Android学习之可滑动当前的Activity视图看见上一个活动的视图

先看一下我的效果图吧：







好大的图啊！！！

百度音乐由一个很酷的功能，当前的UI可以滑动，然后看见上一个活动的UI，当时顿时觉得百度的牛人好多啊，能将如此前沿的技术应用到app上。当然如果你熟悉了Android的框架，熟知Activity的布局原理，那么实现起来还是很简单的。本人粗略的实现过，用的是View.layout(l, t, r, b)方法移动布局，总觉得有点山寨，但终究还是实现了嘛。好了不多说了，看我自己实现的方式吧。

首先准备创建两个Activity，至于布局xml文件怎么写，大家随便了，两个活动用一个xml布局即可。

为了方便大家copy（PS：本来我不想全部代码包括xml文件都粘贴在这里的，但是鉴于有些人实在太懒，连布局文件都不愿意随便写一个，然后在评论里喊，楼主，源码！我还是贴出来吧！）

一个简单的布局xml文件：layout_value_animation_layout

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button" />

<ToggleButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="ToggleButton" />

<CheckBox
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="CheckBox" />

<RadioButton
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="RadioButton" />

<SeekBar
android:layout_width="match_parent"
android:layout_height="wrap_content" />

<RatingBar
android:layout_width="wrap_content"
android:layout_height="wrap_content" />

<TextView
android:id="@+id/layout_value_animation_layout_text"
android:layout_width="fill_parent"
android:layout_height="0dip"
android:layout_weight="1"
android:gravity="center"
android:text="A"
android:textAppearance="?android:attr/textAppearanceLarge"
android:textSize="80sp" />

</LinearLayout>

第一个活动：LayoutValueAnimationExampleA

package org.mrchen.commlib.example;

import android.app.Activity;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.util.TypedValue;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;

public class LayoutValueAnimationExampleA extends Activity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
View root = getLayoutInflater().inflate(R.layout.layout_value_animation_layout, null);
setContentView(root);

//
root.setBackgroundColor(Color.parseColor("#978856"));
TextView text = (TextView) findViewById(R.id.layout_value_animation_layout_text);
text.setTextSize(TypedValue.COMPLEX_UNIT_SP, 25);
text.setText("A\n Click Me go to Activity LayoutValueAnimationExampleB");
text.setOnClickListener(new OnClickListener() {

@Override
public void onClick(View v) {
// TODO Auto-generated method stub
startActivity(new Intent(LayoutValueAnimationExampleA.this, LayoutValueAnimationExampleB.class));
}
});
}
}

第二个活动:LayoutValueAnimationExampleB

package org.mrchen.commlib.example;

import org.mrchen.commlib.animation.LayoutValueAnimation;
import org.mrchen.commlib.animation.LayoutValueAnimation.LayoutValueParams;
import org.mrchen.commlib.animation.SmoothInterpolator;
import org.mrchen.commlib.helper.LogHelper;
import org.mrchen.commlib.helper.ScreenHelper;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.TextView;

/**
* 注意当前的Activity在AndroidManifest.xml中的注册信息，主题应用了透明主题：AppTheme.Transparent
*
* @author chenjianli
*
*/
public class LayoutValueAnimationExampleB extends Activity {

private final String TAG = "LayoutValueAnimationExampleB";

private View mRootView;
private LayoutValueAnimation mLayoutValueAnimation;

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
mRootView = getLayoutInflater().inflate(R.layout.layout_value_animation_layout, null);
setContentView(mRootView);

//
mRootView.setBackgroundColor(Color.parseColor("#46b525"));
TextView text = (TextView) findViewById(R.id.layout_value_animation_layout_text);
text.setText("B");
mRootView.setOnTouchListener(movingEventListener);
}

private OnTouchListener movingEventListener = new OnTouchListener() {

int lastX, lastY;

public boolean onTouch(View v, MotionEvent event) {
if (event.getAction() == MotionEvent.ACTION_DOWN) {
lastX = (int) event.getRawX();
lastY = (int) event.getRawY();
}
if (event.getAction() == MotionEvent.ACTION_MOVE) {
int dx = (int) event.getRawX() - lastX;
int dy = (int) event.getRawY() - lastY;
// TODO
dy = 0;

int left = v.getLeft() + dx;
int top = v.getTop() + dy;
int right = v.getRight() + dx;
int bottom = v.getBottom() + dy;

v.layout(left, top, right, bottom);

lastX = (int) event.getRawX();
lastY = (int) event.getRawY();

}

if (event.getAction() == MotionEvent.ACTION_UP) {

int left = v.getLeft();
int top = v.getTop();
int right = v.getRight();
int bottom = v.getBottom();

