Android: Custom circle ProgressBar with spaces in between

Question

I am trying to create a custom view that has a Circle and in it, I have to have sections in run time as shown in the image below. I tried a lot of stuff in onDraw method but got no luck. I even tried https://github.com/donvigo/CustomProgressControls . Basically, I want to give a number of sections and then in each section I can select colors as per my need.

I am looking for ProgressBar that should have gap/space as shown in the image; in between circles. Say if I have given 5 sections, 3 of which should be "full", it should color the first 3 in red, and the other 2 in green, for example.

To draw I am doing like:

private void initExternalCirclePainter() {
    internalCirclePaint = new Paint(); 
    internalCirclePaint.setAntiAlias(true);    
    internalCirclePaint.setStrokeWidth(internalStrokeWidth);  
    internalCirclePaint.setColor(color); 
    internalCirclePaint.setStyle(Paint.Style.STROKE);
    internalCirclePaint.setPathEffect(new DashPathEffect(new float[]{dashWith, dashSpace}, dashSpace));
} 

Answer 1

I might be a little late to the party, but I actually wrote a custom component that has 2 rings that look quite similar to what you're trying to achieve. You can just remove the outer ring easily. The image of what I got in the end:

Here's the class:

public class RoundedSectionProgressBar extends View {
// The amount of degrees that we wanna reserve for the divider between 2 sections
private static final float DIVIDER_ANGLE = 7;
public static final float DEGREES_IN_CIRCLE = 360;
public static final int PADDING = 18;
public static final int PADDING2 = 12;

protected final Paint paint = new Paint();
protected final Paint waitingPaint = new Paint();
protected final Paint backgroundPaint = new Paint();
private int totalSections = 5;
private int fullSections = 2;
private int waiting = 3; // The outer ring. You can omit this
private RectF rect = new RectF();

public RoundedSectionProgressBar(Context context) {
    super(context);
    init(context, null);
}

public RoundedSectionProgressBar(Context context, @Nullable AttributeSet attrs) {
    super(context, attrs);
    init(context, attrs);
}

public RoundedSectionProgressBar(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
    init(context, attrs);
}

private void init(Context context, AttributeSet attrs) {
    // Can come from attrs if need be?
    int strokeWidth = 3;
    setupPaint(context, strokeWidth, paint, R.color.filled_color_inner_ring);
    setupPaint(context, strokeWidth, waitingPaint, R.color.empty_color_inner_ring);
    setupPaint(context, strokeWidth, backgroundPaint, R.color.filled_color_outer_ring);
}

private void setupPaint(Context context, int strokeWidth, Paint backgroundPaint, int colorRes) {
    backgroundPaint.setStrokeCap(Paint.Cap.SQUARE);
    backgroundPaint.setColor(context.getResources().getColor(colorRes));
    backgroundPaint.setAntiAlias(true);
    backgroundPaint.setStrokeWidth(strokeWidth);
    backgroundPaint.setStyle(Paint.Style.STROKE);
}

public int getTotalSections() {
    return totalSections;
}

public void setTotalSections(int totalSections) {
    this.totalSections = totalSections;
    invalidate();
}

public int getFullSections() {
    return fullSections;
}

public void setNumberOfSections(int fullSections, int totalSections, int waiting) {
    this.fullSections = fullSections;
    this.totalSections = totalSections;
    this.waiting = waiting;
    invalidate();
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    rect.set(getLeft() + PADDING, getTop() + PADDING, getRight() - PADDING, getBottom() - PADDING);
    float angleOfSection = (DEGREES_IN_CIRCLE / totalSections) - DIVIDER_ANGLE;
    // Drawing the inner ring
    for (int i = 0; i < totalSections; i++) {
        // -90 because it doesn't start at the top, so rotate by -90
        // divider_angle/2 especially in 2 sections, it's visibly rotated by Divider angle, so we split this between last and first
        float startAngle = -90 + i * (angleOfSection + DIVIDER_ANGLE) + DIVIDER_ANGLE / 2;
        if (i < fullSections) {
            canvas.drawArc(rect, startAngle, angleOfSection, false, paint);
        } else {
            canvas.drawArc(rect, startAngle, angleOfSection, false, backgroundPaint);
        }
    }
    // Drawing the outer ring
    rect.set(getLeft() + PADDING2, getTop() + PADDING2, getRight() - PADDING2, getBottom() - PADDING2);
    for (int i = 0; i < waiting; i++) {
        float startAngle = -90 + i * (angleOfSection + DIVIDER_ANGLE) + DIVIDER_ANGLE / 2;
        canvas.drawArc(rect, startAngle, angleOfSection, false, waitingPaint);
    }
}
}

Notice that this code won't give you the outer ring's 'empty' slots, since we decided against them in the end. The inner circle will have both the empty and filled slots. The whole class can be reused, and it's responsible just for the 2 rings that are drawn, the 6/6, +3 and the red circle are parts of another view.

The most important piece of the code is the onDraw method. It contains the logic for drawing the arcs in the for loop, as well as the logic for calculating the angles and adding spaces between them. Everything is rotated by -90 degrees, because I needed it to start at the top, rather than on the right, as it is the 0-degree angle in Android. It's not that complex, and you can modify it to fit your needs better should you need to.

Answer 2

I find it easier to do math for drawArc(operating on angle values based on number of sections) rather than computing the arc length. Here's a quick idea, with a lot of hard-coded properties, but you should be able to get the idea:

public class MyStrokeCircleView extends View {
    private Paint mPaint;
    private RectF mRect;
    private int mPadding;

    private int mSections;
    private int mFullArcSliceLength;
    private int mColorArcLineLength;
    private int mArcSectionGap;

    public MyStrokeCircleView(Context context) {
        super(context);
        init(null, 0);
    }

    public MyStrokeCircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs, 0);
    }

    public MyStrokeCircleView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(attrs, defStyle);
    }

    private void init(AttributeSet attrs, int defStyle) {
        mPaint = new Paint();
        mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(10);
        mPaint.setColor(ContextCompat.getColor(getContext(), android.R.color.darker_gray));

        mPadding = 5;
        mRect = new RectF(mPadding, mPadding, mPadding, mPadding);

        mSections = 4;
        mFullArcSliceLength = 360 / mSections;
        mArcSectionGap = mFullArcSliceLength / 10;
        mColorArcLineLength = mFullArcSliceLength - 2 * mArcSectionGap;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mRect.right = getWidth() - mPadding;
        mRect.bottom = getHeight() - mPadding;
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        for (int i = 0; i < mSections; i++) {
            canvas.drawArc(mRect, i * mFullArcSliceLength + mArcSectionGap, mColorArcLineLength, false, mPaint);
        }
    }
}