libs/gtkmm2ext/gtkmm2ext/dndvbox.h

   1 /*
   2     Copyright (C) 2009 Paul Davis
   3
   4     This program is free software; you can redistribute it and/or modify
   5     it under the terms of the GNU General Public License as published by
   6     the Free Software Foundation; either version 2 of the License, or
   7     (at your option) any later version.
   8
   9     This program is distributed in the hope that it will be useful,
  10     but WITHOUT ANY WARRANTY; without even the implied warranty of
  11     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12     GNU General Public License for more details.
  13
  14     You should have received a copy of the GNU General Public License
  15     along with this program; if not, write to the Free Software
  16     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  17
  18 */
  19
  20 #include <gtkmm/box.h>
  21 #include "gtkmm2ext/widget_state.h"
  22
  23 namespace Gtkmm2ext {
  24
  25 /** Parent class for children of a DnDVBox */
  26 class DnDVBoxChild
  27 {
  28 public:
  29         virtual ~DnDVBoxChild () {}
  30
  31         /** @return The widget that is to be put into the DnDVBox */
  32         virtual Gtk::Widget& widget () = 0;
  33
  34         /** @return An EventBox containing the widget that should be used for selection, dragging etc. */
  35         virtual Gtk::EventBox& action_widget () = 0;
  36
  37         /** @return Text to use in the icon that is dragged */
  38         virtual std::string drag_text () const = 0;
  39
  40         /** Set the child's visual state */
  41         virtual void set_visual_state (VisualState, bool onoff) = 0;
  42 };
  43
  44 /** A VBox whose contents can be dragged and dropped */
  45 template <class T>
  46 class DnDVBox : public Gtk::EventBox
  47 {
  48 public:
  49         DnDVBox () : _active (0), _drag_icon (0), _expecting_unwanted_button_event (false), _placeholder (0)
  50         {
  51                 _targets.push_back (Gtk::TargetEntry ("processor"));
  52
  53                 add (_internal_vbox);
  54                 add_events (
  55                         Gdk::KEY_PRESS_MASK | Gdk::KEY_RELEASE_MASK |
  56                         Gdk::ENTER_NOTIFY_MASK | Gdk::LEAVE_NOTIFY_MASK |
  57                         Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK
  58                         );
  59
  60                 signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), (T *) 0));
  61                 signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), (T *) 0));
  62                 signal_drag_motion().connect (mem_fun (*this, &DnDVBox::drag_motion));
  63                 signal_drag_leave().connect (mem_fun (*this, &DnDVBox::drag_leave));
  64
  65                 _internal_vbox.show ();
  66
  67                 drag_dest_set (_targets);
  68                 signal_drag_data_received().connect (mem_fun (*this, &DnDVBox::drag_data_received));
  69         }
  70
  71         virtual ~DnDVBox ()
  72         {
  73                 clear ();
  74
  75                 delete _drag_icon;
  76         }
  77
  78         /** Add a child at the end of the widget.  The DnDVBox will take responsibility for deleting the child */
  79         void add_child (T* child)
  80         {
  81                 child->action_widget().drag_source_set (_targets);
  82                 child->action_widget().signal_drag_begin().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_begin), child));
  83                 child->action_widget().signal_drag_data_get().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_data_get), child));
  84                 child->action_widget().signal_drag_end().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_end), child));
  85                 child->action_widget().signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), child));
  86                 child->action_widget().signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), child));
  87
  88                 _internal_vbox.pack_start (child->widget(), false, false);
  89
  90                 _children.push_back (child);
  91                 child->widget().show ();
  92         }
  93
  94         /** @return Children, sorted into the order that they are currently being displayed in the widget */
  95         std::list<T*> children ()
  96         {
  97                 std::list<T*> sorted_children;
  98
  99                 std::list<Gtk::Widget*> widget_children = _internal_vbox.get_children ();
 100                 for (std::list<Gtk::Widget*>::iterator i = widget_children.begin(); i != widget_children.end(); ++i) {
 101                         T* c = child_from_widget (*i);
 102
 103                         if (c) {
 104                                 sorted_children.push_back (c);
 105                         }
 106                 }
 107
 108                 return sorted_children;
 109         }
 110
 111         /** @return Selected children */
 112         std::list<T*> selection () const {
 113                 return _selection;
 114         }
 115
 116         /** Set the `active' child; this is simply a child which is set to have the
 117          *  visual state "active" for whatever purposes the client may have.
