今天記錄一下TextView的倒影效果，顯示一串文字，然后在文字的下方顯示出它的倒影，先上效果圖：
最重要的就是View中g(shù)etDrawingCache()方法，該方法可以獲取cache中的圖像，然后繪制出來(lái)。
廢話不多說(shuō)，我是想寫一個(gè)帶有倒影的時(shí)間，時(shí)間可以走動(dòng)。首先先寫一個(gè)帶有時(shí)間走動(dòng)的View，這個(gè)很簡(jiǎn)單，獲取當(dāng)前時(shí)間，然后開(kāi)啟一個(gè)線程，隔一秒獲取當(dāng)前時(shí)間一次，然后顯示在TextView上，當(dāng)然，我們寫控件，就需要繼承TextView，代碼如下：
import java.util.Calendar;
import android.content.Context;
import android.os.Handler;
import android.os.Message;
import android.text.format.DateFormat;
import android.util.AttributeSet;
import android.widget.TextView;
public class TimeView extends TextView {
private static final int MESSAGE_TIME = 1;
public TimeView(Context context, AttributeSet attrs) {
super(context, attrs);
new TimeThread().start();
}
public class TimeThread extends Thread {
@Override
public void run() {
do {
try {
Message msg = new Message();
msg.what = MESSAGE_TIME;
mHandler.sendMessage(msg);
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
} while (true);
}
}
private Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
super.handleMessage(msg);
switch (msg.what) {
case MESSAGE_TIME:
setTime();
break;
default:
break;
}
}
};
public void setTime() {
long sysTime = System.currentTimeMillis();
Calendar calendar = Calendar.getInstance();
calendar.setTimeInMillis(sysTime);
String sysTimeStr = DateFormat.format("hh:mm", sysTime).toString();
if(calendar.get(Calendar.AM_PM) == 0) {
sysTimeStr += " AM";
} else {
sysTimeStr += " PM";
}
setText(sysTimeStr.replace("1", " 1"));
}
}
現(xiàn)在只需要在布局文件中調(diào)用該控件就可以實(shí)現(xiàn)一個(gè)走動(dòng)的時(shí)間了。
第二步就是需要給這個(gè)走動(dòng)的時(shí)間加上倒影了，我們就需要寫一個(gè)控件來(lái)繼承上面一個(gè)時(shí)間走動(dòng)的控件，就可以實(shí)現(xiàn)帶有倒影的時(shí)間走動(dòng)的View了，下面是帶有倒影的代碼：
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.LinearGradient;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.PorterDuffXfermode;
import android.graphics.Shader.TileMode;
import android.util.AttributeSet;
public class ReflectTextView extends TimeView {
private Matrix mMatrix;
private Paint mPaint;
public ReflectTextView(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
private void init() {
mMatrix = new Matrix();
mMatrix.preScale(1, -1);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
setMeasuredDimension(getMeasuredWidth(), (int)(getMeasuredHeight()*1.67));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
int height = getHeight();
int width = getWidth();
setDrawingCacheEnabled(true);
Bitmap originalImage = Bitmap.createBitmap(getDrawingCache());
Bitmap reflectionImage = Bitmap.createBitmap(originalImage, 0, height/5, width, height/2, mMatrix, false);
canvas.drawBitmap(reflectionImage, 0, height/3f, null);
if(mPaint == null) {
mPaint = new Paint();
LinearGradient shader = new LinearGradient(0, height/2, 0,
height, 0x7fffffff, 0x0fffffff, TileMode.CLAMP);
mPaint.setShader(shader);
mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
}
canvas.drawRect(0, height/2f, width, height, mPaint);
}
@Override
protected void onTextChanged(CharSequence text, int start,
int lengthBefore, int lengthAfter) {
super.onTextChanged(text, start, lengthBefore, lengthAfter);
buildDrawingCache();
postInvalidate();
}
}
主要功能在onDraw方法里面，先調(diào)用setDrawingCacheEnabled(true);讓cache可用，然后通過(guò)cache創(chuàng)建一個(gè)和原圖片一樣的圖像，通過(guò)mMatrix.preScale(1, -1);使圖片倒過(guò)來(lái)，調(diào)用Bitmap.createBitmap(originalImage, 0, height/5, width, height/2, mMatrix, false);創(chuàng)建一個(gè)倒過(guò)來(lái)的圖像，調(diào)用canvas.drawBitmap(reflectionImage, 0, height/3f, null);把倒過(guò)來(lái)的圖像畫到畫布上。通過(guò)調(diào)用LinearGradient shader = new LinearGradient(0, height/2, 0,
height, 0x7fffffff, 0x0fffffff, TileMode.CLAMP);
mPaint.setShader(shader);
mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));使倒影的圖像的顏色漸變，由灰色變?yōu)楹谏?/P>
時(shí)間走動(dòng)時(shí)調(diào)用buildDrawingCache();
postInvalidate();
讓倒影從新繪制。
調(diào)用setMeasuredDimension(getMeasuredWidth(), (int)(getMeasuredHeight()*1.67));設(shè)置圖像的寬度和高度。
好了，控件已經(jīng)寫完了，現(xiàn)在只要在布局中調(diào)用這個(gè)控件就可以在Activity中顯示一個(gè)帶有倒影的時(shí)間的View了，先寫一個(gè)布局文件：
然后在Activity中顯示這個(gè)布局，我把這個(gè)控件的字體從新設(shè)置了一下，讓它顯示的方方正正。
import android.app.Activity;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class MainActivity extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
final Window win = getWindow();
win.addFlags(WindowManager.LayoutParams.FLAG_SHOW_WHEN_LOCKED
| WindowManager.LayoutParams.FLAG_DISMISS_KEYGUARD);
win.addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON
| WindowManager.LayoutParams.FLAG_TURN_SCREEN_ON);
setContentView(R.layout.activity_main);
TimeView tv = (TimeView) findViewById(R.id.timeView);
tv.setTypeface(Typeface.createFromAsset(getAssets(), "fonts/DS-DIGII.TTF"));
}
}
運(yùn)行代碼，手機(jī)上就回顯示一個(gè)帶有倒影的時(shí)間View，時(shí)間還會(huì)走動(dòng)，是不是很好玩。
好了，就到這里吧。
源碼下載地址：http://xiazai.VeVB.COm/201402/yuanma/ReflectTextView(VeVB.COm).rar
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