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         virtual bool drag_data_get (Glib::RefPtr<Gdk::DragContext> const, Gtk::SelectionData &) { return false; }
  49 };
  50
  51 /** A VBox whose contents can be dragged and dropped */
  52 template <class T>
  53 class /*LIBGTKMM2EXT_API*/ DnDVBox : public Gtk::EventBox
  54 {
  55 public:
  56         DnDVBox (std::list<Gtk::TargetEntry> targets)
  57                 : _targets (targets)
  58                 , _active (0)
  59                 , _drag_icon (0)
  60                 , _expecting_unwanted_button_event (false)
  61                 , _placeholder (0)
  62         {
  63
  64                 add (_internal_vbox);
  65                 add_events (
  66                         Gdk::KEY_PRESS_MASK | Gdk::KEY_RELEASE_MASK |
  67                         Gdk::ENTER_NOTIFY_MASK | Gdk::LEAVE_NOTIFY_MASK |
  68                         Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK
  69                         );
  70
  71                 signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), (T *) 0));
  72                 signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), (T *) 0));
  73                 signal_drag_motion().connect (mem_fun (*this, &DnDVBox::drag_motion));
  74                 signal_drag_leave().connect (mem_fun (*this, &DnDVBox::drag_leave));
  75
  76                 _internal_vbox.show ();
  77
  78                 drag_dest_set (_targets);
  79                 signal_drag_data_received().connect (mem_fun (*this, &DnDVBox::drag_data_received));
  80         }
  81
  82         virtual ~DnDVBox ()
  83         {
  84                 clear ();
  85
  86                 delete _drag_icon;
  87         }
  88
  89         /** Add a child at the end of the widget.  The DnDVBox will take responsibility for deleting the child */
  90         void add_child (T* child)
  91         {
  92                 child->action_widget().drag_source_set (_targets);
  93                 child->action_widget().signal_drag_begin().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_begin), child));
  94                 child->action_widget().signal_drag_data_get().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_data_get), child));
  95                 child->action_widget().signal_drag_end().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_end), child));
  96                 child->action_widget().signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), child));
  97                 child->action_widget().signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), child));
  98
  99                 _internal_vbox.pack_start (child->widget(), false, false);
 100
 101                 _children.push_back (child);
 102                 child->widget().show ();
 103         }
 104
 105         /** @return Children, sorted into the order that they are currently being displayed in the widget */
 106         std::list<T*> children ()
 107         {
 108                 std::list<T*> sorted_children;
 109
 110                 std::list<Gtk::Widget*> widget_children = _internal_vbox.get_children ();
 111                 for (std::list<Gtk::Widget*>::iterator i = widget_children.begin(); i != widget_children.end(); ++i) {
 112                         T* c = child_from_widget (*i);
 113
 114                         if (c) {
 115                                 sorted_children.push_back (c);
 116                         }
 117                 }
 118
 119                 return sorted_children;
 120         }
 121
 122         /** @return Selected children */
 123         std::list<T*> selection () const {
 124                 return _selection;
 125         }
 126
 127         /** Set the `active' child; this is simply a child which is set to have the
 128          *  visual state "active" for whatever purposes the client may have.
 129          *  @param c Child, or 0 for none.
 130          */
 131         void set_active (T* c) {
 132                 T* old_active = _active;
 133                 _active = c;
 134                 if (old_active) {
 135                         setup_child_state (old_active);
 136                 }
 137                 if (_active) {
 138                         setup_child_state (_active);
 139                 }
 140         }
 141
 142         /** @param child Child
 143          *  @return true if the child is selected, otherwise false.
 144          */
 145         bool selected (T* child) const {
 146                 return (find (_selection.begin(), _selection.end(), child) != _selection.end());
 147         }
 148
 149         /** Clear all children from the widget */
 150         void clear ()
 151         {
 152                 _selection.clear ();
 153
 154                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 155                         _internal_vbox.remove ((*i)->widget());
 156                         delete *i;
 157                 }
 158
 159                 _children.clear ();
 160                 _active = 0;
 161         }
 162
 163         void select_all ()
 164         {
 165                 clear_selection ();
 166                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 167                         add_to_selection (*i);
 168                 }
 169
 170                 SelectionChanged (); /* EMIT SIGNAL */
 171         }
 172
 173         void select_none ()
 174         {
 175                 clear_selection ();
 176
 177                 SelectionChanged (); /* EMIT SIGNAL */
 178         }
 179
 180         /** @param y y coordinate.
