Android指南针应用编写

- 日理万妓 2022-09-07 09:47 176阅读 0赞

**目录**

概述

一、运行环境：

二、编码

三、结果

四、总结

--------------------

# 概述 #

由于最近有个地磁项目的需要，重温多年Android知识，通过手机地磁传感器数据，编写了一个指南针App。

## 一、运行环境： ##

1、小米手机 MIUI版本 12.5.4

2、Android Studio Arctic Fox | 2020.3.1

## 二、编码 ##

1、创建MiCompass.java文件（自定义view）

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_Q1NETiBAQ2hfY2hhbXBpb24_size_18_color_FFFFFF_t_70_g_se_x_16][]

package com.example.mycompass;
    
    import android.animation.PropertyValuesHolder;
    import android.animation.TimeInterpolator;
    import android.animation.ValueAnimator;
    import android.content.Context;
    import android.graphics.Canvas;
    import android.graphics.Rect;
    import android.graphics.Shader;
    import android.graphics.Matrix;
    import android.graphics.Camera;
    import android.graphics.Paint;
    import android.graphics.Path;
    import android.graphics.Color;
    import android.graphics.RadialGradient;
    import android.view.MotionEvent;
    import android.view.View;
    
    import androidx.annotation.Nullable;
    import android.util.AttributeSet;
    
    
    
    public class MiCompass extends View{
    
        private Canvas mCanvas;
        private Context mContext;
        //View矩形的宽度
        private int width;
        //指南针圆心点坐标
        private int mCenterX;
        private int mCenterY;
        //外圆半径
        private int mOutSideRadius;
        //外接圆半径
        private int mCircumRadius;
        //指南针文字大小空间高度
        private int mTextHeight;
        //暗红色 外圈笔
        private Paint mDarkRedPaint;
        //深灰 外圈笔
        private Paint mDeepGrayPaint;
        //外三角笔
        private Paint mOutSideCircumPaint;
        //浅灰 外圈笔
        private Paint mLightGrayPaint;
        //指南针上面 文字笔
        private Paint mTextPaint;
        //外接圆，三角形笔
        private Paint mCircumPaint;
        //指南针上面文字的外接矩形,用来测文字大小让文字居中
        private Rect mTextRect;
        //外圈小三角形的Path
        private Path mOutsideTriangle;
        //外接圆小三角形的Path
        private Path mCircumTriangle;
    
        //NESW 文字笔 和文字外接矩形
        private Paint mNorthPaint;
        private Paint mOthersPaint;
        private Rect  mPositionRect;
        //小刻度文字大小矩形和画笔
        private Paint mSamllDegreePaint;
        //两位数的
        private Rect mSencondRect;
        //三位数的
        private Rect mThirdRect;
        //圆心数字矩形
        private Rect mCenterTextRect;
    
        //中心文字笔
        private Paint mCenterPaint;
    
        //内心圆是一个颜色辐射渐变的圆
        private Shader mInnerShader;
        private Paint mInnerPaint;
    
        //定义个点击属性动画
        private ValueAnimator mValueAnimator;
        // camera绕X轴旋转的角度
        private float mCameraRotateX;
        // camera绕Y轴旋转的角度
        private float mCameraRotateY;
        //camera最大旋转角度
        private float mMaxCameraRotate = 10;
    
        // camera绕X轴旋转的角度
        private float mCameraTranslateX;
        // camera绕Y轴旋转的角度
        private float mCameraTranslateY;
        //camera最大旋转角度
        private float mMaxCameraTranslate;
        //camera矩阵
        private Matrix mCameraMatrix;
        //设置camera
        private Camera mCamera;
    
        private float val=0f;
        private float valCompare;
        //偏转角度红线笔
        private Paint mAnglePaint;
    
