ApiDemos-->Graphics->Arc
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API DEMOS演示了drawArc的四种不同用法,你:圆弧4种画法
public void drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint)
oval :指定圆弧的外轮廓矩形区域。
startAngle: 圆弧起始角度,单位为度。
sweepAngle: 圆弧扫过的角度,顺时针方向,单位为度。
useCenter: 如果为True时,在绘制圆弧时将圆心包括在内,通常用来绘制扇形。
paint: 绘制圆弧的画板属性,如颜色,是否填充等。
1. 填充但不含圆心:
<span style="font-family:System;"> <span style="font-size:18px;"> mPaints[0] = new Paint(); mPaints[0].setAntiAlias(true); //抗锯齿 mPaints[0].setStyle(Paint.Style.FILL);//填充 mPaints[0].setColor(0x88FF0000); mUseCenters[0] = false; //不包括圆心</span></span>
2. 填充圆弧带圆心(扇形)
<span style="font-size:24px;"> mPaints[1] = new Paint(mPaints[0]);//画笔包含mPaints[0] mPaints[1].setColor(0x8800FF00); mUseCenters[1] = true; //包括圆心</span>
3. 只绘圆周,不含圆心
<span style="font-size:24px;">mPaints[2] = new Paint(mPaints[0]); mPaints[2].setStyle(Paint.Style.STROKE);//描边 mPaints[2].setStrokeWidth(4); //画笔宽度(用于画圆弧宽度) mPaints[2].setColor(0x880000FF); mUseCenters[2] = false; //不包含圆心 </span>
4. 只绘圆周,带圆心(扇形)
<span style="font-size:24px;"> mPaints[3] = new Paint(mPaints[2]);//画笔包含mPaints[2] mPaints[3].setColor(0x88888888); mUseCenters[3] = true; //包含圆心</span>
API DEMOS 里面 onDraw
@Override protected void <strong><span style="color:#ff0000;">onDraw</span></strong>(Canvas canvas) { canvas.drawColor(Color.WHITE); drawArcs(canvas, mBigOval, mUseCenters[mBigIndex], mPaints[mBigIndex]); for (int i = 0; i < 4; i++) { drawArcs(canvas, mOvals[i], mUseCenters[i], mPaints[i]); } mSweep += SWEEP_INC; if (mSweep > 360) { mSweep -= 360; mStart += START_INC; if (mStart >= 360) { mStart -= 360; } mBigIndex = (mBigIndex + 1) % mOvals.length; } <strong> <span style="color:#ff0000;">invalidate();</span></strong> }
<span style="font-size:24px;">Paint.Style.STROKE);//描边</span>
<span style="font-size:24px;">Paint.Style.FILL);//填充</span>
在onDrow(Canvsa canvas)里面调用invalidate()(重绘,再次执行onDrow(Canvas canvas)),不断刷新重绘 startAngle(起始角度)、sweepAngle(顺时针扫描过的角度),从而形成循环动画
原文链接:http://blog.sina.com.cn/s/blog_783ede0301012im3.htmlhttp://blog.sina.com.cn/u/2017385987
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