 181          *  @return Pair consisting of the child under y (or 0) and the (fractional) index of the child under y (or -1)
 182          */
 183         std::pair<T*, double> get_child_at_position (int y) const
 184         {
 185                 T* before;
 186                 T* after;
 187
 188                 std::pair<T*, double> r;
 189
 190                 r.second = get_children_around_position (y, &before, &r.first, &after);
 191
 192                 return r;
 193         }
 194
 195         void set_spacing (int s) {
 196                 _internal_vbox.set_spacing (s);
 197         }
 198
 199         void remove_placeholder ()
 200         {
 201                 if (_placeholder) {
 202                         _internal_vbox.remove (*_placeholder);
 203                         _placeholder = 0;
 204                 }
 205         }
 206
 207         /** Add a placeholder where a child would be put if it were added at the given y position.
 208          *  @param y y position within the DnDVBox.
 209          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 210          */
 211         int add_placeholder (double y)
 212         {
 213                 return create_or_update_placeholder (get_child_at_position (y).second);
 214         }
 215
 216         /** Children have been reordered by a drag */
 217         sigc::signal<void> Reordered;
 218
 219         /** A button has been pressed over the widget */
 220         sigc::signal<bool, GdkEventButton*, T*> ButtonPress;
 221
 222         /** A button has been release over the widget */
 223         sigc::signal<bool, GdkEventButton*, T*> ButtonRelease;
 224
 225         /** A child has been dropped onto this DnDVBox from another one;
 226          *  Parameters are the source DnDVBox, our child which the other one was dropped on (or 0) and the DragContext.
 227          */
 228         sigc::signal<void, DnDVBox*, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromAnotherBox;
 229         sigc::signal<void, Gtk::SelectionData const &, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromExternal;
 230         sigc::signal<void> SelectionChanged;
 231
 232 private:
 233
 234         /** @return the bottom y position of a child, pretending any placeholder
 235          *  is not there.
 236          */
 237         double bottom_of_child_ignoring_placeholder (T* child) const
 238         {
 239                 Gtk::Allocation const a = child->widget().get_allocation ();
 240                 double bottom = a.get_y() + a.get_height();
 241
 242                 if (_placeholder) {
 243                         Gtk::Allocation const b = _placeholder->get_allocation ();
 244                         if (b.get_y() < a.get_y()) {
 245                                 bottom -= (b.get_height () + _internal_vbox.get_spacing ());
 246                         }
 247                 }
 248
 249                 return bottom;
 250         }
 251
 252         /** Look at a y coordinate and find the children below y, and the ones either side.
 253          *  @param y y position.
 254          *  @param before Filled in with the child before, or 0.
 255          *  @param at Filled in with the child under y, or 0.
 256          *  @param after Filled in with the child after, or 0.
 257          *  @return Fractional position in terms of child height, or -1 if not over a child.
