在Android中绘制具有凸起效果的圆角弧线

Question

我正在尝试开发一个自定义组件，即弧形滑块，我已经完成了弧线和滑块，但是无法弄清楚如何绘制圆角弧和凸起效果。目前，滑块的外观类似于这样：

绘制弧形的代码如下：

private void drawSlider(Canvas canvas) {
    float sweepDegrees = (value * arcWidthInAngle)
            / (maximumValue - minimumValue);

    // the grey empty part of the circle
    drawArc(canvas, startAngle, arcWidthInAngle, mTrackColor);
    // the colored "filled" part of the circle
    drawArc(canvas, startAngle, sweepDegrees, mFillColor);

    // the thumb to drag.       
    int radius = ((diameter/2) - (mArcThickness/2));
    Point thumbPoint = calculatePointOnArc(centerX, centerY, radius, startAngle + sweepDegrees);

    thumbPoint.x = thumbPoint.x - (mThumbDiameter/2);
    thumbPoint.y = thumbPoint.y - (mThumbDiameter/2);

    Bitmap thumbBitmap = BitmapFactory.decodeResource(
            mContext.getResources(), R.drawable.circle25);

    thumbBitmap = getResizedBitmap(thumbBitmap, mThumbDiameter, mThumbDiameter);
    canvas.drawBitmap(thumbBitmap, thumbPoint.x, thumbPoint.y,
            null);  

}

private void drawArc(Canvas canvas, float startAngle, float sweepDegrees,
        Paint paint) {
    if (sweepDegrees <= 0 || sweepDegrees > arcWidthInAngle) {
        return;
    }
    path.reset();
    path.arcTo(outerCircle, startAngle, sweepDegrees);
    path.arcTo(innerCircle, startAngle + sweepDegrees, -sweepDegrees);
    // innerCircle.
    path.close();
    canvas.drawPath(path, paint);
}

I am aiming for the arc something like this

- Shashank

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你能否与我们分享完整的演示源代码，这样我们这些学习者就可以学习了... :) - Sophie

Answer 1

为了获得圆角边缘，您可以使用Paint.setStrokeCap()方法。此外，默认的笔触端点是BUTT。您应该改用Paint.Cap.ROUND端点。

例如：

Paint mFillColor = new Paint();
mFillColor.setStrokeCap(Paint.Cap.ROUND)

- androholic

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你先生是救命恩人！ - gmemario

Answer 2

我成功地构建了类似下面的弧形：

我的做法是计算弧线的起点和终点，然后在那里画直径等于弧厚度的圆。

这是代码:

private void drawSlider(Canvas canvas) {
    float sweepDegrees = (value * arcWidthInAngle)
            / (maximumValue - minimumValue);

    // the grey empty part of the arc       
    drawArc(canvas, startAngle, arcWidthInAngle, mTrackColor);

    // the colored "filled" part of the arc
    drawArc(canvas, startAngle, sweepDegrees, mFillColor);

    // the thumb to drag.       
    int radius = ((diameter/2) - (mArcThickness/2));
    Point thumbPoint = calculatePointOnArc(centerX, centerY, radius, startAngle + sweepDegrees);

    thumbPoint.x = thumbPoint.x - (mThumbDiameter/2);
    thumbPoint.y = thumbPoint.y - (mThumbDiameter/2);

    Bitmap thumbBitmap = BitmapFactory.decodeResource(
            mContext.getResources(), R.drawable.circle25);

    thumbBitmap = getResizedBitmap(thumbBitmap, mThumbDiameter, mThumbDiameter);
    canvas.drawBitmap(thumbBitmap, thumbPoint.x, thumbPoint.y,
            null);

    //drawArc(canvas, startAngle, startAngle + sweepDegrees, white);
}
private void drawArc(Canvas canvas, float startAngle, float sweepDegrees,
        Paint paint) {
    if (sweepDegrees <= 0 || sweepDegrees > arcWidthInAngle) {
        return;
    }
    path.reset();


    int radius = ((diameter/2) - (mArcThickness/2));
    Point startPoint = calculatePointOnArc(centerX, centerY, radius, startAngle);
    Point endPoint = calculatePointOnArc(centerX, centerY, radius, startAngle + sweepDegrees);


    path.arcTo(outerCircle, startAngle, sweepDegrees);
    path.arcTo(innerCircle, startAngle + sweepDegrees, -sweepDegrees);
    // drawing the circle at both the end point of the arc to git it rounded look.
    path.addCircle(startPoint.x, startPoint.y, mArcThickness/2, Path.Direction.CW);
    path.addCircle(endPoint.x, endPoint.y, mArcThickness/2, Path.Direction.CW);

    path.close();            

    canvas.drawPath(path, paint);
}
    // this is to calculate the end points of the arc
private Point calculatePointOnArc(int circleCeX, int circleCeY, int circleRadius, float endAngle) 
    {
    Point point = new Point();
    double endAngleRadian = endAngle * (Math.PI / 180);

    int pointX = (int) Math.round((circleCeX + circleRadius * Math.cos(endAngleRadian)));
    int pointY = (int) Math.round((circleCeY + circleRadius * Math.sin(endAngleRadian)));

    point.x = pointX;
    point.y = pointY;

    return point;
}
// for the emboss effect set maskfilter of the paint to EmbossMaskFilter 
    private Paint mTrackColor = new Paint();
    MaskFilter  mEmboss = new EmbossMaskFilter(new float[] { 0.0f, -1.0f, 0.5f},
            0.8f, 15, 1.0f);
    mTrackColor.setMaskFilter(mEmboss);

- Shashank

Answer 3

使用Paint.setStrokeCap()方法。需要使用Paint.Cap.ROUND。默认值为Paint.Cap.BUTT。还有一个类似的Path属性，称为路径连接。它确定如何绘制构成路径的各个线段连接的部分。要设置它，请使用Path.setPathJoin()。您将来可能会需要它。祝好运。

- Lennon Henk

Answer 4

您正在使用路径绘制弧线。请使用CornerPathEffect来使角落变圆。这里有一个示例：CornerPathEffect example。

这是浮雕效果的示例，我不确定它是否符合您的要求。 Embossed effect example。

- Shaiful

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请在完成后与我们分享您的最终结果。 - Shaiful