListContainer::scrollTo);
 231         m_horizontalSmoothScroller->setTargetObject(current);
 232         m_verticalSmoothScroller->setTargetObject(current);
 233         updateSmoothScrollers(current->scrollOrientation());
 234     }
 235 }
 236
 237 void KItemListContainer::scrollTo(qreal offset)
 238 {
 239     const KItemListView* view = m_controller->view();
 240     if (view) {
 241         if (view->scrollOrientation() == Qt::Vertical) {
 242             m_verticalSmoothScroller->scrollTo(offset);
 243         } else {
 244             m_horizontalSmoothScroller->scrollTo(offset);
 245         }
 246     }
 247 }
 248
 249 void KItemListContainer::updateScrollOffsetScrollBar()
 250 {
 251     const KItemListView* view = m_controller->view();
 252     if (!view) {
 253         return;
 254     }
 255
 256     KItemListSmoothScroller* smoothScroller = nullptr;
 257     QScrollBar* scrollOffsetScrollBar = nullptr;
 258     int singleStep = 0;
 259     int pageStep = 0;
 260     int maximum = 0;
 261     if (view->scrollOrientation() == Qt::Vertical) {
 262         smoothScroller = m_verticalSmoothScroller;
 263         scrollOffsetScrollBar = verticalScrollBar();
 264
 265         // Don't scroll super fast when using a wheel mouse:
 266         // We want to consider one "line" to be the text label which has a
 267         // roughly fixed height rather than using the height of the icon which
 268         // may be very tall
 269         const QFontMetrics metrics(font());
 270         singleStep = metrics.height() * QApplication::wheelScrollLines();
 271
 272         // We cannot use view->size().height() because this height might
 273         // include the header widget, which is not part of the scrolled area.
 274         pageStep = view->verticalPageStep();
 275
 276         // However, the total height of the view must be considered for the
 277         // maximum value of the scroll bar. Note that the view's scrollOffset()
 278         // refers to the offset of the top part of the view, which might be
 279         // hidden behind the header.
 280         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().height()));
 281     } else {
 282         smoothScroller = m_horizontalSmoothScroller;
 283         scrollOffsetScrollBar = horizontalScrollBar();
 284         singleStep = view->itemSize().width();
 285         pageStep = view->size().width();
 286         maximum = qMax(0, int(view->maximumScrollOffset() - view->size().width()));
 287     }
 288
 289     const int value = view->scrollOffset();
 290     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 291         const bool updatePolicy = (scrollOffsetScrollBar->maximum() > 0 && maximum == 0)
 292                                   || horizontalScrollBarPolicy() == Qt::ScrollBarAlwaysOn;
 293
 294         scrollOffsetScrollBar->setSingleStep(singleStep);
 295         scrollOffsetScrollBar->setPageStep(pageStep);
 296         scrollOffsetScrollBar->setMinimum(0);
 297         scrollOffsetScrollBar->setMaximum(maximum);
 298         scrollOffsetScrollBar->setValue(value);
 299
 300         if (updatePolicy) {
 301             // Prevent a potential endless layout loop (see bug #293318).