LogHelper.d(TAG, "l:" + left + ",t:" + top + ",r:" + right + ",b:" + bottom);
finishActivity(v, ScreenHelper.mScreenWidth - left);
}
return true;
}
};

public boolean onKeyDown(int keyCode, android.view.KeyEvent event) {
if (!isFinishing()) {
finishActivity(mRootView, ScreenHelper.mScreenWidth);
return true;
}
return super.onKeyDown(keyCode, event);
};

private void finishActivity(View v, int size) {
int duration = 666;
if (mLayoutValueAnimation == null) {
ScreenHelper.initialize(LayoutValueAnimationExampleB.this);
mLayoutValueAnimation = new LayoutValueAnimation(new LayoutValueParams(size,
LayoutValueParams.DIRECTION_RIGHT), duration);
mLayoutValueAnimation.setInterpolator(new SmoothInterpolator());
}
mLayoutValueAnimation.startAnimation(v);

v.postDelayed(new Runnable() {
@Override
public void run() {
LayoutValueAnimationExampleB.this.finish();
}
}, duration);
}
}

许多人可能要崩溃了，怎么回事，这么多类没有，由一些类是我自己库中常用的工具类，比如ScreenHelper，这个类没什么功能，就是得到屏幕的宽度啥的，调用初始化方法

initialize(context)

完成初始化的工作，就可以拿来用了。

这里由必要贴一下

LayoutValueAnimation

类，这个类是拜一位大侠的文章所赐，产生出的属于我自己的衍生品，大家拿来用就好，具体的注释我已经卸载类里面了。

package org.mrchen.commlib.animation;

import org.mrchen.commlib.animation.LayoutValueAnimation.LayoutValueParams;
import org.mrchen.commlib.helper.LogHelper;

import android.view.View;
import android.view.animation.AnimationUtils;

/**
* 促使调用mTargetView.layout(l,t,r,b); <br>
* 参数配置类:{@link LayoutValueParams}
*
* @author chenjianli
*
*/
public class LayoutValueAnimation extends AbstractAnimation {

private final static String TAG = "LayoutValueAnimation";

private int mCurrSize;
private int originalLeft;
private int originalRight;
private int originalTop;
private int originalBottom;

private int targetLeft;
private int targetRight;
private int targetTop;
private int targetBottom;

/**
* {@link LayoutValueAnimation} 的辅助参数类，用于指定位移和移动方向 <br>
*
* @author chenjianli
*
*/
public static class LayoutValueParams {
public int size;

public static final int DIRECTION_LEFT = 1;
public static final int DIRECTION_RIGHT = 2;
public static final int DIRECTION_TOP = 3;
public static final int DIRECTION_BOTTOM = 4;

public int direction;

/**
*
* @param size
*            只能是正整数
* @param direction
*            指明运动方向，有<br>
*            {@link LayoutValueParams.DIRECTION_LEFT}，<br>
*            {@link LayoutValueParams.DIRECTION_RIGHT}，<br>
*            {@link LayoutValueParams.DIRECTION_TOP}，<br>
*            {@link LayoutValueParams.DIRECTION_BOTTOM}，<br>
*/
public LayoutValueParams(int size, int direction) {
this.size = size;
this.direction = direction;
}
}

private LayoutValueParams mParams;

public LayoutValueAnimation(LayoutValueParams params, int duration) {
mParams = params;
mDuration = duration;
}

// 启动动画
public void startAnimation(View view) {
if (view != null) {
mTargetView = view;
} else {
LogHelper.e(TAG, "view 不能为空");
return;
}

if (isFinished) {
mDurationReciprocal = 1.0f / (float) mDuration;
isFinished = false;
// 记录下动画开始的时间
mStartTime = AnimationUtils.currentAnimationTimeMillis();
mDSize = mParams.size;
LogHelper.d(TAG, "mDSize=" + mDSize);
int l = mTargetView.getLeft();
int t = mTargetView.getTop();
int r = mTargetView.getRight();
int b = mTargetView.getBottom();
LogHelper.d(TAG, "startAnimation >原始的> l = " + l + ", t = " + t + ", r = " + r + ", b = " + b);
originalLeft = l;
originalRight = r;
originalTop = t;
originalBottom = b;
mHandler.start();
}
}

@Override
public boolean computeSize() {
// TODO Auto-generated method stub
if (isFinished) {
return isFinished;
}
int timePassed = (int) (AnimationUtils.currentAnimationTimeMillis() - mStartTime);
if (timePassed <= mDuration) {
float x = timePassed * mDurationReciprocal;
if (mInterpolator != null) {
x = mInterpolator.getInterpolation(x);
}
switch (mParams.direction) {
case LayoutValueParams.DIRECTION_LEFT:
case LayoutValueParams.DIRECTION_TOP:
mCurrSize = -Math.round(x * mDSize);
break;
case LayoutValueParams.DIRECTION_RIGHT:
case LayoutValueParams.DIRECTION_BOTTOM:
mCurrSize = Math.round(x * mDSize);
break;
}
} else {
isFinished = true;
switch (mParams.direction) {
case LayoutValueParams.DIRECTION_LEFT:
case LayoutValueParams.DIRECTION_TOP:
mCurrSize = -mDSize;
break;
case LayoutValueParams.DIRECTION_RIGHT:
case LayoutValueParams.DIRECTION_BOTTOM:
mCurrSize = mDSize;
break;
}
}

