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         virtual bool can_copy_state (DnDVBoxChild*) const = 0;
  51 };
  52
  53 /** A VBox whose contents can be dragged and dropped */
  54 template <class T>
  55 class /*LIBGTKMM2EXT_API*/ DnDVBox : public Gtk::EventBox
  56 {
  57 public:
  58         DnDVBox (std::list<Gtk::TargetEntry> targets)
  59                 : _targets (targets)
  60                 , _active (0)
  61                 , _drag_icon (0)
  62                 , _expecting_unwanted_button_event (false)
  63                 , _placeholder (0)
  64                 , _drag_child (0)
  65         {
  66
  67                 add (_internal_vbox);
  68                 add_events (
  69                         Gdk::KEY_PRESS_MASK | Gdk::KEY_RELEASE_MASK |
  70                         Gdk::ENTER_NOTIFY_MASK | Gdk::LEAVE_NOTIFY_MASK |
  71                         Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK
  72                         );
  73
  74                 signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), (T *) 0));
  75                 signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), (T *) 0));
  76                 signal_drag_motion().connect (mem_fun (*this, &DnDVBox::drag_motion));
  77                 signal_drag_leave().connect (mem_fun (*this, &DnDVBox::drag_leave));
  78
  79                 _internal_vbox.show ();
  80
  81                 drag_dest_set (_targets);
  82                 signal_drag_data_received().connect (mem_fun (*this, &DnDVBox::drag_data_received));
  83         }
  84
  85         virtual ~DnDVBox ()
  86         {
  87                 clear ();
  88
  89                 delete _drag_icon;
  90         }
  91
  92         /** Add a child at the end of the widget.  The DnDVBox will take responsibility for deleting the child */
  93         void add_child (T* child, std::list<Gtk::TargetEntry> targets = std::list<Gtk::TargetEntry>())
  94         {
  95                 if (targets.empty ()) {
  96                         child->action_widget().drag_source_set (_targets);
  97                 } else {
  98                         child->action_widget().drag_source_set (targets);
  99                 }
 100                 child->action_widget().signal_drag_begin().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_begin), child));
 101                 child->action_widget().signal_drag_data_get().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_data_get), child));
 102                 child->action_widget().signal_drag_end().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_end), child));
 103                 child->action_widget().signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), child));
 104                 child->action_widget().signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), child));
 105
 106                 _internal_vbox.pack_start (child->widget(), false, false);
 107
 108                 _children.push_back (child);
 109                 child->widget().show ();
 110         }
 111
 112         /** @return Children, sorted into the order that they are currently being displayed in the widget */
 113         std::list<T*> children ()
 114         {
 115                 std::list<T*> sorted_children;
 116
 117                 std::list<Gtk::Widget*> widget_children = _internal_vbox.get_children ();
 118                 for (std::list<Gtk::Widget*>::iterator i = widget_children.begin(); i != widget_children.end(); ++i) {
 119                         T* c = child_from_widget (*i);
 120
 121                         if (c) {
 122                                 sorted_children.push_back (c);
 123                         }
 124                 }
 125
 126                 return sorted_children;
 127         }
 128
 129         /** @return Selected children */
 130         std::list<T*> selection () const {
 131                 return _selection;
 132         }
 133
 134         /** Set the `active' child; this is simply a child which is set to have the
 135          *  visual state "active" for whatever purposes the client may have.
 136          *  @param c Child, or 0 for none.
 137          */
 138         void set_active (T* c) {
 139                 T* old_active = _active;
 140                 _active = c;
 141                 if (old_active) {
 142                         setup_child_state (old_active);
 143                 }
 144                 if (_active) {
 145                         setup_child_state (_active);
 146                 }
 147         }
 148
 149         /** @param child Child
 150          *  @return true if the child is selected, otherwise false.
 151          */
 152         bool selected (T* child) const {
 153                 return (find (_selection.begin(), _selection.end(), child) != _selection.end());
 154         }
 155
 156         /** Clear all children from the widget */
 157         void clear ()
 158         {
 159                 _selection.clear ();
 160
 161                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 162                         _internal_vbox.remove ((*i)->widget());
 163                         delete *i;
 164                 }
 165
 166                 _children.clear ();
 167                 _active = 0;
 168         }
 169
 170         void select_all ()
 171         {
 172                 clear_selection ();
 173                 for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
 174                         add_to_selection (*i);
 175                 }
 176
 177                 SelectionChanged (); /* EMIT SIGNAL */
 178         }
 179
 180         void select_none ()
 181         {
 182                 clear_selection ();
 183
 184                 SelectionChanged (); /* EMIT SIGNAL */
 185         }
 186
 187         /** @param y y coordinate.