        //方位文字
        private String text="北";
    
        public float getVal() {
            return val;
        }
    
        public void setVal(float val) {
            this.val = val;
            invalidate();
        }
    
        public MiCompass(Context context) {
            this(context,null);
        }
    
        public MiCompass(Context context, @Nullable AttributeSet attrs) {
            this(context, attrs,0);
        }
    
        public MiCompass(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
            super(context, attrs, defStyleAttr);
            mContext = context;
    
            mDarkRedPaint = new Paint();
            mDarkRedPaint.setStyle(Paint.Style.STROKE);
            mDarkRedPaint.setAntiAlias(true);
            mDarkRedPaint.setColor(context.getResources().getColor(R.color.darkRed));
    
    
            mDeepGrayPaint = new Paint();
            mDeepGrayPaint.setStyle(Paint.Style.STROKE);
            mDeepGrayPaint.setAntiAlias(true);
            mDeepGrayPaint.setColor(context.getResources().getColor(R.color.deepGray));
    
    
            mLightGrayPaint = new Paint();
            mLightGrayPaint.setStyle(Paint.Style.FILL);
            mLightGrayPaint.setAntiAlias(true);
            mLightGrayPaint.setColor(context.getResources().getColor(R.color.lightGray));
    
            mTextPaint = new Paint();
            mTextPaint.setStyle(Paint.Style.STROKE);
            mTextPaint.setAntiAlias(true);
            mTextPaint.setTextSize(80);
            mTextPaint.setColor(context.getResources().getColor(R.color.white));
    
            mCircumPaint = new Paint();
            mCircumPaint.setStyle(Paint.Style.FILL);
            mCircumPaint.setAntiAlias(true);
            mCircumPaint.setColor(context.getResources().getColor(R.color.red));
    
            mOutSideCircumPaint = new Paint();
            mOutSideCircumPaint.setStyle(Paint.Style.FILL);
            mOutSideCircumPaint.setAntiAlias(true);
            mOutSideCircumPaint.setColor(context.getResources().getColor(R.color.lightGray));
    
            mTextRect = new Rect();
            mOutsideTriangle = new Path();
            mCircumTriangle = new Path();
    
            mNorthPaint = new Paint();
            mNorthPaint.setStyle(Paint.Style.STROKE);
            mNorthPaint.setAntiAlias(true);
            mNorthPaint.setTextSize(40);
            mNorthPaint.setColor(context.getResources().getColor(R.color.red));
    
            mOthersPaint = new Paint();
            mOthersPaint.setStyle(Paint.Style.STROKE);
            mOthersPaint.setAntiAlias(true);
            mOthersPaint.setTextSize(40);
            mOthersPaint.setColor(context.getResources().getColor(R.color.white));
    
            mPositionRect = new Rect();
            mCenterTextRect = new Rect();
    
            mCenterPaint = new Paint();
            mCenterPaint.setStyle(Paint.Style.STROKE);
            mCenterPaint.setAntiAlias(true);
            mCenterPaint.setTextSize(120);
            mCenterPaint.setColor(context.getResources().getColor(R.color.white));
    
            mSamllDegreePaint = new Paint();
            mSamllDegreePaint.setStyle(Paint.Style.STROKE);
            mSamllDegreePaint.setAntiAlias(true);
            mSamllDegreePaint.setTextSize(30);
            mSamllDegreePaint.setColor(context.getResources().getColor(R.color.lightGray));
    
            mSencondRect = new Rect();
            mThirdRect = new Rect();
    
            mInnerPaint = new Paint();
            mInnerPaint.setStyle(Paint.Style.FILL);
            mInnerPaint.setAntiAlias(true);
    
            mAnglePaint = new Paint();
            mAnglePaint.setStyle(Paint.Style.STROKE);
            mAnglePaint.setAntiAlias(true);
            mAnglePaint.setColor(context.getResources().getColor(R.color.red));
    
            mCameraMatrix = new Matrix();
            mCamera = new Camera();
    
        }
    
    
    
        @Override
        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);
            mCanvas = canvas;
            //设置Camera矩阵 实现3D效果
            set3DMetrix();
            //画文字
            drawText();
            //画指南针外圈
            drawCompassOutSide();
            //画指南针外接圆
            drawCompassCircum();
            //画内部渐变颜色圆
            drawInnerCricle();
            //画指南针内部刻度
            drawCompassDegreeScale();
            //画圆心数字
            drawCenterText();
        }
    
