src/cobalt/debug/devtools/front_end/layer_viewer/TransformController.js

/*
 * Copyright 2014 The Chromium Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

/**
 * @unrestricted
 */
LayerViewer.TransformController = class extends Common.Object {
  /**
   * @param {!Element} element
   * @param {boolean=} disableRotate
   */
  constructor(element, disableRotate) {
    super();
    this._shortcuts = {};
    this.element = element;
    if (this.element.tabIndex < 0)
      this.element.tabIndex = 0;
    this._registerShortcuts();
    UI.installDragHandle(
        element, this._onDragStart.bind(this), this._onDrag.bind(this), this._onDragEnd.bind(this), 'move', null);
    element.addEventListener('keydown', this._onKeyDown.bind(this), false);
    element.addEventListener('keyup', this._onKeyUp.bind(this), false);
    element.addEventListener('mousewheel', this._onMouseWheel.bind(this), false);
    this._minScale = 0;
    this._maxScale = Infinity;

    this._controlPanelToolbar = new UI.Toolbar('transform-control-panel');

    /** @type {!Object<string, !UI.ToolbarToggle>} */
    this._modeButtons = {};
    if (!disableRotate) {
      const panModeButton = new UI.ToolbarToggle(Common.UIString('Pan mode (X)'), 'largeicon-pan');
      panModeButton.addEventListener(
          UI.ToolbarButton.Events.Click, this._setMode.bind(this, LayerViewer.TransformController.Modes.Pan));
      this._modeButtons[LayerViewer.TransformController.Modes.Pan] = panModeButton;
      this._controlPanelToolbar.appendToolbarItem(panModeButton);
      const rotateModeButton = new UI.ToolbarToggle(Common.UIString('Rotate mode (V)'), 'largeicon-rotate');
      rotateModeButton.addEventListener(
          UI.ToolbarButton.Events.Click, this._setMode.bind(this, LayerViewer.TransformController.Modes.Rotate));
      this._modeButtons[LayerViewer.TransformController.Modes.Rotate] = rotateModeButton;
      this._controlPanelToolbar.appendToolbarItem(rotateModeButton);
    }
    this._setMode(LayerViewer.TransformController.Modes.Pan);

    const resetButton = new UI.ToolbarButton(Common.UIString('Reset transform (0)'), 'largeicon-center');
    resetButton.addEventListener(UI.ToolbarButton.Events.Click, this.resetAndNotify.bind(this, undefined));
    this._controlPanelToolbar.appendToolbarItem(resetButton);

    this._reset();
  }

  /**
   * @return {!UI.Toolbar}
   */
  toolbar() {
    return this._controlPanelToolbar;
  }

  _onKeyDown(event) {
    if (event.keyCode === UI.KeyboardShortcut.Keys.Shift.code) {
      this._toggleMode();
      return;
    }

    const shortcutKey = UI.KeyboardShortcut.makeKeyFromEventIgnoringModifiers(event);
    const handler = this._shortcuts[shortcutKey];
    if (handler && handler(event))
      event.consume();
  }

  _onKeyUp(event) {
    if (event.keyCode === UI.KeyboardShortcut.Keys.Shift.code)
      this._toggleMode();
  }

  _addShortcuts(keys, handler) {
    for (let i = 0; i < keys.length; ++i)
      this._shortcuts[keys[i].key] = handler;
  }

  _registerShortcuts() {
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.ResetView, this.resetAndNotify.bind(this));
    this._addShortcuts(
        UI.ShortcutsScreen.LayersPanelShortcuts.PanMode,
        this._setMode.bind(this, LayerViewer.TransformController.Modes.Pan));
    this._addShortcuts(
        UI.ShortcutsScreen.LayersPanelShortcuts.RotateMode,
        this._setMode.bind(this, LayerViewer.TransformController.Modes.Rotate));
    const zoomFactor = 1.1;
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.ZoomIn, this._onKeyboardZoom.bind(this, zoomFactor));
    this._addShortcuts(
        UI.ShortcutsScreen.LayersPanelShortcuts.ZoomOut, this._onKeyboardZoom.bind(this, 1 / zoomFactor));
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.Up, this._onKeyboardPanOrRotate.bind(this, 0, -1));
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.Down, this._onKeyboardPanOrRotate.bind(this, 0, 1));
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.Left, this._onKeyboardPanOrRotate.bind(this, -1, 0));
    this._addShortcuts(UI.ShortcutsScreen.LayersPanelShortcuts.Right, this._onKeyboardPanOrRotate.bind(this, 1, 0));
  }

  _postChangeEvent() {
    this.dispatchEventToListeners(LayerViewer.TransformController.Events.TransformChanged);
  }

  _reset() {
    this._scale = 1;
    this._offsetX = 0;
    this._offsetY = 0;
    this._rotateX = 0;
    this._rotateY = 0;
  }

  _toggleMode() {
    this._setMode(
        this._mode === LayerViewer.TransformController.Modes.Pan ? LayerViewer.TransformController.Modes.Rotate :
                                                                   LayerViewer.TransformController.Modes.Pan);
  }

