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
  22 #include "gtkmm2ext/visibility.h"
  23 #include "gtkmm2ext/widget_state.h"
  24
  25 namespace Gtkmm2ext {
  26
  27 /** Parent class for children of a DnDVBox */
  28 class /*LIBGTKMM2EXT_API*/ DnDVBoxChild
  29 {
  30 public:
  31         virtual ~DnDVBoxChild () {}
  32
  33         /** @return The widget that is to be put into the DnDVBox */
  34         virtual Gtk::Widget& widget () = 0;
  35
  36         /** @return An EventBox containing the widget that should be used for selection, dragging etc. */
  37         virtual Gtk::EventBox& action_widget () = 0;
  38
  39         /** @return Text to use in the icon that is dragged */
  40         virtual std::string drag_text () const = 0;
  41
  42         /** Set the child's visual state */
  43         virtual void set_visual_state (VisualState, bool onoff) = 0;
  44
  45         /** @return True if the child can be selected in the list ( if you don't want it to copy/paste/drag then turn this off ) */
  46         virtual bool is_selectable () const = 0;
  47 };
  48
  49 /** A VBox whose contents can be dragged and dropped */
  50 template <class T>
  51 class /*LIBGTKMM2EXT_API*/ DnDVBox : public Gtk::EventBox
  52 {
  53 public:
  54         DnDVBox () : _active (0), _drag_icon (0), _expecting_unwanted_button_event (false), _placeholder (0)
  55         {
  56                 _targets.push_back (Gtk::TargetEntry ("processor"));
  57
  58                 add (_internal_vbox);
  59                 add_events (
  60                         Gdk::KEY_PRESS_MASK | Gdk::KEY_RELEASE_MASK |
  61                         Gdk::ENTER_NOTIFY_MASK | Gdk::LEAVE_NOTIFY_MASK |
  62                         Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK
  63                         );
  64
  65                 signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), (T *) 0));
  66                 signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), (T *) 0));
  67                 signal_drag_motion().connect (mem_fun (*this, &DnDVBox::drag_motion));
  68                 signal_drag_leave().connect (mem_fun (*this, &DnDVBox::drag_leave));
  69
  70                 _internal_vbox.show ();
  71
  72                 drag_dest_set (_targets);
  73                 signal_drag_data_received().connect (mem_fun (*this, &DnDVBox::drag_data_received));
  74         }
  75
  76         virtual ~DnDVBox ()
  77         {
  78                 clear ();
  79
  80                 delete _drag_icon;
  81         }
  82
  83         /** Add a child at the end of the widget.  The DnDVBox will take responsibility for deleting the child */
  84         void add_child (T* child)
  85         {
  86                 child->action_widget().drag_source_set (_targets);
  87                 child->action_widget().signal_drag_begin().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_begin), child));
  88                 child->action_widget().signal_drag_data_get().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_data_get), child));
  89                 child->action_widget().signal_drag_end().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_end), child));
  90                 child->action_widget().signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), child));
  91                 child->action_widget().signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), child));
  92
  93                 _internal_vbox.pack_start (child->widget(), false, false);
  94
  95                 _children.push_back (child);
  96                 child->widget().show ();
  97         }
  98
  99         /** @return Children, sorted into the order that they are currently being displayed in the widget */
 100         std::list<T*> children ()
 101         {
 102                 std::list<T*> sorted_children;
 103
 104                 std::list<Gtk::Widget*> widget_children = _internal_vbox.get_children ();
 105                 for (std::list<Gtk::Widget*>::iterator i = widget_children.begin(); i != widget_children.end(); ++i) {
 106                         T* c = child_from_widget (*i);
 107
 108                         if (c) {
 109                                 sorted_children.push_back (c);
 110                         }
 111                 }
 112
 113                 return sorted_children;
 114         }
 115
 116         /** @return Selected children */
 117         std::list<T*> selection () const {
 118                 return _selection;
 119         }
 120
 121         /** Set the `active' child; this is simply a child which is set to have the
 122          *  visual state "active" for whatever purposes the client may have.
 123          *  @param c Child, or 0 for none.
