gnome-shell/js/ui/grabHelper.js

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// -*- mode: js; js-indent-level: 4; indent-tabs-mode: nil -*-
const Clutter = imports.gi.Clutter;
const Gtk = imports.gi.Gtk;
const Lang = imports.lang;
const Meta = imports.gi.Meta;
const Shell = imports.gi.Shell;
const St = imports.gi.St;
const Main = imports.ui.main;
const Params = imports.misc.params;
let _capturedEventId = 0;
let _grabHelperStack = [];
function _onCapturedEvent(actor, event) {
let grabHelper = _grabHelperStack[_grabHelperStack.length - 1];
return grabHelper.onCapturedEvent(event);
}
function _pushGrabHelper(grabHelper) {
_grabHelperStack.push(grabHelper);
if (_capturedEventId == 0)
_capturedEventId = global.stage.connect('captured-event', _onCapturedEvent);
}
function _popGrabHelper(grabHelper) {
let poppedHelper = _grabHelperStack.pop();
if (poppedHelper != grabHelper)
throw new Error("incorrect grab helper pop");
if (_grabHelperStack.length == 0) {
global.stage.disconnect(_capturedEventId);
_capturedEventId = 0;
}
}
// GrabHelper:
// @owner: the actor that owns the GrabHelper
// @params: optional parameters to pass to Main.pushModal()
//
// Creates a new GrabHelper object, for dealing with keyboard and pointer grabs
// associated with a set of actors.
//
// Note that the grab can be automatically dropped at any time by the user, and
// your code just needs to deal with it; you shouldn't adjust behavior directly
// after you call ungrab(), but instead pass an 'onUngrab' callback when you
// call grab().
const GrabHelper = new Lang.Class({
Name: 'GrabHelper',
_init: function(owner, params) {
this._owner = owner;
this._modalParams = params;
this._grabStack = [];
this._actors = [];
this._ignoreRelease = false;
this._modalCount = 0;
},
// addActor:
// @actor: an actor
//
// Adds @actor to the set of actors that are allowed to process events
// during a grab.
addActor: function(actor) {
actor.__grabHelperDestroyId = actor.connect('destroy', Lang.bind(this, function() { this.removeActor(actor); }));
this._actors.push(actor);
},
// removeActor:
// @actor: an actor
//
// Removes @actor from the set of actors that are allowed to
// process events during a grab.
removeActor: function(actor) {
let index = this._actors.indexOf(actor);
if (index != -1)
this._actors.splice(index, 1);
if (actor.__grabHelperDestroyId) {
actor.disconnect(actor.__grabHelperDestroyId);
delete actor.__grabHelperDestroyId;
}
},
_isWithinGrabbedActor: function(actor) {
let currentActor = this.currentGrab.actor;
while (actor) {
if (this._actors.indexOf(actor) != -1)
return true;
if (actor == currentActor)
return true;
actor = actor.get_parent();
}
return false;
},
get currentGrab() {
return this._grabStack[this._grabStack.length - 1] || {};
},
get grabbed() {
return this._grabStack.length > 0;
},
get grabStack() {
return this._grabStack;
},
_findStackIndex: function(actor) {
if (!actor)
return -1;
for (let i = 0; i < this._grabStack.length; i++) {
if (this._grabStack[i].actor === actor)
return i;
}
return -1;
},
_actorInGrabStack: function(actor) {
while (actor) {
let idx = this._findStackIndex(actor);
if (idx >= 0)
return idx;
actor = actor.get_parent();
}
return -1;
},
isActorGrabbed: function(actor) {
return this._findStackIndex(actor) >= 0;
},
// grab:
// @params: A bunch of parameters, see below
//
// The general effect of a "grab" is to ensure that the passed in actor
// and all actors inside the grab get exclusive control of the mouse and
// keyboard, with the grab automatically being dropped if the user tries
// to dismiss it. The actor is passed in through @params.actor.
//
// grab() can be called multiple times, with the scope of the grab being
// changed to a different actor every time. A nested grab does not have
// to have its grabbed actor inside the parent grab actors.
//
// Grabs can be automatically dropped if the user tries to dismiss it
// in one of two ways: the user clicking outside the currently grabbed
// actor, or the user typing the Escape key.