 258          */
 259         double get_children_around_position (int y, T** before, T** at, T** after) const
 260         {
 261                 if (_children.empty()) {
 262                         *before = *at = *after = 0;
 263                         return -1;
 264                 }
 265
 266                 *before = 0;
 267
 268                 typename std::list<T*>::const_iterator j = _children.begin ();
 269
 270                 /* index of current child */
 271                 int i = 0;
 272                 /* top of current child */
 273                 double top = 0;
 274                 /* bottom of current child */
 275                 double bottom = bottom_of_child_ignoring_placeholder (*j);
 276
 277                 while (y >= bottom && j != _children.end()) {
 278
 279                         top = bottom;
 280
 281                         *before = *j;
 282                         ++i;
 283                         ++j;
 284
 285                         if (j != _children.end()) {
 286                                 bottom = bottom_of_child_ignoring_placeholder (*j);
 287                         }
 288                 }
 289
 290                 if (j == _children.end()) {
 291                         *at = 0;
 292                         *after = 0;
 293                         return -1;
 294                 }
 295
 296                 *at = *j;
 297
 298                 ++j;
 299                 *after = j != _children.end() ? *j : 0;
 300
 301                 return i + ((y - top) / (bottom - top));
 302         }
 303
 304         void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)
 305         {
 306                 _drag_child = child;
 307
 308                 /* make up an icon for the drag */
 309                 _drag_icon = new Gtk::Window (Gtk::WINDOW_POPUP);
 310
 311                 Gtk::Allocation a = child->action_widget().get_allocation ();
 312                 _drag_icon->set_size_request (a.get_width(), a.get_height());
 313
 314                 _drag_icon->signal_expose_event().connect (sigc::mem_fun (*this, &DnDVBox::icon_expose));
 315                 _drag_icon->set_name (get_name ());
 316
 317                 /* make the icon transparent if possible */
 318                 Glib::RefPtr<Gdk::Screen const> s = _drag_icon->get_screen ();
 319                 Glib::RefPtr<Gdk::Colormap const> c = s->get_rgba_colormap ();
 320                 if (c) {
 321                         _drag_icon->set_colormap (c);
 322                 }
 323
 324                 int w, h;
 325                 _drag_icon->get_size (w, h);
 326                 _drag_icon->drag_set_as_icon (context, w / 2, h / 2);
 327
 328                 _drag_source = this;
 329         }
 330
 331         /* Draw the drag icon */
 332         bool icon_expose (GdkEventExpose*)
 333         {
 334                 /* Just grab the child's widget and use that */
 335
 336                 int w, h;
 337                 _drag_icon->get_size (w, h);
 338
 339                 cairo_t* cr = gdk_cairo_create (_drag_icon->get_window()->gobj ());
 340
 341                 Glib::RefPtr<Gdk::Pixmap> p = _drag_child->action_widget().get_snapshot();
 342                 gdk_cairo_set_source_pixmap (cr, p->gobj(), 0, 0);
 343                 cairo_rectangle (cr, 0, 0, w, h);
 344                 cairo_fill (cr);
 345                 cairo_destroy (cr);
 346
 347                 return false;
 348         }
 349
 350         void drag_data_get (Glib::RefPtr<Gdk::DragContext> const &context, Gtk::SelectionData & selection_data, guint, guint, T* child)
 351         {
 352                 if (!child->drag_data_get(context, selection_data)) {
 353                         selection_data.set (selection_data.get_target(), 8, (const guchar *) &child, sizeof (&child));
 354                 }
 355         }
 356
 357         void drag_data_received (
 358                 Glib::RefPtr<Gdk::DragContext> const & context, int /*x*/, int y, Gtk::SelectionData const & selection_data, guint /*info*/, guint time
 359                 )
 360         {
 361                 /* work out where it was dropped */
 362                 std::pair<T*, double> const drop = get_child_at_position (y);
 363
 364                 if (selection_data.get_target () != _targets.front ().get_target ()) {
 365                         DropFromExternal (selection_data, drop.first, context);
 366                         context->drag_finish (false, false, time);
 367                         return;
 368                 }
 369
 370                 if (_drag_source == this) {
 371
 372                         /* dropped from ourselves onto ourselves */
 373
 374                         T* child = *((T * const *) selection_data.get_data());
 375
 376                         if (drop.first == 0) {
 377                                 _internal_vbox.reorder_child (child->widget(), -1);
 378                         } else {
 379
 380                                 /* where in the list this child should be dropped */
 381                                 int target = drop.second + 0.5;
 382
 383                                 /* find out whether the child was `picked up' from before the drop position */
 384                                 int n = 0;
 385                                 typename std::list<T*>::const_iterator i = _children.begin ();
 386                                 while (i != _children.end() && *i != child && n < target) {
 387                                         ++i;
 388                                         ++n;
 389                                 }
 390
 391                                 /* if so, adjust the drop position to account for this */
 392                                 if (n < target) {
 393                                         --target;
 394                                 }
 395
 396                                 _internal_vbox.reorder_child (child->widget(), target);
 397                         }
 398
 399                 } else {
 400
 401                         /* drag started in another DnDVBox; raise a signal to say what happened */
 402
 403                         std::list<T*> dropped = _drag_source->selection ();
 404                         DropFromAnotherBox (_drag_source, drop.first, context);
 405                 }
 406
 407                 context->drag_finish (false, false, time);
 408         }
 409
 410         void drag_end (Glib::RefPtr<Gdk::DragContext> const &, T *)
 411         {
 412                 delete _drag_icon;
 413                 _drag_icon = 0;
 414
 415                 _drag_child = 0;
 416                 remove_placeholder ();
 417
 418                 Reordered (); /* EMIT SIGNAL */
 419         }
 420
 421         /** Insert a placeholder at a given fractional child position, creating it if necessary.