 124          */
 125         void set_active (T* c) {
 126                 T* old_active = _active;
 127                 _active = c;
 128                 if (old_active) {
 129                         setup_child_state (old_active);
 130                 }
 131                 if (_active) {
 132                         setup_child_state (_active);
 133                 }
 134         }
 135
 136         /** @param child Child
 137          *  @return true if the child is selected, otherwise false.
 138          */
 139         bool selected (T* child) const {
 140                 return (find (_selection.begin(), _selection.end(), child) != _selection.end());
 141         }
 142
 143         /** Clear all children from the widget */
 144         void clear ()
 145         {
 146                 _selection.clear ();
 147
 148                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 149                         _internal_vbox.remove ((*i)->widget());
 150                         delete *i;
 151                 }
 152
 153                 _children.clear ();
 154                 _active = 0;
 155         }
 156
 157         void select_all ()
 158         {
 159                 clear_selection ();
 160                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 161                         add_to_selection (*i);
 162                 }
 163
 164                 SelectionChanged (); /* EMIT SIGNAL */
 165         }
 166
 167         void select_none ()
 168         {
 169                 clear_selection ();
 170
 171                 SelectionChanged (); /* EMIT SIGNAL */
 172         }
 173
 174         /** @param y y coordinate.
 175          *  @return Pair consisting of the child under y (or 0) and the (fractional) index of the child under y (or -1)
 176          */
 177         std::pair<T*, double> get_child_at_position (int y) const
 178         {
 179                 T* before;
 180                 T* after;
 181
 182                 std::pair<T*, double> r;
 183
 184                 r.second = get_children_around_position (y, &before, &r.first, &after);
 185
 186                 return r;
 187         }
 188
 189         void set_spacing (int s) {
 190                 _internal_vbox.set_spacing (s);
 191         }
 192
 193         void remove_placeholder ()
 194         {
 195                 if (_placeholder) {
 196                         _internal_vbox.remove (*_placeholder);
 197                         _placeholder = 0;
 198                 }
 199         }
 200
 201         /** Add a placeholder where a child would be put if it were added at the given y position.
 202          *  @param y y position within the DnDVBox.
 203          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 204          */
 205         int add_placeholder (double y)
 206         {
 207                 return create_or_update_placeholder (get_child_at_position (y).second);
 208         }
 209
 210         /** Children have been reordered by a drag */
 211         sigc::signal<void> Reordered;
 212
 213         /** A button has been pressed over the widget */
 214         sigc::signal<bool, GdkEventButton*, T*> ButtonPress;
 215
 216         /** A button has been release over the widget */
 217         sigc::signal<bool, GdkEventButton*, T*> ButtonRelease;
 218
 219         /** A child has been dropped onto this DnDVBox from another one;
 220          *  Parameters are the source DnDVBox, our child which the other one was dropped on (or 0) and the DragContext.
 221          */
 222         sigc::signal<void, DnDVBox*, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromAnotherBox;
 223         sigc::signal<void> SelectionChanged;
 224
 225 private:
 226
 227         /** @return the bottom y position of a child, pretending any placeholder
 228          *  is not there.
 229          */
 230         double bottom_of_child_ignoring_placeholder (T* child) const
 231         {
 232                 Gtk::Allocation const a = child->widget().get_allocation ();
 233                 double bottom = a.get_y() + a.get_height();
 234
 235                 if (_placeholder) {
 236                         Gtk::Allocation const b = _placeholder->get_allocation ();
 237                         if (b.get_y() < a.get_y()) {
 238                                 bottom -= (b.get_height () + _internal_vbox.get_spacing ());
 239                         }
 240                 }
 241
 242                 return bottom;
 243         }
 244
 245         /** Look at a y coordinate and find the children below y, and the ones either side.
 246          *  @param y y position.
 247          *  @param before Filled in with the child before, or 0.
 248          *  @param at Filled in with the child under y, or 0.
 249          *  @param after Filled in with the child after, or 0.
 250          *  @return Fractional position in terms of child height, or -1 if not over a child.
