[游戏开发]自定义View实现可调节温度控制圈

/**
 * 温度控制
 */
public class TempControlView extends View {

    // 控件宽
    private int width;
    // 控件高
    private int height;
    // 刻度盘半径
    private int dialRadius;
    // 圆弧半径
    private int arcRadius;
    // 刻度高
    private int scaleHeight = dp2px(10);
    // 刻度盘画笔
    private Paint dialPaint;
    // 圆弧画笔
    private Paint arcPaint;
    // 标题画笔
    private Paint titlePaint;
    // 温度标识画笔
    private Paint tempFlagPaint;
    // 旋转按钮画笔
    private Paint buttonPaint;
    // 温度显示画笔
    private Paint tempPaint;
    // 文本提示
    private String title = "最高温度设置";
    // 温度
    private int temperature = 15;
    // 最低温度
    private int minTemp = 15;
    // 最高温度
    private int maxTemp = 30;
    // 四格代表温度1度
    private int angleRate = 4;
    // 每格的角度
    private float angleOne = (float) 270 / (maxTemp - minTemp) / angleRate;
    // 按钮图片
    private Bitmap buttonImage = BitmapFactory.decodeResource(getResources(),
            R.mipmap.btn_rotate);
    // 按钮图片阴影
    private Bitmap buttonImageShadow = BitmapFactory.decodeResource(getResources(),
            R.mipmap.btn_rotate_shadow);
    // 抗锯齿
    private PaintFlagsDrawFilter paintFlagsDrawFilter;
    // 温度改变监听
    private OnTempChangeListener onTempChangeListener;
    // 控件点击监听
    private OnClickListener onClickListener;

    // 以下为旋转按钮相关

    // 当前按钮旋转的角度
    private float rotateAngle;
    // 当前的角度
    private float currentAngle;
    /**
     * 是否可以旋转
     */
    private boolean canRotate = false;

    public TempControlView(Context context) {
        this(context, null);
    }

    public TempControlView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public TempControlView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        init();
    }

    private void init() {
        dialPaint = new Paint();
        dialPaint.setAntiAlias(true);
        dialPaint.setStrokeWidth(dp2px(2));
        dialPaint.setStyle(Paint.Style.STROKE);

        arcPaint = new Paint();
        arcPaint.setAntiAlias(true);
        arcPaint.setColor(Color.parseColor("#3CB7EA"));
        arcPaint.setStrokeWidth(dp2px(2));
        arcPaint.setStyle(Paint.Style.STROKE);

        titlePaint = new Paint();
        titlePaint.setAntiAlias(true);
        titlePaint.setTextSize(sp2px(15));
        titlePaint.setColor(Color.parseColor("#3CB7EB"));
        titlePaint.setStyle(Paint.Style.STROKE);

        tempFlagPaint = new Paint();
        tempFlagPaint.setAntiAlias(true);
        tempFlagPaint.setTextSize(sp2px(25));
        tempFlagPaint.setColor(Color.parseColor("#E4A07E"));
        tempFlagPaint.setStyle(Paint.Style.STROKE);

        buttonPaint = new Paint();
        tempFlagPaint.setAntiAlias(true);
        paintFlagsDrawFilter = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG);

        tempPaint = new Paint();
        tempPaint.setAntiAlias(true);
        tempPaint.setTextSize(sp2px(60));
        tempPaint.setColor(Color.parseColor("#E27A3F"));
        tempPaint.setStyle(Paint.Style.STROKE);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        // 控件宽、高
        width = height = Math.min(h, w);
        // 刻度盘半径
        dialRadius = width / 2 - dp2px(20);
        // 圆弧半径
        arcRadius = dialRadius - dp2px(20);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        drawScale(canvas);
        drawArc(canvas);
        drawText(canvas);
        drawButton(canvas);
        drawTemp(canvas);
    }


    /**
     * 绘制刻度盘
     *
     * @param canvas 画布
     */
    private void drawScale(Canvas canvas) {
        canvas.save();
        canvas.translate(getWidth() / 2, getHeight() / 2);
        // 顺时针旋转135-2度
        canvas.rotate(133);
        //未达到的温度
        dialPaint.setColor(Color.parseColor("#3CB7EA"));
        for (int i = angleRate * maxTemp; i > angleRate * temperature; i--) {
            canvas.drawLine(0, -dialRadius, 0, -dialRadius + scaleHeight, dialPaint);
            canvas.rotate(-angleOne);
        }

        //已经达到的温度
        dialPaint.setColor(Color.parseColor("#E37364"));
        for (int i = temperature * angleRate; i >= minTemp * angleRate; i--) {
            canvas.drawLine(0, -dialRadius, 0, -dialRadius + scaleHeight, dialPaint);
            canvas.rotate(-angleOne);
        }
        canvas.restore();
    }

