android 开发技巧(9)--为文本添加发亮的效果

把一个界面做成类似于LED灯一样的效果，需要定义一个类，加载特殊字体。为了实现发光效果，需要实现TextView类中的public void setShadowLayer (float radius, float dx, float dy, int color)，也可以通过 XML 中的 android:shadowColor, android:shadowDx、
android:shadowDy 和 android:shadowRadius 属 性 使 用 这 种 效 果。修改 android:shadowDx 和 android:shadowDy 属性的值可以改
变阴影与文本之间的偏移。指定 android:shadowRadius 属性可以让
用户产生一种文本更亮的错觉

先将digital-7.ttf字体放在assets下的fonts文件夹下，自定义一个LedTextView继承自TextView

public class LedTextView extends TextView {

  private static final String FONTS_FOLDER = "fonts";
  private static final String FONT_DIGITAL_7 = FONTS_FOLDER
      + File.separator + "digital-7.ttf";

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

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

  public LedTextView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);
    init(context);
  }

  private void init(Context context) {
    AssetManager assets = context.getAssets();
    final Typeface font = Typeface.createFromAsset(assets,
        FONT_DIGITAL_7);
    setTypeface(font);
  }

}

public class Hack11Activity extends Activity {
    private static final String DATE_FORMAT = "%02d:%02d:%02d";
    private static final int REFRESH_DELAY = 500;

    private final Handler mHandler = new Handler();
    private final Runnable mTimeRefresher = new Runnable() {
        @Override
        public void run() {
            final Date d = new Date();
            mTextView.setText(String.format(DATE_FORMAT, d.getHours(),
                    d.getMinutes(), d.getSeconds()));
            mHandler.postDelayed(this, REFRESH_DELAY);
        }
    };

    private TextView mTextView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_hack11);
        mTextView = (TextView) findViewById(R.id.main_clock_time);
    }

    @Override
    protected void onResume() {
        super.onResume();
        mHandler.post(mTimeRefresher);
    }

    @Override
    protected void onStop() {
        super.onStop();
        mHandler.removeCallbacks(mTimeRefresher);
    }
}

activity_hack11.xml

<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android" >

    <boerpower.com.android50hacks.view.LedTextView  android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:text="@string/default_time" android:textColor="#3300ff00" android:textSize="80sp" />

    <boerpower.com.android50hacks.view.LedTextView  android:id="@+id/main_clock_time" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_gravity="center" android:shadowColor="#00ff00" android:shadowDx="0" android:shadowDy="0" android:shadowRadius="10" android:textColor="#00ff00" android:textSize="80sp" />

</merge>

<string name="default_time">88:88:88</string>

字体下载