 302             updateScrollOffsetScrollBarPolicy();
 303         }
 304     }
 305 }
 306
 307 void KItemListContainer::updateItemOffsetScrollBar()
 308 {
 309     const KItemListView* view = m_controller->view();
 310     if (!view) {
 311         return;
 312     }
 313
 314     KItemListSmoothScroller* smoothScroller = nullptr;
 315     QScrollBar* itemOffsetScrollBar = nullptr;
 316     int singleStep = 0;
 317     int pageStep = 0;
 318     if (view->scrollOrientation() == Qt::Vertical) {
 319         smoothScroller = m_horizontalSmoothScroller;
 320         itemOffsetScrollBar = horizontalScrollBar();
 321         singleStep = view->size().width() / 10;
 322         pageStep = view->size().width();
 323     } else {
 324         smoothScroller = m_verticalSmoothScroller;
 325         itemOffsetScrollBar = verticalScrollBar();
 326         singleStep = view->size().height() / 10;
 327         pageStep = view->size().height();
 328     }
 329
 330     const int value = view->itemOffset();
 331     const int maximum = qMax(0, int(view->maximumItemOffset()) - pageStep);
 332     if (smoothScroller->requestScrollBarUpdate(maximum)) {
 333         itemOffsetScrollBar->setSingleStep(singleStep);
 334         itemOffsetScrollBar->setPageStep(pageStep);
 335         itemOffsetScrollBar->setMinimum(0);
 336         itemOffsetScrollBar->setMaximum(maximum);
 337         itemOffsetScrollBar->setValue(value);
 338     }
 339 }
 340
 341 void KItemListContainer::updateGeometries()
 342 {
 343     QRect rect = geometry();
 344
 345     int extra = frameWidth() * 2;
 346     QStyleOption option;
 347     option.initFrom(this);
 348     int scrollbarSpacing = 0;
 349     if (style()->styleHint(QStyle::SH_ScrollView_FrameOnlyAroundContents, &option, this)) {
 350         scrollbarSpacing = style()->pixelMetric(QStyle::PM_ScrollView_ScrollBarSpacing, &option, this);
 351     }
 352
 353     const int widthDec = verticalScrollBar()->isVisible()
 354                          ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 355                          : extra;
 356
 357     const int heightDec = horizontalScrollBar()->isVisible()
 358                           ? extra + scrollbarSpacing + style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this)
 359                           : extra;
 360
 361     const QRectF newGeometry(0, 0, rect.width() - widthDec,
 362                              rect.height() - heightDec);
 363     if (m_controller->view()->geometry() != newGeometry) {
 364         m_controller->view()->setGeometry(newGeometry);
 365
 366         // Get the real geometry of the view again since the scrollbars
 367         // visibilities and the view geometry may have changed in re-layout.
 368         static_cast<KItemListContainerViewport*>(viewport())->scene()->setSceneRect(m_controller->view()->geometry());
 369         static_cast<KItemListContainerViewport*>(viewport())->viewport()->setGeometry(m_controller->view()->geometry().toRect());
 370
 371         updateScrollOffsetScrollBar();
 372         updateItemOffsetScrollBar();
 373     }
 374 }
 375
 376 void KItemListContainer::updateSmoothScrollers(Qt::Orientation orientation)
 377 {
 378     if (orientation == Qt::Vertical) {
 379         m_verticalSmoothScroller->setPropertyName("scrollOffset");
 380         m_horizontalSmoothScroller->setPropertyName("itemOffset");
 381     } else {
 382         m_horizontalSmoothScroller->setPropertyName("scrollOffset");
 383         m_verticalSmoothScroller->setPropertyName("itemOffset");
 384     }
 385 }
 386
 387 void KItemListContainer::updateScrollOffsetScrollBarPolicy()
 388 {
 389     const KItemListView* view = m_controller->view();
 390     Q_ASSERT(view);
 391     const bool vertical = (view->scrollOrientation() == Qt::Vertical);
 392
 393     QStyleOption option;
 394     option.initFrom(this);
 395     const int scrollBarInc = style()->pixelMetric(QStyle::PM_ScrollBarExtent, &option, this);
 396
 397     QSizeF newViewSize = m_controller->view()->size();
 398     if (vertical) {
 399         newViewSize.rwidth() += scrollBarInc;
 400     } else {
 401         newViewSize.rheight() += scrollBarInc;
 402     }
 403
 404     const Qt::ScrollBarPolicy policy = view->scrollBarRequired(newViewSize)
 405                                        ? Qt::ScrollBarAlwaysOn : Qt::ScrollBarAsNeeded;
 406     if (vertical) {
 407         setVerticalScrollBarPolicy(policy);
 408     } else {
 409         setHorizontalScrollBarPolicy(policy);
 410     }
 411 }
 412
 413 #include "kitemlistcontainer.moc"