    /**
     * 绘制刻度盘下的圆弧
     *
     * @param canvas 画布
     */
    private void drawArc(Canvas canvas) {
        canvas.save();
        canvas.translate(getWidth() / 2, getHeight() / 2);
        canvas.rotate(135 + 2);
        RectF rectF = new RectF(-arcRadius, -arcRadius, arcRadius, arcRadius);
        canvas.drawArc(rectF, 0, 265, false, arcPaint);
        canvas.restore();
    }

    /**
     * 绘制标题与温度标识
     *
     * @param canvas 画布
     */
    private void drawText(Canvas canvas) {
        canvas.save();

        // 绘制标题
        float titleWidth = titlePaint.measureText(title);
        canvas.drawText(title, (width - titleWidth) / 2, dialRadius * 2 + dp2px(15), titlePaint);

        // 绘制最小温度标识
        // 最小温度如果小于10，显示为0x
        String minTempFlag = "";
        if (minTemp <= 0) {
            minTempFlag = minTemp + "";
        } else {
            minTempFlag = minTemp < 10 ? "0" + minTemp : minTemp + "";
        }

        float tempFlagWidth = titlePaint
                .measureText(maxTemp + "");
        canvas.rotate(55, width / 2, height / 2);
        canvas.drawText(minTempFlag,
                (width - tempFlagWidth) / 2, height + dp2px(5), tempFlagPaint);

        // 绘制最大温度标识
        canvas.rotate(-105, width / 2, height / 2);
        canvas.drawText(maxTemp + "",
                (width - tempFlagWidth) / 2, height + dp2px(5), tempFlagPaint);
        canvas.restore();
    }

    /**
     * 绘制旋转按钮
     *
     * @param canvas 画布
     */
    private void drawButton(Canvas canvas) {
        // 按钮宽高
        int buttonWidth = buttonImage.getWidth();
        int buttonHeight = buttonImage.getHeight();
        // 按钮阴影宽高
        int buttonShadowWidth = buttonImageShadow.getWidth();
        int buttonShadowHeight = buttonImageShadow.getHeight();

        // 绘制按钮阴影
        canvas.drawBitmap(buttonImageShadow, (width - buttonShadowWidth) / 2,
                (height - buttonShadowHeight) / 2, buttonPaint);

        Matrix matrix = new Matrix();
        // 设置按钮位置，移动到控件中心
        matrix.setTranslate((width - buttonWidth) / 2, (height - buttonHeight) / 2);
        // 设置旋转角度，旋转中心为控件中心，当前也是按钮中心
        matrix.postRotate(45 + rotateAngle, width / 2, height / 2);

        //设置抗锯齿
        canvas.setDrawFilter(paintFlagsDrawFilter);
        canvas.drawBitmap(buttonImage, matrix, buttonPaint);
    }

    /**
     * 绘制温度
     *
     * @param canvas 画布
     */
    private void drawTemp(Canvas canvas) {
        canvas.save();
        canvas.translate(getWidth() / 2, getHeight() / 2);

        float tempWidth = tempPaint.measureText(temperature + "");
        float tempHeight = (tempPaint.ascent() + tempPaint.descent()) / 2;
        canvas.drawText(temperature + "°", -tempWidth / 2 - dp2px(5), -tempHeight, tempPaint);
        canvas.restore();
    }

    private boolean isDown;
    private boolean isMove;

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (!canRotate) {
            return super.onTouchEvent(event);
        } else {
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    isDown = true;
                    float downX = event.getX();
                    float downY = event.getY();
                    currentAngle = calcAngle(downX, downY);
                    break;

                case MotionEvent.ACTION_MOVE:
                    isMove = true;
                    float targetX;
                    float targetY;
                    downX = targetX = event.getX();
                    downY = targetY = event.getY();
                    float angle = calcAngle(targetX, targetY);

                    // 滑过的角度增量
                    float angleIncreased = angle - currentAngle;

                    // 防止越界
                    if (angleIncreased < -270) {
                        angleIncreased = angleIncreased + 360;
                    } else if (angleIncreased > 270) {
                        angleIncreased = angleIncreased - 360;
                    }

                    IncreaseAngle(angleIncreased);
                    currentAngle = angle;
                    invalidate();
                    break;

                case MotionEvent.ACTION_CANCEL:
                case MotionEvent.ACTION_UP: {
                    if (isDown) {
                        if (isMove) {
                            // 纠正指针位置
                            rotateAngle = (float) ((temperature - minTemp) * angleRate * angleOne);
                            invalidate();
                            // 回调温度改变监听
                            if (onTempChangeListener != null) {
                                onTempChangeListener.change(temperature);
                            }
                            isMove = false;
                        } else {
                            // 点击事件
                            if (onClickListener != null) {
                                onClickListener.onClick(temperature);
                            }
                        }
                        isDown = false;
                    }
                    break;
                }
            }
            return true;
        }
    }