 118          *  @param c Child, or 0 for none.
 119          */
 120         void set_active (T* c) {
 121                 T* old_active = _active;
 122                 _active = c;
 123                 if (old_active) {
 124                         setup_child_state (old_active);
 125                 }
 126                 if (_active) {
 127                         setup_child_state (_active);
 128                 }
 129         }
 130
 131         /** @param child Child
 132          *  @return true if the child is selected, otherwise false.
 133          */
 134         bool selected (T* child) const {
 135                 return (find (_selection.begin(), _selection.end(), child) != _selection.end());
 136         }
 137
 138         /** Clear all children from the widget */
 139         void clear ()
 140         {
 141                 _selection.clear ();
 142
 143                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 144                         _internal_vbox.remove ((*i)->widget());
 145                         delete *i;
 146                 }
 147
 148                 _children.clear ();
 149                 _active = 0;
 150         }
 151
 152         void select_all ()
 153         {
 154                 clear_selection ();
 155                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 156                         add_to_selection (*i);
 157                 }
 158
 159                 SelectionChanged (); /* EMIT SIGNAL */
 160         }
 161
 162         void select_none ()
 163         {
 164                 clear_selection ();
 165
 166                 SelectionChanged (); /* EMIT SIGNAL */
 167         }
 168
 169         /** @param y y coordinate.
 170          *  @return Pair consisting of the child under y (or 0) and the (fractional) index of the child under y (or -1)
 171          */
 172         std::pair<T*, double> get_child_at_position (int y) const
 173         {
 174                 T* before;
 175                 T* after;
 176
 177                 std::pair<T*, double> r;
 178
 179                 r.second = get_children_around_position (y, &before, &r.first, &after);
 180
 181                 return r;
 182         }
 183
 184         void set_spacing (int s) {
 185                 _internal_vbox.set_spacing (s);
 186         }
 187
 188         void remove_placeholder ()
 189         {
 190                 if (_placeholder) {
 191                         _internal_vbox.remove (*_placeholder);
 192                         _placeholder = 0;
 193                 }
 194         }
 195
 196         /** Add a placeholder where a child would be put if it were added at the given y position.
 197          *  @param y y position within the DnDVBox.
 198          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 199          */
 200         int add_placeholder (double y)
 201         {
 202                 return create_or_update_placeholder (get_child_at_position (y).second);
 203         }
 204
 205         /** Children have been reordered by a drag */
 206         sigc::signal<void> Reordered;
 207
 208         /** A button has been pressed over the widget */
 209         sigc::signal<bool, GdkEventButton*, T*> ButtonPress;
 210
 211         /** A button has been release over the widget */
 212         sigc::signal<bool, GdkEventButton*, T*> ButtonRelease;
 213
 214         /** A child has been dropped onto this DnDVBox from another one;
 215          *  Parameters are the source DnDVBox, our child which the other one was dropped on (or 0) and the DragContext.
 216          */
 217         sigc::signal<void, DnDVBox*, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromAnotherBox;
 218         sigc::signal<void> SelectionChanged;
 219
 220 private:
 221
 222         /** @return the bottom y position of a child, pretending any placeholder
 223          *  is not there.
 224          */
 225         double bottom_of_child_ignoring_placeholder (T* child) const
 226         {
 227                 Gtk::Allocation const a = child->widget().get_allocation ();
 228                 double bottom = a.get_y() + a.get_height();
 229
 230                 if (_placeholder) {
 231                         Gtk::Allocation const b = _placeholder->get_allocation ();
 232                         if (b.get_y() < a.get_y()) {
 233                                 bottom -= (b.get_height () + _internal_vbox.get_spacing ());
 234                         }
 235                 }
 236
 237                 return bottom;
 238         }
 239
 240         /** Look at a y coordinate and find the children below y, and the ones either side.
 241          *  @param y y position.
 242          *  @param before Filled in with the child before, or 0.
 243          *  @param at Filled in with the child under y, or 0.
 244          *  @param after Filled in with the child after, or 0.