    
    
        /**
         * 设置camera相关
         */
        private void set3DMetrix() {
            mCameraMatrix.reset();
            mCamera.save();
            mCamera.rotateX(mCameraRotateX);
            mCamera.rotateY(mCameraRotateY);
            mCamera.getMatrix(mCameraMatrix);
            mCamera.restore();
            //camera默认旋转是View左上角为旋转中心
            //所以动作之前要，设置矩阵位置 -mTextHeight-mOutSideRadius
            mCameraMatrix.preTranslate(-getWidth()/2,-getHeight()/2);
            //动作之后恢复位置
            mCameraMatrix.postTranslate(getWidth()/2,getHeight()/2);
            mCanvas.concat(mCameraMatrix);
        }
    
        private void drawInnerCricle() {
    
            mInnerShader = new RadialGradient(width/2,mOutSideRadius+mTextHeight,mCircumRadius-40, Color.parseColor("#323232"),
                    Color.parseColor("#000000"),Shader.TileMode.CLAMP);
            mInnerPaint.setShader(mInnerShader);
            mCanvas.drawCircle(width/2,mOutSideRadius+mTextHeight,mCircumRadius-40,mInnerPaint);
    
        }
    
        private void drawCenterText() {
            String centerText=String.valueOf((int) val+"°");
            mCenterPaint.getTextBounds(centerText,0,centerText.length(),mCenterTextRect);
            int centerTextWidth = mCenterTextRect.width();
            int centerTextHeight = mCenterTextRect.height();
            mCanvas.drawText(centerText,width/2-centerTextWidth/2,mTextHeight+mOutSideRadius+centerTextHeight/5,mCenterPaint);
    
        }
    
        private void drawCompassDegreeScale() {
            mCanvas.save();
            //获取N文字的宽度
            mNorthPaint.getTextBounds("N",0,1,mPositionRect);
            int mPositionTextWidth = mPositionRect.width();
            int mPositionTextHeight = mPositionRect.height();
            //获取W文字宽度,因为W比较宽 所以要单独获取
            mNorthPaint.getTextBounds("W",0,1,mPositionRect);
            int mWPositionTextWidth = mPositionRect.width();
            int mWPositionTextHeight = mPositionRect.height();
            //获取小刻度，两位数的宽度
            mSamllDegreePaint.getTextBounds("30",0,1,mSencondRect);
            int mSencondTextWidth = mSencondRect.width();
            int mSencondTextHeight = mSencondRect.height();
            //获取小刻度，3位数的宽度
            mSamllDegreePaint.getTextBounds("30",0,1,mThirdRect);
            int mThirdTextWidth = mThirdRect.width();
            int mThirdTextHeight = mThirdRect.height();
    
            mCanvas.rotate(-val,width/2,mOutSideRadius+mTextHeight);
    
    
            //画刻度线
            for (int i = 0; i < 240; i++) {
    
                if (i==0||i==60||i==120||i==180){
                    mCanvas.drawLine(getWidth() / 2, mTextHeight+mOutSideRadius-mCircumRadius+10,
                            getWidth() / 2,  mTextHeight+mOutSideRadius-mCircumRadius+30, mDeepGrayPaint);
                }else{
                    mCanvas.drawLine(getWidth() / 2, mTextHeight+mOutSideRadius-mCircumRadius+10,
                            getWidth() / 2,  mTextHeight+mOutSideRadius-mCircumRadius+30, mLightGrayPaint);
                }
                if (i==0){
                    mCanvas.drawText("N", this.width /2-mPositionTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mPositionTextHeight,mNorthPaint);
                }else if (i==60){
                    mCanvas.drawText("E", this.width /2-mPositionTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mPositionTextHeight,mOthersPaint);
                }else if (i==120){
                    mCanvas.drawText("S", this.width /2-mPositionTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mPositionTextHeight,mOthersPaint);
                }else if (i==180){
                    mCanvas.drawText("W", this.width /2-mWPositionTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mWPositionTextHeight,mOthersPaint);
                }else if (i==20){
                    mCanvas.drawText("30", this.width /2-mSencondTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mSencondTextHeight,mSamllDegreePaint);
                }else if (i==40){
                    mCanvas.drawText("60", this.width /2-mSencondTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mSencondTextHeight,mSamllDegreePaint);
                }else if (i==80){
                    mCanvas.drawText("120", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }else if (i==100){
                    mCanvas.drawText("150", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }else if (i==140){
                    mCanvas.drawText("210", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }else if (i==160){
                    mCanvas.drawText("240", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }else if (i==200){
                    mCanvas.drawText("300", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }else if (i==220){
                    mCanvas.drawText("330", this.width /2-mThirdTextWidth/2,mTextHeight+mOutSideRadius-mCircumRadius+40+mThirdTextHeight,mSamllDegreePaint);
                }
                mCanvas.rotate(1.5f, mCenterX, mOutSideRadius+mTextHeight);
            }
            mCanvas.restore();
    
