一个计算角度的类

分类：Android, Java 阅读 (446)

4月 062019

转载请注明原文地址：http://bcoder.com/java/a-class-for-calc-angle-in-android

本代码是个半成品，只作为参考

使用时，将此类作为android组件放到布局中即可

计算红线与绿线之间的角度，效果图如下：

代码如下：

package com.bcoder.widgets;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.PointF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

import androidx.annotation.Nullable;

import java.util.ArrayList;
import java.util.List;


public class AngleCalcView extends View {
    private static final String LOG_TAG = "AngleCalcView";

    private List<PointF> mPoints = new ArrayList<>();
    private Paint mPointPaint;
    private Paint mBaseLinePaint;

    public AngleCalcView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);

        mPointPaint = new Paint();
        mPointPaint.setStrokeWidth(2);
        mPointPaint.setColor(Color.RED);
        mPointPaint.setTextSize(20);

        mBaseLinePaint = new Paint();
        mBaseLinePaint.setStrokeWidth(5);
        mBaseLinePaint.setColor(Color.GREEN);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawColor(Color.WHITE);

        //666, 749，这是view中心的坐标，因为只是临时测试，我手动获取添加到程序的
        float centerX = 666;
        float centerY = 749;


        canvas.drawLine(centerX, centerY, centerX, getHeight(), mBaseLinePaint);

        for(int i = 0; i < mPoints.size(); i++){
            Log.d(LOG_TAG, "x: " + mPoints.get(i).x + ", y: " + mPoints.get(i).y);
            canvas.drawPoint(mPoints.get(i).x, mPoints.get(i).y, mPointPaint);
            double a = (mPoints.get(i).x - centerX) / (mPoints.get(i).y - centerY);
            double b = Math.atan(a) / Math.PI * 180;
            canvas.drawText(String.format("%.2f", b), mPoints.get(i).x + 10, mPoints.get(i).y, mPointPaint);
            canvas.drawLine(centerX, centerY, mPoints.get(i).x, mPoints.get(i).y, mPointPaint);
        }
    }

    @Override
    public boolean dispatchTouchEvent(MotionEvent event) {
        if(event.getAction() == MotionEvent.ACTION_DOWN){
            mPoints.add(new PointF(event.getX(), event.getY()));
        }
        invalidate();
        return super.dispatchTouchEvent(event);
    }
}

package com.bcoder.widgets;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.Point;

import android.graphics.PointF;

import android.util.AttributeSet;

import android.util.Log;

import android.view.MotionEvent;

import android.view.View;

import androidx.annotation.Nullable;

import java.util.ArrayList;

import java.util.List;

public class AngleCalcView extends View {

private static final String LOG_TAG = "AngleCalcView";

private List<PointF> mPoints = new ArrayList<>();

private Paint mPointPaint;

private Paint mBaseLinePaint;

public AngleCalcView(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

mPointPaint = new Paint();

mPointPaint.setStrokeWidth(2);

mPointPaint.setColor(Color.RED);

mPointPaint.setTextSize(20);

mBaseLinePaint = new Paint();

mBaseLinePaint.setStrokeWidth(5);

mBaseLinePaint.setColor(Color.GREEN);

}

@Override

protected void onDraw(Canvas canvas) {

super.onDraw(canvas);

canvas.drawColor(Color.WHITE);

//666, 749，这是view中心的坐标，因为只是临时测试，我手动获取添加到程序的

float centerX = 666;

float centerY = 749;

canvas.drawLine(centerX, centerY, centerX, getHeight(), mBaseLinePaint);

for(int i = 0; i < mPoints.size(); i++){

Log.d(LOG_TAG, "x: " + mPoints.get(i).x + ", y: " + mPoints.get(i).y);

canvas.drawPoint(mPoints.get(i).x, mPoints.get(i).y, mPointPaint);

double a = (mPoints.get(i).x - centerX) / (mPoints.get(i).y - centerY);

double b = Math.atan(a) / Math.PI * 180;

canvas.drawText(String.format("%.2f", b), mPoints.get(i).x + 10, mPoints.get(i).y, mPointPaint);

canvas.drawLine(centerX, centerY, mPoints.get(i).x, mPoints.get(i).y, mPointPaint);

}

@Override

public boolean dispatchTouchEvent(MotionEvent event) {

if(event.getAction() == MotionEvent.ACTION_DOWN){

mPoints.add(new PointF(event.getX(), event.getY()));

}

invalidate();

return super.dispatchTouchEvent(event);

}

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