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Improve drag and drop action event consuming #2628

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1a3ce93
WindowClone: Don't consume button press events
leolost2605 Nov 12, 2025
6c1b00e
DragDropAction: Don't consume events before drag started
leolost2605 Nov 12, 2025
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210 changes: 113 additions & 97 deletions lib/DragDropAction.vala
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Original file line number Diff line number Diff line change
Expand Up @@ -201,7 +201,6 @@ namespace Gala {
return Clutter.EVENT_PROPAGATE;
}

grab_actor (actor, event.get_device ());
clicked = true;

float x, y;
Expand All @@ -210,8 +209,78 @@ namespace Gala {
last_x = x;
last_y = y;

// We didn't start dragging yet, so allow propagation (maybe somebody else wants
// to handle this as well)
return Clutter.EVENT_PROPAGATE;

case Clutter.EventType.MOTION:
case Clutter.EventType.TOUCH_UPDATE:
if (!is_valid_touch_event (event)) {
return Clutter.EVENT_PROPAGATE;
}

if (!clicked) {
return Clutter.EVENT_PROPAGATE;
}

float x, y;
event.get_coords (out x, out y);

#if HAS_MUTTER47
var drag_threshold = actor.context.get_settings ().dnd_drag_threshold;
#else
var drag_threshold = Clutter.Settings.get_default ().dnd_drag_threshold;
#endif
if (Math.fabsf (last_x - x) < drag_threshold && Math.fabsf (last_y - y) < drag_threshold) {
// Not moved far enough yet, continue waiting and allowing propagation
return Clutter.EVENT_PROPAGATE;
}

// We have moved enough, start the drag
handle = drag_begin (last_x, last_y);
if (handle == null) {
critical ("No handle has been returned by the started signal, aborting drag.");
return Clutter.EVENT_PROPAGATE;
}

clicked = false;
dragging = true;

grab_actor (handle, event.get_device ());

var source_list = sources.@get (drag_id);
if (source_list != null) {
var dest_list = destinations[drag_id];
foreach (var actor in source_list) {
// Do not unset reactivity on destinations
if (dest_list == null || actor in dest_list) {
continue;
}

actor.reactive = false;
}
}

return Clutter.EVENT_STOP;

case Clutter.EventType.BUTTON_RELEASE:
case Clutter.EventType.TOUCH_END:
float x, y, ex, ey;
event.get_coords (out ex, out ey);
actor.get_transformed_position (out x, out y);

// release has happened within bounds of actor
if (clicked && x < ex && x + actor.width > ex && y < ey && y + actor.height > ey) {
actor_clicked (
event.get_type () == BUTTON_RELEASE ? event.get_button () : Clutter.Button.PRIMARY,
event.get_source_device ().get_device_type ()
);
}

clicked = false;

return Clutter.EVENT_PROPAGATE;

default:
break;
}
Expand Down Expand Up @@ -247,6 +316,8 @@ namespace Gala {
}

private bool on_event (Clutter.Event event) {
assert (dragging);
Comment on lines 318 to +319
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@lenemter lenemter Nov 15, 2025

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Suggested change
private bool on_event (Clutter.Event event) {
assert (dragging);
private bool on_event (Clutter.Event event) requires (dragging) {


var device = event.get_device ();

if (grabbed_device != null &&
Expand All @@ -269,32 +340,11 @@ namespace Gala {
return Clutter.EVENT_PROPAGATE;
}

if (dragging) {
if (hovered != null) {
finish ();
hovered = null;
} else {
cancel ();
}

return Clutter.EVENT_STOP;
}

float x, y, ex, ey;
event.get_coords (out ex, out ey);
actor.get_transformed_position (out x, out y);

