Android編程基于自定義控件實現時鐘功能的方法

更新時間：2018年03月13日 14:49:01 作者：lizonghuan

這篇文章主要介紹了Android編程基于自定義控件實現時鐘功能的方法,結合實例形式詳細分析了Android自定義控件的定義及時鐘功能相關實現技巧,需要的朋友可以參考下

本文實例講述了Android編程基于自定義控件實現時鐘功能的方法。分享給大家供大家參考，具體如下：

在學習安卓群英傳自定義控件章節(jié)的時候，有一個例子是繪制時鐘，在實現了書上的例子后就想看這個時鐘能不能動起來。

這里選擇延遲一秒發(fā)送消息重繪view來實現的動畫，對外提供了開啟時鐘，關閉時鐘的方法，當activity執(zhí)行onResume方法的時候，執(zhí)行startClock()方法，當移除view或activity執(zhí)行onStop方法的時候可以執(zhí)行stopClock()方法。

首先根據view的寬高來確定圓心的位置，并畫出一個圓。再通過view高度的一半減去圓的半徑，確定刻度的起始位置，選擇刻度的長度并繪制出來。然后再刻度下方繪制出數字。最終將畫布進行旋轉，時鐘總共有60個刻度，循環(huán)旋轉，每次旋轉6度即可。

最后是繪制指針，通過計算算出指針對應每個刻度的X,Y坐標并繪制直線。

代碼實現

自定義控件的代碼（ClockView.java）：

package com.example.clock;
import java.util.Calendar;
import java.util.Date;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.os.Looper;
import android.os.Message;
import android.util.AttributeSet;
import android.view.View;
public class ClockView extends View {
  private Paint circlePaint, dialPaint, numberPaint;
  // view 的寬高
  private float mWidth, mHeight;
  // 圓的半徑
  private float circleRadius;
  // 圓心X,Y坐標
  private float circleX, circleY;
  private int second, minute;
  private double hour;
  private Handler handler = new Handler(Looper.getMainLooper()) {
    @Override
    public void handleMessage(Message msg) {
      super.handleMessage(msg);
      if (msg.what == 0) {
        invalidate();
      }
    }
  };
  public ClockView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initPaint();
  }
  private void initPaint() {
    // 刻盤圓，小時刻度，時針和分針的畫筆
    circlePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    circlePaint.setColor(Color.BLACK);
    circlePaint.setStyle(Paint.Style.STROKE);
    circlePaint.setStrokeWidth(10);
    // 分鐘刻度的畫筆
    dialPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    dialPaint.setColor(Color.BLACK);
    dialPaint.setStrokeWidth(5);
    // 數字的畫筆
    numberPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    numberPaint.setColor(Color.BLACK);
    numberPaint.setStrokeWidth(5);
    numberPaint.setTextSize(30);
  }
  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    mWidth = getMeasuredWidth();
    mHeight = getMeasuredHeight();
    if (mWidth < mHeight) {
      // 圓的半徑為view的寬度的一半再減9，防止貼邊
      circleRadius = mWidth / 2 - 9;
      circleX = mWidth / 2;
      circleY = mHeight / 2;
    } else {
      circleRadius = mHeight / 2 - 9;
      circleX = mWidth / 2;
      circleY = mHeight / 2;
    }
  }
  @Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    setTimes();
    drawCirclePoint(canvas);
    drawCircle(canvas);
    drawDial(canvas);
    drawPointer(canvas);
  }
  /**
   * 圓心
   * 
   * @param canvas
   */
  private void drawCirclePoint(Canvas canvas) {
    canvas.drawCircle(circleX, circleY, 5, circlePaint);
  }
  private void drawCircle(Canvas canvas) {
    canvas.drawCircle(circleX, circleY, circleRadius, circlePaint);
  }
  /**
   * 畫刻度及時間
   * 
   * @param canvas
   */
  private void drawDial(Canvas canvas) {
    // 時鐘用長一點的刻度，畫筆用畫圓的畫筆
    Point hourStartPoint = new Point(circleX, circleY - circleRadius);
    Point hourEndPoint = new Point(circleX, circleY - circleRadius + 40);
    // 分鐘的刻度要稍微短一些，畫筆用畫圓的畫筆
    Point startPoint2 = new Point(circleX, circleY - circleRadius);
    Point endPoint2 = new Point(circleX, circleY - circleRadius + 10);
    // 開始畫刻度和數字，總共60個刻度，12個時鐘刻度，被5整除畫一個時鐘刻度，被其余的為分針刻度
    String clockNumber;
    for (int i = 0; i < 60; i++) {
      if (i % 5 == 0) {
        if (i == 0) {
          clockNumber = "12";
        } else {
          clockNumber = String.valueOf(i / 5);
        }
        // 時針刻度
        canvas.drawLine(hourStartPoint.getX(), hourStartPoint.getY(),
            hourEndPoint.getX(), hourEndPoint.getY(), circlePaint);
        // 畫數字，需在時針刻度末端加30
        canvas.drawText(clockNumber,
            circleX - numberPaint.measureText(clockNumber) / 2,
            hourEndPoint.getY() + 30, numberPaint);
      } else {
        // 畫分針刻度
        canvas.drawLine(startPoint2.getX(), startPoint2.getY(),
            endPoint2.getX(), endPoint2.getY(), circlePaint);
      }
      // 畫布旋轉6度
      canvas.rotate(360 / 60, circleX, circleY);
    }
  }
  /**
   * 畫指針 X點坐標 cos(弧度)*r Y點坐標 sin(弧度)*r toRadians將角度轉成弧度
   * 安卓坐標系與數學坐標系不同的地方是X軸是相反的，所以為了調整方向，需要將角度+270度
   * 
   * @param canvas
   */
  private void drawPointer(Canvas canvas) {
    canvas.translate(circleX, circleY);
    float hourX = (float) Math.cos(Math.toRadians(hour * 30 + 270))
        * circleRadius * 0.5f;
    float hourY = (float) Math.sin(Math.toRadians(hour * 30 + 270))
        * circleRadius * 0.5f;
    float minuteX = (float) Math.cos(Math.toRadians(minute * 6 + 270))
        * circleRadius * 0.8f;
    float minuteY = (float) Math.sin(Math.toRadians(minute * 6 + 270))
        * circleRadius * 0.8f;
    float secondX = (float) Math.cos(Math.toRadians(second * 6 + 270))
        * circleRadius * 0.8f;
    float secondY = (float) Math.sin(Math.toRadians(second * 6 + 270))
        * circleRadius * 0.8f;
    canvas.drawLine(0, 0, hourX, hourY, circlePaint);
    canvas.drawLine(0, 0, minuteX, minuteY, circlePaint);
    canvas.drawLine(0, 0, secondX, secondY, dialPaint);
    // 一秒重繪一次
    handler.sendEmptyMessageDelayed(0, 1000);
  }
  public void startClock() {
    setTimes();
    invalidate();
  }
  private void setTimes() {
    Date date = new Date();
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(date);
    second = getTimes(date, Calendar.SECOND);
    minute = getTimes(date, Calendar.MINUTE);
    hour = getTimes(date, Calendar.HOUR) + minute / 12 * 0.2;
  }
  private int getTimes(Date date, int calendarField) {
    Calendar calendar = Calendar.getInstance();
    calendar.setTime(date);
    return calendar.get(calendarField);
  }
  public void stopClock() {
    handler.removeMessages(0);
  }
}