 422          *  @param c Fractional child position.
 423          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 424          */
 425         int create_or_update_placeholder (double c)
 426         {
 427                 if (_placeholder == 0) {
 428                         _placeholder = manage (new Gtk::Label (""));
 429                         _internal_vbox.pack_start (*_placeholder, false, false);
 430                         _placeholder->show ();
 431                 }
 432
 433                 /* round up the index, unless we're off the end of the children */
 434                 int const n = c < 0 ? -1 : int (c + 0.5);
 435                 _internal_vbox.reorder_child (*_placeholder, n);
 436                 return n;
 437         }
 438
 439         bool drag_motion (Glib::RefPtr<Gdk::DragContext> const &, int /*x*/, int y, guint)
 440         {
 441                 if (_children.empty ()) {
 442                         return false;
 443                 }
 444
 445                 T* before;
 446                 T* at;
 447                 T* after;
 448
 449                 /* decide where we currently are */
 450                 double const c = get_children_around_position (y, &before, &at, &after);
 451
 452                 /* whether we're in the top or bottom half of the child that we're over */
 453                 bool top_half = (c - int (c)) < 0.5;
 454
 455                 /* Note that when checking on whether to remove a placeholder, we never do
 456                    so if _drag_child is 0 as this means that the child being dragged is
 457                    coming from a different DnDVBox, so it will never be the same as any
 458                    of our children.
 459                 */
 460
 461                 if (top_half && _drag_child && (before == _drag_child || at == _drag_child)) {
 462                         /* dropping here would have no effect, so remove the visual cue */
 463                         remove_placeholder ();
 464                         return false;
 465                 }
 466
 467                 if (!top_half && _drag_child && (at == _drag_child || after == _drag_child)) {
 468                         /* dropping here would have no effect, so remove the visual cue */
 469                         remove_placeholder ();
 470                         return false;
 471                 }
 472
 473                 create_or_update_placeholder (c);
 474                 return false;
 475         }
 476
 477         void drag_leave (Glib::RefPtr<Gdk::DragContext> const &, guint)
 478         {
 479                 remove_placeholder ();
 480         }
 481
 482         bool button_press (GdkEventButton* ev, T* child)
 483         {
 484                 if (_expecting_unwanted_button_event == true && child == 0) {
 485                         _expecting_unwanted_button_event = false;
 486                         return true;
 487                 }
 488
 489                 if (child) {
 490                         _expecting_unwanted_button_event = true;
 491                 }
 492
 493                 if (ev->button == 1 || ev->button == 3) {
 494
 495                         if (!selected (child)) {
 496
 497                                 if ((ev->state & Gdk::SHIFT_MASK) && !_selection.empty()) {
 498
 499                                         /* Shift-click; select all between the clicked child and any existing selections */
 500
 501                                         bool selecting = false;
 502                                         bool done = false;
 503                                         for (typename std::list<T*>::const_iterator i = _children.begin(); i != _children.end(); ++i) {
 504
 505                                                 bool const was_selected = selected (*i);
 506
 507                                                 if (selecting && !was_selected) {
 508                                                         add_to_selection (*i);
 509                                                 }
 510
 511                                                 if (!selecting && !done) {
 512                                                         if (selected (*i)) {
 513                                                                 selecting = true;
 514                                                         } else if (*i == child) {
 515                                                                 selecting = true;
 516                                                                 add_to_selection (child);
 517                                                         }
 518                                                 } else if (selecting) {