 251          */
 252         double get_children_around_position (int y, T** before, T** at, T** after) const
 253         {
 254                 if (_children.empty()) {
 255                         *before = *at = *after = 0;
 256                         return -1;
 257                 }
 258
 259                 *before = 0;
 260
 261                 typename std::list<T*>::const_iterator j = _children.begin ();
 262
 263                 /* index of current child */
 264                 int i = 0;
 265                 /* top of current child */
 266                 double top = 0;
 267                 /* bottom of current child */
 268                 double bottom = bottom_of_child_ignoring_placeholder (*j);
 269
 270                 while (y >= bottom && j != _children.end()) {
 271
 272                         top = bottom;
 273
 274                         *before = *j;
 275                         ++i;
 276                         ++j;
 277
 278                         if (j != _children.end()) {
 279                                 bottom = bottom_of_child_ignoring_placeholder (*j);
 280                         }
 281                 }
 282
 283                 if (j == _children.end()) {
 284                         *at = 0;
 285                         *after = 0;
 286                         return -1;
 287                 }
 288
 289                 *at = *j;
 290
 291                 ++j;
 292                 *after = j != _children.end() ? *j : 0;
 293
 294                 return i + ((y - top) / (bottom - top));
 295         }
 296
 297         void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)
 298         {
 299                 _drag_child = child;
 300
 301                 /* make up an icon for the drag */
 302                 _drag_icon = new Gtk::Window (Gtk::WINDOW_POPUP);
 303
 304                 Gtk::Allocation a = child->action_widget().get_allocation ();
 305                 _drag_icon->set_size_request (a.get_width(), a.get_height());
 306
 307                 _drag_icon->signal_expose_event().connect (sigc::mem_fun (*this, &DnDVBox::icon_expose));
 308                 _drag_icon->set_name (get_name ());
 309
 310                 /* make the icon transparent if possible */
 311                 Glib::RefPtr<Gdk::Screen const> s = _drag_icon->get_screen ();
 312                 Glib::RefPtr<Gdk::Colormap const> c = s->get_rgba_colormap ();
 313                 if (c) {
 314                         _drag_icon->set_colormap (c);
 315                 }
 316
 317                 int w, h;
 318                 _drag_icon->get_size (w, h);
 319                 _drag_icon->drag_set_as_icon (context, w / 2, h / 2);
 320
 321                 _drag_source = this;
 322         }
 323
 324         /* Draw the drag icon */
 325         bool icon_expose (GdkEventExpose*)
 326         {
 327                 /* Just grab the child's widget and use that */
 328
 329                 int w, h;
 330                 _drag_icon->get_size (w, h);
 331
 332                 cairo_t* cr = gdk_cairo_create (_drag_icon->get_window()->gobj ());
 333
 334                 Glib::RefPtr<Gdk::Pixmap> p = _drag_child->action_widget().get_snapshot();
 335                 gdk_cairo_set_source_pixmap (cr, p->gobj(), 0, 0);
 336                 cairo_rectangle (cr, 0, 0, w, h);
 337                 cairo_fill (cr);
 338                 cairo_destroy (cr);
 339
 340                 return false;
 341         }
 342
 343         void drag_data_get (Glib::RefPtr<Gdk::DragContext> const &, Gtk::SelectionData & selection_data, guint, guint, T* child)
 344         {
 345                 selection_data.set (selection_data.get_target(), 8, (const guchar *) &child, sizeof (&child));
 346         }
 347
 348         void drag_data_received (
 349                 Glib::RefPtr<Gdk::DragContext> const & context, int /*x*/, int y, Gtk::SelectionData const & selection_data, guint /*info*/, guint time
 350                 )
 351         {
 352                 /* work out where it was dropped */
 353                 std::pair<T*, double> const drop = get_child_at_position (y);
 354
 355                 if (_drag_source == this) {
 356
 357                         /* dropped from ourselves onto ourselves */
 358
 359                         T* child = *((T * const *) selection_data.get_data());
 360
 361                         if (drop.first == 0) {
 362                                 _internal_vbox.reorder_child (child->widget(), -1);
 363                         } else {
 364
 365                                 /* where in the list this child should be dropped */
 366                                 int target = drop.second + 0.5;
 367
 368                                 /* find out whether the child was `picked up' from before the drop position */
 369                                 int n = 0;
 370                                 typename std::list<T*>::const_iterator i = _children.begin ();
 371                                 while (i != _children.end() && *i != child && n < target) {
 372                                         ++i;
 373                                         ++n;
 374                                 }
 375
 376                                 /* if so, adjust the drop position to account for this */
 377                                 if (n < target) {
 378                                         --target;
 379                                 }
 380
 381                                 _internal_vbox.reorder_child (child->widget(), target);
 382                         }
 383
 384                 } else {
 385
 386                         /* drag started in another DnDVBox; raise a signal to say what happened */
 387
 388                         std::list<T*> dropped = _drag_source->selection ();
 389                         DropFromAnotherBox (_drag_source, drop.first, context);
 390                 }
 391
 392                 context->drag_finish (false, false, time);
 393         }
 394
 395         void drag_end (Glib::RefPtr<Gdk::DragContext> const &, T *)
 396         {
 397                 delete _drag_icon;
 398                 _drag_icon = 0;
 399
 400                 _drag_child = 0;
 401                 remove_placeholder ();
 402
 403                 Reordered (); /* EMIT SIGNAL */
 404         }
 405
 406         /** Insert a placeholder at a given fractional child position, creating it if necessary.
