近来公司事前较少，再来找几个有意思的View练练手，下面是原生华为天气预报界面： 
下面是仿的UI交互效果：
**思路：
1.平移画布到View中心，先绘制一个圆弧，绘制中间文字
2.旋转画布，绘制小短线，同时绘制中间的温度和下边的图片
3.确定0摄氏度的位置，确定每日温差之间共覆盖多少角度
4.算出最小温度的起始角，根据cos,sin计算坐标，绘制温度数字。
5.算出最小温度的短线索引，加粗变色绘制。**
1.首先在onMeasure中保证View宽高。
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int wrap_Len = 600;
int width = measureDimension(wrap_Len, widthMeasureSpec);
int height = measureDimension(wrap_Len, heightMeasureSpec);
int len=Math.min(width,height);
//保证是一个正方形
setMeasuredDimension(len,len);
}
public int measureDimension(int defaultSize, int measureSpec){
int result;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
if(specMode == MeasureSpec.EXACTLY){
result = specSize;
}else{
result = defaultSize; //UNSPECIFIED
if(specMode == MeasureSpec.AT_MOST){
result = Math.min(result, specSize);
}
}
return result;
}然后开始平移画布，绘制一个圆弧
mWidth=getWidth();
mHeight=getHeight();
radius=(mWidth-getPaddingLeft()-getPaddingRight())/2;//半径
canvas.translate(mWidth/2,mHeight/2);
private void drawArcView(Canvas canvas) {
RectF mRect=new RectF(-radius,-radius,radius,radius);
//canvas.drawRect(mRect,mArcPaint);
canvas.drawArc(mRect,startAngle,sweepAngle,false,mArcPaint);
}效果如图： 
2.旋转画布，绘制小短线
以一定的角度旋转画布，循环画出短线
private void drawLine(Canvas canvas) {
canvas.save();
float angle = (float)sweepAngle/count;//刻度间隔
canvas.rotate(-270+startAngle);//将起始刻度点旋转到正上方
for(int i=0;i<=count;i++){
if(i==0 || i==count){
mLinePaint.setStrokeWidth(1);
mLinePaint.setColor(Color.WHITE);
canvas.drawLine(0,-radius,0,-radius+40,mLinePaint);
}else if(i>=getStartLineIndex(minTemp,maxTemp) && i<=getEndLineIndex(minTemp,maxTemp)){
mLinePaint.setStrokeWidth(3);
mLinePaint.setColor(getRealColor(minTemp,maxTemp));
canvas.drawLine(0,-radius,0,-radius+30,mLinePaint);
}else {
mLinePaint.setStrokeWidth(2);
mLinePaint.setColor(Color.WHITE);
canvas.drawLine(0,-radius,0,-radius+30,mLinePaint);
}
canvas.rotate(angle);//逆时针旋转
}
canvas.restore();
}效果如图：
然后绘制中间的温度和下边的图片，并注释掉绘制圆环的方法
private void drawTextBitmapView(Canvas canvas) {
mTextPaint.setTextSize(144);
canvas.drawText(currentTemp+"°",0,0+getTextPaintOffset(mTextPaint),mTextPaint);
canvas.drawBitmap(bitmap,0-bitmap.getWidth()/2,radius-bitmap.getHeight()/2-30,null);
}其中getTextPaintOffset（）函数改变文字的Y坐标偏移量
public float getTextPaintOffset(Paint paint){
Paint.FontMetricsInt fontMetrics = paint.getFontMetricsInt();
return -fontMetrics.descent+(fontMetrics.bottom-fontMetrics.top)/2;
}效果如图：
3.然后确定0摄氏度在圆环中的位置，设为230度的位置为0度
计算圆环中230度的X，y坐标。
//根据角获得X坐标 R*cos&+getTextPaintOffset(mTextPaint)-off
private float getCosX(int Angle){
return (float) (radius*Math.cos(Angle*Math.PI/180))+getTextPaintOffset(mTextPaint);
}
private float getSinY(int Angle){
return (float)(radius*Math.sin(Angle*Math.PI/180))+getTextPaintOffset(mTextPaint);
} 因为平移的坐标系，此时要根据象限决定偏移量的正负
private float getRealCosX(int Angle,int off,boolean outoff){
if(!outoff){
off=-off;
}
if(getCosX(Angle)<0){
return getCosX(Angle)-off;
}else{
return getCosX(Angle)+off;
}
}
private float getRealSinY(int Angle,int off,boolean outoff){
if(!outoff){
off=-off;
}
if(getSinY(Angle)<0){
return getSinY(Angle)-off;
}else{
return getSinY(Angle)+off;
}
