gecko-dev/widget/nsIScreen.idl

/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

%{C++
/**
 * The display type of nsIScreen belongs to.
 */
enum class DisplayType: int32_t {
  DISPLAY_PRIMARY,  // primary screen
  DISPLAY_EXTERNAL, // wired displays, such as HDMI, DisplayPort, etc.
  DISPLAY_VIRTUAL   // wireless displays, such as Chromecast, WiFi-Display, etc.
};
%}

[scriptable, uuid(826e80c8-d70f-42e2-8aa9-82c05f2a370a)]
interface nsIScreen : nsISupports
{
  /**
   * These report screen dimensions in (screen-specific) device pixels
   */
  void GetRect(out long left, out long top, out long width, out long height);
  void GetAvailRect(out long left, out long top, out long width, out long height);

  /**
   * And these report in desktop pixels
   */
  void GetRectDisplayPix(out long left, out long top, out long width, out long height);
  void GetAvailRectDisplayPix(out long left, out long top, out long width, out long height);

  readonly attribute long pixelDepth;
  readonly attribute long colorDepth;

  /**
   * The number of device pixels per desktop pixel for this screen (for
   * hidpi configurations where there may be multiple device pixels per
   * desktop px and/or per CSS px).
   *
   * This seems poorly named (something like devicePixelsPerDesktopPixel
   * would be more accurate/explicit), but given that it is exposed to
   * front-end code and may also be used by add-ons, it's probably not
   * worth the disruption of changing it.
   *
   * Returns 1.0 if HiDPI mode is disabled or unsupported, or if the
   * host OS uses device pixels as its desktop pixel units (e.g. Windows 7 or
   * GTK/X11). Per-monitor DPI is available in Windows 8.1+, GTK/Wayland or
   * macOS.
   */
  readonly attribute double contentsScaleFactor;

  /**
   * The default number of device pixels per unscaled CSS pixel for this
   * screen. This is probably what contentsScaleFactor originally meant
   * to be, prior to confusion between CSS pixels and desktop pixel units.
   */
  readonly attribute double defaultCSSScaleFactor;

  /**
   * The DPI of the screen.
   */
  readonly attribute float dpi;
};