        }
    
        /**
         * 指南针外接圆，和外部圆换道理差不多
         */
        private void drawCompassCircum() {
            mCanvas.save();
            //外接圆小三角形的高度
            int mTriangleHeight=(mOutSideRadius-mCircumRadius)/2;
    
            mCanvas.rotate(-val,width/2,mOutSideRadius+mTextHeight);
            mCircumTriangle.moveTo(width/2,mTriangleHeight+mTextHeight);
            //内接三角形的边长,简单数学运算
            float mTriangleSide = (float) ((mTriangleHeight/(Math.sqrt(3)))*2);
            mCircumTriangle.lineTo(width/2-mTriangleSide/2,mTextHeight+mTriangleHeight*2);
            mCircumTriangle.lineTo(width/2+mTriangleSide/2,mTextHeight+mTriangleHeight*2);
            mCircumTriangle.close();
            mCanvas.drawPath(mCircumTriangle,mCircumPaint);
            mCanvas.drawArc(width/2-mCircumRadius,mTextHeight+mOutSideRadius-mCircumRadius,
                    width/2+mCircumRadius,mTextHeight+mOutSideRadius+mCircumRadius,-85,350,false,mDeepGrayPaint);
            mAnglePaint.setStrokeWidth(5f);
            if (val<=180){
                valCompare = val;
                mCanvas.drawArc(width/2-mCircumRadius,mTextHeight+mOutSideRadius-mCircumRadius,
                        width/2+mCircumRadius,mTextHeight+mOutSideRadius+mCircumRadius,-85,valCompare,false,mAnglePaint);
            }else{
                valCompare = 360-val;
                mCanvas.drawArc(width/2-mCircumRadius,mTextHeight+mOutSideRadius-mCircumRadius,
                        width/2+mCircumRadius,mTextHeight+mOutSideRadius+mCircumRadius,-95,-valCompare,false,mAnglePaint);
            }
    
            mCanvas.restore();
        }
    
        /**
         * 指南针外部可简单分为两部分
         * 1、用Path实现小三角形
         * 2、两个圆弧
         */
        private void drawCompassOutSide() {
            mCanvas.save();
            //小三角形的高度
            int mTriangleHeight=40;
            //定义Path画小三角形
            mOutsideTriangle.moveTo(width/2,mTextHeight-mTriangleHeight);
            //小三角形的边长
            float mTriangleSide = 46.18f;
            //画出小三角形
            mOutsideTriangle.lineTo(width/2-mTriangleSide/2,mTextHeight);
            mOutsideTriangle.lineTo(width/2+mTriangleSide/2,mTextHeight);
            mOutsideTriangle.close();
            mCanvas.drawPath(mOutsideTriangle,mOutSideCircumPaint);
    