}有了正确的X,Y坐标即可绘制出文字。有了0摄氏度的位置就能确定当天温度范围的具体角。
//根据当天温度范围获得扇形开始角。
private int getStartAngle(int minTemp,int maxTemp){
int startFgAngle=0;
if(minTemp>=maxTemp){
Log.e("ws","getStartAngle---?fail");
return startFgAngle;
}
if(minTemp<=0){
startFgAngle=ocAngle - (0 - minTemp)*fgAngle/(maxTemp-minTemp);
}else{
startFgAngle=ocAngle+(minTemp-0)*fgAngle/(maxTemp-minTemp);
}
//边界 start
if(startFgAngle<=startAngle){//如果开始角小于startAngle，防止过边界
startFgAngle=startAngle+10;
}else if((startFgAngle+fgAngle)>=(startAngle+sweepAngle)){//如果结束角大于(startAngle+sweepAngle)
startFgAngle =startAngle+sweepAngle-20-fgAngle;
}
//边界 end
return startFgAngle;
}求出具体角后就可以确定X，Y坐标了
private void drawTempLineView(Canvas canvas) {
mTextPaint.setTextSize(24);
canvas.drawText("0°C",getRealCosX(ocAngle,offset,true),getRealSinY(ocAngle,offset,true),mTextPaint);//固定0度的位置
int startTempAngle=getStartAngle(minTemp,maxTemp);
/* if(startTempAngle<=startAngle){//如果开始角小于startAngle，防止过边界
startTempAngle=startAngle+10;
}else if((startTempAngle+fgAngle)>=(startAngle+sweepAngle)){//如果结束角大于(startAngle+sweepAngle)
startTempAngle =startAngle+sweepAngle-20-fgAngle;
}*/
canvas.drawText(minTemp + "°", getRealCosX(startTempAngle, offset,true), getRealSinY(startTempAngle, offset,true), mTextPaint);
canvas.drawText(maxTemp + "°", getRealCosX(startTempAngle+fgAngle, offset,true), getRealSinY(startTempAngle+fgAngle, offset,true), mTextPaint);
// int circleAngle = startTempAngle+(currentTemp-minTemp)*fgAngle/(maxTemp-minTemp);
// mPointPaint.setColor(getRealColor(minTemp,maxTemp));
//canvas.drawCircle(getRealCosX(circleAngle,50,false),getRealSinY(circleAngle,50,false),7,mPointPaint);
}
然后就是要绘制这段温度范围的线颜色，以及当前温度的点
绘制点：
int circleAngle = startTempAngle+(currentTemp-minTemp)*fgAngle/(maxTemp-minTemp);
mPointPaint.setColor(getRealColor(minTemp,maxTemp));
canvas.drawCircle(getRealCosX(circleAngle,50,false),getRealSinY(circleAngle,50,false),7,mPointPaint);绘制当天温度范围的线，即在drawLine方法中加上
else if(i>=getStartLineIndex(minTemp,maxTemp) && i<=getEndLineIndex(minTemp,maxTemp)){
mLinePaint.setStrokeWidth(3);
mLinePaint.setColor(getRealColor(minTemp,maxTemp));
canvas.drawLine(0,-radius,0,-radius+30,mLinePaint);
//根据当天温度范围获取开始短线的索引
private int getStartLineIndex(int minTemp,int maxTemp){
return (getStartAngle(minTemp,maxTemp)-startAngle)/(sweepAngle/count);
}
private int getEndLineIndex(int minTemp,int maxTemp){
return (getStartAngle(minTemp,maxTemp)-startAngle)/(sweepAngle/count)+fgAngle/(sweepAngle/count);
}
//根据温度返回颜色值
public int getRealColor(int minTemp,int maxTemp){
if(maxTemp<=0){
return Color.parseColor("#00008B");//深海蓝
}else if(minTemp<=0 && maxTemp>0){
return Color.parseColor("#4169E1");//黄君兰
}else if(minTemp>0 && minTemp<15 ){
return Color.parseColor("#40E0D0");//宝石绿
}else if(minTemp>=15 && minTemp<25){
return Color.parseColor("#00FF00");//酸橙绿
}else if(minTemp>=25 &&minTemp<30){
return Color.parseColor("#FFD700");//金色
}else if(minTemp>=30){
return Color.parseColor("#CD5C5C");//印度红
}
return Color.parseColor("#00FF00");//酸橙绿;
}最终效果图 
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.Log;
import android.view.View;
/**
* Created by ws on 2017/2/25.
