gr-opacity-diff-mode/gr-opacity-diff-mode.js

// Copyright (C) 2018 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
(function() {
  'use strict';
  Polymer({
    is: 'gr-opacity-diff-mode',

    properties: {
      baseImage: Object,
      revisionImage: Object,
      opacityValue: Number,
      _maxHeight: {
        type: Number,
        value: 0,
      },
      _maxWidth: {
        type: Number,
        value: 0,
      },
    },

    observers: [
      '_handleImageChange(baseImage, revisionImage)',
      '_handleHeightChange(_maxHeight)',
      '_handleWidthChange(_maxWidth)',
    ],

    _onImageLoad(e) {
      this._maxHeight = Math.max(this._maxHeight,
          Polymer.dom(e).rootTarget.naturalHeight);
      this._maxWidth = Math.max(this._maxWidth,
          Polymer.dom(e).rootTarget.naturalWidth);
    },

    _handleImageChange(baseImage, revisionImage) {
      this.$.imageRevision.setAttribute('src',
          this.computeSrcString(this.revisionImage));
      this.$.imageBase.setAttribute('src',
          this.computeSrcString(this.baseImage));
      this.handleOpacityChange();
    },

    handleOpacityChange() {
      this.customStyle['--my-opacity-value'] = this.$.opacitySlider.value;
      this.updateStyles();
    },

    computeSrcString(image) {
      return 'data:' + image['type'] + ';base64, ' + image['body'];
    },

    handleScaleSizesToggle() {
      let width;
      let height;
      if (this.$.scaleSizesToggle.checked) {
        width = this._maxWidth;
        height = this._maxHeight;
      }

      this.customStyle['--img-width'] = width ? width + 'px' : null;
      this.customStyle['--img-height'] = height ? height + 'px' : null;
      this.updateStyles();
    },

    _handleHeightChange(height) {
      if (!height) { return; }
      this.customStyle['--div-height'] = height + 'px';
      this.updateStyles();
    },

    _handleWidthChange(width) {
      if (!width) { return; }
      this.customStyle['--div-width'] = width + 'px';
      this.updateStyles();
    },
  });
})();