android 1.6 launcher研究之launcher的左右滑动

http://lipeng88213.iteye.com/blog/1073463

2011.06.08——— android 1.6 launcher研究之launcher的左右滑动

AndroidRESTvelocityOpenSourceBlog
2011.06.08——— android 1.6 launcher研究之launcher的左右滑动

参考：http://blog.csdn.net/assassin4824/archive/2011/05/30/6454923.aspx

http://blog.sina.com.cn/s/blog_4d142b550100s1sx.html

http://blog.csdn.net/xiaoxiaobian3310903/archive/2011/05/24/6443250.aspx

http://www.ibm.com/developerworks/cn/opensource/os-cn-android-anmt2/

ScrollLayout.java

Java代码







package com.lp;
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;
/**
* 仿Launcher中的WorkSapce，可以左右滑动切换屏幕的类
*/
public class ScrollLayout extends ViewGroup {
private static final String TAG = "ScrollLayout";
private Scroller mScroller;
private VelocityTracker mVelocityTracker;

private int mCurScreen;
private int mDefaultScreen = 0;

private static final int TOUCH_STATE_REST = 0;

private static final int TOUCH_STATE_SCROLLING = 1;

private static final int SNAP_VELOCITY = 600;

private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop;
private float mLastMotionX;
private float mLastMotionY;
public ScrollLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub

}
public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub

mScroller = new Scroller(context);
//默认显示第一屏
mCurScreen = mDefaultScreen;
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {

// TODO Auto-generated method stub

if (changed) {
int childLeft = 0;
final int childCount = getChildCount();

for (int i=0; i<childCount; i++) {
final View childView = getChildAt(i);
if (childView.getVisibility() != View.GONE) {
final int childWidth = childView.getMeasuredWidth();
childView.layout(childLeft, 0,
childLeft+childWidth, childView.getMeasuredHeight());
childLeft += childWidth;
//很明显 0 - 320 | 320 - 640 | 640 - 960 ...（假设屏幕宽320）

}
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

Log.e(TAG, "onMeasure");
super.onMeasure(widthMeasureSpec, heightMeasureSpec);

final int width = MeasureSpec.getSize(widthMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ScrollLayout only canmCurScreen run at EXACTLY mode!");
}

final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ScrollLayout only can run at EXACTLY mode!");
}

// The children are given the same width and height as the scrollLayout

final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
// Log.e(TAG, "moving to screen "+mCurScreen);

//x坐标 y坐标
//移动到第几屏
scrollTo(mCurScreen * width, 0);
}

/**
* According to the position of current layout

* scroll to the destination page.
* 判断滑动的位置
* 如果大于当前屏中间的位置 则换屏
* 否则 仍然是这个屏
* getScrollX x方向的偏移量
*/

public void snapToDestination() {
final int screenWidth = getWidth();
//判断
final int destScreen = (getScrollX()+ screenWidth/2)/screenWidth;
snapToScreen(destScreen);
}

public void snapToScreen(int whichScreen) {
// get the valid layout page

whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));
if (getScrollX() != (whichScreen*getWidth())) {

final int delta = whichScreen*getWidth()-getScrollX();
//开始滚动
//x，y，x方向移动量，y方向移动量，滚动持续时间，负数往左滚

mScroller.startScroll(getScrollX(), 0,
delta, 0, Math.abs(delta)*2);
mCurScreen = whichScreen;
invalidate(); // Redraw the layout

}
}

public void setToScreen(int whichScreen) {
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));
mCurScreen = whichScreen;
scrollTo(whichScreen*getWidth(), 0);
}

public int getCurScreen() {
return mCurScreen;
}
//只有当前LAYOUT中的某个CHILD导致SCROLL发生滚动，才会致使自己的COMPUTESCROLL被调用

@Override
public void computeScroll() {
// TODO Auto-generated method stub

Log.e(TAG,"computeScroll");
//如果返回true，表示动画还没有结束
//因为前面startScroll，所以只有在startScroll完成时 才会为false

if (mScroller.computeScrollOffset()) {
Log.e(TAG, mScroller.getCurrX()+"======"+mScroller.getCurrY());
//产生了动画效果 每次滚动一点
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub

Log.e(TAG,"onTouchEvent start");
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);

final int action = event.getAction();
final float x = event.getX();
final float y = event.getY();

switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "event down! "+mScroller.isFinished());
//如果屏幕的滚动动画没有结束 你就按下了 就结束动画

if (!mScroller.isFinished()){
mScroller.abortAnimation();
}
mLastMotionX = x;
break;

case MotionEvent.ACTION_MOVE:
Log.e(TAG, "event move!");
//取得偏移量
int deltaX = (int)(mLastMotionX - x);
Log.e(TAG,"detaX: "+deltaX);
mLastMotionX = x;
//x方向的偏移量 y方向的偏移量
scrollBy(deltaX, 0);
break;

case MotionEvent.ACTION_UP:
Log.e(TAG, "event : up");
// if (mTouchState == TOUCH_STATE_SCROLLING) {

final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
Log.e(TAG, "velocityX:"+velocityX);

if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
// Fling enough to move left

