src/ui/QFingerScrollArea.cc

   1 /* Shopper
   2  * Copyright (C) 2008 David Greaves
   3  *
   4  * This software is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU Lesser General Public License
   6  * as published by the Free Software Foundation; either version 2.1 of
   7  * the License, or (at your option) any later version.
   8  *
   9  * This software is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12  * Lesser General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU Lesser General Public
  15  * License along with this software; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  17  * 02110-1301 USA
  18  *
  19  */
  20 //#define DEBUG_SHOPPER 1
  21 #include "shopper.h"           // automake, i8n, gettext
  22 #include "QFingerScrollArea.h"
  23 #include <QtGui>
  24
  25 #define SCROLL_SENSITIVITY 20   // pixels before we scroll
  26 #define SCROLL_SCALE  0.1       // sensitivity to movement
  27 #define KINETIC_REFRESH 100     // ms
  28 #define VSCALE 100              // velocity scaling to ensure not lost in int rounding
  29 #define DECEL 0.75              // velocity reduction factor/kinetic refresh
  30 #define DECEL_DURATION 1000     // ms
  31
  32 #define DEBOUNCE 200            // after a mouseRelease we disallow MousePress for this long
  33
  34 // QFingerScrollArea a QScrollArea that responds to fingers
  35 QFingerScrollArea::QFingerScrollArea(QWidget * parent) :
  36         QScrollArea(parent),
  37         allowHoriz(false),
  38         allowVert(true),
  39         scrollPaper(true),
  40         direction(1),
  41         scrolling(false),
  42         recently_scrolling(false),
  43         scrolling_setup(false),
  44         scroll_start_x(0),
  45         scroll_start_y(0),
  46         start_x(0),
  47         start_y(0),
  48         curr_x(0),
  49         curr_y(0),
  50         scroll_range_x(0),
  51         scroll_range_y(0),
  52         scale_x(0),
  53         scale_y(0),
  54         kinetic(true),
  55         last_x(0),
  56         last_y(0),
  57         vel_x(0),
  58         vel_y(0),
  59         vel_x1(0),
  60         vel_y1(0),
  61         last_ev_time(0),
  62         curr_time(0),
  63         kineticTimer(0),
  64         debounceTimer(0),
  65         kinetic_cycles(0)
  66 {
  67         max_x= qApp->desktop()->screenGeometry().width();
  68         max_y= qApp->desktop()->screenGeometry().height();
  69 }
  70
  71 ////////////////////////////////////////////////////////////////
  72 // Interface
  73 void QFingerScrollArea::setScrollConstraints(bool AllowHoriz, bool AllowVert)
  74 {
  75         allowVert = AllowVert;
  76         allowHoriz = AllowHoriz;
  77         if (!(allowHoriz or allowVert)) allowVert = true; // Don't
  78 }
  79 void QFingerScrollArea::setScrollPaper(bool _scrollPaper)
  80 {
  81         scrollPaper = _scrollPaper;
  82 }
  83 void QFingerScrollArea::setKinetic(bool _kinetic)
  84 {
  85         kinetic = _kinetic;
  86 }
  87 ////////////////////////////////////////////////////////////////
  88 // Finger scroll implementation - movement
  89 void QFingerScrollArea::mousePressEvent ( QMouseEvent * event )
  90 {
  91         if (event->button() == Qt::LeftButton){
  92                 setupEvent ( event );
  93         }
  94         QScrollArea::mousePressEvent(event);
  95 }
  96 void QFingerScrollArea::setupEvent ( QMouseEvent * event )
  97 {
  98         start_y = event->globalY();
  99         scroll_start_y = verticalScrollBar()->value();
 100         scroll_range_y = verticalScrollBar()->maximum() - verticalScrollBar()->minimum();
 101
 102         start_x = event->globalX();
 103         scroll_start_x = horizontalScrollBar()->value();
 104         scroll_range_x = horizontalScrollBar()->maximum() - horizontalScrollBar()->minimum();
 105
 106         if (scrollPaper) {
 107                 scale_x = widget()->width()-width();
 108                 scale_y = widget()->height()-height();
 109                 direction = 1;
 110         } else {
 111                 scale_x = width();
 112                 scale_y = height();
 113                 direction = -1;
 114         }
 115         event_time.start();
 116         last_ev_time=0;
 117         scrolling_setup = true;
 118         DEBUG("scroll setup " <<start_x<<":"<<start_y);
 119 }
 120 void QFingerScrollArea::mouseMoveEvent ( QMouseEvent * event )
 121 {
 122         // We should get a mousePressedEvent - but we don't always...