 519                                                         if (was_selected || *i == child) {
 520                                                                 selecting = false;
 521                                                                 done = true;
 522                                                         }
 523                                                 }
 524                                         }
 525
 526                                 } else {
 527
 528                                         if ((ev->state & Gdk::CONTROL_MASK) == 0) {
 529                                                 clear_selection ();
 530                                         }
 531
 532                                         if (child) {
 533                                                 add_to_selection (child);
 534                                         }
 535
 536                                 }
 537
 538                                 SelectionChanged (); /* EMIT SIGNAL */
 539
 540                         } else {
 541                                 /* XXX THIS NEEDS GENERALIZING FOR OS X */
 542                                 if (ev->button == 1 && (ev->state & Gdk::CONTROL_MASK)) {
 543                                         if (child && selected (child)) {
 544                                                 remove_from_selection (child);
 545                                                 SelectionChanged (); /* EMIT SIGNAL */
 546                                         }
 547                                 }
 548                         }
 549                 }
 550
 551                 return ButtonPress (ev, child); /* EMIT SIGNAL */
 552         }
 553
 554         bool button_release (GdkEventButton* ev, T* child)
 555         {
 556                 if (_expecting_unwanted_button_event == true && child == 0) {
 557                         _expecting_unwanted_button_event = false;
 558                         return true;
 559                 }
 560
 561                 if (child) {
 562                         _expecting_unwanted_button_event = true;
 563                 }
 564
 565                 return ButtonRelease (ev, child); /* EMIT SIGNAL */
 566         }
 567
 568         /** Setup a child's visual state correctly */
 569         void setup_child_state (T* c)
 570         {
 571                 assert (c);
 572                 c->set_visual_state (Selected, (selected (c) || (_active == c)));
 573         }
 574
 575         void clear_selection ()
 576         {
 577                 std::list<T*> old_selection = _selection;
 578                 _selection.clear ();
 579                 for (typename std::list<T*>::iterator i = old_selection.begin(); i != old_selection.end(); ++i) {
 580                         setup_child_state (*i);
 581                 }
 582         }
 583
 584         void add_to_selection (T* child)
 585         {
 586                 if ( !child->is_selectable() )
 587                         return;
 588                 _selection.push_back (child);
 589                 setup_child_state (child);
 590         }
 591
 592         void remove_from_selection (T* child)
 593         {
 594                 typename std::list<T*>::iterator x = find (_selection.begin(), _selection.end(), child);
 595                 if (x != _selection.end()) {
 596                         T* c = *x;
 597                         _selection.erase (x);
 598                         setup_child_state (c);
 599                 }
 600         }
 601
 602         T* child_from_widget (Gtk::Widget const * w) const
 603         {
 604                 typename std::list<T*>::const_iterator i = _children.begin();
 605                 while (i != _children.end() && &(*i)->widget() != w) {
 606                         ++i;
 607                 }
 608
 609                 if (i == _children.end()) {
 610                         return 0;
 611                 }
 612
 613                 return *i;
 614         }
 615
 616         Gtk::VBox _internal_vbox;
 617         std::list<Gtk::TargetEntry> _targets;
 618         std::list<T*> _children;
 619         std::list<T*> _selection;
 620         T* _active;
 621         Gtk::Window* _drag_icon;
 622         bool _expecting_unwanted_button_event;
 623         /** A blank label used as a placeholder to indicate where an item would
 624          *  go if it were dropped or inserted "now".
 625          */
 626         Gtk::Label* _placeholder;
 627         /** Our child being dragged, or 0 */
 628         T* _drag_child;
 629
 630         static DnDVBox* _drag_source;
 631
 632 };
 633
 634 template <class T>
 635 DnDVBox<T>* DnDVBox<T>::_drag_source = 0;
 636
 637 }