 245          *  @return Fractional position in terms of child height, or -1 if not over a child.
 246          */
 247         double get_children_around_position (int y, T** before, T** at, T** after) const
 248         {
 249                 if (_children.empty()) {
 250                         *before = *at = *after = 0;
 251                         return -1;
 252                 }
 253
 254                 *before = 0;
 255
 256                 typename std::list<T*>::const_iterator j = _children.begin ();
 257
 258                 /* index of current child */
 259                 int i = 0;
 260                 /* top of current child */
 261                 double top = 0;
 262                 /* bottom of current child */
 263                 double bottom = bottom_of_child_ignoring_placeholder (*j);
 264
 265                 while (y >= bottom && j != _children.end()) {
 266
 267                         top = bottom;
 268
 269                         *before = *j;
 270                         ++i;
 271                         ++j;
 272
 273                         if (j != _children.end()) {
 274                                 bottom = bottom_of_child_ignoring_placeholder (*j);
 275                         }
 276                 }
 277
 278                 if (j == _children.end()) {
 279                         *at = 0;
 280                         *after = 0;
 281                         return -1;
 282                 }
 283
 284                 *at = *j;
 285
 286                 ++j;
 287                 *after = j != _children.end() ? *j : 0;
 288
 289                 return i + ((y - top) / (bottom - top));
 290         }
 291
 292         void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)
 293         {
 294                 _drag_child = child;
 295
 296                 /* make up an icon for the drag */
 297                 _drag_icon = new Gtk::Window (Gtk::WINDOW_POPUP);
 298
 299                 Gtk::Allocation a = child->widget().get_allocation ();
 300                 _drag_icon->set_size_request (a.get_width(), a.get_height());
 301
 302                 _drag_icon->signal_expose_event().connect (sigc::mem_fun (*this, &DnDVBox::icon_expose));
 303                 _drag_icon->set_name (get_name ());
 304
 305                 /* make the icon transparent if possible */
 306                 Glib::RefPtr<Gdk::Screen const> s = _drag_icon->get_screen ();
 307                 Glib::RefPtr<Gdk::Colormap const> c = s->get_rgba_colormap ();
 308                 if (c) {
 309                         _drag_icon->set_colormap (c);
 310                 }
 311
 312                 int w, h;
 313                 _drag_icon->get_size (w, h);
 314                 _drag_icon->drag_set_as_icon (context, w / 2, h / 2);
 315
 316                 _drag_source = this;
 317         }
 318
 319         /* Draw the drag icon */
 320         bool icon_expose (GdkEventExpose*)
 321         {
 322                 /* Just grab the child's widget and use that */
 323
 324                 int w, h;
 325                 _drag_icon->get_size (w, h);
 326
 327                 cairo_t* cr = gdk_cairo_create (_drag_icon->get_window()->gobj ());
 328
 329                 Glib::RefPtr<Gdk::Pixmap> p = _drag_child->widget().get_snapshot();
 330                 gdk_cairo_set_source_pixmap (cr, p->gobj(), 0, 0);
 331                 cairo_rectangle (cr, 0, 0, w, h);
 332                 cairo_fill (cr);
 333                 cairo_destroy (cr);
 334
 335                 return false;
 336         }
 337
 338         void drag_data_get (Glib::RefPtr<Gdk::DragContext> const &, Gtk::SelectionData & selection_data, guint, guint, T* child)
 339         {
 340                 selection_data.set (selection_data.get_target(), 8, (const guchar *) &child, sizeof (&child));
 341         }
 342
 343         void drag_data_received (
 344                 Glib::RefPtr<Gdk::DragContext> const & context, int /*x*/, int y, Gtk::SelectionData const & selection_data, guint /*info*/, guint time
 345                 )
 346         {
 347                 /* work out where it was dropped */
 348                 std::pair<T*, double> const drop = get_child_at_position (y);
 349
 350                 if (_drag_source == this) {
 351
 352                         /* dropped from ourselves onto ourselves */
 353
 354                         T* child = *((T * const *) selection_data.get_data());
 355
 356                         if (drop.first == 0) {
 357                                 _internal_vbox.reorder_child (child->widget(), -1);
 358                         } else {
 359
 360                                 /* where in the list this child should be dropped */
 361                                 int target = drop.second + 0.5;
 362
 363                                 /* find out whether the child was `picked up' from before the drop position */
 364                                 int n = 0;
 365                                 typename std::list<T*>::const_iterator i = _children.begin ();
 366                                 while (i != _children.end() && *i != child && n < target) {
 367                                         ++i;
 368                                         ++n;
 369                                 }
 370