Point.java：

package com.example.clock;
public class Point {
  private float x;
  private float y;
  public Point(float x, float y) {
    this.x = x;
    this.y = y;
  }
  public float getX() {
    return x;
  }
  public void setX(float x) {
    this.x = x;
  }
  public float getY() {
    return y;
  }
  public void setY(float y) {
    this.y = y;
  }
}

Acitivity（ClockActivity.java）：

package com.example.clock;
import android.app.Activity;
import android.os.Bundle;
public class ClockActivity extends Activity {
  /** Called when the activity is first created. */
  private ClockView clockView;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    clockView = (ClockView) findViewById(R.id.clock);
  }
  @Override
  protected void onResume() {
    super.onResume();
    clockView.startClock();
  }
  @Override
  protected void onStop() {
    super.onStop();
    clockView.stopClock();
  }
}

xml布局（main.xml）：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
  android:orientation="vertical"
  android:layout_width="match_parent"
  android:gravity="center"
  android:layout_height="match_parent">
  <com.example.customview.view.ClockView
    android:layout_width="match_parent"
    android:id="@+id/clock"
    android:layout_height="match_parent" />
</LinearLayout>

更多關于Android相關內容感興趣的讀者可查看本站專題：《Android開發(fā)入門與進階教程》、《Android調試技巧與常見問題解決方法匯總》、《Android基本組件用法總結》、《Android視圖View技巧總結》、《Android布局layout技巧總結》及《Android控件用法總結》

希望本文所述對大家Android程序設計有所幫助。

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