 188          *  @return Pair consisting of the child under y (or 0) and the (fractional) index of the child under y (or -1)
 189          */
 190         std::pair<T*, double> get_child_at_position (int y) const
 191         {
 192                 T* before;
 193                 T* after;
 194
 195                 std::pair<T*, double> r;
 196
 197                 r.second = get_children_around_position (y, &before, &r.first, &after);
 198
 199                 return r;
 200         }
 201
 202         void set_spacing (int s) {
 203                 _internal_vbox.set_spacing (s);
 204         }
 205
 206         void remove_placeholder ()
 207         {
 208                 if (_placeholder) {
 209                         _internal_vbox.remove (*_placeholder);
 210                         _placeholder = 0;
 211                 }
 212         }
 213
 214         /** Add a placeholder where a child would be put if it were added at the given y position.
 215          *  @param y y position within the DnDVBox.
 216          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 217          */
 218         int add_placeholder (double y)
 219         {
 220                 return create_or_update_placeholder (get_child_at_position (y).second);
 221         }
 222
 223         /** Children have been reordered by a drag */
 224         sigc::signal<void> Reordered;
 225
 226         /** A button has been pressed over the widget */
 227         sigc::signal<bool, GdkEventButton*, T*> ButtonPress;
 228
 229         /** A button has been release over the widget */
 230         sigc::signal<bool, GdkEventButton*, T*> ButtonRelease;
 231
 232         /** A child has been dropped onto this DnDVBox from another one;
 233          *  Parameters are the source DnDVBox, our child which the other one was dropped on (or 0) and the DragContext.
 234          */
 235         sigc::signal<void, DnDVBox*, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromAnotherBox;
 236         sigc::signal<void, Gtk::SelectionData const &, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromExternal;
 237         sigc::signal<void> SelectionChanged;
 238
 239 private:
 240
 241         /** @return the bottom y position of a child, pretending any placeholder
 242          *  is not there.
 243          */
 244         double bottom_of_child_ignoring_placeholder (T* child) const
 245         {
 246                 Gtk::Allocation const a = child->widget().get_allocation ();
 247                 double bottom = a.get_y() + a.get_height();
 248
 249                 if (_placeholder) {
 250                         Gtk::Allocation const b = _placeholder->get_allocation ();
 251                         if (b.get_y() < a.get_y()) {
 252                                 bottom -= (b.get_height () + _internal_vbox.get_spacing ());
 253                         }
 254                 }
 255
 256                 return bottom;
 257         }
 258
 259         /** Look at a y coordinate and find the children below y, and the ones either side.
 260          *  @param y y position.
 261          *  @param before Filled in with the child before, or 0.
 262          *  @param at Filled in with the child under y, or 0.
 263          *  @param after Filled in with the child after, or 0.
 264          *  @return Fractional position in terms of child height, or -1 if not over a child.
