px-vis-cell-canvas.html

<!--
Copyright (c) 2018, General Electric

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.
-->

<link rel="import" href="../polymer/polymer.html"/>
<link rel="import" href="px-vis-behavior-common.html" />
<link rel="import" href="px-vis-behavior-d3.html" />
<link rel="import" href="css/px-vis-styles.html">

<!--

### Usage
      <px-vis-svg-canvas
        width="[[width]]"
        height="[[height]]"
        margin="[[margin]]"
        canvas-context="{{canvasContext}}">
      </px-vis-svg-canvas>
      <px-vis-scale
        x-axis-type="time"
        y-axis-type="linear"
        complete-series-config="[[seriesConfig]]"
        data-extents="[[dataExtents]]"
        width="[[width]]"
        height="[[height]]"
        margin="[[margin]]"
        chart-data={{chartData}}
        x="{{x}}"
        y="{{y}}"
        domainChanged="{{domainChanged}}"
        selected-domain="[[selectedDomain]]">
      </px-vis-scale>
      <px-vis-cell-canvas
        series-id="mySeries"
        complete-series-config="[[seriesConfig]]"
        chart-data="[[chartData]]"
        x="[[x]]"
        y="[[y]]"
        width="[[width]]"
        height="[[height]]"
        margin="[[margin]]"
        canvas-context="[[canvasContext]]"
        domain-changed="[[domainChanged]]">
      </px-vis-cell-canvas>

@element px-vis-line
@blurb Element which draws cells onto the chart
@homepage index.html
@demo demo.html
-->

<dom-module id="px-vis-cell-canvas">
    <template>
      <style include="px-vis-styles"></style>

    </template>
</dom-module>

<script>
  Polymer({
    is: 'px-vis-cell-canvas',

    behaviors: [
      PxVisBehaviorD3.canvasContext,
      PxVisBehavior.sizing,
      PxVisBehavior.dataset,
      PxVisBehavior.commonMethods,
      PxVisBehavior.completeSeriesConfig,
      PxVisBehavior.rendererType,
      PxVisBehaviorD3.clipPathBoolean
    ],

    /**
     * Properties block, expose attribute values to the DOM via 'reflect'
     *
     * @property properties
     * @type Object
     */
    properties: {
      showCellValue: {
        type: Boolean,
        value: false
      },
      colorScale: {
        type: Object
      },
      /**
       * Options currently in use for drawing lines: opacity, color, etc.
       */
      _currentDrawingOptions: {
        type: Object,
        value:function() {
          return {};
        },

        squareMode: {
          type: Boolean,
          value: false
        }
      }
    },

    attached: function() {
      this.fire('px-vis-renderer-register', {'type': 'cell', 'renderMode': 'canvas', 'rendererType': this.rendererType, 'priority': 0});
    },

    detached: function() {
      this.fire('px-vis-renderer-unregister',{'renderMode': 'canvas','rendererType': this.rendererType});
    },

    /**
     * Defines the appropriate line generator and updates drawing
     * variables: opacity, colors, etc.
     */
    initializeDrawingSession: function() {

      this._currentDrawingOptions.cellTextColor = this._checkThemeVariable('--px-vis-cell-text-color', 'rgb(0,0,0)');
      this._currentDrawingOptions.cellTextSize = this._checkThemeVariable('--px-vis-cell-text-size', '12');

    },

    /**
     * Draws a clip path for canvas.
     *
     * @method drawClipPath
     */
    drawClipPath: function() {
      this.canvasContext.beginPath();

      var w = Math.max(this.width - this.margin.left - this.margin.right,0),
          h = Math.max(this.height - this.margin.top - this.margin.bottom,0);

      this.canvasContext.rect(0, 0, w, h);
      this.canvasContext.clip();
    },

    renderOneBatch: function(start, stop) {

      this.canvasContext.save();

      if(this.clipPath) {
        this.drawClipPath();
      }

      for(var i=start; i<stop; i++) {
        this._drawCell(this.chartData[i]);
      }

      this.canvasContext.restore();
    },

    _drawCell: function(cellData) {
        const borderWidth = this.cellBorderWidth,
              valueKey = this.completeSeriesConfig[this.seriesId].value,
              xKey = this.completeSeriesConfig[this.seriesId].x,
              yKey = this.completeSeriesConfig[this.seriesId].y;
        let width,
            height;

        if(this.squareMode) {
          width = Math.min(this.x.bandwidth(), this.y.bandwidth());
          height = width;
        } else {
          width = this.x.bandwidth();
          height = this.y.bandwidth();
        }


        // draw and fill rectangle
        this.canvasContext.beginPath();
        this.canvasContext.fillStyle = this.colorScale(cellData[valueKey]);
        this.canvasContext.fillRect(this.x(cellData[xKey]), this.y(cellData[yKey]), width, height);

        // draw text value if needed
        if (this.showCellValue) {
          const xPos = this.x(cellData[xKey]) + width / 2;
          const yPos = this.y(cellData[yKey]) + height / 2;
          this.canvasContext.beginPath();
          this.canvasContext.font = this._currentDrawingOptions.cellTextSize + ' Arial';
          this.canvasContext.fillStyle = this._currentDrawingOptions.cellTextColor;
          this.canvasContext.textAlign = 'center';
          this.canvasContext.textBaseline = 'middle';
          this.canvasContext.fillText(cellData[valueKey], xPos, yPos, width);
        }
      },
  });
</script>