How to draw a pie chart in android
Download the jar from
http://www.achartengine.org/content/download.html
Add the jar to the projects lib folder. There is a sample also provided by the developers. You can check that and modify the same as you wish.
There is also a demo @
http://www.achartengine.org/content/demo.html
The docs
http://www.achartengine.org/content/javadoc/org/achartengine/chart/PieChart.html
Example:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<LinearLayout
android:id="@+id/chart"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:orientation="horizontal" >
</LinearLayout>
</LinearLayout>
The Activity class
public class AChartEnginePieChartActivity extends Activity {
private static int[] COLORS = new int[] { Color.GREEN, Color.BLUE,Color.MAGENTA, Color.CYAN };
private static double[] VALUES = new double[] { 10, 11, 12, 13 };
private static String[] NAME_LIST = new String[] { "A", "B", "C", "D" };
private CategorySeries mSeries = new CategorySeries("");
private DefaultRenderer mRenderer = new DefaultRenderer();
private GraphicalView mChartView;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mRenderer.setApplyBackgroundColor(true);
mRenderer.setBackgroundColor(Color.argb(100, 50, 50, 50));
mRenderer.setChartTitleTextSize(20);
mRenderer.setLabelsTextSize(15);
mRenderer.setLegendTextSize(15);
mRenderer.setMargins(new int[] { 20, 30, 15, 0 });
mRenderer.setZoomButtonsVisible(true);
mRenderer.setStartAngle(90);
for (int i = 0; i < VALUES.length; i++) {
mSeries.add(NAME_LIST[i] + " " + VALUES[i], VALUES[i]);
SimpleSeriesRenderer renderer = new SimpleSeriesRenderer();
renderer.setColor(COLORS[(mSeries.getItemCount() - 1) % COLORS.length]);
mRenderer.addSeriesRenderer(renderer);
}
if (mChartView != null) {
mChartView.repaint();
}
}
@Override
protected void onResume() {
super.onResume();
if (mChartView == null) {
LinearLayout layout = (LinearLayout) findViewById(R.id.chart);
mChartView = ChartFactory.getPieChartView(this, mSeries, mRenderer);
mRenderer.setClickEnabled(true);
mRenderer.setSelectableBuffer(10);
mChartView.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
SeriesSelection seriesSelection = mChartView.getCurrentSeriesAndPoint();
if (seriesSelection == null) {
Toast.makeText(AChartEnginePieChartActivity.this,"No chart element was clicked",Toast.LENGTH_SHORT).show();
}
else {
Toast.makeText(AChartEnginePieChartActivity.this,"Chart element data point index "+ (seriesSelection.getPointIndex()+1) + " was clicked" + " point value="+ seriesSelection.getValue(), Toast.LENGTH_SHORT).show();
}
}
});
mChartView.setOnLongClickListener(new View.OnLongClickListener() {
@Override
public boolean onLongClick(View v) {
SeriesSelection seriesSelection = mChartView.getCurrentSeriesAndPoint();
if (seriesSelection == null) {
Toast.makeText(AChartEnginePieChartActivity.this,"No chart element was long pressed", Toast.LENGTH_SHORT);
return false;
}
else {
Toast.makeText(AChartEnginePieChartActivity.this,"Chart element data point index "+ seriesSelection.getPointIndex()+ " was long pressed",Toast.LENGTH_SHORT);
return true;
}
}
});
layout.addView(mChartView, new LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT));
}
else {
mChartView.repaint();
}
}
}
Alternatively, if you don't want to use thrid-party libraries, you can use this formula to get points on the circle, given radius r
:
x = r * Math.cos(2 * Math.PI) //This will give you r
y = r * Math.sin(2 * Math.PI) //This will give you 0
For other points of the circle you need to modify your cosine argument, for example:
x = r * Math.cos(2 * Math.PI / 6) //This will give you r/2
y = r * Math.sin(2 * Math.PI / 6) //This will give you r*sqrt(3/2)
If you want to fill out the entire circle with a fixed step n:
for(int i=0;i<n;i++) {
x = r * Math.cos(2 * Math.PI * i / n)
y = r * Math.sin(2 * Math.PI * i / n)
//Draw PointF(x,y)
}