public class GradientView extends View {
private String TAG = " GradientView " ;
private Handler mTimeTickHandler;
private int mIndex = 190 ;
private Shader mShader;
private Bitmap mBitmapBg;
private Bitmap mBitmapWord;
private int mMinWidth = 190 ;
private int mMaxWidth ;
private int mUpdateStep = 20 ;
private Paint mPaint = new Paint();
public GradientView(Context context) {
super (context);
}

public GradientView(Context context, AttributeSet attrs) {
super (context, attrs);
mTimeTickHandler = new Handler();
setFocusable( true );
InputStream is = context.getResources().openRawResource(R.drawable.sliding_channel_background);
mBitmapBg = BitmapFactory.decodeStream(is);
mMaxWidth = mBitmapBg.getWidth();
mBitmapWord = Bitmap.createBitmap(mBitmapBg.getWidth(), mBitmapBg.getHeight(), Bitmap.Config.ALPHA_8);
drawIntoBitmap(mBitmapWord, context);
mTimeTickHandler.post(mTimeTickRunnable);
}

private void drawIntoBitmap(Bitmap bm, Context context) {
float x = bm.getWidth();
float y = bm.getHeight();
Canvas c = new Canvas(bm);
Paint p = new Paint();
p.setAntiAlias( true );
p.setColor(Color.WHITE);
p.setTextSize( 45 );
p.setTextAlign(Paint.Align.CENTER);
c.drawText(context.getResources().getString(R.string.slide_unlock), x / 2 + 10 , y / 2 , p);
}

@Override
protected void onDraw(Canvas canvas) {

// canvas.drawBitmap(mBitmapBg, 0, 0, p);
mPaint.setShader(mShader);
canvas.drawBitmap(mBitmapWord, 50 , 13 , mPaint);
}

public void removeHandlerGradient(){
mTimeTickHandler.removeCallbacks(mTimeTickRunnable);
}

private Runnable mTimeTickRunnable = new Runnable(){

public void run() {

mIndex += mUpdateStep;
if (mIndex >= mMaxWidth){

mIndex = mMinWidth;
}
mShader = new LinearGradient( 0 , 150 , mIndex, 150 , new int [] { Color.GRAY,Color.GRAY,Color.GRAY, Color.GRAY,
Color.WHITE }, null , Shader.TileMode.MIRROR);

postInvalidate();
mTimeTickHandler.postDelayed(mTimeTickRunnable, 100 );
}
};
}

本文转自wanqi博客园博客，原文链接： http://www.cnblogs.com/wanqieddy/archive/2011/07/11/2103301.html 如需转载请自行联系原作者