 407          *  @param c Fractional child position.
 408          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 409          */
 410         int create_or_update_placeholder (double c)
 411         {
 412                 if (_placeholder == 0) {
 413                         _placeholder = manage (new Gtk::Label (""));
 414                         _internal_vbox.pack_start (*_placeholder, false, false);
 415                         _placeholder->show ();
 416                 }
 417
 418                 /* round up the index, unless we're off the end of the children */
 419                 int const n = c < 0 ? -1 : int (c + 0.5);
 420                 _internal_vbox.reorder_child (*_placeholder, n);
 421                 return n;
 422         }
 423
 424         bool drag_motion (Glib::RefPtr<Gdk::DragContext> const &, int /*x*/, int y, guint)
 425         {
 426                 if (_children.empty ()) {
 427                         return false;
 428                 }
 429
 430                 T* before;
 431                 T* at;
 432                 T* after;
 433
 434                 /* decide where we currently are */
 435                 double const c = get_children_around_position (y, &before, &at, &after);
 436
 437                 /* whether we're in the top or bottom half of the child that we're over */
 438                 bool top_half = (c - int (c)) < 0.5;
 439
 440                 /* Note that when checking on whether to remove a placeholder, we never do
 441                    so if _drag_child is 0 as this means that the child being dragged is
 442                    coming from a different DnDVBox, so it will never be the same as any
 443                    of our children.
 444                 */
 445
 446                 if (top_half && _drag_child && (before == _drag_child || at == _drag_child)) {
 447                         /* dropping here would have no effect, so remove the visual cue */
 448                         remove_placeholder ();
 449                         return false;
 450                 }
 451
 452                 if (!top_half && _drag_child && (at == _drag_child || after == _drag_child)) {
 453                         /* dropping here would have no effect, so remove the visual cue */
 454                         remove_placeholder ();
 455                         return false;
 456                 }
 457
 458                 create_or_update_placeholder (c);
 459                 return false;
 460         }
 461
 462         void drag_leave (Glib::RefPtr<Gdk::DragContext> const &, guint)
 463         {
 464                 remove_placeholder ();
 465         }
 466
 467         bool button_press (GdkEventButton* ev, T* child)
 468         {
 469                 if (_expecting_unwanted_button_event == true && child == 0) {
 470                         _expecting_unwanted_button_event = false;
 471                         return true;
 472                 }
 473
 474                 if (child) {
 475                         _expecting_unwanted_button_event = true;
 476                 }
 477
 478                 if (ev->button == 1 || ev->button == 3) {
 479
 480                         if (!selected (child)) {
 481
 482                                 if ((ev->state & Gdk::SHIFT_MASK) && !_selection.empty()) {
 483
 484                                         /* Shift-click; select all between the clicked child and any existing selections */
 485
 486                                         bool selecting = false;
 487                                         bool done = false;
 488                                         for (typename std::list<T*>::const_iterator i = _children.begin(); i != _children.end(); ++i) {
 489
 490                                                 bool const was_selected = selected (*i);
 491
 492                                                 if (selecting && !was_selected) {
 493                                                         add_to_selection (*i);
 494                                                 }
 495
 496                                                 if (!selecting && !done) {
 497                                                         if (selected (*i)) {
 498                                                                 selecting = true;
 499                                                         } else if (*i == child) {
 500                                                                 selecting = true;
 501                                                                 add_to_selection (child);
 502                                                         }
 503                                                 } else if (selecting) {