            //画圆弧
            mDarkRedPaint.setStrokeWidth((float) 5);
            mLightGrayPaint.setStrokeWidth((float)5);
            mDeepGrayPaint.setStrokeWidth((float)3);
            mLightGrayPaint.setStyle(Paint.Style.STROKE);
            mCanvas.drawArc(width/2-mOutSideRadius,mTextHeight,width/2+mOutSideRadius,mTextHeight+mOutSideRadius*2,-80,120,false,mLightGrayPaint);
            mCanvas.drawArc(width/2-mOutSideRadius,mTextHeight,width/2+mOutSideRadius,mTextHeight+mOutSideRadius*2,40,20,false,mDeepGrayPaint);
            mCanvas.drawArc(width/2-mOutSideRadius,mTextHeight,width/2+mOutSideRadius,mTextHeight+mOutSideRadius*2,-100,-20,false,mLightGrayPaint);
            mCanvas.drawArc(width/2-mOutSideRadius,mTextHeight,width/2+mOutSideRadius,mTextHeight+mOutSideRadius*2,-120,-120,false,mDarkRedPaint);
            mCanvas.restore();
        }
    
        private void drawText() {
            if (val<=15||val>=345){
                text = "北";
            }else if (val>15&&val<=75){
                text= "东北";
            }else if (val>75&&val<=105){
                text= "东";
            }else if (val>105&&val<=165){
                text="东南";
            }else if (val>165&&val<=195){
                text = "南";
            }else if (val>195&&val<=255){
                text = "西南";
            }else if (val>255&&val<=285){
                text = "西";
            }else if (val>285&&val<345){
                text="西北";
            }
    
            mTextPaint.getTextBounds(text,0,text.length(),mTextRect);
            //文字宽度
            int mTextWidth = mTextRect.width();
            //让文字水平居中显示
            mCanvas.drawText(text,width/2-mTextWidth/2,mTextHeight/2,mTextPaint);
    
        }
    
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            super.onMeasure(widthMeasureSpec, heightMeasureSpec);
            int widthSize = MeasureSpec.getSize(widthMeasureSpec);
            int widthMode = MeasureSpec.getMode(widthMeasureSpec);
            int heightSize = MeasureSpec.getSize(heightMeasureSpec);
            int heightMode = MeasureSpec.getMode(heightMeasureSpec);
            width = Math.min(widthSize, heightSize);
            if (widthMode == MeasureSpec.UNSPECIFIED) {
                width = heightSize;
            } else if (heightMode == MeasureSpec.UNSPECIFIED) {
                width = widthSize;
            }
            //为指南针上面的文字预留空间，定为1/3边张
            mTextHeight = width/3;
            //设置圆心点坐标
            mCenterX = width/2;
            mCenterY = width/2+mTextHeight;
            //外部圆的外径
            mOutSideRadius = width*3/8;
            //外接圆的半径
            mCircumRadius = mOutSideRadius*4/5;
            //camera最大平移距离
            mMaxCameraTranslate = 0.02f*mOutSideRadius;
            setMeasuredDimension(width, width+width/3 );
        }
    
        @Override
        public boolean onTouchEvent(MotionEvent event) {
            switch (event.getAction()){
                case MotionEvent.ACTION_DOWN:
                    if (mValueAnimator!=null&&mValueAnimator.isRunning()){
                        mValueAnimator.cancel();
                    }
                    //3D 效果让Camera旋转,获取旋转偏移大小
                    getCameraRotate(event);
                    //获取平移大小
                    getCameraTranslate(event);
                    break;
                case MotionEvent.ACTION_MOVE:
                    //3D 效果让Camera旋转,获取旋转偏移大小
                    getCameraRotate(event);
                    //获取平移大小
                    getCameraTranslate(event);
                    break;
                case MotionEvent.ACTION_UP:
                    //松开手 复原动画
                    startRestore();
                    break;
            }
            return true;
    
