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ardour/libs/gtkmm2ext/gtkmm2ext/dndvbox.h

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/*
Copyright (C) 2009 Paul Davis
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <gtkmm/box.h>
namespace Gtkmm2ext {
/** Parent class for children of a DnDVBox */
class DnDVBoxChild
{
public:
virtual ~DnDVBoxChild () {}
/** @return The widget that is to be put into the DnDVBox */
virtual Gtk::Widget& widget () = 0;
/** @return An EventBox containing the widget that should be used for selection, dragging etc. */
virtual Gtk::EventBox& action_widget () = 0;
/** @return Text to use in the icon that is dragged */
virtual std::string drag_text () const = 0;
/** Set the child's visual state */
virtual void set_visual_state (Gtk::StateType) = 0;
};
/** A VBox whose contents can be dragged and dropped */
template <class T>
class DnDVBox : public Gtk::EventBox
{
public:
DnDVBox () : _active (0), _drag_icon (0), _expecting_unwanted_button_event (false), _drag_placeholder (0)
{
_targets.push_back (Gtk::TargetEntry ("processor"));
add (_internal_vbox);
add_events (
Gdk::KEY_PRESS_MASK | Gdk::KEY_RELEASE_MASK |
Gdk::ENTER_NOTIFY_MASK | Gdk::LEAVE_NOTIFY_MASK |
Gdk::BUTTON_PRESS_MASK | Gdk::BUTTON_RELEASE_MASK
);
signal_button_press_event().connect (bind (mem_fun (*this, &DnDVBox::button_press), (T *) 0));
signal_button_release_event().connect (bind (mem_fun (*this, &DnDVBox::button_release), (T *) 0));
signal_drag_motion().connect (mem_fun (*this, &DnDVBox::drag_motion));
signal_drag_leave().connect (mem_fun (*this, &DnDVBox::drag_leave));
_internal_vbox.show ();
drag_dest_set (_targets);
signal_drag_data_received().connect (mem_fun (*this, &DnDVBox::drag_data_received));
}
virtual ~DnDVBox ()
{
clear ();
delete _drag_icon;
}
/** Add a child at the end of the widget. The DnDVBox will take responsibility for deleting the child */
void add_child (T* child)
{
child->action_widget().drag_source_set (_targets);
child->action_widget().signal_drag_begin().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_begin), child));
child->action_widget().signal_drag_data_get().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_data_get), child));
child->action_widget().signal_drag_end().connect (sigc::bind (mem_fun (*this, &DnDVBox::drag_end), child));
child->action_widget().signal_button_press_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_press), child));
child->action_widget().signal_button_release_event().connect (sigc::bind (mem_fun (*this, &DnDVBox::button_release), child));
_internal_vbox.pack_start (child->widget(), false, false);
_children.push_back (child);
child->widget().show ();
}
/** @return Children, sorted into the order that they are currently being displayed in the widget */
std::list<T*> children ()
{
std::list<T*> sorted_children;
std::list<Gtk::Widget*> widget_children = _internal_vbox.get_children ();
for (std::list<Gtk::Widget*>::iterator i = widget_children.begin(); i != widget_children.end(); ++i) {
T* c = child_from_widget (*i);
if (c) {
sorted_children.push_back (c);
}
}
return sorted_children;
}
/** @return Selected children */
std::list<T*> selection () const {
return _selection;
}
/** Set the `active' child; this is simply a child which is set to have the Gtk
* STATE_ACTIVE for whatever purposes the client may have.
* @param c Child, or 0 for none.
*/
void set_active (T* c) {
T* old_active = _active;
_active = c;
if (old_active) {
setup_child_state (old_active);
}
if (_active) {
setup_child_state (_active);
}
}
/** @param child Child
* @return true if the child is selected, otherwise false.
*/
bool selected (T* child) const {
return (find (_selection.begin(), _selection.end(), child) != _selection.end());
}
/** Clear all children from the widget */
void clear ()
{
_selection.clear ();
for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
_internal_vbox.remove ((*i)->widget());
delete *i;
}
_children.clear ();
_active = 0;
}
void select_all ()
{
clear_selection ();
for (typename std::list<T*>::iterator i = _children.begin(); i != _children.end(); ++i) {
add_to_selection (*i);
}
SelectionChanged (); /* EMIT SIGNAL */
}
void select_none ()
{
clear_selection ();
SelectionChanged (); /* EMIT SIGNAL */
}
/** Look at a y coordinate and find the children below y, and the ones either side.
* @param y y position.
* @param before Filled in with the child before, or 0.
* @param at Filled in with the child under y, or 0.
* @param after Filled in with the child after, or 0.
* @return Fractional position in terms of child height, or -1 if not over a child.
