CODEWITHSUNDEEP
androidandroid-canvasondraw
Raghav Sood
Raghav Sood

Reputation: 82563

Canvas.drawArc() doesn't draw anything

I'm trying to draw an arc to overlay on top of some part of an existing circle. Both of my circles draw perfectly fine, but neither my drawArc() call or my drawRect() call seem to do anything. The app does not crash, there is no exception. It just fails silently.

onDraw() code:

@Override
protected void onDraw(Canvas canvas) {
    int width = getWidth();
    int height = getHeight();

    int size = (width > height) ? height : width;

    float cx = width / 2;
    float cy = height / 2;
    float radius = size / 2;

    float left = cx - radius;
    float right = cx + radius;
    float top = cy - radius;
    float bottom = cy + radius;

    RectF rect = new RectF(left, top, right, bottom);
    RectF rect2 = new RectF(canvas.getClipBounds());

    Log.d("MyTag", "Left: " + rect.left + "Right: " + rect.right + "Top: " + rect.top + "Bottom: " + rect.bottom);
    Log.d("MyTag", "Left: " + rect2.left + "Right: " + rect2.right + "Top: " + rect2.top + "Bottom: "
            + rect2.bottom);

    canvas.drawCircle(cx, cy, radius, circleRing);//Works
    canvas.drawCircle(cx, cy, radius - barWidth, innerColor);//Works
    canvas.drawArc(rect, 0, angle, true, circleColor);//Doesn't work
    canvas.drawRect(rect, circleColor);//Doesn't work

    super.onDraw(canvas);
}

I have confirmed that my circleColor Paint is properly setup, and that angle is a valid value for an arc.

My paints are setup as follows in a {} block so that all constructors use it:

{
    circleColor = new Paint();
    innerColor = new Paint();
    circleRing = new Paint();

    circleColor.setColor(color.holo_blue_light);
    innerColor.setColor(Color.BLACK);
    circleRing.setColor(Color.GRAY);

    circleColor.setAntiAlias(true);
    innerColor.setAntiAlias(true);
    circleRing.setAntiAlias(true);

    circleColor.setStrokeWidth(50);
    innerColor.setStrokeWidth(5);
    circleRing.setStrokeWidth(5);

    circleColor.setStyle(Paint.Style.FILL);
}

What I have tried:

The Logcat shows that my RectF has valid points, just top and bottom scaled to form a square:

01-25 13:33:39.877: D/MyTag(21612): Left: 0.0 Right: 720.0 Top: 159.0 Bottom: 879.0 //Mine
01-25 13:33:39.877: D/MyTag(21612): Left: 0.0 Right: 720.0 Top: 0.0 Bottom: 1038.0 //Canvas'

Does anybody know what could be causing this?

Upvotes: 2

Views: 4096

Answers (1)

Raghav Sood
Raghav Sood

Reputation: 82563

Turns out the problem was the line

circleColor.setColor(color.holo_blue_light);

While the Android SDK defines this as:

A light Holo shade of blue

Constant Value: 17170450 (0x01060012)

It doesn't seem to be a valid color as far as my Canvas is concerned (note that this was added in API 14, and I'm testing on Android 4.2 so it should be available to me). However, changing it to use a more... normal color works fine:

circleColor.setColor(Color.GREEN);

Upvotes: 1

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