android - 自定义 View 仅在 XML 预览中未正确对齐

Question

我有一个自定义 View (一个圆圈)，它在应用程序运行时正确呈现。但是，在 XML 预览 Pane 中查看时， View 未正确对齐。

下面是对齐不正确的预览 Pane 的屏幕截图。

下面是同一 View 在运行的应用程序上绘制时正确对齐的屏幕截图。

这是定义自定义 View 的代码 -

public class LinearTimerView extends View {

    private Paint arcPaint;
    private RectF rectF;

    private int initialColor;
    private int progressColor;
    private int circleRadiusInDp;

    // The point from where the color-fill animation will start.
    private int startingAngle = 270;

    // The point up-till which user wants the circle to be pre-filled.
    private float preFillAngle;

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

        TypedArray typedArray = getContext().obtainStyledAttributes(attrs,
                R.styleable.LinearTimerView);

        // Retrieve the view attributes.
        this.circleRadiusInDp =
                (int) typedArray.getDimension(R.styleable.LinearTimerView_radius, 5);
        int strokeWidthInDp =
                (int) typedArray.getDimension(R.styleable.LinearTimerView_strokeWidth, 2);
        this.initialColor =
                typedArray.getColor(R.styleable.LinearTimerView_initialColor,
                        ContextCompat.getColor(getContext(), R.color.colorInitial));
        this.progressColor =
                typedArray.getColor(R.styleable.LinearTimerView_progressColor,
                        ContextCompat.getColor(getContext(), R.color.colorProgress));
        this.startingAngle =
                typedArray.getInt(R.styleable.LinearTimerView_startingPoint, 270);

        // Define the size of the circle.
        rectF = new RectF(
                (int) convertDpIntoPixel(strokeWidthInDp),
                (int) convertDpIntoPixel(strokeWidthInDp),
                (int) convertDpIntoPixel(circleRadiusInDp * 2)
                        + (int) convertDpIntoPixel(strokeWidthInDp),
                (int) convertDpIntoPixel(circleRadiusInDp * 2)
                        + (int) convertDpIntoPixel(strokeWidthInDp));

        arcPaint = new Paint();
        arcPaint.setAntiAlias(true);
        arcPaint.setStyle(Paint.Style.STROKE);
        arcPaint.setStrokeWidth((int) convertDpIntoPixel(strokeWidthInDp));

        typedArray.recycle();
    }

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

        try {
            // Grey Circle - This circle will be there by default.
            arcPaint.setColor(initialColor);
            canvas.drawCircle(rectF.centerX(), rectF.centerY(),
                    (int) convertDpIntoPixel(circleRadiusInDp), arcPaint);

            // Green Arc (Arc with 360 angle) - This circle will be animated as time progresses.
            arcPaint.setColor(progressColor);
            canvas.drawArc(rectF, startingAngle, preFillAngle, false, arcPaint);
        } catch (NullPointerException ex) {
            ex.printStackTrace();
        }
    }

    /**
     * Method to get the degrees up-till which the arc is already pre-filled.
     * @return
     */
    public float getPreFillAngle() {
        return preFillAngle;
    }

    public void setPreFillAngle(float preFillAngle) {
        this.preFillAngle = preFillAngle;
    }

    /**
     * Method to get the starting point of the angle
     * @return
     */
    public int getStartingPoint() {
        return startingAngle;
    }

    public void setStartingPoint(int startingPointInDegrees) {
        this.startingAngle = startingPointInDegrees;
    }

    /**
     * Method to convert DPs into Pixels.
     */
    private float convertDpIntoPixel(float dp) {
        float scale = getResources().getDisplayMetrics().density;
        return dp * scale + 0.5f;
    } }

我该如何解决这个问题？

Answer 1

事实证明我没有覆盖 onMeasure() 方法。

我采用了提示形式 this回答并能够解决问题。