PieChart.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 java.util.ArrayList;
import java.util.List;

import org.achartengine.model.CategorySeries;
import org.achartengine.model.Point;
import org.achartengine.model.SeriesSelection;
import org.achartengine.renderer.DefaultRenderer;

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

/**
 * The pie chart rendering class.
 */
public class PieChart extends RoundChart {

  /** Handles returning values when tapping on PieChart. */
  private PieMapper mPieMapper;

  /**
   * Builds a new pie chart instance.
   * 
   * @param dataset the series dataset
   * @param renderer the series renderer
   */
  public PieChart(CategorySeries dataset, DefaultRenderer renderer) {
    super(dataset, renderer);
    mPieMapper = new PieMapper();
  }

  /**
   * The graphical representation of the pie chart.
   * 
   * @param canvas the canvas to paint to
   * @param x the top left x value of the view to draw to
   * @param y the top left y value of the view to draw to
   * @param width the width of the view to draw to
   * @param height the height of the view to draw to
   * @param paint the paint
   */
  @Override
  public void draw(Canvas canvas, int x, int y, int width, int height, Paint paint) {
    paint.setAntiAlias(mRenderer.isAntialiasing());
    paint.setStyle(Style.FILL);
    paint.setTextSize(mRenderer.getLabelsTextSize());
    int legendSize = getLegendSize(mRenderer, height / 5, 0);
    int left = x;
    int top = y;
    int right = x + width;
    int sLength = mDataset.getItemCount();
    double total = 0;
    String[] titles = new String[sLength];
    for (int i = 0; i < sLength; i++) {
      total += mDataset.getValue(i);
      titles[i] = mDataset.getCategory(i);
    }
    if (mRenderer.isFitLegend()) {
      legendSize = drawLegend(canvas, mRenderer, titles, left, right, y, width, height, legendSize,
          paint, true);
    }
    int bottom = y + height - legendSize;
    drawBackground(mRenderer, canvas, x, y, width, height, paint, false, DefaultRenderer.NO_COLOR);

    float currentAngle = 0;
    int mRadius = Math.min(Math.abs(right - left), Math.abs(bottom - top));

    int radius = (int) (mRadius * 0.35 * mRenderer.getScale());

    if (mCenterX == NO_VALUE) {
      mCenterX = (left + right) / 2;
    }
    if (mCenterY == NO_VALUE) {
      mCenterY = (bottom + top) / 2;
    }

    // Hook in clip detection after center has been calculated
    mPieMapper.setDimensions(radius, mCenterX, mCenterY);
    boolean loadPieCfg = !mPieMapper.areAllSegmentPresent(sLength);
    if (loadPieCfg) {
      mPieMapper.clearPieSegments();
    }

    float shortRadius = radius * 0.9f;
    float longRadius = radius * 1.1f;

    RectF oval = new RectF(mCenterX - radius, mCenterY - radius, mCenterX + radius, mCenterY
        + radius);
    List<RectF> prevLabelsBounds = new ArrayList<RectF>();

    for (int i = 0; i < sLength; i++) {
      paint.setColor(mRenderer.getSeriesRendererAt(i).getColor());
      float value = (float) mDataset.getValue(i);
      float angle = (float) (value / total * 360);
      canvas.drawArc(oval, currentAngle, angle, true, paint);
      drawLabel(canvas, mDataset.getCategory(i), mRenderer, prevLabelsBounds, mCenterX, mCenterY,
          shortRadius, longRadius, currentAngle, angle, left, right, paint);

      // Save details for getSeries functionality
      if (loadPieCfg) {
        mPieMapper.addPieSegment(i, value, currentAngle, angle);
      }
      currentAngle += angle;
    }
    prevLabelsBounds.clear();
    drawLegend(canvas, mRenderer, titles, left, right, y, width, height, legendSize, paint, false);
    drawTitle(canvas, x, y, width, paint);
  }

  public SeriesSelection getSeriesAndPointForScreenCoordinate(Point screenPoint) {
    return mPieMapper.getSeriesAndPointForScreenCoordinate(screenPoint);
  }

}