    /**
     * 以按钮圆心为坐标圆点，建立坐标系，求出(targetX, targetY)坐标与x轴的夹角
     *
     * @param targetX x坐标
     * @param targetY y坐标
     * @return (targetX, targetY)坐标与x轴的夹角
     */
    private float calcAngle(float targetX, float targetY) {
        float x = targetX - width / 2;
        float y = targetY - height / 2;
        double radian;

        if (x != 0) {
            float tan = Math.abs(y / x);
            if (x > 0) {
                if (y >= 0) {
                    radian = Math.atan(tan);
                } else {
                    radian = 2 * Math.PI - Math.atan(tan);
                }
            } else {
                if (y >= 0) {
                    radian = Math.PI - Math.atan(tan);
                } else {
                    radian = Math.PI + Math.atan(tan);
                }
            }
        } else {
            if (y > 0) {
                radian = Math.PI / 2;
            } else {
                radian = -Math.PI / 2;
            }
        }
        return (float) ((radian * 180) / Math.PI);
    }

    /**
     * 增加旋转角度
     *
     * @param angle 增加的角度
     */
    private void IncreaseAngle(float angle) {
        rotateAngle += angle;
        if (rotateAngle < 0) {
            rotateAngle = 0;
        } else if (rotateAngle > 270) {
            rotateAngle = 270;
        }
        // 加上0.5是为了取整时四舍五入
        temperature = (int) ((rotateAngle / angleOne) / angleRate + 0.5) + minTemp;
    }

    /**
     * 设置几格代表1度，默认4格
     *
     * @param angleRate 几格代表1度
     */
    public void setAngleRate(int angleRate) {
        this.angleRate = angleRate;
    }

    /**
     * 设置温度
     *
     * @param temp 设置的温度
     */
    public void setTemp(int temp) {
        setTemp(minTemp, maxTemp, temp);
    }

    /**
     * 设置温度
     *
     * @param minTemp 最小温度
     * @param maxTemp 最大温度
     * @param temp    设置的温度
     */
    public void setTemp(int minTemp, int maxTemp, int temp) {
        this.minTemp = minTemp;
        this.maxTemp = maxTemp;
        if (temp < minTemp) {
            this.temperature = minTemp;
        } else {
            this.temperature = temp;
        }
        // 计算每格的角度
        angleOne = (float) 270 / (maxTemp - minTemp) / angleRate;
        // 计算旋转角度
        rotateAngle = (float) ((temp - minTemp) * angleRate * angleOne);

        invalidate();
    }

    /**
     * 设置旋钮是否可以旋转
     *
     * @param canRotate
     */
    public void setCanRotate(boolean canRotate) {
        this.canRotate = canRotate;
    }

    public boolean getCanRotate() {
        return this.canRotate;
    }


    /**
     * 设置温度改变监听
     *
     * @param onTempChangeListener 监听接口
     */
    public void setOnTempChangeListener(OnTempChangeListener onTempChangeListener) {
        this.onTempChangeListener = onTempChangeListener;
    }

    /**
     * 设置点击监听
     *
     * @param onClickListener 点击回调接口
     */
    public void setOnClickListener(OnClickListener onClickListener) {
        this.onClickListener = onClickListener;
    }

    /**
     * 温度改变监听接口
     */
    public interface OnTempChangeListener {
        /**
         * 回调方法
         *
         * @param temp 温度
         */
        void change(int temp);
    }

    /**
     * 点击回调接口
     */
    public interface OnClickListener {
        /**
         * 点击回调方法
         *
         * @param temp 温度
         */
        void onClick(int temp);
    }

    public int dp2px(float dp) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, dp,
                getResources().getDisplayMetrics());
    }

    private int sp2px(float sp) {
        return (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, sp,
                getResources().getDisplayMetrics());
    }
}

public class WenDuJiActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_wen_du_ji);
        TempControlView tempControl = findViewById(R.id.temp_control);
        //设置三格代表1温度
        tempControl.setAngleRate(1);
        tempControl.setTemp(16, 37, 20);
        tempControl.setCanRotate(true);
        tempControl.setOnTempChangeListener(new TempControlView.OnTempChangeListener() {
            @Override
            public void change(int temp) {
                Toast.makeText(WenDuJiActivity.this, temp + "°", Toast.LENGTH_SHORT).show();
            }
        });
        tempControl.setOnClickListener(new TempControlView.OnClickListener() {
            @Override
            public void onClick(int temp) {
                Toast.makeText(WenDuJiActivity.this, temp + "°", Toast.LENGTH_SHORT).show();
            }
        });


    }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
    tools:context=".wenduji.WenDuJiActivity">
    <com.example.javaexo.wenduji.TempControlView
        android:id="@+id/temp_control"
        android:layout_width="260dp"
        android:layout_height="260dp"
        android:layout_centerInParent="true"/>

</RelativeLayout>