PieGraph, showing progress on a circle chart.

attrs.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <declare-styleable name="PieGraph">
        <attr name="pieProgressPercent" format="integer"/>
        <attr name="pieBackgroundColor" format="color"/>
        <attr name="pieProgressColor" format="color"/>
    </declare-styleable>

</resources>

inside_my_layout.xml

...

<org.mycompany.myapp.ui.common.PieGraph
  android:layout_width="24dp"
  android:layout_height="24dp"
  app:pieBackgroundColor="#ffffff"
  app:pieProgressColor="#000000"
  app:pieProgressPercent="25"/>

...

PieGraph.java

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;

/**
 * Shows progress on a circle chart.
 */
public class PieGraph extends View {

    private Paint backgroundPaint = new Paint(), progressPaint = new Paint();
    private RectF drawRectF;
    private int progressRadius;

    public PieGraph(Context context, AttributeSet attrs) {
        super(context, attrs);

        initPaint();

        parseValuesFromAttributes(context, attrs);
    }

    /**
     * Sets the progress percentage of this pie graph. Same as using 'pieProgressPercent' in xml.
     */
    public void setProgressPercent(int progressPercent) {

        this.progressRadius = (int) ((360f / 100f) * progressPercent);

        invalidate();
    }

    private void initPaint() {

        backgroundPaint.setAntiAlias(true);
        backgroundPaint.setDither(true);
        backgroundPaint.setStyle(Paint.Style.FILL);

        progressPaint.setAntiAlias(true);
        progressPaint.setDither(true);
        progressPaint.setStyle(Paint.Style.FILL);
    }

    private void parseValuesFromAttributes(Context context, AttributeSet attrs) {

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.PieGraph);

        try {

            backgroundPaint.setColor(a.getColor(R.styleable.PieGraph_pieBackgroundColor, 0));
            progressPaint.setColor(a.getColor(R.styleable.PieGraph_pieProgressColor, 0));

            setProgressPercent(a.getInt(R.styleable.PieGraph_pieProgressPercent, 0));

        } finally {
            a.recycle();
        }
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {

        super.onSizeChanged(w, h, oldw, oldh);

        drawRectF = new RectF(0, 0, h, h);
    }

    @Override
    protected void onDraw(Canvas canvas) {

        canvas.drawArc(drawRectF, -90, progressRadius, true, progressPaint);
        canvas.drawArc(drawRectF, -90 + progressRadius, 360 - progressRadius, true, backgroundPaint);
    }
}

PieGraphBindingAdapters.java

/**
 * Binding adapters for PieGraph. Only needed when you use data binding.
 */
public class PieGraphBindingAdapters {

    @BindingAdapter("pieProgressPercent")
    public static void setPieProgressPercent(PieGraph view, int pieProgressPercent) {
        view.setProgressPercent(pieProgressPercent);
    }
}