//
// If the user clicks outside the grabbed actors, and the clicked on
// actor is part of a previous grab in the stack, grabs will be popped
// until that grab is active. However, the click event will not be
// replayed to the actor.
//
// If the user types the Escape key, one grab from the grab stack will
// be popped.
//
// When a grab is popped by user interacting as described above, if you
// pass a callback as @params.onUngrab, it will be called with %true.
//
// If @params.focus is not null, we'll set the key focus directly
// to that actor instead of navigating in @params.actor. This is for
// use cases like menus, where we want to grab the menu actor, but keep
// focus on the clicked on menu item.
grab: function(params) {
params = Params.parse(params, { actor: null,
focus: null,
onUngrab: null });
let focus = global.stage.key_focus;
let hadFocus = focus && this._isWithinGrabbedActor(focus);
let newFocus = params.actor;
if (this.isActorGrabbed(params.actor))
return true;
params.savedFocus = focus;
if (!this._takeModalGrab())
return false;
this._grabStack.push(params);
if (params.focus) {
params.focus.grab_key_focus();
} else if (newFocus && hadFocus) {
if (!newFocus.navigate_focus(null, Gtk.DirectionType.TAB_FORWARD, false))
newFocus.grab_key_focus();
}
return true;
},
_takeModalGrab: function() {
let firstGrab = (this._modalCount == 0);
if (firstGrab) {
if (!Main.pushModal(this._owner, this._modalParams))
return false;
_pushGrabHelper(this);
}
this._modalCount++;
return true;
},
_releaseModalGrab: function() {
this._modalCount--;
if (this._modalCount > 0)
return;
_popGrabHelper(this);
this._ignoreRelease = false;
Main.popModal(this._owner);
global.sync_pointer();
},
// ignoreRelease:
//
// Make sure that the next button release event evaluated by the
// capture event handler returns false. This is designed for things
// like the ComboBoxMenu that go away on press, but need to eat
// the next release event.
ignoreRelease: function() {
this._ignoreRelease = true;
},
// ungrab:
// @params: The parameters for the grab; see below.
//
// Pops @params.actor from the grab stack, potentially dropping
// the grab. If the actor is not on the grab stack, this call is
// ignored with no ill effects.
//
// If the actor is not at the top of the grab stack, grabs are
// popped until the grabbed actor is at the top of the grab stack.
// The onUngrab callback for every grab is called for every popped
// grab with the parameter %false.
ungrab: function(params) {
params = Params.parse(params, { actor: this.currentGrab.actor,
isUser: false });
let grabStackIndex = this._findStackIndex(params.actor);
if (grabStackIndex < 0)
return;
let focus = global.stage.key_focus;
let hadFocus = focus && this._isWithinGrabbedActor(focus);
let poppedGrabs = this._grabStack.slice(grabStackIndex);
// "Pop" all newly ungrabbed actors off the grab stack
// by truncating the array.
this._grabStack.length = grabStackIndex;
for (let i = poppedGrabs.length - 1; i >= 0; i--) {
let poppedGrab = poppedGrabs[i];
if (poppedGrab.onUngrab)
poppedGrab.onUngrab(params.isUser);
this._releaseModalGrab();
}
if (hadFocus) {
let poppedGrab = poppedGrabs[0];
if (poppedGrab.savedFocus)
poppedGrab.savedFocus.grab_key_focus();
}
},
onCapturedEvent: function(event) {
let type = event.type();
if (type == Clutter.EventType.KEY_PRESS &&
event.get_key_symbol() == Clutter.KEY_Escape) {
this.ungrab({ isUser: true });
return true;
}
let press = type == Clutter.EventType.BUTTON_PRESS;
let release = type == Clutter.EventType.BUTTON_RELEASE;
let button = press || release;
if (release && this._ignoreRelease) {
this._ignoreRelease = false;
return true;
}
if (this._isWithinGrabbedActor(event.get_source()))
return false;
if (Main.keyboard.shouldTakeEvent(event))
return false;
if (button) {
// If we have a press event, ignore the next event,
// which should be a release event.
if (press)
this._ignoreRelease = true;
let i = this._actorInGrabStack(event.get_source()) + 1;
this.ungrab({ actor: this._grabStack[i].actor, isUser: true });
return true;
}
return true;
},
});