Android画个时钟玩玩
先看下最终的效果
开始实现
新建一个clockview集成view
public class clockview extends view { }
先重写onmeasure方法,这里要先说一下view的测量模式,一共有三种:
1、exactly
即精确值模式,当我们将控件的layout_width属性或layout_height属性指定为具体数值时,比如android:layout_width="100dp",或者指定为math_parent属性时(占据父view的大小),系统使用的是exactly模式。
2、at_most
即最大值模式,当控件的layout_width属性或layout_height属性指定为wrap_content时,控件大小一般随着控件的子控件或内容的变化而变化,此时控件的尺寸只要不超过父控件允许的最大尺寸即可。
3、unspecified
这个属性比较奇怪——它不指定其大小测量模式,view想多大就多大,通常情况下在绘制自定义view时才会使用。
因为view的onmeasure方法只支持exactly模式,当layout_width和layout_height为wrap_content时,view的大小就显得很奇怪了,如下图。
所以我们重写一下onmeasure方法可以指定view width、height的最小值
/** * 当布局为wrap_content时设置默认长宽 * @param widthmeasurespec * @param heightmeasurespec */ @override protected void onmeasure(int widthmeasurespec, int heightmeasurespec) { setmeasureddimension(measure(widthmeasurespec), measure(heightmeasurespec)); } private int measure(int origin){ int result = default_min_width; int specmode = measurespec.getmode(origin); int specsize = measurespec.getsize(origin); if(specmode == measurespec.exactly){ result = specsize; }else{ if(specmode == measurespec.at_most){ result = math.min(result, specsize); } } return result; }
下面就是最重要的重写ondraw方法来绘制表盘、刻度、指针……,大致流程如下
1、画表盘,用drawcircle绘制一个圆作为表盘, 圆心坐标为(getwidth()/2, getheight()/2),半径为math.min(getheight()/2, getwidth()/2)。
//画外圆 float borderwidth = default_border_width; paint paintcircle = new paint(); paintcircle.setstyle(paint.style.stroke); paintcircle.setantialias(true); paintcircle.setstrokewidth(borderwidth); canvas.drawcircle(getwidth() / 2, getheight() / 2, math.min(getheight() / 2, getwidth() / 2) - borderwidth / 2, paintcircle);
2、画刻度线,在这里我们可以利用一个`canvas.rotate'方法就可以不用计算角度了
//画刻度线 float degreelength = 0f; paint paintdegree = new paint(); paintdegree.setantialias(true); for(int i=0;i<60;i++){ if(i % 5 == 0){ paintdegree.setstrokewidth(6); degreelength = default_long_degree_length; }else{ paintdegree.setstrokewidth(3); degreelength = default_short_degree_length; } canvas.drawline(getwidth()/2, math.abs(getwidth()/2 - getheight()/2), getwidth()/2, math.abs(getwidth()/2 - getheight()/2) + degreelength, paintdegree); canvas.rotate(360/60, getwidth()/2, getheight()/2); }
3、画刻度上的数字
//刻度数字 int degressnumbersize = 30; canvas.translate(getwidth() / 2, getheight() / 2); paint paintdegreenumber = new paint(); paintdegreenumber.settextalign(paint.align.center); paintdegreenumber.settextsize(degressnumbersize); paintdegreenumber.setfakeboldtext(true); for(int i=0;i<12;i++){ float[] temp = calculatepoint((i+1)*30, r - default_long_degree_length - degressnumbersize/2 - 15); canvas.drawtext((i+1)+"", temp[2], temp[3] + degressnumbersize/2-6, paintdegreenumber); } /** * 根据角度和长度计算线段的起点和终点的坐标 * @param angle * @param length * @return */ private float[] calculatepoint(float angle, float length){ float[] points = new float[4]; if(angle <= 90f){ points[0] = -(float) math.sin(angle*math.pi/180) * default_point_back_length; points[1] = (float) math.cos(angle*math.pi/180) * default_point_back_length; points[2] = (float) math.sin(angle*math.pi/180) * length; points[3] = -(float) math.cos(angle*math.pi/180) * length; }else if(angle <= 180f){ points[0] = -(float) math.cos((angle-90)*math.pi/180) * default_point_back_length; points[1] = -(float) math.sin((angle-90)*math.pi/180) * default_point_back_length; points[2] = (float) math.cos((angle-90)*math.pi/180) * length; points[3] = (float) math.sin((angle-90)*math.pi/180) * length; }else if(angle <= 270f){ points[0] = (float) math.sin((angle-180)*math.pi/180) * default_point_back_length; points[1] = -(float) math.cos((angle-180)*math.pi/180) * default_point_back_length; points[2] = -(float) math.sin((angle-180)*math.pi/180) * length; points[3] = (float) math.cos((angle-180)*math.pi/180) * length; }else if(angle <= 360f){ points[0] = (float) math.cos((angle-270)*math.pi/180) * default_point_back_length; points[1] = (float) math.sin((angle-270)*math.pi/180) * default_point_back_length; points[2] = -(float) math.cos((angle-270)*math.pi/180) * length; points[3] = -(float) math.sin((angle-270)*math.pi/180) * length; } return points; }
4、画指针
//画指针 paint painthour = new paint(); painthour.setantialias(true); painthour.setstrokewidth(15); paint paintminute = new paint(); paintminute.setantialias(true); paintminute.setstrokewidth(10); paint paintsecond = new paint(); paintsecond.setantialias(true); paintsecond.setstrokewidth(5); calendar now = calendar.getinstance(); float[] hourpoints = calculatepoint(now.get(calendar.hour_of_day)%12/12f*360, hourpointerlength); canvas.drawline(hourpoints[0], hourpoints[1], hourpoints[2], hourpoints[3], painthour); float[] minutepoints = calculatepoint(now.get(calendar.minute)/60f*360, minutepointerlength); canvas.drawline(minutepoints[0], minutepoints[1], minutepoints[2], minutepoints[3], paintminute); float[] secondpoints = calculatepoint(now.get(calendar.second)/60f*360, secondpointerlength); canvas.drawline(secondpoints[0], secondpoints[1], secondpoints[2], secondpoints[3], paintsecond);
5、画圆心
//画圆心 paint paintcenter = new paint(); paintcenter.setcolor(color.white); canvas.drawcircle(0, 0, 2, paintcenter); 最后只要启动一个无限循环的线程,每隔1秒针重绘一下view就能让指针动起来了 private thread timethread = new thread() { @override public void run() { try { while(true){ updatehandler.sendemptymessage(0); thread.sleep(1000); } } catch (interruptedexception e) { e.printstacktrace(); } } }; private handler updatehandler = new handler() { @override public void handlemessage(message msg) { invalidate(); } };
以上就是教大家如何利用android画个时钟的详细步骤代码,希望对大家的学习android软件编程有所帮助。