 123         if (!scrolling_setup) {
 124                 setupEvent(event);
 125         }
 126
 127         if (abs(start_x - event->globalX()) > SCROLL_SENSITIVITY or
 128                 abs(start_y - event->globalY()) > SCROLL_SENSITIVITY) {
 129                 if ((allowVert and scroll_range_y) or
 130                         (allowHoriz and scroll_range_x))
 131                         scrolling = true;
 132         }
 133         if (!scrolling) {
 134                 QScrollArea::mouseMoveEvent(event);
 135                 return;
 136         }
 137         curr_y = event->globalY();
 138         curr_x = event->globalX();
 139
 140         if (allowVert and scroll_range_y) {
 141                 // (curr_y - start_y) = delta_pixels
 142                 // scroll_start / scroll_range = fraction_value_of_scrollbar
 143                 // fraction_value_of_scrollbar * scale_y = pixels above widget base
 144                 // pixels above widget base + delta_pixels = new_fraction_value_of_scrollbar * scale
 145                 // new_fraction_value_of_scrollbar = new_value_of_scrollbar / scroll_range
 146                 // v2 = ((scroll_start / scroll_range) * scale + (curr - start))/scale)*scroll_range
 147                 //
 148                 // if scale is the scrollarea height then moving will match the scrollbar
 149                 //
 150                 // if scale is the child widget height then moving will scroll pixel by pixel
 151
 152
 153 //              DEBUG(scroll_start_y<<" + (("<<start_y<<" - "<<curr_y<<") * "<<scroll_range_y<<")/"<<scale_y);
 154                 int v_y = scroll_start_y +  direction * ((start_y - curr_y) * scroll_range_y)/scale_y;
 155                 verticalScrollBar()->setValue(v_y);
 156         }
 157         if (allowHoriz and scroll_range_x) {
 158                 int v_x = scroll_start_x +  direction * ((start_x - curr_x) * scroll_range_x)/scale_x;
 159                 verticalScrollBar()->setValue(v_x);
 160         }
 161         curr_time = event_time.elapsed();
 162         DEBUG("scroll move " <<curr_x<<":"<<curr_y<<"  time:"<<curr_time);
 163
 164         if (curr_time > last_ev_time){
 165                 if (last_ev_time){  // first time round we set v to zero
 166                         vel_x1 = vel_x;
 167                         vel_x= (last_x - curr_x)*VSCALE / (curr_time - last_ev_time);
 168                         vel_y1 = vel_y;
 169                         vel_y= (last_y - curr_y)*VSCALE / (curr_time - last_ev_time);
 170                         DEBUG("Velocity last_y:"<<last_y<< " curr_y:"<<curr_y <<"  curr_time:"<<curr_time <<" last_ev_time:"<<last_ev_time << "  Velocity: "<<vel_y);
 171                 } else {
 172                         vel_x = vel_y = 0;
 173                         vel_x1 = vel_y1 = 0;
 174                 }
 175                 // Store the last values
 176                 last_ev_time =  curr_time;
 177                 last_x = curr_x;
 178                 last_y = curr_y;
 179         }
 180         event->accept();
 181 }
 182 void QFingerScrollArea::mouseReleaseEvent ( QMouseEvent * event )
 183 {
 184 //      _ENTER;
 185         if (scrolling and event->button() == Qt::LeftButton) {
 186                 event->accept();
 187                 if (kinetic and last_ev_time) { // Only do velocity if we had a last_ev_time
 188                         curr_time = event_time.elapsed();
 189 #ifdef DEBUG_SHOPPER
 190                         int y = event->globalY();
 191                         int x = event->globalX();
 192 #endif
 193                         DEBUG("scroll stop " <<x<<":"<<y<<"  time:"<<curr_time);
 194
 195                         kinetic_cycles = 0;
 196                         kineticTimer=startTimer(KINETIC_REFRESH);
 197                 }
 198                 scrolling = false;
 199                 scrolling_setup = false;
 200                 recently_scrolling = true;
 201                 debounceTimer = startTimer(DEBOUNCE);
 202                 return;
 203         }
 204         QScrollArea::mouseReleaseEvent(event);
 205 }
 206 ////////////////////////////////////////////////////////////////
 207 // Kinetics
 208 void QFingerScrollArea::timerEvent(QTimerEvent *event)
 209 {
 210         if (event->timerId() == debounceTimer) {
 211                 recently_scrolling = false;
 212                 killTimer(debounceTimer);
 213                 debounceTimer = 0;
