我有以下自定义视图:
这是我通过使用Canvas的drawArc()
方法实现的。然而,使用这种drawArc()
方法我不能限制弧的内半径。
我想拥有的是这样的:
只剩下一个外环的地方。
我需要的是一个drawArc()
函数,我可以设置弧的内半径。任何人都知道如何做到这一点?
(顺便说一句,覆盖内部区域不起作用,因为它需要是透明的。在绘制红色和蓝色锥体后用Color.TRANSPARENT
绘制一个内圈不会去除旧的颜色。它只是将另一层放在顶部,这是透明,我仍然可以看到红色和蓝色)
您可以使用名为“Clear”的PorterDuff xfermode在内部区域上绘画。这将擦除像素。
你可以这样做:
Paint paint = new Paint();
final RectF rect = new RectF();
//Example values
rect.set(mWidth/2- mRadius, mHeight/2 - mRadius, mWidth/2 + mRadius, mHeight/2 + mRadius);
paint.setColor(Color.GREEN);
paint.setStrokeWidth(20);
paint.setAntiAlias(true);
paint.setStrokeCap(Paint.Cap.ROUND);
paint.setStyle(Paint.Style.STROKE);
canvas.drawArc(rect, -90, 360, false, paint);
关键是在paint.setStyle(Paint.Style.STROKE);
中,它使用您在setStrokeWidth中定义的笔划裁剪弧的中心(在示例中绘制半径为mRadius且厚度为20px的弧)。
希望能帮助到你!
private static final float CIRCLE_LIMIT = 359.9999f;
/**
* Draws a thick arc between the defined angles, see {@link Canvas#drawArc} for more.
* This method is equivalent to
* <pre><code>
* float rMid = (rInn + rOut) / 2;
* paint.setStyle(Style.STROKE); // there's nothing to fill
* paint.setStrokeWidth(rOut - rInn); // thickness
* canvas.drawArc(new RectF(cx - rMid, cy - rMid, cx + rMid, cy + rMid), startAngle, sweepAngle, false, paint);
* </code></pre>
* but supports different fill and stroke paints.
*
* @param canvas
* @param cx horizontal middle point of the oval
* @param cy vertical middle point of the oval
* @param rInn inner radius of the arc segment
* @param rOut outer radius of the arc segment
* @param startAngle see {@link Canvas#drawArc}
* @param sweepAngle see {@link Canvas#drawArc}, capped at ±360
* @param fill filling paint, can be <code>null</code>
* @param stroke stroke paint, can be <code>null</code>
* @see Canvas#drawArc
*/
public static void drawArcSegment(Canvas canvas, float cx, float cy, float rInn, float rOut, float startAngle,
float sweepAngle, Paint fill, Paint stroke) {
if (sweepAngle > CIRCLE_LIMIT) {
sweepAngle = CIRCLE_LIMIT;
}
if (sweepAngle < -CIRCLE_LIMIT) {
sweepAngle = -CIRCLE_LIMIT;
}
RectF outerRect = new RectF(cx - rOut, cy - rOut, cx + rOut, cy + rOut);
RectF innerRect = new RectF(cx - rInn, cy - rInn, cx + rInn, cy + rInn);
Path segmentPath = new Path();
double start = toRadians(startAngle);
segmentPath.moveTo((float)(cx + rInn * cos(start)), (float)(cy + rInn * sin(start)));
segmentPath.lineTo((float)(cx + rOut * cos(start)), (float)(cy + rOut * sin(start)));
segmentPath.arcTo(outerRect, startAngle, sweepAngle);
double end = toRadians(startAngle + sweepAngle);
segmentPath.lineTo((float)(cx + rInn * cos(end)), (float)(cy + rInn * sin(end)));
segmentPath.arcTo(innerRect, startAngle + sweepAngle, -sweepAngle);
if (fill != null) {
canvas.drawPath(segmentPath, fill);
}
if (stroke != null) {
canvas.drawPath(segmentPath, stroke);
}
}
通过在x和y方向上复制rInn
和rOut
,可以扩展到椭圆弧。
也不是问题的一部分,而是在段的中间绘制文本:
textPaint.setTextAlign(Align.CENTER);
Path midway = new Path();
float r = (rIn + rOut) / 2;
RectF segment = new RectF(cx - r, cy - r, cx + r, cy + r);
midway.addArc(segment, startAngle, sweepAngle);
canvas.drawTextOnPath("label", midway, 0, 0, textPaint);
您可以尝试遵循ShapeDrawable
<?xml version="1.0" encoding="utf-8"?>
<layer-list xmlns:android="http://schemas.android.com/apk/res/android" >
<item>
<shape android:shape="oval" >
<size
android:height="56dp"
android:width="56dp" />
<stroke
android:width="10dp"
android:color="#0000ff" />
</shape>
</item>
<item>
<shape android:shape="oval" >
<size
android:height="24dp"
android:width="25dp" />
<stroke
android:dashGap="10dp"
android:dashWidth="10dp"
android:width="10dp"
android:color="#FF0000" />
</shape>
</item>
绘制圆和圆弧。以下代码有点脏,但它可能有所帮助
int sweepAngle sweepAngle = (360/7)%360;
int startAngle = -90;
int x = getWidth()/2;
int y = getHeight()/2;
int radius;
radius = getWidth()/2-50;
paint.setStyle(Paint.Style.STROKE);
paint.setStrokeWidth(50);
paint.setColor(Color.WHITE);
paint.setColor(Color.parseColor("#CD5C5C"));
mBarPaintFill.setAntiAlias(true);
canvas.drawCircle(x , y , radius, paint);
paint.setColor(Color.BLUE);
for (int i = 1 ; i<=5 ; i++){
canvas.drawArc(x-radius,y-radius,x+radius,y+radius,startAngle,sweepAngle,false,paint);
startAngle = (startAngle + sweepAngle+20)%360;
}