*/
double get_children_around_position (int y, T** before, T** at, T** after) const
{
if (_children.empty()) {
*before = *at = *after = 0;
return -1;
}
*before = 0;
typename std::list<T*>::const_iterator j = _children.begin ();
/* index of current child */
int i = 0;
/* top of current child */
double top = 0;
/* bottom of current child */
double bottom = (*j)->widget().get_allocation().get_height ();
while (y >= bottom && j != _children.end()) {
top = bottom;
*before = *j;
++i;
++j;
if (j != _children.end()) {
bottom += (*j)->widget().get_allocation().get_height ();
}
}
if (j == _children.end()) {
*at = 0;
*after = 0;
return -1;
}
*at = *j;
++j;
*after = j != _children.end() ? *j : 0;
return i + ((y - top) / (*at)->widget().get_allocation().get_height());
}
/** @param y y coordinate.
* @return Pair consisting of the child under y (or 0) and the (fractional) index of the child under y (or -1)
*/
std::pair<T*, double> get_child_at_position (int y) const
{
T* before;
T* after;
std::pair<T*, double> r;
r.second = get_children_around_position (y, &before, &r.first, &after);
return r;
}
void set_spacing (int s) {
_internal_vbox.set_spacing (s);
}
/** Children have been reordered by a drag */
sigc::signal<void> Reordered;
/** A button has been pressed over the widget */
sigc::signal<bool, GdkEventButton*, T*> ButtonPress;
/** A button has been release over the widget */
sigc::signal<bool, GdkEventButton*, T*> ButtonRelease;
/** A child has been dropped onto this DnDVBox from another one;
* Parameters are the source DnDVBox, our child which the other one was dropped on (or 0) and the DragContext.
*/
sigc::signal<void, DnDVBox*, T*, Glib::RefPtr<Gdk::DragContext> const & > DropFromAnotherBox;
sigc::signal<void> SelectionChanged;
private:
void drag_begin (Glib::RefPtr<Gdk::DragContext> const & context, T* child)
{
_drag_child = child;
/* make up an icon for the drag */
_drag_icon = new Gtk::Window (Gtk::WINDOW_POPUP);
Gtk::Allocation a = child->widget().get_allocation ();
_drag_icon->set_size_request (a.get_width(), a.get_height());
_drag_icon->signal_expose_event().connect (sigc::mem_fun (*this, &DnDVBox::icon_expose));
_drag_icon->set_name (get_name ());
/* make the icon transparent if possible */
Glib::RefPtr<Gdk::Screen const> s = _drag_icon->get_screen ();
Glib::RefPtr<Gdk::Colormap const> c = s->get_rgba_colormap ();
if (c) {
_drag_icon->set_colormap (c);
_have_alpha = true;
} else {
_have_alpha = false;
}
int w, h;
_drag_icon->get_size (w, h);
_drag_icon->drag_set_as_icon (context, w / 2, h / 2);
_drag_source = this;
}
/* Draw the drag icon */
bool icon_expose (GdkEventExpose* ev)
{
/* Just grab the child's widget and use that */
int w, h;
_drag_icon->get_size (w, h);
cairo_t* cr = gdk_cairo_create (_drag_icon->get_window()->gobj ());
Glib::RefPtr<Gdk::Pixmap> p = _drag_child->widget().get_snapshot();
gdk_cairo_set_source_pixmap (cr, p->gobj(), 0, 0);
cairo_rectangle (cr, 0, 0, w, h);
cairo_fill (cr);
cairo_destroy (cr);
return false;
}
void drag_data_get (Glib::RefPtr<Gdk::DragContext> const &, Gtk::SelectionData & selection_data, guint, guint, T* child)
{
selection_data.set (selection_data.get_target(), 8, (const guchar *) &child, sizeof (&child));
}
void drag_data_received (
Glib::RefPtr<Gdk::DragContext> const & context, int x, int y, Gtk::SelectionData const & selection_data, guint /*info*/, guint time
)
{
/* work out where it was dropped */
std::pair<T*, double> const drop = get_child_at_position (y);
if (_drag_source == this) {
/* dropped from ourselves onto ourselves */
T* child = *((T **) selection_data.get_data());
if (drop.first == 0) {
_internal_vbox.reorder_child (child->widget(), -1);
} else {
/* where in the list this child should be dropped */
int target = drop.second + 0.5;
/* find out whether the child was `picked up' from before the drop position */
int n = 0;
typename std::list<T*>::const_iterator i = _children.begin ();
while (i != _children.end() && *i != child && n < target) {
++i;
++n;
}
/* if so, adjust the drop position to account for this */
if (n < target) {
--target;
}
_internal_vbox.reorder_child (child->widget(), target);
}
} else {
/* drag started in another DnDVBox; raise a signal to say what happened */
std::list<T*> dropped = _drag_source->selection ();
DropFromAnotherBox (_drag_source, drop.first, context);
}
context->drag_finish (false, false, time);
}
void drag_end (Glib::RefPtr<Gdk::DragContext> const &, T *)
{
delete _drag_icon;
_drag_icon = 0;
_drag_child = 0;
remove_drag_placeholder ();
Reordered (); /* EMIT SIGNAL */
}
void remove_drag_placeholder ()