 371                                 /* if so, adjust the drop position to account for this */
 372                                 if (n < target) {
 373                                         --target;
 374                                 }
 375
 376                                 _internal_vbox.reorder_child (child->widget(), target);
 377                         }
 378
 379                 } else {
 380
 381                         /* drag started in another DnDVBox; raise a signal to say what happened */
 382
 383                         std::list<T*> dropped = _drag_source->selection ();
 384                         DropFromAnotherBox (_drag_source, drop.first, context);
 385                 }
 386
 387                 context->drag_finish (false, false, time);
 388         }
 389
 390         void drag_end (Glib::RefPtr<Gdk::DragContext> const &, T *)
 391         {
 392                 delete _drag_icon;
 393                 _drag_icon = 0;
 394
 395                 _drag_child = 0;
 396                 remove_placeholder ();
 397
 398                 Reordered (); /* EMIT SIGNAL */
 399         }
 400
 401         /** Insert a placeholder at a given fractional child position, creating it if necessary.
 402          *  @param c Fractional child position.
 403          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 404          */
 405         int create_or_update_placeholder (double c)
 406         {
 407                 if (_placeholder == 0) {
 408                         _placeholder = manage (new Gtk::Label (""));
 409                         _internal_vbox.pack_start (*_placeholder, false, false);
 410                         _placeholder->show ();
 411                 }
 412
 413                 /* round up the index, unless we're off the end of the children */
 414                 int const n = c < 0 ? -1 : int (c + 0.5);
 415                 _internal_vbox.reorder_child (*_placeholder, n);
 416                 return n;
 417         }
 418
 419         bool drag_motion (Glib::RefPtr<Gdk::DragContext> const &, int /*x*/, int y, guint)
 420         {
 421                 if (_children.empty ()) {
 422                         return false;
 423                 }
 424
 425                 T* before;
 426                 T* at;
 427                 T* after;
 428
 429                 /* decide where we currently are */
 430                 double const c = get_children_around_position (y, &before, &at, &after);
 431
 432                 /* whether we're in the top or bottom half of the child that we're over */
 433                 bool top_half = (c - int (c)) < 0.5;
 434
 435                 /* Note that when checking on whether to remove a placeholder, we never do
 436                    so if _drag_child is 0 as this means that the child being dragged is
 437                    coming from a different DnDVBox, so it will never be the same as any
 438                    of our children.
 439                 */
 440
 441                 if (top_half && _drag_child && (before == _drag_child || at == _drag_child)) {
 442                         /* dropping here would have no effect, so remove the visual cue */
 443                         remove_placeholder ();
 444                         return false;
 445                 }
 446
 447                 if (!top_half && _drag_child && (at == _drag_child || after == _drag_child)) {
 448                         /* dropping here would have no effect, so remove the visual cue */
 449                         remove_placeholder ();
 450                         return false;
 451                 }
 452
 453                 create_or_update_placeholder (c);
 454                 return false;
 455         }
 456
 457         void drag_leave (Glib::RefPtr<Gdk::DragContext> const &, guint)
 458         {
 459                 remove_placeholder ();
 460         }
 461
 462         bool button_press (GdkEventButton* ev, T* child)
 463         {
 464                 if (_expecting_unwanted_button_event == true && child == 0) {
 465                         _expecting_unwanted_button_event = false;
 466                         return true;
 467                 }
 468
 469                 if (child) {
 470                         _expecting_unwanted_button_event = true;
 471                 }
 472
 473                 if (ev->button == 1 || ev->button == 3) {
 474
 475                         if (!selected (child)) {
 476
 477                                 if ((ev->state & Gdk::SHIFT_MASK) && !_selection.empty()) {
 478
 479                                         /* Shift-click; select all between the clicked child and any existing selections */
 480
 481                                         bool selecting = false;
 482                                         bool done = false;
 483                                         for (typename std::list<T*>::const_iterator i = _children.begin(); i != _children.end(); ++i) {
 484
 485                                                 bool const was_selected = selected (*i);
 486
 487                                                 if (selecting && !was_selected) {
 488                                                         add_to_selection (*i);
 489                                                 }
 490