*/
public class NowHwWeatherView extends View {
private Paint mArcPaint;
private Paint mLinePaint;
private Paint mTextPaint;
private Paint mPointPaint;
private float mWidth;
private float mHeight;
private float radius;//半径
private int startAngle;//圆弧开始角
private int sweepAngle;//圆弧总角度数
private int count;//圆弧被分的份数
private int currentTemp;//当前温度
private int maxTemp;
private int minTemp;
private Bitmap bitmap;
private int ocAngle;//0度初始角
private int fgAngle;//总覆盖的角
private int offset;
public NowHwWeatherView(Context context) {
this(context,null);
}
public NowHwWeatherView(Context context, AttributeSet attrs) {
this(context, attrs,0);
}
public NowHwWeatherView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}
private void init(Context context) {
initPaint();
startAngle=120;
sweepAngle=300;
count=60;//刻度份数
currentTemp=26;
maxTemp=27;
minTemp=20;
bitmap= BitmapFactory.decodeResource(context.getResources(), R.drawable.w16);
ocAngle=230;
fgAngle=90;
offset=22;
}
private void initPaint() {
mArcPaint=new Paint();
mArcPaint.setColor(Color.WHITE);
mArcPaint.setStrokeWidth(2);
mArcPaint.setStyle(Paint.Style.STROKE);
mArcPaint.setAntiAlias(true);
mLinePaint=new Paint();
mLinePaint.setColor(Color.WHITE);
mLinePaint.setStrokeWidth(2);
mLinePaint.setStyle(Paint.Style.STROKE);
mLinePaint.setAntiAlias(true);
mTextPaint=new TextPaint();
mTextPaint.setColor(Color.WHITE);
mTextPaint.setStrokeWidth(4);
mTextPaint.setAntiAlias(true);
mTextPaint.setTextAlign(Paint.Align.CENTER);
mTextPaint.setTextSize(144);
mPointPaint=new Paint();
mPointPaint.setColor(Color.WHITE);
mPointPaint.setStrokeWidth(2);
mPointPaint.setStyle(Paint.Style.FILL);
mPointPaint.setAntiAlias(true);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
int wrap_Len = 600;
int width = measureDimension(wrap_Len, widthMeasureSpec);
int height = measureDimension(wrap_Len, heightMeasureSpec);
int len=Math.min(width,height);
//保证是一个正方形
setMeasuredDimension(len,len);
}
public int measureDimension(int defaultSize, int measureSpec){
int result;
int specMode = MeasureSpec.getMode(measureSpec);
int specSize = MeasureSpec.getSize(measureSpec);
if(specMode == MeasureSpec.EXACTLY){
result = specSize;
}else{
result = defaultSize; //UNSPECIFIED
if(specMode == MeasureSpec.AT_MOST){
result = Math.min(result, specSize);
}
}
return result;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
mWidth=getWidth();
mHeight=getHeight();
radius=(mWidth-getPaddingLeft()-getPaddingRight())/2;//半径
canvas.translate(mWidth/2,mHeight/2);
//drawArcView(canvas);//画圆环
drawLine(canvas);//画短线
drawTextBitmapView(canvas);//画中间的温度和下边的图片
drawTempLineView(canvas);//画动态温度
}
private void drawTempLineView(Canvas canvas) {
mTextPaint.setTextSize(24);
//canvas.drawText("0°C",getRealCosX(ocAngle,offset,true),getRealSinY(ocAngle,offset,true),mTextPaint);//固定0度的位置
int startTempAngle=getStartAngle(minTemp,maxTemp);
/* if(startTempAngle<=startAngle){//如果开始角小于startAngle，防止过边界
startTempAngle=startAngle+10;
}else if((startTempAngle+fgAngle)>=(startAngle+sweepAngle)){//如果结束角大于(startAngle+sweepAngle)
startTempAngle =startAngle+sweepAngle-20-fgAngle;
}*/
canvas.drawText(minTemp + "°", getRealCosX(startTempAngle, offset,true), getRealSinY(startTempAngle, offset,true), mTextPaint);
canvas.drawText(maxTemp + "°", getRealCosX(startTempAngle+fgAngle, offset,true), getRealSinY(startTempAngle+fgAngle, offset,true), mTextPaint);
int circleAngle = startTempAngle+(currentTemp-minTemp)*fgAngle/(maxTemp-minTemp);
mPointPaint.setColor(getRealColor(minTemp,maxTemp));