// release has happened within bounds of actor
if (clicked && x < ex && x + actor.width > ex && y < ey && y + actor.height > ey) {
actor_clicked (
event.get_type () == BUTTON_RELEASE ? event.get_button () : Clutter.Button.PRIMARY,
event.get_source_device ().get_device_type ()
);
}

if (clicked) {
ungrab_actor ();
clicked = false;
if (hovered != null) {
finish ();
hovered = null;
} else {
cancel ();
}

return Clutter.EVENT_STOP;
Expand All @@ -308,89 +358,55 @@ namespace Gala {
float x, y;
event.get_coords (out x, out y);

if (!dragging && clicked) {
#if HAS_MUTTER47
var drag_threshold = actor.context.get_settings ().dnd_drag_threshold;
#else
var drag_threshold = Clutter.Settings.get_default ().dnd_drag_threshold;
#endif
if (Math.fabsf (last_x - x) > drag_threshold || Math.fabsf (last_y - y) > drag_threshold) {
handle = drag_begin (last_x, last_y);
if (handle == null) {
ungrab_actor ();
critical ("No handle has been returned by the started signal, aborting drag.");
return Clutter.EVENT_PROPAGATE;
}

clicked = false;
dragging = true;

ungrab_actor ();
grab_actor (handle, event.get_device ());

var source_list = sources.@get (drag_id);
if (source_list != null) {
var dest_list = destinations[drag_id];
foreach (var actor in source_list) {
// Do not unset reactivity on destinations
if (dest_list == null || actor in dest_list) {
continue;
}

actor.reactive = false;
}
}
}
return Clutter.EVENT_STOP;
if (!dragging) {
return Clutter.EVENT_PROPAGATE;
}

} else if (dragging) {
handle.x -= last_x - x;
handle.y -= last_y - y;
last_x = x;
last_y = y;

var stage = actor.get_stage ();
var actor = stage.get_actor_at_pos (NONE, (int) x, (int) y);
DragDropAction action = null;
// if we're allowed to bubble and this actor is not a destination, check its parents
if (actor != null && (action = get_drag_drop_action (actor)) == null && allow_bubbling) {
while ((actor = actor.get_parent ()) != stage) {
if ((action = get_drag_drop_action (actor)) != null)
break;
}
}
handle.x -= last_x - x;
handle.y -= last_y - y;
last_x = x;
last_y = y;

// didn't change, no need to do anything
if (actor == hovered) {
if (hovered != null) {
destination_motion (hovered, x - hovered.x, y - hovered.y);
}
return Clutter.EVENT_STOP;
var stage = actor.get_stage ();
var actor = stage.get_actor_at_pos (NONE, (int) x, (int) y);
DragDropAction action = null;
// if we're allowed to bubble and this actor is not a destination, check its parents
if (actor != null && (action = get_drag_drop_action (actor)) == null && allow_bubbling) {
while ((actor = actor.get_parent ()) != stage) {
if ((action = get_drag_drop_action (actor)) != null)
break;
}
}

if (action == null) {
// apparently we left ours if we had one before
if (hovered != null) {
emit_crossed (hovered, false);
hovered = null;
}

return Clutter.EVENT_STOP;
// didn't change, no need to do anything
if (actor == hovered) {
if (hovered != null) {
destination_motion (hovered, x - hovered.x, y - hovered.y);
}
return Clutter.EVENT_STOP;
}

// signal the previous one that we left it
if (action == null) {
// apparently we left ours if we had one before
if (hovered != null) {
emit_crossed (hovered, false);
hovered = null;
}

// tell the new one that it is hovered
hovered = actor;
emit_crossed (hovered, true);

return Clutter.EVENT_STOP;
}

break;
// signal the previous one that we left it
if (hovered != null) {
emit_crossed (hovered, false);
}

// tell the new one that it is hovered
hovered = actor;
emit_crossed (hovered, true);

return Clutter.EVENT_STOP;

default:
break;
}
Expand Down
4 changes: 0 additions & 4 deletions src/Widgets/MultitaskingView/WindowClone.vala
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Original file line number Diff line number Diff line change
Expand Up @@ -372,10 +372,6 @@ public class Gala.WindowClone : ActorTarget, RootTarget {
window_title.allocate (window_title_alloc);
}

public override bool button_press_event (Clutter.Event event) {
return Clutter.EVENT_STOP;
}

private void update_hover_widgets (bool? animating = null) {
if (animating != null) {
in_slot_animation = animating;
Expand Down