 504                                                         if (was_selected || *i == child) {
 505                                                                 selecting = false;
 506                                                                 done = true;
 507                                                         }
 508                                                 }
 509                                         }
 510
 511                                 } else {
 512
 513                                         if ((ev->state & Gdk::CONTROL_MASK) == 0) {
 514                                                 clear_selection ();
 515                                         }
 516
 517                                         if (child) {
 518                                                 add_to_selection (child);
 519                                         }
 520
 521                                 }
 522
 523                                 SelectionChanged (); /* EMIT SIGNAL */
 524
 525                         } else {
 526                                 /* XXX THIS NEEDS GENERALIZING FOR OS X */
 527                                 if (ev->button == 1 && (ev->state & Gdk::CONTROL_MASK)) {
 528                                         if (child && selected (child)) {
 529                                                 remove_from_selection (child);
 530                                                 SelectionChanged (); /* EMIT SIGNAL */
 531                                         }
 532                                 }
 533                         }
 534                 }
 535
 536                 return ButtonPress (ev, child); /* EMIT SIGNAL */
 537         }
 538
 539         bool button_release (GdkEventButton* ev, T* child)
 540         {
 541                 if (_expecting_unwanted_button_event == true && child == 0) {
 542                         _expecting_unwanted_button_event = false;
 543                         return true;
 544                 }
 545
 546                 if (child) {
 547                         _expecting_unwanted_button_event = true;
 548                 }
 549
 550                 return ButtonRelease (ev, child); /* EMIT SIGNAL */
 551         }
 552
 553         /** Setup a child's visual state correctly */
 554         void setup_child_state (T* c)
 555         {
 556                 assert (c);
 557                 c->set_visual_state (Selected, (selected (c) || (_active == c)));
 558         }
 559
 560         void clear_selection ()
 561         {
 562                 std::list<T*> old_selection = _selection;
 563                 _selection.clear ();
 564                 for (typename std::list<T*>::iterator i = old_selection.begin(); i != old_selection.end(); ++i) {
 565                         setup_child_state (*i);
 566                 }
 567         }
 568
 569         void add_to_selection (T* child)
 570         {
 571                 if ( !child->is_selectable() )
 572                         return;
 573                 _selection.push_back (child);
 574                 setup_child_state (child);
 575         }
 576
 577         void remove_from_selection (T* child)
 578         {
 579                 typename std::list<T*>::iterator x = find (_selection.begin(), _selection.end(), child);
 580                 if (x != _selection.end()) {
 581                         T* c = *x;
 582                         _selection.erase (x);
 583                         setup_child_state (c);
 584                 }
 585         }
 586
 587         T* child_from_widget (Gtk::Widget const * w) const
 588         {
 589                 typename std::list<T*>::const_iterator i = _children.begin();
 590                 while (i != _children.end() && &(*i)->widget() != w) {
 591                         ++i;
 592                 }
 593
 594                 if (i == _children.end()) {
 595                         return 0;
 596                 }
 597
 598                 return *i;
 599         }
 600
 601         Gtk::VBox _internal_vbox;
 602         std::list<Gtk::TargetEntry> _targets;
 603         std::list<T*> _children;
 604         std::list<T*> _selection;
 605         T* _active;
 606         Gtk::Window* _drag_icon;
 607         bool _expecting_unwanted_button_event;
 608         /** A blank label used as a placeholder to indicate where an item would
 609          *  go if it were dropped or inserted "now".
 610          */
 611         Gtk::Label* _placeholder;
 612         /** Our child being dragged, or 0 */
 613         T* _drag_child;
 614
 615         static DnDVBox* _drag_source;
 616
 617 };
 618
 619 template <class T>
 620 DnDVBox<T>* DnDVBox<T>::_drag_source = 0;
 621
 622 }