I want to draw charts like pie charts to display stats in my Android
app. As Android doesn't support Swing and AWT, i wonder how can i draw
charts in Android? Please note that i don't want to use a third party
tool.
This is something i have come up with after looking into API Demos:
package com.examples.piechart;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.os.Bundle;
import android.view.View;
public class PieChart extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(new SampleView(this));
}
private static class SampleView extends View{
private Paint[] mPaints;
private Paint mFramePaint;
private boolean[] mUseCenters;
private RectF[] mOvals;
private RectF mBigOval;
private float mStart;
private float mSweep;
private int mBigIndex;
private static final float SWEEP_INC = 2;
private static final float START_INC = 30;
public SampleView(Context context) {
super(context);
mPaints = new Paint[4];
mUseCenters = new boolean[4];
mOvals = new RectF[4];
mPaints[0] = new Paint();
mPaints[0].setAntiAlias(true);
mPaints[0].setStyle(Paint.Style.FILL);
mPaints[0].setColor(0x88FF0000);
mUseCenters[0] = false;
mPaints[1] = new Paint(mPaints[0]);
mPaints[1].setColor(0x8800FF00);
mUseCenters[1] = true;
mPaints[2] = new Paint(mPaints[0]);
mPaints[2].setStyle(Paint.Style.STROKE);
mPaints[2].setStrokeWidth(4);
mPaints[2].setColor(0x880000FF);
mUseCenters[2] = false;
mPaints[3] = new Paint(mPaints[2]);
mPaints[3].setColor(0x88888888);
mUseCenters[3] = true;
mBigOval = new RectF(40, 10, 280, 250);
//mOvals[0] = new RectF( 10, 270, 70, 330);
mOvals[1] = new RectF( 90, 270, 150, 330);
mOvals[2] = new RectF(170, 270, 230, 330);
mOvals[3] = new RectF(250, 270, 310, 330);
mFramePaint = new Paint();
mFramePaint.setAntiAlias(true);
mFramePaint.setStyle(Paint.Style.STROKE);
mFramePaint.setStrokeWidth(0);
}
private void drawArcs(Canvas canvas, RectF oval, boolean
useCenter,
Paint paint) {
canvas.drawRect(oval, mFramePaint);
canvas.drawArc(oval, mStart, mSweep, useCenter, paint);
}
@Override protected void onDraw(Canvas canvas) {
canvas.drawColor(Color.WHITE);
drawArcs(canvas, mBigOval, mUseCenters[1],
mPaints[1]);
/*
for (int i = 0; i < 2; i++) {
drawArcs(canvas, mOvals[i], mUseCenters[i],
mPaints[i]);
drawArcs(canvas, mOvals[1], mUseCenters[1],
mPaints[1]);
}
*/
drawArcs(canvas, mOvals[1], mUseCenters[1], mPaints[1]);
mSweep += SWEEP_INC;
//We need to set the mSweep to a percentage of 360
degrees.
if (mSweep > 360) {
mSweep -= 360;
mStart += START_INC;
if (mStart >= 360) {
mStart -= 360;
}
mBigIndex = (mBigIndex + 1) % mOvals.length;
}
invalidate();
}
}
};
Wonder how can we improve this code further?
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