dash-to-panel/desktopIconsIntegration.js

/*
 * The code in this file is distributed under a "1-clause BSD license",
 * which makes it compatible with GPLv2 and GPLv3 too, and others.
 *
 * License text:
 *
 * Copyright (C) 2021 Sergio Costas (rastersoft@gmail.com)
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 * this list of conditions and the following disclaimer.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

/*******************************************************************************
 * Integration class
 *
 * This class must be added to other extensions in order to integrate
 * them with Desktop Icons NG. It allows an extension to notify how much margin
 * it uses in each side of each monitor.
 *
 * DON'T SEND PATCHES TO THIS FILE TO THE EXTENSION MAINTAINER. SEND THEM TO
 * DESKTOP ICONS NG MAINTAINER: https://gitlab.com/rastersoft/desktop-icons-ng
 *
 * In the *enable()* function, create a *DesktopIconsUsableAreaClass()*
 * object with
 *
 *     new DesktopIconsIntegration.DesktopIconsUsableAreaClass(object);
 *
 * Now, in the *disable()* function just call to the *destroy()* method before
 * nullifying the pointer. You must create a new object in enable() the next
 * time the extension is enabled.
 *
 * In your code, every time you change the margins, you should call first to
 * *resetMargins()* method to clear the current margins, and then call to
 * *setMargins(...)* method as many times as you need to set the margins in each
 * monitor. You don't need to call it for all the monitors, only for those where
 * you are painting something. If you don't set values for a monitor, they will
 * be considered zero.
 *
 * The margins values are relative to the monitor border.
 *
 *******************************************************************************/

import GLib from 'gi://GLib'
import * as Main from 'resource:///org/gnome/shell/ui/main.js'
import * as ExtensionUtils from 'resource:///org/gnome/shell/misc/extensionUtils.js'
import { Extension } from 'resource:///org/gnome/shell/extensions/extension.js'

const IDENTIFIER_UUID = '130cbc66-235c-4bd6-8571-98d2d8bba5e2'

export class DesktopIconsUsableAreaClass {
  _checkIfExtensionIsEnabled(extension) {
    return (
      extension?.state === ExtensionUtils.ExtensionState.ENABLED ||
      extension?.state === ExtensionUtils.ExtensionState.ACTIVE
    )
  }

  constructor() {
    const Me = Extension.lookupByURL(import.meta.url)
    this._UUID = Me.uuid
    this._extensionManager = Main.extensionManager
    this._timedMarginsID = 0
    this._margins = {}
    this._emID = this._extensionManager.connect(
      'extension-state-changed',
      (_obj, extension) => {
        if (!extension) return

        // If an extension is being enabled and lacks the DesktopIconsUsableArea object, we can avoid launching a refresh
        if (this._checkIfExtensionIsEnabled(extension)) {
          this._sendMarginsToExtension(extension)
          return
        }
        // if the extension is being disabled, we must do a full refresh, because if there were other extensions originally
        // loaded after that extension, those extensions will be disabled and enabled again without notification
        this._changedMargins()
      },
    )
  }

  /**
   * Sets or updates the top, bottom, left and right margins for a
   * monitor. Values are measured from the monitor border (and NOT from
   * the workspace border).
   *
   * @param {int} monitor Monitor number to which set the margins.
   *                      A negative value means "the primary monitor".
   * @param {int} top Top margin in pixels
   * @param {int} bottom Bottom margin in pixels
   * @param {int} left Left margin in pixels
   * @param {int} right Right margin in pixels
   */
  setMargins(monitor, top, bottom, left, right) {
    this._margins[monitor] = {
      top: top,
      bottom: bottom,
      left: left,
      right: right,
    }
    this._changedMargins()
  }

  /**
   * Clears the current margins. Must be called before configuring the monitors
   * margins with setMargins().
   */
  resetMargins() {
    this._margins = {}
    this._changedMargins()
  }

  /**
   * Disconnects all the signals and removes the margins.
   */
  destroy() {
    if (this._emID) {
      this._extensionManager.disconnect(this._emID)
      this._emID = 0
    }
    if (this._timedMarginsID) {
      GLib.source_remove(this._timedMarginsID)
      this._timedMarginsID = 0
    }
    this._margins = null
    this._changedMargins()
  }

  _changedMargins() {
    if (this._timedMarginsID) {
      GLib.source_remove(this._timedMarginsID)
    }
    this._timedMarginsID = GLib.timeout_add(GLib.PRIORITY_DEFAULT, 100, () => {
      this._sendMarginsToAll()
      this._timedMarginsID = 0
      return GLib.SOURCE_REMOVE
    })
  }

  _sendMarginsToAll() {
    this._extensionManager
      .getUuids()
      .forEach((uuid) =>
        this._sendMarginsToExtension(this._extensionManager.lookup(uuid)),
      )
  }

  _sendMarginsToExtension(extension) {
    // check that the extension is an extension that has the logic to accept
    // working margins
    if (!this._checkIfExtensionIsEnabled(extension)) return

    const usableArea = extension?.stateObj?.DesktopIconsUsableArea
    if (usableArea?.uuid === IDENTIFIER_UUID)
      usableArea.setMarginsForExtension(this._UUID, this._margins)
  }
}