gnome-shell/js/ui/slider.js

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/* -*- mode: js2; js2-basic-offset: 4; indent-tabs-mode: nil -*- */
const Cairo = imports.cairo;
const Clutter = imports.gi.Clutter;
const Lang = imports.lang;
const St = imports.gi.St;
const Signals = imports.signals;
const SLIDER_SCROLL_STEP = 0.05; /* Slider scrolling step in % */
const Slider = new Lang.Class({
Name: "Slider",
_init: function(value) {
if (isNaN(value))
// Avoid spreading NaNs around
throw TypeError('The slider value must be a number');
this._value = Math.max(Math.min(value, 1), 0);
this.actor = new St.DrawingArea({ style_class: 'slider',
can_focus: true,
reactive: true });
this.actor.connect('repaint', Lang.bind(this, this._sliderRepaint));
this.actor.connect('button-press-event', Lang.bind(this, this._startDragging));
this.actor.connect('scroll-event', Lang.bind(this, this._onScrollEvent));
this.actor.connect('key-press-event', Lang.bind(this, this._onKeyPressEvent));
this._releaseId = this._motionId = 0;
this._dragging = false;
},
setValue: function(value) {
if (isNaN(value))
throw TypeError('The slider value must be a number');
this._value = Math.max(Math.min(value, 1), 0);
this.actor.queue_repaint();
},
_sliderRepaint: function(area) {
let cr = area.get_context();
let themeNode = area.get_theme_node();
let [width, height] = area.get_surface_size();
let handleRadius = themeNode.get_length('-slider-handle-radius');
let handleBorderWidth = themeNode.get_length('-slider-handle-border-width');
let [hasHandleColor, handleBorderColor] =
themeNode.lookup_color('-slider-handle-border-color', false);
let sliderHeight = themeNode.get_length('-slider-height');
let sliderBorderWidth = themeNode.get_length('-slider-border-width');
let sliderBorderRadius = Math.min(width, sliderHeight) / 2;
let sliderBorderColor = themeNode.get_color('-slider-border-color');
let sliderColor = themeNode.get_color('-slider-background-color');
let sliderActiveBorderColor = themeNode.get_color('-slider-active-border-color');
let sliderActiveColor = themeNode.get_color('-slider-active-background-color');
const TAU = Math.PI * 2;
let handleX = handleRadius + (width - 2 * handleRadius) * this._value;
cr.arc(sliderBorderRadius + sliderBorderWidth, height / 2, sliderBorderRadius, TAU * 1/4, TAU * 3/4);
cr.lineTo(handleX, (height - sliderHeight) / 2);
cr.lineTo(handleX, (height + sliderHeight) / 2);
cr.lineTo(sliderBorderRadius + sliderBorderWidth, (height + sliderHeight) / 2);
Clutter.cairo_set_source_color(cr, sliderActiveColor);
cr.fillPreserve();
Clutter.cairo_set_source_color(cr, sliderActiveBorderColor);
cr.setLineWidth(sliderBorderWidth);
cr.stroke();
cr.arc(width - sliderBorderRadius - sliderBorderWidth, height / 2, sliderBorderRadius, TAU * 3/4, TAU * 1/4);
cr.lineTo(handleX, (height + sliderHeight) / 2);
cr.lineTo(handleX, (height - sliderHeight) / 2);
cr.lineTo(width - sliderBorderRadius - sliderBorderWidth, (height - sliderHeight) / 2);
Clutter.cairo_set_source_color(cr, sliderColor);
cr.fillPreserve();
Clutter.cairo_set_source_color(cr, sliderBorderColor);
cr.setLineWidth(sliderBorderWidth);
cr.stroke();
let handleY = height / 2;
let color = themeNode.get_foreground_color();
Clutter.cairo_set_source_color(cr, color);
cr.arc(handleX, handleY, handleRadius, 0, 2 * Math.PI);
cr.fillPreserve();
if (hasHandleColor && handleBorderWidth) {
Clutter.cairo_set_source_color(cr, handleBorderColor);
cr.setLineWidth(handleBorderWidth);
cr.stroke();
}
cr.$dispose();
},
_startDragging: function(actor, event) {
if (this._dragging) // don't allow two drags at the same time
return false;
this._dragging = true;
// FIXME: we should only grab the specific device that originated
// the event, but for some weird reason events are still delivered
// outside the slider if using clutter_grab_pointer_for_device
Clutter.grab_pointer(this.actor);
this._releaseId = this.actor.connect('button-release-event', Lang.bind(this, this._endDragging));
this._motionId = this.actor.connect('motion-event', Lang.bind(this, this._motionEvent));
let absX, absY;
[absX, absY] = event.get_coords();
this._moveHandle(absX, absY);
return true;
},
_endDragging: function() {
if (this._dragging) {
this.actor.disconnect(this._releaseId);
this.actor.disconnect(this._motionId);
Clutter.ungrab_pointer();
this._dragging = false;
this.emit('drag-end');
}
return true;
},
scroll: function(event) {
let direction = event.get_scroll_direction();
let delta;
if (event.is_pointer_emulated())
return;
if (direction == Clutter.ScrollDirection.DOWN) {
delta = -SLIDER_SCROLL_STEP;
} else if (direction == Clutter.ScrollDirection.UP) {
delta = +SLIDER_SCROLL_STEP;
} else if (direction == Clutter.ScrollDirection.SMOOTH) {
let [dx, dy] = event.get_scroll_delta();
// Even though the slider is horizontal, use dy to match
// the UP/DOWN above.
delta = -dy / 10;
}
this._value = Math.min(Math.max(0, this._value + delta), 1);
this.actor.queue_repaint();
this.emit('value-changed', this._value);
},
_onScrollEvent: function(actor, event) {
this.scroll(event);
},
_motionEvent: function(actor, event) {
let absX, absY;
[absX, absY] = event.get_coords();
this._moveHandle(absX, absY);
return true;
},
_onKeyPressEvent: function (actor, event) {
let key = event.get_key_symbol();
if (key == Clutter.KEY_Right || key == Clutter.KEY_Left) {
let delta = key == Clutter.KEY_Right ? 0.1 : -0.1;
this._value = Math.max(0, Math.min(this._value + delta, 1));
this._slider.queue_repaint();
this.emit('value-changed', this._value);
this.emit('drag-end');
return true;
}
return false;
},
_moveHandle: function(absX, absY) {
let relX, relY, sliderX, sliderY;
[sliderX, sliderY] = this.actor.get_transformed_position();
relX = absX - sliderX;
relY = absY - sliderY;
let width = this.actor.width;
let handleRadius = this.actor.get_theme_node().get_length('-slider-handle-radius');
let newvalue;
if (relX < handleRadius)
newvalue = 0;
else if (relX > width - handleRadius)
newvalue = 1;
else
newvalue = (relX - handleRadius) / (width - 2 * handleRadius);
this._value = newvalue;
this.actor.queue_repaint();
this.emit('value-changed', this._value);
},
get value() {
return this._value;
}
});
Signals.addSignalMethods(Slider.prototype);