Log.e(TAG, "snap left");
snapToScreen(mCurScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurScreen < getChildCount() - 1) {
// Fling enough to move right

Log.e(TAG, "snap right");
snapToScreen(mCurScreen + 1);
} else {
//一般都掉用这个
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
// }
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
break;
}

return true;
}
//这个感觉没什么作用 不管true还是false 都是会执行onTouchEvent的 因为子view里面onTouchEvent返回false了

@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// TODO Auto-generated method stub

Log.e(TAG, "onInterceptTouchEvent-slop:"+mTouchSlop);

final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) &&
(mTouchState != TOUCH_STATE_REST)) {
return true;
}

final float x = ev.getX();
final float y = ev.getY();

switch (action) {
case MotionEvent.ACTION_MOVE:
Log.e(TAG,"onInterceptTouchEvent move");
final int xDiff = (int)Math.abs(mLastMotionX-x);
if (xDiff>mTouchSlop) {
mTouchState = TOUCH_STATE_SCROLLING;

}
break;

case MotionEvent.ACTION_DOWN:
Log.e(TAG,"onInterceptTouchEvent down");
mLastMotionX = x;
mLastMotionY = y;
Log.e(TAG,mScroller.isFinished()+"");
mTouchState = mScroller.isFinished()? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
break;

case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
Log.e(TAG,"onInterceptTouchEvent up or cancel");
mTouchState = TOUCH_STATE_REST;
break;
}
Log.e(TAG,mTouchState+"===="+TOUCH_STATE_REST);
return mTouchState != TOUCH_STATE_REST;
}

}

package com.lp;
import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.widget.Scroller;
/**
* 仿Launcher中的WorkSapce，可以左右滑动切换屏幕的类
*/
public class ScrollLayout extends ViewGroup {
private static final String TAG = "ScrollLayout";
private Scroller mScroller;
private VelocityTracker mVelocityTracker;

private int mCurScreen;
private int mDefaultScreen = 0;

private static final int TOUCH_STATE_REST = 0;
private static final int TOUCH_STATE_SCROLLING = 1;

private static final int SNAP_VELOCITY = 600;

private int mTouchState = TOUCH_STATE_REST;
private int mTouchSlop;
private float mLastMotionX;
private float mLastMotionY;
public ScrollLayout(Context context, AttributeSet attrs) {
this(context, attrs, 0);
// TODO Auto-generated constructor stub
}
public ScrollLayout(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
// TODO Auto-generated constructor stub
mScroller = new Scroller(context);
//默认显示第一屏
mCurScreen = mDefaultScreen;
mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
// TODO Auto-generated method stub
if (changed) {
int childLeft = 0;
final int childCount = getChildCount();

for (int i=0; i<childCount; i++) {
final View childView = getChildAt(i);
if (childView.getVisibility() != View.GONE) {
final int childWidth = childView.getMeasuredWidth();
childView.layout(childLeft, 0,
childLeft+childWidth, childView.getMeasuredHeight());
childLeft += childWidth;
//很明显 0 - 320 | 320 - 640 | 640 - 960 ...（假设屏幕宽320）
}
}
}
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
Log.e(TAG, "onMeasure");
super.onMeasure(widthMeasureSpec, heightMeasureSpec);

final int width = MeasureSpec.getSize(widthMeasureSpec);
final int widthMode = MeasureSpec.getMode(widthMeasureSpec);
if (widthMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ScrollLayout only canmCurScreen run at EXACTLY mode!");
}

final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode != MeasureSpec.EXACTLY) {
throw new IllegalStateException("ScrollLayout only can run at EXACTLY mode!");
}

// The children are given the same width and height as the scrollLayout
final int count = getChildCount();
for (int i = 0; i < count; i++) {
getChildAt(i).measure(widthMeasureSpec, heightMeasureSpec);
}
// Log.e(TAG, "moving to screen "+mCurScreen);
//x坐标 y坐标
//移动到第几屏
scrollTo(mCurScreen * width, 0);
}