canvas.drawCircle(getRealCosX(circleAngle,50,false),getRealSinY(circleAngle,50,false),7,mPointPaint);
}
private void drawArcView(Canvas canvas) {
RectF mRect=new RectF(-radius,-radius,radius,radius);
//canvas.drawRect(mRect,mArcPaint);
canvas.drawArc(mRect,startAngle,sweepAngle,false,mArcPaint);
}
private void drawLine(Canvas canvas) {
canvas.save();
float angle = (float)sweepAngle/count;//刻度间隔
canvas.rotate(-270+startAngle);//将起始刻度点旋转到正上方
for(int i=0;i<=count;i++){
if(i==0 || i==count){
mLinePaint.setStrokeWidth(1);
mLinePaint.setColor(Color.WHITE);
canvas.drawLine(0,-radius,0,-radius+40,mLinePaint);
}else if(i>=getStartLineIndex(minTemp,maxTemp) && i<=getEndLineIndex(minTemp,maxTemp)){
mLinePaint.setStrokeWidth(3);
mLinePaint.setColor(getRealColor(minTemp,maxTemp));
canvas.drawLine(0,-radius,0,-radius+30,mLinePaint);
}else {
mLinePaint.setStrokeWidth(2);
mLinePaint.setColor(Color.WHITE);
canvas.drawLine(0,-radius,0,-radius+30,mLinePaint);
}
canvas.rotate(angle);//逆时针旋转
}
canvas.restore();
}
private void drawTextBitmapView(Canvas canvas) {
mTextPaint.setTextSize(144);
canvas.drawText(currentTemp+"°",0,0+getTextPaintOffset(mTextPaint),mTextPaint);
canvas.drawBitmap(bitmap,0-bitmap.getWidth()/2,radius-bitmap.getHeight()/2-30,null);
}
public float getTextPaintOffset(Paint paint){
Paint.FontMetricsInt fontMetrics = paint.getFontMetricsInt();
return -fontMetrics.descent+(fontMetrics.bottom-fontMetrics.top)/2;
}
//根据角获得X坐标 R*cos&+getTextPaintOffset(mTextPaint)-off
private float getCosX(int Angle){
return (float) (radius*Math.cos(Angle*Math.PI/180))+getTextPaintOffset(mTextPaint);
}
private float getSinY(int Angle){
return (float)(radius*Math.sin(Angle*Math.PI/180))+getTextPaintOffset(mTextPaint);
}
//根据象限加一个偏移量
private float getRealCosX(int Angle,int off,boolean outoff){
if(!outoff){
off=-off;
}
if(getCosX(Angle)<0){
return getCosX(Angle)-off;
}else{
return getCosX(Angle)+off;
}
}
private float getRealSinY(int Angle,int off,boolean outoff){
if(!outoff){
off=-off;
}
if(getSinY(Angle)<0){
return getSinY(Angle)-off;
}else{
return getSinY(Angle)+off;
}
}
//根据当天温度范围获得扇形开始角。
private int getStartAngle(int minTemp,int maxTemp){
int startFgAngle=0;
if(minTemp>=maxTemp){
Log.e("ws","getStartAngle---?fail");
return startFgAngle;
}
if(minTemp<=0){
startFgAngle=ocAngle - (0 - minTemp)*fgAngle/(maxTemp-minTemp);
}else{
startFgAngle=ocAngle+(minTemp-0)*fgAngle/(maxTemp-minTemp);
}
//边界 start
if(startFgAngle<=startAngle){//如果开始角小于startAngle，防止过边界
startFgAngle=startAngle+10;
}else if((startFgAngle+fgAngle)>=(startAngle+sweepAngle)){//如果结束角大于(startAngle+sweepAngle)
startFgAngle =startAngle+sweepAngle-20-fgAngle;
}
//边界 end
return startFgAngle;
}
//根据当天温度范围获取开始短线的索引
private int getStartLineIndex(int minTemp,int maxTemp){
return (getStartAngle(minTemp,maxTemp)-startAngle)/(sweepAngle/count);
}
private int getEndLineIndex(int minTemp,int maxTemp){
return (getStartAngle(minTemp,maxTemp)-startAngle)/(sweepAngle/count)+fgAngle/(sweepAngle/count);
}
//根据温度返回颜色值
public int getRealColor(int minTemp,int maxTemp){
if(maxTemp<=0){
return Color.parseColor("#00008B");//深海蓝
}else if(minTemp<=0 && maxTemp>0){
return Color.parseColor("#4169E1");//黄君兰
}else if(minTemp>0 && minTemp<15 ){
return Color.parseColor("#40E0D0");//宝石绿
}else if(minTemp>=15 && minTemp<25){
return Color.parseColor("#00FF00");//酸橙绿
}else if(minTemp>=25 &&minTemp<30){
return Color.parseColor("#FFD700");//金色
}else if(minTemp>=30){
return Color.parseColor("#CD5C5C");//印度红
}
return Color.parseColor("#00FF00");//酸橙绿;
}
public void setBitmap(Bitmap mBitmap){
this.bitmap=mBitmap;
invalidate();
}
}