 491                                                 if (!selecting && !done) {
 492                                                         if (selected (*i)) {
 493                                                                 selecting = true;
 494                                                         } else if (*i == child) {
 495                                                                 selecting = true;
 496                                                                 add_to_selection (child);
 497                                                         }
 498                                                 } else if (selecting) {
 499                                                         if (was_selected || *i == child) {
 500                                                                 selecting = false;
 501                                                                 done = true;
 502                                                         }
 503                                                 }
 504                                         }
 505
 506                                 } else {
 507
 508                                         if ((ev->state & Gdk::CONTROL_MASK) == 0) {
 509                                                 clear_selection ();
 510                                         }
 511
 512                                         if (child) {
 513                                                 add_to_selection (child);
 514                                         }
 515
 516                                 }
 517
 518                                 SelectionChanged (); /* EMIT SIGNAL */
 519
 520                         } else {
 521                                 /* XXX THIS NEEDS GENERALIZING FOR OS X */
 522                                 if (ev->button == 1 && (ev->state & Gdk::CONTROL_MASK)) {
 523                                         if (child && selected (child)) {
 524                                                 remove_from_selection (child);
 525                                                 SelectionChanged (); /* EMIT SIGNAL */
 526                                         }
 527                                 }
 528                         }
 529                 }
 530
 531                 return ButtonPress (ev, child); /* EMIT SIGNAL */
 532         }
 533
 534         bool button_release (GdkEventButton* ev, T* child)
 535         {
 536                 if (_expecting_unwanted_button_event == true && child == 0) {
 537                         _expecting_unwanted_button_event = false;
 538                         return true;
 539                 }
 540
 541                 if (child) {
 542                         _expecting_unwanted_button_event = true;
 543                 }
 544
 545                 return ButtonRelease (ev, child); /* EMIT SIGNAL */
 546         }
 547
 548         /** Setup a child's visual state correctly */
 549         void setup_child_state (T* c)
 550         {
 551                 assert (c);
 552                 c->set_visual_state (Selected, (selected (c) || (_active == c)));
 553         }
 554
 555         void clear_selection ()
 556         {
 557                 std::list<T*> old_selection = _selection;
 558                 _selection.clear ();
 559                 for (typename std::list<T*>::iterator i = old_selection.begin(); i != old_selection.end(); ++i) {
 560                         setup_child_state (*i);
 561                 }
 562         }
 563
 564         void add_to_selection (T* child)
 565         {
 566                 _selection.push_back (child);
 567                 setup_child_state (child);
 568         }
 569
 570         void remove_from_selection (T* child)
 571         {
 572                 typename std::list<T*>::iterator x = find (_selection.begin(), _selection.end(), child);
 573                 if (x != _selection.end()) {
 574                         T* c = *x;
 575                         _selection.erase (x);
 576                         setup_child_state (c);
 577                 }
 578         }
 579
 580         T* child_from_widget (Gtk::Widget const * w) const
 581         {
 582                 typename std::list<T*>::const_iterator i = _children.begin();
 583                 while (i != _children.end() && &(*i)->widget() != w) {
 584                         ++i;
 585                 }
 586
 587                 if (i == _children.end()) {
 588                         return 0;
 589                 }
 590
 591                 return *i;
 592         }
 593
 594         Gtk::VBox _internal_vbox;
 595         std::list<Gtk::TargetEntry> _targets;
 596         std::list<T*> _children;
 597         std::list<T*> _selection;
 598         T* _active;
 599         Gtk::Window* _drag_icon;
 600         bool _expecting_unwanted_button_event;
 601         /** A blank label used as a placeholder to indicate where an item would
 602          *  go if it were dropped or inserted "now".
 603          */
 604         Gtk::Label* _placeholder;
 605         /** Our child being dragged, or 0 */
 606         T* _drag_child;
 607
 608         static DnDVBox* _drag_source;
 609
 610 };
 611
 612 template <class T>
 613 DnDVBox<T>* DnDVBox<T>::_drag_source = 0;
 614
 615 }