pub/charted/lib/charts/chart_renderer.dart

/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file or at
 * https://developers.google.com/open-source/licenses/bsd
 */

part of charted.charts;

/**
 * Renders the chart on a compatible [ChartArea].
 */
abstract class ChartRenderer {
  /**
   * Returns extent of the series. This extent is used by [ChartArea] to
   * set the output range of the corresponding scale/axis of the series.
   *
   * Extent has valid values only if [prepare] was already called.
   */
  Extent get extent;

  /**
   * Indicates if this renderer uses range "band" on any of the dimension
   * axis. Band is space taken on the dimension axis (if more than a point).
   *
   * Examples:
   *   A bar chart takes up space (width of the bar) on the dimension axis.
   *   A line chart does not take any space
   */
  Iterable<int> get dimensionsUsingBand;

  /**
   * Hint for padding between two bands that the ChartArea could use. This
   * getter is called only for renderers that have [dimensionsUsingBand]
   * set to non-empty list.
   */
  double get bandInnerPadding;

  /**
   * Hint for padding before the first and after the last bands that the
   * ChartArea could use.  This getter is called only for renderers that have
   * [dimensionsUsingBand] set to non-empty list.
   */
  double get bandOuterPadding;

  /**
   * Stream of events that indicate that user clicked on a displayed value
   */
  Stream<ChartEvent> get onValueMouseClick;

  /**
   * Stream of events that indicate that user moved the mouse pointer out
   * over a displayed value
   */
  Stream<ChartEvent> get onValueMouseOver;

  /**
   * Stream of events that indicate that user moved the mouse pointer out
   * of a displayed value
   */
  Stream<ChartEvent> get onValueMouseOut;

  /**
   * Prepare the chart for rendering.
   * - [area] represents the [ChartArea] on which the chart is rendered.
   * - [series] represents the [ChartSeries] that is rendered
   */
  bool prepare(ChartArea area, ChartSeries series);

  /**
   * Render series data on the passed [host].
   * Draw will not be successful if [prepare] was not already called.
   */
  void draw(Element host);

  /**
   * Clears DOM created by this renderer and releases
   * references to passed objects.
   */
  void dispose();
}