// 计算最终目标坐标
switch (mParams.direction) {
case LayoutValueParams.DIRECTION_LEFT:
case LayoutValueParams.DIRECTION_RIGHT:
targetLeft = originalLeft + mCurrSize;
targetRight = originalRight + mCurrSize;
targetTop = originalTop;
targetBottom = originalBottom;
break;
case LayoutValueParams.DIRECTION_TOP:
case LayoutValueParams.DIRECTION_BOTTOM:
targetTop = originalTop + mCurrSize;
targetBottom = originalBottom + mCurrSize;
targetLeft = originalLeft;
targetRight = originalRight;
break;
}
LogHelper.d(TAG, "computeSize >目标> l = " + targetLeft + ", t = " + targetTop + ", r = " + targetRight
+ ", b = " + targetBottom);
applySize();
return isFinished;
}

@Override
public void applySize() {
// TODO Auto-generated method stub
if (mTargetView != null && mTargetView.getVisibility() != View.GONE) {
mTargetView.layout(targetLeft, targetTop, targetRight, targetBottom);
}
}
}

卧槽，又有一个类：AbstractAnimation

package org.mrchen.commlib.animation;

import android.os.Handler;
import android.os.Message;
import android.view.View;
import android.view.animation.Interpolator;

public abstract class AbstractAnimation implements AbstractAnimationImpl {

private final int FRAME_TIME = 20;// 一帧的时间 毫秒
protected View mTargetView;// 执行"动画"的目标View
protected Interpolator mInterpolator;// 插值器
protected boolean isFinished = true;// 动画结束标识;

protected int mDuration; // 动画运行的时间
protected long mStartTime;// 动画开始时间
protected float mDurationReciprocal;// Reciprocal:相互的，倒数的
protected int mDSize; // 需要改变view大小的增量

private AnimationListener mAnimationListener;

public interface AnimationListener {
public void animationEnd(View v);
}

public void setOnAnimationListener(AnimationListener listener) {
mAnimationListener = listener;
}

public void setInterpolator(Interpolator interpolator) {
mInterpolator = interpolator;
}

public boolean isFinished() {
return isFinished;
}

public void setDuration(int duration) {
mDuration = duration;
}

protected AnimationHandler mHandler = new AnimationHandler();

class AnimationHandler extends Handler {
@Override
public void handleMessage(Message msg) {

if (msg.what == 1) {
if (!computeSize()) {
mHandler.sendEmptyMessageDelayed(1, FRAME_TIME);
} else {
if (mAnimationListener != null) {
mAnimationListener.animationEnd(mTargetView);
}
}
}
super.handleMessage(msg);
}

public void start() {
sendEmptyMessage(1);
}
}

}

没完了：AbstractAnimationImpl

package org.mrchen.commlib.animation;

import android.view.View;

public interface AbstractAnimationImpl {
public boolean computeSize();// 计算变量

public void applySize();// 应用计算的变量

public void startAnimation(View v);// 启动动画
}

好了，代码基本上差不多了，最后贴一下AndroidManifest.xml文件就打工告成了，大家可以运行看下效果。

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="org.mrchen.commlib.example"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="14" />

<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="org.mrchen.commlib.example.LayoutValueAnimationExampleA"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="org.mrchen.commlib.example.LayoutValueAnimationExampleB"
android:label="@string/app_name"
android:theme="@style/AppTheme.Transparent" >
</activity>
</application>

</manifest>

看来还有主题没贴出来：

<resources>

<!--
Base application theme, dependent on API level. This theme is replaced
by AppBaseTheme from res/values-vXX/styles.xml on newer devices.
-->
<style name="AppBaseTheme" parent="android:Theme.Black.NoTitleBar">
<!--
Theme customizations available in newer API levels can go in
res/values-vXX/styles.xml, while customizations related to
backward-compatibility can go here.
-->
</style>

<!-- Application theme. -->
<style name="AppTheme" parent="AppBaseTheme">

<!-- All customizations that are NOT specific to a particular API-level can go here. -->
<item name="android:windowContentOverlay">@null</item>
</style>

<style name="AppTheme.Transparent" parent="AppTheme">

<!-- All customizations that are NOT specific to a particular API-level can go here. -->
<item name="android:windowBackground">@android:color/transparent</item>
<item name="android:colorBackgroundCacheHint">@null</item>
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowAnimationStyle">@android:style/Animation</item>
</style>
</resources>