        }
    
        private void startRestore() {
            final String cameraRotateXName = "cameraRotateX";
            final String cameraRotateYName = "cameraRotateY";
            final String canvasTranslateXName = "canvasTranslateX";
            final String canvasTranslateYName = "canvasTranslateY";
            PropertyValuesHolder cameraRotateXHolder =
                    PropertyValuesHolder.ofFloat(cameraRotateXName, mCameraRotateX, 0);
            PropertyValuesHolder cameraRotateYHolder =
                    PropertyValuesHolder.ofFloat(cameraRotateYName, mCameraRotateY, 0);
            PropertyValuesHolder canvasTranslateXHolder =
                    PropertyValuesHolder.ofFloat(canvasTranslateXName, mCameraTranslateX, 0);
            PropertyValuesHolder canvasTranslateYHolder =
                    PropertyValuesHolder.ofFloat(canvasTranslateYName, mCameraTranslateY, 0);
            mValueAnimator = ValueAnimator.ofPropertyValuesHolder(cameraRotateXHolder,
                    cameraRotateYHolder, canvasTranslateXHolder, canvasTranslateYHolder);
            mValueAnimator.setInterpolator(new TimeInterpolator() {
                @Override
                public float getInterpolation(float input) {
                    float f = 0.571429f;
                    return (float) (Math.pow(2, -2 * input) * Math.sin((input - f / 4) * (2 * Math.PI) / f) + 1);
                }
            });
            mValueAnimator.setDuration(1000);
            mValueAnimator.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() {
                @Override
                public void onAnimationUpdate(ValueAnimator animation) {
                    mCameraRotateX = (float) animation.getAnimatedValue(cameraRotateXName);
                    mCameraRotateY = (float) animation.getAnimatedValue(cameraRotateYName);
                    mCameraTranslateX = (float) animation.getAnimatedValue(canvasTranslateXName);
                    mCameraTranslateX = (float) animation.getAnimatedValue(canvasTranslateYName);
                }
            });
            mValueAnimator.start();
        }
    
        /**
         * 获取Camera，平移大小
         * @param event
         */
        private void getCameraTranslate(MotionEvent event) {
            float translateX = (event.getX() - getWidth() / 2);
            float translateY = (event.getY() - getHeight()/2);
            //求出此时位移的大小与半径之比
            float[] percentArr = getPercent(translateX, translateY);
            //最终位移的大小按比例匀称改变
            mCameraTranslateX = percentArr[0] * mMaxCameraTranslate;
            mCameraTranslateY = percentArr[1] * mMaxCameraTranslate;
        }
    
        /**
         * 让Camera旋转,获取旋转偏移大小
         * @param event
         */
        private void getCameraRotate(MotionEvent event) {
            float mRotateX = -(event.getY()-(getHeight())/2);
            float mRotateY = (event.getX()-getWidth()/2);
            //求出旋转大小与半径之比
            float[] percentArr = getPercent(mRotateX,mRotateY);
            mCameraRotateX = percentArr[0]*mMaxCameraRotate;
            mCameraRotateY = percentArr[1]*mMaxCameraRotate;
        }
    
        /**
         * 获取比例
         * @param mCameraRotateX
         * @param mCameraRotateY
         * @return
         */
        private float[] getPercent(float mCameraRotateX, float mCameraRotateY) {
            float[] percentArr = new float[2];
            float percentX = mCameraRotateX/width;
            float percentY = mCameraRotateY/width;
            //处理一下比例值
            if (percentX > 1) {
                percentX = 1;
            } else if (percentX < -1) {
                percentX = -1;
            }
            if (percentY > 1) {
                percentY = 1;
            } else if (percentY < -1) {
                percentY = -1;
            }
            percentArr[0] = percentX;
            percentArr[1] = percentY;
            return percentArr;
        }
    
    
    }

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_Q1NETiBAQ2hfY2hhbXBpb24_size_54_color_FFFFFF_t_70_g_se_x_16][]

2、colors.xml文件

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_Q1NETiBAQ2hfY2hhbXBpb24_size_23_color_FFFFFF_t_70_g_se_x_16][]

<?xml version="1.0" encoding="utf-8"?>
    <resources>
        <color name="colorPrimary">#3F51B5</color>
        <color name="colorPrimaryDark">#303F9F</color>
        <color name="colorAccent">#FF4081</color>
        <color name="black">#000</color>
        <color name="darkRed">#702216</color>
        <color name="lightGray">#323232</color>
        <color name="deepGray">#8B8B8B</color>
        <color name="white">#fff</color>
        <color name="red">#f00</color>
        <color name="ocbg">#237EAD</color>
    </resources>