{
if (_drag_placeholder) {
_internal_vbox.remove (*_drag_placeholder);
_drag_placeholder = 0;
}
}
bool drag_motion (Glib::RefPtr<Gdk::DragContext> const &, int x, int y, guint)
{
if (_children.empty ()) {
return false;
}
T* before;
T* at;
T* after;
/* decide where we currently are */
double const c = get_children_around_position (y, &before, &at, &after);
/* whether we're in the top or bottom half of the child that we're over */
bool top_half = (c - int (c)) < 0.5;
if (top_half && (before == _drag_child || at == _drag_child)) {
/* dropping here would have no effect, so remove the visual cue */
remove_drag_placeholder ();
return false;
}
if (!top_half && (at == _drag_child || after == _drag_child)) {
/* dropping here would have no effect, so remove the visual cue */
remove_drag_placeholder ();
return false;
}
/* the index that the placeholder should be put at */
int const n = int (c + 0.5);
if (_drag_placeholder == 0) {
_drag_placeholder = manage (new Gtk::Label (""));
_internal_vbox.pack_start (*_drag_placeholder, false, false);
_drag_placeholder->show ();
}
if (c < 0) {
_internal_vbox.reorder_child (*_drag_placeholder, -1);
} else {
_internal_vbox.reorder_child (*_drag_placeholder, n);
}
return false;
}
void drag_leave (Glib::RefPtr<Gdk::DragContext> const &, guint)
{
remove_drag_placeholder ();
}
bool button_press (GdkEventButton* ev, T* child)
{
if (_expecting_unwanted_button_event == true && child == 0) {
_expecting_unwanted_button_event = false;
return true;
}
if (child) {
_expecting_unwanted_button_event = true;
}
if (ev->button == 1 || ev->button == 3) {
if (!selected (child)) {
if ((ev->state & Gdk::SHIFT_MASK) && !_selection.empty()) {
/* Shift-click; select all between the clicked child and any existing selections */
bool selecting = false;
bool done = false;
for (typename std::list<T*>::const_iterator i = _children.begin(); i != _children.end(); ++i) {
bool const was_selected = selected (*i);
if (selecting && !was_selected) {
add_to_selection (*i);
}
if (!selecting && !done) {
if (selected (*i)) {
selecting = true;
} else if (*i == child) {
selecting = true;
add_to_selection (child);
}
} else if (selecting) {
if (was_selected || *i == child) {
selecting = false;
done = true;
}
}
}
} else {
if ((ev->state & Gdk::CONTROL_MASK) == 0) {
clear_selection ();
}
if (child) {
add_to_selection (child);
}
}
SelectionChanged (); /* EMIT SIGNAL */
} else {
/* XXX THIS NEEDS GENERALIZING FOR OS X */
if (ev->button == 1 && (ev->state & Gdk::CONTROL_MASK)) {
if (child && selected (child)) {
remove_from_selection (child);
SelectionChanged (); /* EMIT SIGNAL */
}
}
}
}
return ButtonPress (ev, child); /* EMIT SIGNAL */
}
bool button_release (GdkEventButton* ev, T* child)
{
if (_expecting_unwanted_button_event == true && child == 0) {
_expecting_unwanted_button_event = false;
return true;
}
if (child) {
_expecting_unwanted_button_event = true;
}
return ButtonRelease (ev, child); /* EMIT SIGNAL */
}
/** Setup a child's GTK state correctly */
void setup_child_state (T* c)
{
assert (c);
if (c == _active) {
c->set_visual_state (Gtk::STATE_ACTIVE);
} else if (selected (c)) {
c->set_visual_state (Gtk::STATE_SELECTED);
} else {
c->set_visual_state (Gtk::STATE_NORMAL);
}
}
void clear_selection ()
{
std::list<T*> old_selection = _selection;
_selection.clear ();
for (typename std::list<T*>::iterator i = old_selection.begin(); i != old_selection.end(); ++i) {
setup_child_state (*i);
}
}
void add_to_selection (T* child)
{
_selection.push_back (child);
setup_child_state (child);
}
void remove_from_selection (T* child)
{
typename std::list<T*>::iterator x = find (_selection.begin(), _selection.end(), child);
if (x != _selection.end()) {
_selection.erase (x);
setup_child_state (*x);
}
}
T* child_from_widget (Gtk::Widget const * w) const
{
typename std::list<T*>::const_iterator i = _children.begin();
while (i != _children.end() && &(*i)->widget() != w) {
++i;
}
if (i == _children.end()) {
return 0;
}
return *i;
}
Gtk::VBox _internal_vbox;
std::list<Gtk::TargetEntry> _targets;
std::list<T*> _children;
std::list<T*> _selection;
T* _active;
Gtk::Window* _drag_icon;
bool _expecting_unwanted_button_event;
/** A blank label used as a placeholder to indicate where a dragged item would
* go if it were dropped now.
*/
Gtk::Label* _drag_placeholder;
/** Our child being dragged, or 0 */
T* _drag_child;
/** true if we can have an alpha-blended drag icon */
bool _have_alpha;
static DnDVBox* _drag_source;
};
template <class T>
DnDVBox<T>* DnDVBox<T>::_drag_source = 0;
}
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