/**
* According to the position of current layout
* scroll to the destination page.
* 判断滑动的位置
* 如果大于当前屏中间的位置 则换屏
* 否则 仍然是这个屏
* getScrollX x方向的偏移量
*/

public void snapToDestination() {
final int screenWidth = getWidth();
//判断
final int destScreen = (getScrollX()+ screenWidth/2)/screenWidth;
snapToScreen(destScreen);
}

public void snapToScreen(int whichScreen) {
// get the valid layout page
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));
if (getScrollX() != (whichScreen*getWidth())) {

final int delta = whichScreen*getWidth()-getScrollX();
//开始滚动
//x，y，x方向移动量，y方向移动量，滚动持续时间，负数往左滚
mScroller.startScroll(getScrollX(), 0,
delta, 0, Math.abs(delta)*2);
mCurScreen = whichScreen;
invalidate();       // Redraw the layout
}
}

public void setToScreen(int whichScreen) {
whichScreen = Math.max(0, Math.min(whichScreen, getChildCount()-1));
mCurScreen = whichScreen;
scrollTo(whichScreen*getWidth(), 0);
}

public int getCurScreen() {
return mCurScreen;
}
//只有当前LAYOUT中的某个CHILD导致SCROLL发生滚动，才会致使自己的COMPUTESCROLL被调用
@Override
public void computeScroll() {
// TODO Auto-generated method stub
Log.e(TAG,"computeScroll");
//如果返回true，表示动画还没有结束
//因为前面startScroll，所以只有在startScroll完成时 才会为false
if (mScroller.computeScrollOffset()) {
Log.e(TAG, mScroller.getCurrX()+"======"+mScroller.getCurrY());
//产生了动画效果 每次滚动一点
scrollTo(mScroller.getCurrX(), mScroller.getCurrY());
postInvalidate();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
// TODO Auto-generated method stub
Log.e(TAG,"onTouchEvent start");
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(event);

final int action = event.getAction();
final float x = event.getX();
final float y = event.getY();

switch (action) {
case MotionEvent.ACTION_DOWN:
Log.e(TAG, "event down! "+mScroller.isFinished());
//如果屏幕的滚动动画没有结束 你就按下了 就结束动画
if (!mScroller.isFinished()){
mScroller.abortAnimation();
}
mLastMotionX = x;
break;

case MotionEvent.ACTION_MOVE:
Log.e(TAG, "event move!");
//取得偏移量
int deltaX = (int)(mLastMotionX - x);
Log.e(TAG,"detaX: "+deltaX);
mLastMotionX = x;
//x方向的偏移量 y方向的偏移量
scrollBy(deltaX, 0);
break;

case MotionEvent.ACTION_UP:
Log.e(TAG, "event : up");
// if (mTouchState == TOUCH_STATE_SCROLLING) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000);
int velocityX = (int) velocityTracker.getXVelocity();
Log.e(TAG, "velocityX:"+velocityX);

if (velocityX > SNAP_VELOCITY && mCurScreen > 0) {
// Fling enough to move left
Log.e(TAG, "snap left");
snapToScreen(mCurScreen - 1);
} else if (velocityX < -SNAP_VELOCITY
&& mCurScreen < getChildCount() - 1) {
// Fling enough to move right
Log.e(TAG, "snap right");
snapToScreen(mCurScreen + 1);
} else {
//一般都掉用这个
snapToDestination();
}
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
// }
mTouchState = TOUCH_STATE_REST;
break;
case MotionEvent.ACTION_CANCEL:
mTouchState = TOUCH_STATE_REST;
break;
}

return true;
}
//这个感觉没什么作用 不管true还是false 都是会执行onTouchEvent的 因为子view里面onTouchEvent返回false了
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
// TODO Auto-generated method stub
Log.e(TAG, "onInterceptTouchEvent-slop:"+mTouchSlop);

final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) &&
(mTouchState != TOUCH_STATE_REST)) {
return true;
}

final float x = ev.getX();
final float y = ev.getY();

switch (action) {
case MotionEvent.ACTION_MOVE:
Log.e(TAG,"onInterceptTouchEvent move");
final int xDiff = (int)Math.abs(mLastMotionX-x);
if (xDiff>mTouchSlop) {
mTouchState = TOUCH_STATE_SCROLLING;

}
break;

case MotionEvent.ACTION_DOWN:
Log.e(TAG,"onInterceptTouchEvent down");
mLastMotionX = x;
mLastMotionY = y;
Log.e(TAG,mScroller.isFinished()+"");
mTouchState = mScroller.isFinished()? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING;
break;

case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
Log.e(TAG,"onInterceptTouchEvent up or cancel");
mTouchState = TOUCH_STATE_REST;
break;
}
Log.e(TAG,mTouchState+"===="+TOUCH_STATE_REST);
return mTouchState != TOUCH_STATE_REST;
}

}

main.xml

Java代码







<?xml version="1.0" encoding="utf-8"?>
<com.lp.ScrollLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/ScrollLayoutTest"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<LinearLayout
android:background="#FF00"
android:layout_width="fill_parent"
android:layout_height="fill_parent"></LinearLayout>

<FrameLayout
android:background="#F0F0"
android:layout_width="fill_parent"
android:layout_height="fill_parent"></FrameLayout>

<FrameLayout
android:background="#F00F"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
</FrameLayout>

<LinearLayout
android:background="#FF00"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button1" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Button2" />
</LinearLayout>
</com.lp.ScrollLayout>