这是转盘的第二个版本，添加了外围的圆圈
第一个demo在这儿可以找到
Android 自定义View 抽奖大转盘（1）
项目github链接 https://github.com/yukunkun/RotateView
镇楼图
S171011-11370203.jpg
项目的本来来源来自于
添加外围的圆圈，主要由两部分组成
1.画小圆。2.圆盘位置的定位
圆盘位置如下
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
//就是让两个view居中，没有其他的操作
int centerX = (right - left)/2;
int centerY = (bottom - top)/2;
boolean panReady = false;
for(int i=0;i<getChildCount();i++){
View child = getChildAt(i);
if(child instanceof RotateView){
rotatePan = (RotateView) child;
int panWidth = child.getWidth();
int panHeight = child.getHeight();
child.layout(centerX - panWidth/2 , centerY - panHeight/2,centerX + panWidth/2, centerY + panHeight/2);
panReady = true;
}else if(child instanceof ImageView){
// if(TextUtils.equals((String) child.getTag(),START_BTN_TAG)){
startBtn = (ImageView) child;
int btnWidth = child.getWidth();
int btnHeight = child.getHeight();
child.layout(centerX - btnWidth/2 , centerY - btnHeight/2 , centerX + btnWidth/2, centerY + btnHeight/2 );
// }
}
}
}
这里一看就能明白，两个View，居中显示，在onLayout方法里面
下面是画圆的方法
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
this.canvas = canvas;
final int paddingLeft = getPaddingLeft();
final int paddingRight = getPaddingRight();
final int paddingTop = getPaddingTop();
final int paddingBottom = getPaddingBottom();
int width = getWidth() - paddingLeft - paddingRight;
int height = getHeight() - paddingTop - paddingBottom;
int MinValue = Math.min(width,height);
radius = MinValue /2;
CircleX = getWidth() /2;
CircleY = getHeight() /2;
//画背景
canvas.drawCircle(CircleX,CircleY,radius,backgroundPaint);
//画圆圈，主要功能也就在这里
drawSmallCircle(isYellow);
}
private void drawSmallCircle(boolean FirstYellow) {
//位置要在内部，每次的半径相应的变短一点
int pointDistance = radius - Util.dip2px(context,10);
//每次增加20度，也就是能够得到18个点
for(int i=0;i<=360;i+=20){
//每次获取到圆心的位置，由i控制位置
int x = (int) (pointDistance * Math.sin(Util.change(i))) + CircleX;
int y = (int) (pointDistance * Math.cos(Util.change(i))) + CircleY;
//两个不同颜色圆
if(FirstYellow)
canvas.drawCircle(x,y,Util.dip2px(context,6),yellowPaint);
else
canvas.drawCircle(x,y,Util.dip2px(context,6),whitePaint);
FirstYellow = !FirstYellow;
}
}