 265          */
 266         double get_children_around_position (int y, T** before, T** at, T** after) const
 267         {
 268                 if (_children.empty()) {
 269                         *before = *at = *after = 0;
 270                         return -1;
 271                 }
 272
 273                 *before = 0;
 274
 275                 typename std::list<T*>::const_iterator j = _children.begin ();
 276
 277                 /* index of current child */
 278                 int i = 0;
 279                 /* top of current child */
 280                 double top = 0;
 281                 /* bottom of current child */
 282                 double bottom = bottom_of_child_ignoring_placeholder (*j);
 283
 284                 while (y >= bottom && j != _children.end()) {
 285
 286                         top = bottom;
 287
 288                         *before = *j;
 289                         ++i;
 290                         ++j;
 291
 292                         if (j != _children.end()) {
 293                                 bottom = bottom_of_child_ignoring_placeholder (*j);
 294                         }
 295                 }
 296
 297                 if (j == _children.end()) {
 298                         *at = 0;
 299                         *after = 0;
 300                         return -1;
 301                 }
 302
 303                 *at = *j;
 304
 305                 ++j;
 306                 *after = j != _children.end() ? *j : 0;
 307
 308                 return i + ((y - top) / (bottom - top));
 309         }
 310
 311         void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)
 312         {
 313                 _drag_child = child;
 314
 315                 /* make up an icon for the drag */
 316                 _drag_icon = new Gtk::Window (Gtk::WINDOW_POPUP);
 317
 318                 Gtk::Allocation a = child->action_widget().get_allocation ();
 319                 _drag_icon->set_size_request (a.get_width(), a.get_height());
 320
 321                 _drag_icon->signal_expose_event().connect (sigc::mem_fun (*this, &DnDVBox::icon_expose));
 322                 _drag_icon->set_name (get_name ());
 323
 324                 /* make the icon transparent if possible */
 325                 Glib::RefPtr<Gdk::Screen const> s = _drag_icon->get_screen ();
 326                 Glib::RefPtr<Gdk::Colormap const> c = s->get_rgba_colormap ();
 327                 if (c) {
 328                         _drag_icon->set_colormap (c);
 329                 }
 330
 331                 int w, h;
 332                 _drag_icon->get_size (w, h);
 333                 _drag_icon->drag_set_as_icon (context, w / 2, h / 2);
 334
 335                 _drag_source = this;
 336         }
 337
 338         /* Draw the drag icon */
 339         bool icon_expose (GdkEventExpose*)
 340         {
 341                 /* Just grab the child's widget and use that */
 342
 343                 int w, h;
 344                 _drag_icon->get_size (w, h);
 345
 346                 cairo_t* cr = gdk_cairo_create (_drag_icon->get_window()->gobj ());
 347
 348                 Glib::RefPtr<Gdk::Pixmap> p = _drag_child->action_widget().get_snapshot();
 349                 gdk_cairo_set_source_pixmap (cr, p->gobj(), 0, 0);
 350                 cairo_rectangle (cr, 0, 0, w, h);
 351                 cairo_fill (cr);
 352                 cairo_destroy (cr);
 353
 354                 return false;
 355         }
 356
 357         void drag_data_get (Glib::RefPtr<Gdk::DragContext> const &context, Gtk::SelectionData & selection_data, guint, guint, T* child)
 358         {
 359                 if (!child->drag_data_get(context, selection_data)) {
 360                         selection_data.set (selection_data.get_target(), 8, (const guchar *) &child, sizeof (&child));
 361                 }
 362         }
 363
 364         void drag_data_received (
 365                 Glib::RefPtr<Gdk::DragContext> const & context, int /*x*/, int y, Gtk::SelectionData const & selection_data, guint /*info*/, guint time
 366                 )
 367         {
 368                 /* work out where it was dropped */
 369                 std::pair<T*, double> const drop = get_child_at_position (y);
 370
 371                 if (selection_data.get_target () != _targets.front ().get_target ()) {
 372                         DropFromExternal (selection_data, drop.first, context);
 373                         context->drag_finish (false, false, time);
 374                         return;
 375                 }
 376
 377                 if (_drag_source == this) {
 378
 379                         /* dropped from ourselves onto ourselves */
 380
 381                         T* child = *((T * const *) selection_data.get_data());
 382
 383                         if (drop.first == 0) {
 384                                 _internal_vbox.reorder_child (child->widget(), -1);
 385                         } else {
 386
 387                                 /* where in the list this child should be dropped */
 388                                 int target = drop.second + 0.5;
 389
 390                                 /* find out whether the child was `picked up' from before the drop position */
 391                                 int n = 0;
 392                                 typename std::list<T*>::const_iterator i = _children.begin ();
 393                                 while (i != _children.end() && *i != child && n < target) {
 394                                         ++i;
 395                                         ++n;
 396                                 }
 397
 398                                 /* if so, adjust the drop position to account for this */
 399                                 if (n < target) {
 400                                         --target;
 401                                 }
 402
 403                                 _internal_vbox.reorder_child (child->widget(), target);
 404                         }
 405
 406                 } else {
 407
 408                         /* drag started in another DnDVBox; raise a signal to say what happened */
 409
 410                         std::list<T*> dropped = _drag_source->selection ();
 411                         DropFromAnotherBox (_drag_source, drop.first, context);
 412                 }
 413
 414                 context->drag_finish (false, false, time);
 415         }
 416
 417         void drag_end (Glib::RefPtr<Gdk::DragContext> const &, T *)
 418         {
 419                 delete _drag_icon;
 420                 _drag_icon = 0;
 421                 _drag_source = 0;
 422
 423                 _drag_child = 0;
 424                 remove_placeholder ();
 425
 426                 Reordered (); /* EMIT SIGNAL */
 427         }
 428
 429         /** Insert a placeholder at a given fractional child position, creating it if necessary.