3、value\\themes.xml、value-nigth\\themes.xml文件

此时有两个报错，不用怕，挨个解决，挨个创建即可。

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAQ2hfY2hhbXBpb24_size_20_color_FFFFFF_t_70_g_se_x_16][]

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAQ2hfY2hhbXBpb24_size_20_color_FFFFFF_t_70_g_se_x_16 1][]

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAQ2hfY2hhbXBpb24_size_20_color_FFFFFF_t_70_g_se_x_16 2][] ![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAQ2hfY2hhbXBpb24_size_20_color_FFFFFF_t_70_g_se_x_16 3][]

报错的地方，按照以上方法，挨个创建即可，创建好之后如下所示：

![watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBAQ2hfY2hhbXBpb24_size_20_color_FFFFFF_t_70_g_se_x_16 4][]

4、activity\_main.xml文件  
![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_Q1NETiBAQ2hfY2hhbXBpb24_size_37_color_FFFFFF_t_70_g_se_x_16][]

<?xml version="1.0" encoding="utf-8"?>
    <androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@color/black"
        tools:context=".MainActivity">
    
        <com.example.mycompass.MiCompass
            android:id="@+id/miui"
            android:layout_centerInParent="true"
            android:layout_gravity="center"
            android:background="@color/black"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            tools:ignore="MissingConstraints" />
    
    </androidx.constraintlayout.widget.ConstraintLayout>

5、MainActivity.java文件

package com.example.mycompass;
    
    import androidx.appcompat.app.AppCompatActivity;
    
    import android.hardware.Sensor;
    import android.hardware.SensorEvent;
    import android.hardware.SensorEventListener;
    import android.hardware.SensorManager;
    import android.os.Bundle;
    
    public class MainActivity extends AppCompatActivity {
    
        private SensorManager sensorManager;
        private SensorEventListener sensorEventListener;
        private MiCompass miui;
        private  float val;
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            miui = findViewById(R.id.miui);
            sensorManager = (SensorManager) getSystemService(SENSOR_SERVICE);
            sensorEventListener = new SensorEventListener() {
                @Override
                public void onSensorChanged(SensorEvent sensorEvent) {
                    val = sensorEvent.values[0];
                    System.out.println(val);
                    miui.setVal(val);
                }
    
                @Override
                public void onAccuracyChanged(Sensor sensor, int i) {
    
                }
            };
    //        sensorManager.registerListener(sensorEventListener, sensorManager.getDefaultSensor(Sensor.TYPE_GRAVITY)
    //        ,sensorManager.SENSOR_DELAY_GAME);
            sensorManager.registerListener(sensorEventListener,sensorManager.getDefaultSensor(Sensor.TYPE_ORIENTATION),
                    SensorManager.SENSOR_DELAY_GAME);
        }
    
        @Override
        protected void onDestroy() {
            super.onDestroy();
            sensorManager.unregisterListener(sensorEventListener);
        }
    }

## 三、结果 ##

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_Q1NETiBAQ2hfY2hhbXBpb24_size_10_color_FFFFFF_t_70_g_se_x_16][]

## 四、总结 ##

在此，做个笔录，没想到多年没碰Android，现在还是初恋的感觉 哈哈^\_^。在这希望能帮到各个技术攻城狮。基本多部分都是参考以下文章编写而成，在此非常感谢！这位大佬无私贡献。

源码（csdn代码仓库）：[Ch\_champion / MyCompass · CODE CHINA][Ch_champion _ MyCompass _ CODE CHINA]

参考文章：

[android学习笔记之磁场传感器制做指南针\_晓晓的博客-CSDN博客][android_-CSDN]

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[Ch_champion _ MyCompass _ CODE CHINA]: https://codechina.csdn.net/qq_36075612/mycompass
[android_-CSDN]: https://blog.csdn.net/qq_34423913/article/details/104989963