Android自定义控件（一）——开关控件

Google 在 API 14 开始才新增了Switch 控件。

因此，我们可以选择自己封装一个Switch 。

效果如图：

View主要代码：

public class SwitchView extends LinearLayout {
    private ImageView maskImage;              // 开关遮盖图片
    private boolean open;                     // 开关当前状态
    private boolean isAninFinish = true;      // 动画是否结束
    private float x;                          // 记录ACTION_DOWN时候的横坐标
    private boolean isChangedByTouch = false; // 是否在一次事件中已经切换过状态
    private OnSwitchChangeListener switchChangeListener; // 监控开关状态

    public interface OnSwitchChangeListener {
        void onSwitchChanged(boolean open);
    }

    public SwitchView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    public SwitchView(Context context) {
        super(context);
        init();
    }

    private void init() {
        setBackgroundResource(R.drawable.switch_bg);
        maskImage = new ImageView(getContext());
        maskImage.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
        maskImage.setImageResource(R.drawable.switch_mask);
        addView(maskImage);
    }

    public boolean getSwitchStatus() {
        return open;
    }

    public void setSwitchStatus(boolean isOpen) {
        this.open = isOpen;
        if (isOpen) {
            setGravity(Gravity.RIGHT);
        } else {
            setGravity(Gravity.LEFT);
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN: {
            x = event.getX();
            break;
        }
        case MotionEvent.ACTION_MOVE: {
            if (event.getX() - x > 5 && !open) { // 向右
                changeStatus();
            } else if (event.getX() - x < -5 && open) { // 向左
                changeStatus();
            }
            break;
        }
        case MotionEvent.ACTION_UP: {
            if (Math.abs(event.getX() - x) <= 5) {
                changeStatus();
            }
            isChangedByTouch = false;
            break;
        }
        case MotionEvent.ACTION_CANCEL: {
            isChangedByTouch = false;
            break;
        }
        }
        return true;
    }

    private void changeStatus() {
        if (isAninFinish && !isChangedByTouch) {
            isChangedByTouch = true;
            open = !open;
            isAninFinish = false;
            if (switchChangeListener != null) {
                switchChangeListener.onSwitchChanged(open);
            }
            changeOpenStatusWithAnim(open);
        }
    }

    private void changeOpenStatusWithAnim(boolean open) {
        if (open) {
            // 左到右
            Animation leftToRight = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0,
                    Animation.ABSOLUTE, getWidth() - maskImage.getWidth(),
                    Animation.RELATIVE_TO_SELF, 0,
                    Animation.RELATIVE_TO_SELF, 0);
            leftToRight.setDuration(300);
            leftToRight.setAnimationListener(new AnimationListener() {
                @Override
                public void onAnimationStart(Animation animation) {
                }

                @Override
                public void onAnimationRepeat(Animation animation) {
                }

                @Override
                public void onAnimationEnd(Animation animation) {
                    maskImage.clearAnimation();
                    setGravity(Gravity.RIGHT);
                    isAninFinish = true;
                }
            });
            maskImage.startAnimation(leftToRight);
        } else {
            // 右到左
            Animation rightToLeft = new TranslateAnimation(Animation.RELATIVE_TO_SELF, 0,
                    Animation.ABSOLUTE, maskImage.getWidth() - getWidth(),
                    Animation.RELATIVE_TO_SELF, 0,
                    Animation.RELATIVE_TO_SELF, 0);
            rightToLeft.setDuration(300);
            rightToLeft.setAnimationListener(new AnimationListener() {
                @Override
                public void onAnimationStart(Animation animation) {
                }

                @Override
                public void onAnimationRepeat(Animation animation) {
                }

                @Override
                public void onAnimationEnd(Animation animation) {
                    maskImage.clearAnimation();
                    setGravity(Gravity.LEFT);
                    isAninFinish = true;
                }
            });
            maskImage.startAnimation(rightToLeft);
        }
    }

    public OnSwitchChangeListener getSwitchChangeListener() {
        return switchChangeListener;
    }

    public void setOnSwitchChangeListener(OnSwitchChangeListener switchChangeListener) {
        this.switchChangeListener = switchChangeListener;
    }

}

测试用代码：

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SwitchView switchView = (SwitchView) findViewById(R.id.switchview);
        switchView.setSwitchStatus(true);
        switchView.setOnSwitchChangeListener(new OnSwitchChangeListener() {
            @Override
            public void onSwitchChanged(boolean open) {
                Toast.makeText(MainActivity.this, "开关状态:" + open, Toast.LENGTH_SHORT).show();
            }
        });
    }
}

测试用布局：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="20dp"
    >
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="自定义开关状态:"
        />
    <com.fancyy.switchview.SwitchView
        android:layout_marginLeft="20dp"
        android:id="@+id/switchview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

</LinearLayout>

测试代码下载：http://download.csdn.net/detail/a105865708/6800519