 430          *  @param c Fractional child position.
 431          *  @return index of child that the placeholder represents, or -1 if it is at the end of all children.
 432          */
 433         int create_or_update_placeholder (double c)
 434         {
 435                 if (_placeholder == 0) {
 436                         _placeholder = manage (new Gtk::Label (""));
 437                         _internal_vbox.pack_start (*_placeholder, false, false);
 438                         _placeholder->show ();
 439                 }
 440
 441                 /* round up the index, unless we're off the end of the children */
 442                 int const n = c < 0 ? -1 : int (c + 0.5);
 443                 _internal_vbox.reorder_child (*_placeholder, n);
 444                 return n;
 445         }
 446
 447         bool drag_motion (Glib::RefPtr<Gdk::DragContext> const & ctx, int /*x*/, int y, guint tme)
 448         {
 449                 if (_children.empty ()) {
 450                         return false;
 451                 }
 452
 453                 T* before;
 454                 T* at = NULL;
 455                 T* after;
 456
 457                 /* decide where we currently are */
 458                 double const c = get_children_around_position (y, &before, &at, &after);
 459
 460                 /* whether we're in the top or bottom half of the child that we're over */
 461                 bool top_half = (c - int (c)) < .5;
 462                 bool bottom_half = !top_half;
 463
 464                 if (_drag_source != this /* re-order */
 465                                 && _drag_source && at
 466                                 && _drag_source->_drag_child
 467                                 && _drag_source->selection ().size () == 1
 468                                 && at != _drag_source->_drag_child // can't happen or can it?
 469                                 && at->can_copy_state (_drag_source->_drag_child))
 470                 {
 471                         top_half = (c - int (c)) < 0.33;
 472                         bottom_half = (c - int (c)) > 0.8; // increase area >> 0.66; plugin below will move, or there's space
 473                 }
 474
 475                 /* Note that when checking on whether to remove a placeholder, we never do
 476                    so if _drag_child is 0 as this means that the child being dragged is
 477                    coming from a different DnDVBox, so it will never be the same as any
 478                    of our children.
 479                 */
 480
 481                 if (top_half && _drag_child && (before == _drag_child || at == _drag_child)) {
 482                         /* dropping here would have no effect, so remove the visual cue */
 483                         remove_placeholder ();
 484                         return false;
 485                 }
 486
 487                 if (bottom_half && _drag_child && (at == _drag_child || after == _drag_child)) {
 488                         /* dropping here would have no effect, so remove the visual cue */
 489                         remove_placeholder ();
 490                         return false;
 491                 }
 492
 493                 if (top_half || bottom_half) {
 494                         create_or_update_placeholder (c);
 495                         if (_drag_source == this /* re-order */) {
 496                                 ctx->drag_status (Gdk::ACTION_MOVE, tme);
 497                         } else {
 498                                 ctx->drag_status (Gdk::ACTION_COPY, tme);
 499                         }
 500                 } else {
 501                         ctx->drag_status (Gdk::ACTION_LINK, tme);
 502                         remove_placeholder ();
 503                 }
 504                 return true;
 505         }
 506
 507         void drag_leave (Glib::RefPtr<Gdk::DragContext> const &, guint)
 508         {
 509                 remove_placeholder ();
 510         }
 511
 512         bool button_press (GdkEventButton* ev, T* child)
 513         {
 514                 if (_expecting_unwanted_button_event == true && child == 0) {
 515                         _expecting_unwanted_button_event = false;
 516                         return true;
 517                 }
 518
 519                 if (child) {
 520                         _expecting_unwanted_button_event = true;
 521                 }
 522
 523                 if (ev->button == 1 || ev->button == 3) {
 524
 525                         if (!selected (child)) {
 526
 527                                 if ((ev->state & Gdk::SHIFT_MASK) && !_selection.empty()) {
 528
 529                                         /* Shift-click; select all between the clicked child and any existing selections */
 530
 531                                         bool selecting = false;
 532                                         bool done = false;
 533                                         for (typename std::list<T*>::const_iterator i = _children.begin(); i != _children.end(); ++i) {
 534
 535                                                 bool const was_selected = selected (*i);
 536
 537                                                 if (selecting && !was_selected) {
 538                                                         add_to_selection (*i);
 539                                                 }
