android---手电筒之警告灯

警告灯的实现是通过线程操作两个图片来回切换实现的,原理很简单,但是小细节比较多,下面叙述下

class changewarnlight extends Thread{

        @Override
        public void run() {
            warnlightstates = true;
            while(warnlightstates){
            try {
                Thread.sleep(100);
                handler.sendEmptyMessage(0);
            } catch (InterruptedException e) {
                e.printStackTrace();
            }
            }
        }

    }

下面是handler

/* * 因为线程只能访问当前线程所在的java文件里面的资源,所以使用handler来传递继承下来的资源 */
    Handler handler = new Handler(){

        @Override
        public void handleMessage(Message msg) {
            if(warnlightstyle){
                warnlightoff.setImageResource(R.drawable.warning_light_on);
                warnlighton.setImageResource(R.drawable.warning_light_off);
                warnlightstyle = false;
            }else {
                warnlightoff.setImageResource(R.drawable.warning_light_off);
                warnlighton.setImageResource(R.drawable.warning_light_on);
                warnlightstyle = true;
            }
        }

    };

下面是对屏幕亮度的控制

/* * 设置屏幕亮度 */
    protected void setscreenlight(float value) {
        WindowManager.LayoutParams layout = getWindow().getAttributes();
        layout.screenBrightness = value;
        getWindow().setAttributes(layout);
    }
    /* * 恢复屏幕亮度 */
    protected int defaultscreenlight() {

        int value = 0;
        try {
            value = android.provider.Settings.System.getInt(
                    getContentResolver(),
                    android.provider.Settings.System.SCREEN_BRIGHTNESS);
        } catch (Exception e) {
        }
        return value;

    }

下面是页面布局的实现

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/linearlayout_warnlight" android:layout_width="match_parent" android:layout_marginTop="40dp" android:layout_height="match_parent" android:visibility="gone" android:orientation="vertical" >

    <ImageView  android:id="@+id/imageView_warning_light_on" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginTop="10dp" android:layout_weight="1" android:src="@drawable/warning_light_on" />
    <ImageView  android:id="@+id/imageView_warning_light_off" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:src="@drawable/warning_light_off" />

</LinearLayout>