LineChart.java

/**
 * Copyright (C) 2009, 2010 SC 4ViewSoft SRL
 *  
 * 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.
 */
package org.achartengine.chart;

import org.achartengine.model.XYMultipleSeriesDataset;
import org.achartengine.renderer.SimpleSeriesRenderer;
import org.achartengine.renderer.XYMultipleSeriesRenderer;
import org.achartengine.renderer.XYSeriesRenderer;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.RectF;

/**
 * The line chart rendering class.
 */
public class LineChart extends XYChart {
  /** The constant to identify this chart type. */
  public static final String TYPE = "Line";
  /** The legend shape width. */
  private static final int SHAPE_WIDTH = 30;
  /** The scatter chart to be used to draw the data points. */
  private ScatterChart pointsChart;

  LineChart() {
  }

  /**
   * Builds a new line chart instance.
   * 
   * @param dataset the multiple series dataset
   * @param renderer the multiple series renderer
   */
  public LineChart(XYMultipleSeriesDataset dataset, XYMultipleSeriesRenderer renderer) {
    super(dataset, renderer);
    pointsChart = new ScatterChart(dataset, renderer);
  }

  /**
   * Sets the series and the renderer.
   * 
   * @param dataset the series dataset
   * @param renderer the series renderer
   */
  protected void setDatasetRenderer(XYMultipleSeriesDataset dataset,
      XYMultipleSeriesRenderer renderer) {
    super.setDatasetRenderer(dataset, renderer);
    pointsChart = new ScatterChart(dataset, renderer);
  }

  /**
   * The graphical representation of a series.
   * 
   * @param canvas the canvas to paint to
   * @param paint the paint to be used for drawing
   * @param points the array of points to be used for drawing the series
   * @param seriesRenderer the series renderer
   * @param yAxisValue the minimum value of the y axis
   * @param seriesIndex the index of the series currently being drawn
   */
  public void drawSeries(Canvas canvas, Paint paint, float[] points,
      SimpleSeriesRenderer seriesRenderer, float yAxisValue, int seriesIndex) {
    int length = points.length;
    XYSeriesRenderer renderer = (XYSeriesRenderer) seriesRenderer;
    float lineWidth = paint.getStrokeWidth();
    paint.setStrokeWidth(renderer.getLineWidth());
    if (renderer.isFillBelowLine()) {
      paint.setColor(renderer.getFillBelowLineColor());
      int pLength = points.length;
      float[] fillPoints = new float[pLength + 4];
      System.arraycopy(points, 0, fillPoints, 0, length);
      fillPoints[0] = points[0] + 1;
      fillPoints[length] = fillPoints[length - 2];
      fillPoints[length + 1] = yAxisValue;
      fillPoints[length + 2] = fillPoints[0];
      fillPoints[length + 3] = fillPoints[length + 1];
      paint.setStyle(Style.FILL);
      drawPath(canvas, fillPoints, paint, true);
    }
    paint.setColor(seriesRenderer.getColor());
    paint.setStyle(Style.STROKE);
    drawPath(canvas, points, paint, false);
    paint.setStrokeWidth(lineWidth);
  }

  @Override
  protected RectF[] clickableAreasForPoints(float[] points, float yAxisValue, int seriesIndex) {
    int length = points.length;
    RectF[] ret = new RectF[length / 2];
    for (int i = 0; i < length; i += 2) {
      int selectableBuffer = mRenderer.getSelectableBuffer();
      ret[i / 2] = new RectF(points[i] - selectableBuffer, points[i + 1] - selectableBuffer,
          points[i] + selectableBuffer, points[i + 1] + selectableBuffer);
    }
    return ret;
  }

  /**
   * Returns the legend shape width.
   * 
   * @param seriesIndex the series index
   * @return the legend shape width
   */
  public int getLegendShapeWidth(int seriesIndex) {
    return SHAPE_WIDTH;
  }

  /**
   * The graphical representation of the legend shape.
   * 
   * @param canvas the canvas to paint to
   * @param renderer the series renderer
   * @param x the x value of the point the shape should be drawn at
   * @param y the y value of the point the shape should be drawn at
   * @param seriesIndex the series index
   * @param paint the paint to be used for drawing
   */
  public void drawLegendShape(Canvas canvas, SimpleSeriesRenderer renderer, float x, float y,
      int seriesIndex, Paint paint) {
    canvas.drawLine(x, y, x + SHAPE_WIDTH, y, paint);
    if (isRenderPoints(renderer)) {
      pointsChart.drawLegendShape(canvas, renderer, x + 5, y, seriesIndex, paint);
    }
  }

  /**
   * Returns if the chart should display the points as a certain shape.
   * 
   * @param renderer the series renderer
   */
  public boolean isRenderPoints(SimpleSeriesRenderer renderer) {
    return ((XYSeriesRenderer) renderer).getPointStyle() != PointStyle.POINT;
  }

  /**
   * Returns the scatter chart to be used for drawing the data points.
   * 
   * @return the data points scatter chart
   */
  public ScatterChart getPointsChart() {
    return pointsChart;
  }

  /**
   * Returns the chart type identifier.
   * 
   * @return the chart type
   */
  public String getChartType() {
    return TYPE;
  }

}