 540
 541                                                 if (!selecting && !done) {
 542                                                         if (selected (*i)) {
 543                                                                 selecting = true;
 544                                                         } else if (*i == child) {
 545                                                                 selecting = true;
 546                                                                 add_to_selection (child);
 547                                                         }
 548                                                 } else if (selecting) {
 549                                                         if (was_selected || *i == child) {
 550                                                                 selecting = false;
 551                                                                 done = true;
 552                                                         }
 553                                                 }
 554                                         }
 555
 556                                 } else {
 557
 558                                         if ((ev->state & Gdk::CONTROL_MASK) == 0) {
 559                                                 clear_selection ();
 560                                         }
 561
 562                                         if (child) {
 563                                                 add_to_selection (child);
 564                                         }
 565
 566                                 }
 567
 568                                 SelectionChanged (); /* EMIT SIGNAL */
 569
 570                         } else {
 571                                 /* XXX THIS NEEDS GENERALIZING FOR OS X */
 572                                 if (ev->button == 1 && (ev->state & Gdk::CONTROL_MASK)) {
 573                                         if (child && selected (child)) {
 574                                                 remove_from_selection (child);
 575                                                 SelectionChanged (); /* EMIT SIGNAL */
 576                                         }
 577                                 }
 578                         }
 579                 }
 580
 581                 return ButtonPress (ev, child); /* EMIT SIGNAL */
 582         }
 583
 584         bool button_release (GdkEventButton* ev, T* child)
 585         {
 586                 if (_expecting_unwanted_button_event == true && child == 0) {
 587                         _expecting_unwanted_button_event = false;
 588                         return true;
 589                 }
 590
 591                 if (child) {
 592                         _expecting_unwanted_button_event = true;
 593                 }
 594
 595                 return ButtonRelease (ev, child); /* EMIT SIGNAL */
 596         }
 597
 598         /** Setup a child's visual state correctly */
 599         void setup_child_state (T* c)
 600         {
 601                 assert (c);
 602                 c->set_visual_state (Selected, (selected (c) || (_active == c)));
 603         }
 604
 605         void clear_selection ()
 606         {
 607                 std::list<T*> old_selection = _selection;
 608                 _selection.clear ();
 609                 for (typename std::list<T*>::iterator i = old_selection.begin(); i != old_selection.end(); ++i) {
 610                         setup_child_state (*i);
 611                 }
 612         }
 613
 614         void add_to_selection (T* child)
 615         {
 616                 if ( !child->is_selectable() )
 617                         return;
 618                 _selection.push_back (child);
 619                 setup_child_state (child);
 620         }
 621
 622         void remove_from_selection (T* child)
 623         {
 624                 typename std::list<T*>::iterator x = find (_selection.begin(), _selection.end(), child);
 625                 if (x != _selection.end()) {
 626                         T* c = *x;
 627                         _selection.erase (x);
 628                         setup_child_state (c);
 629                 }
 630         }
 631
 632         T* child_from_widget (Gtk::Widget const * w) const
 633         {
 634                 typename std::list<T*>::const_iterator i = _children.begin();
 635                 while (i != _children.end() && &(*i)->widget() != w) {
 636                         ++i;
 637                 }
 638
 639                 if (i == _children.end()) {
 640                         return 0;
 641                 }
 642
 643                 return *i;
 644         }
 645
 646         Gtk::VBox _internal_vbox;
 647         std::list<Gtk::TargetEntry> _targets;
 648         std::list<T*> _children;
 649         std::list<T*> _selection;
 650         T* _active;
 651         Gtk::Window* _drag_icon;
 652         bool _expecting_unwanted_button_event;
 653         /** A blank label used as a placeholder to indicate where an item would
 654          *  go if it were dropped or inserted "now".
 655          */
 656         Gtk::Label* _placeholder;
 657         /** Our child being dragged, or 0 */
 658         T* _drag_child;
 659
 660         static DnDVBox* _drag_source;
 661
 662 };
 663
 664 template <class T>
 665 DnDVBox<T>* DnDVBox<T>::_drag_source = 0;
 666
 667 }