  /**
   * @param {!LayerViewer.TransformController.Modes} mode
   */
  _setMode(mode) {
    if (this._mode === mode)
      return;
    this._mode = mode;
    this._updateModeButtons();
    this.element.focus();
  }

  _updateModeButtons() {
    for (const mode in this._modeButtons)
      this._modeButtons[mode].setToggled(mode === this._mode);
  }

  /**
   * @param {!Event=} event
   */
  resetAndNotify(event) {
    this._reset();
    this._postChangeEvent();
    if (event)
      event.preventDefault();
    this.element.focus();
  }

  /**
   * @param {number} minScale
   * @param {number} maxScale
   */
  setScaleConstraints(minScale, maxScale) {
    this._minScale = minScale;
    this._maxScale = maxScale;
    this._scale = Number.constrain(this._scale, minScale, maxScale);
  }

  /**
   * @param {number} minX
   * @param {number} maxX
   * @param {number} minY
   * @param {number} maxY
   */
  clampOffsets(minX, maxX, minY, maxY) {
    this._offsetX = Number.constrain(this._offsetX, minX, maxX);
    this._offsetY = Number.constrain(this._offsetY, minY, maxY);
  }

  /**
   * @return {number}
   */
  scale() {
    return this._scale;
  }

  /**
   * @return {number}
   */
  offsetX() {
    return this._offsetX;
  }

  /**
   * @return {number}
   */
  offsetY() {
    return this._offsetY;
  }

  /**
   * @return {number}
   */
  rotateX() {
    return this._rotateX;
  }

  /**
   * @return {number}
   */
  rotateY() {
    return this._rotateY;
  }

  /**
   * @param {number} scaleFactor
   * @param {number} x
   * @param {number} y
   */
  _onScale(scaleFactor, x, y) {
    scaleFactor = Number.constrain(this._scale * scaleFactor, this._minScale, this._maxScale) / this._scale;
    this._scale *= scaleFactor;
    this._offsetX -= (x - this._offsetX) * (scaleFactor - 1);
    this._offsetY -= (y - this._offsetY) * (scaleFactor - 1);
    this._postChangeEvent();
  }

  /**
   * @param {number} offsetX
   * @param {number} offsetY
   */
  _onPan(offsetX, offsetY) {
    this._offsetX += offsetX;
    this._offsetY += offsetY;
    this._postChangeEvent();
  }

  /**
   * @param {number} rotateX
   * @param {number} rotateY
   */
  _onRotate(rotateX, rotateY) {
    this._rotateX = rotateX;
    this._rotateY = rotateY;
    this._postChangeEvent();
  }

  /**
   * @param {number} zoomFactor
   */
  _onKeyboardZoom(zoomFactor) {
    this._onScale(zoomFactor, this.element.clientWidth / 2, this.element.clientHeight / 2);
  }

  /**
   * @param {number} xMultiplier
   * @param {number} yMultiplier
   */
  _onKeyboardPanOrRotate(xMultiplier, yMultiplier) {
    const panStepInPixels = 6;
    const rotateStepInDegrees = 5;

    if (this._mode === LayerViewer.TransformController.Modes.Rotate) {
      // Sic! _onRotate treats X and Y as "rotate around X" and "rotate around Y", so swap X/Y multiplers.
      this._onRotate(
          this._rotateX + yMultiplier * rotateStepInDegrees, this._rotateY + xMultiplier * rotateStepInDegrees);
    } else {
      this._onPan(xMultiplier * panStepInPixels, yMultiplier * panStepInPixels);
    }
  }

  /**
   * @param {!Event} event
   */
  _onMouseWheel(event) {
    /** @const */
    const zoomFactor = 1.1;
    /** @const */
    const mouseWheelZoomSpeed = 1 / 120;
    const scaleFactor = Math.pow(zoomFactor, event.wheelDeltaY * mouseWheelZoomSpeed);
    this._onScale(
        scaleFactor, event.clientX - this.element.totalOffsetLeft(), event.clientY - this.element.totalOffsetTop());
  }

  /**
   * @param {!Event} event
   */
  _onDrag(event) {
    if (this._mode === LayerViewer.TransformController.Modes.Rotate) {
      this._onRotate(
          this._oldRotateX + (this._originY - event.clientY) / this.element.clientHeight * 180,
          this._oldRotateY - (this._originX - event.clientX) / this.element.clientWidth * 180);
    } else {
      this._onPan(event.clientX - this._originX, event.clientY - this._originY);
      this._originX = event.clientX;
      this._originY = event.clientY;
    }
  }

  /**
   * @param {!MouseEvent} event
   */
  _onDragStart(event) {
    this.element.focus();
    this._originX = event.clientX;
    this._originY = event.clientY;
    this._oldRotateX = this._rotateX;
    this._oldRotateY = this._rotateY;
    return true;
  }

  _onDragEnd() {
    delete this._originX;
    delete this._originY;
    delete this._oldRotateX;
    delete this._oldRotateY;
  }
};

/** @enum {symbol} */
LayerViewer.TransformController.Events = {
  TransformChanged: Symbol('TransformChanged')
};

/**
 * @enum {string}
 */
LayerViewer.TransformController.Modes = {
  Pan: 'Pan',
  Rotate: 'Rotate',
};