 214                 return;
 215         }
 216
 217         if (event->timerId() == kineticTimer) {
 218                 if (allowVert) {
 219                         int v_y = verticalScrollBar()->value() +
 220                                 direction * vel_y1 * KINETIC_REFRESH/VSCALE * scroll_range_y / scale_y;
 221                         verticalScrollBar()->setValue(v_y);
 222                         vel_y1 *= DECEL;
 223                 }
 224
 225                 if (allowHoriz) {
 226                         int v_x = horizontalScrollBar()->value() +
 227                                 direction * vel_x1 * KINETIC_REFRESH/VSCALE * scroll_range_x / scale_x;
 228                         horizontalScrollBar()->setValue(v_x);
 229                         vel_x1 *= DECEL;
 230                 }
 231                 show();
 232                 kinetic_cycles++;
 233                 if (scrolling or kinetic_cycles > DECEL_DURATION/KINETIC_REFRESH or
 234                         (vel_x1 == 0 and vel_y1 ==0)) {
 235                         killTimer(kineticTimer);
 236                 }
 237         }
 238 }
 239
 240 ////////////////////////////////////////////////////////////////
 241 // Child management - event filtering
 242 // Handle events down the hierarchy : FIX: as children are added, register them
 243 void QFingerScrollArea::childEvent ( QChildEvent * event )
 244 {
 245         DEBUG("childEvent is a " << event->type());
 246         if (event->type() == QEvent::ChildAdded or
 247                 event->type() == 70) {    // FIX is this a Qt bug? 70 is ChildInserted which is deprecated in 4.4
 248                 registerChildrenForFingerScrolling(event->child());
 249         }
 250         if (event->removed()) {
 251                 deregisterChildrenForFingerScrolling(event->child());
 252         }
 253 }
 254
 255 void QFingerScrollArea::registerChildrenForFingerScrolling(QObject *top)
 256 {
 257         top->installEventFilter(this);
 258         DEBUG("registered a " << top->metaObject()->className());
 259         QObject *obj;
 260         QList<QObject *> children = top->findChildren<QObject *>();
 261         foreach (obj, children){
 262                 DEBUG("registered a " << obj->metaObject()->className());
 263                 obj->installEventFilter(this);
 264         }
 265 }
 266 void QFingerScrollArea::deregisterChildrenForFingerScrolling(QObject *top)
 267 {
 268         top->removeEventFilter(this);
 269         DEBUG("deregistered a " << top->metaObject()->className());
 270         QObject *obj;
 271         QList<QObject *> children = top->findChildren<QObject *>();
 272         foreach (obj, children){
 273                 obj->removeEventFilter(this);
 274                 DEBUG("deregistered a " << obj->metaObject()->className());
 275         }
 276 }
 277
 278 bool QFingerScrollArea::eventFilter(QObject *obj, QEvent *event)
 279 {
 280         switch (event->type()) {
 281         case QEvent::MouseButtonPress :
 282                 if (recently_scrolling) {
 283                         return true;
 284                 }
 285                 if (static_cast<QMouseEvent *>(event)->button() == Qt::LeftButton){
 286                         setupEvent ( static_cast<QMouseEvent *>(event));
 287                 }
 288                 break;
 289         case QEvent::MouseButtonRelease :
 290                 if (scrolling) {
 291                         mouseReleaseEvent(static_cast<QMouseEvent *>(event));
 292                         return true;
 293                 }
 294                 if (recently_scrolling) {
 295                         return true;
 296                 }
 297                 break;
 298         case QEvent::MouseMove :
 299                 if (scrolling) {
 300                         mouseMoveEvent(static_cast<QMouseEvent *>(event));
 301                         return true;
 302                 }
 303                 break;
 304         case QEvent::ChildAdded :
 305                 registerChildrenForFingerScrolling(static_cast<QChildEvent *>(event)->child());
 306                 break;
 307         case QEvent::ChildRemoved :
 308                 deregisterChildrenForFingerScrolling(static_cast<QChildEvent *>(event)->child());
 309                 break;
 310         default:
 311                 break;
 312         }
 313         // standard event processing
 314         return QScrollArea::eventFilter(obj, event);
 315 }
 316