android显示TextView文字的倒影效果实现代码

今天记录一下textview的倒影效果，显示一串文字，然后在文字的下方显示出它的倒影，先上效果图：

最重要的就是view中getdrawingcache()方法，该方法可以获取cache中的图像，然后绘制出来。

废话不多说，我是想写一个带有倒影的时间，时间可以走动。首先先写一个带有时间走动的view，这个很简单，获取当前时间，然后开启一个线程，隔一秒获取当前时间一次，然后显示在textview上，当然，我们写控件，就需要继承textview，代码如下：

package com.alex.reflecttextview;

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"));
    }
}

现在只需要在布局文件中调用该控件就可以实现一个走动的时间了。

第二步就是需要给这个走动的时间加上倒影了，我们就需要写一个控件来继承上面一个时间走动的控件，就可以实现带有倒影的时间走动的view了，下面是带有倒影的代码：

package com.alex.reflecttextview;

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，先调用setdrawingcacheenabled(true);让cache可用，然后通过cache创建一个和原图片一样的图像，通过mmatrix.prescale(1, -1);使图片倒过来，调用bitmap.createbitmap(originalimage, 0, height/5, width, height/2, mmatrix, false);创建一个倒过来的图像，调用canvas.drawbitmap(reflectionimage, 0, height/3f, null);把倒过来的图像画到画布上。通过调用lineargradient shader = new lineargradient(0, height/2, 0,
height, 0x7fffffff, 0x0fffffff, tilemode.clamp);
mpaint.setshader(shader);
mpaint.setxfermode(new porterduffxfermode(mode.dst_in));使倒影的图像的颜色渐变，由灰色变为黑色。

时间走动时调用builddrawingcache();
postinvalidate();

让倒影从新绘制。

调用setmeasureddimension(getmeasuredwidth(), (int)(getmeasuredheight()*1.67));设置图像的宽度和高度。

好了，控件已经写完了，现在只要在布局中调用这个控件就可以在activity中显示一个带有倒影的时间的view了，先写一个布局文件：

<?xml version="1.0" encoding="utf-8"?>
<relativelayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#000000"
    android:paddingtop="@dimen/activity_vertical_margin" >

    <com.alex.reflecttextview.reflecttextview
            android:id="@+id/timeview"
             android:textsize="@dimen/reflect_size"
              android:layout_width="match_parent"
              android:layout_height="wrap_content"
              android:layout_alignparentbottom="true"
              android:gravity="top|center_horizontal" />
</relativelayout>

然后在activity中显示这个布局，我把这个控件的字体从新设置了一下，让它显示的方方正正。

package com.alex.reflecttextview;

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"));
    }
}

运行代码，手机上就回显示一个带有倒影的时间view，时间还会走动，是不是很好玩。

好了，就到这里吧。

源码下载地址：http://xiazai.jb51.net/201402/yuanma/reflecttextview(jb51.net).rar