【移动应用开发技术】如何在android中使用水平循环滚动控件

【移动应用开发技术】如何在android中使用水平循环滚动控件

这期内容当中在下将会给大家带来有关如何在android中使用水平循环滚动控件，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。具体内容如下CycleScrollView.javapackage

com.example.test;

import

android.content.Context;

import

android.graphics.Rect;

import

android.os.Handler;

import

android.util.AttributeSet;

import

android.view.GestureDetector;

import

android.view.GestureDetector.OnGestureListener;

import

android.view.MotionEvent;

import

android.view.View;

import

android.view.ViewGroup;

import

android.widget.Scroller;

@SuppressWarnings("deprecation")

public

class

CycleScrollView<T>

extends

ViewGroup

implements

OnGestureListener

{

static

final

String

TAG

=

"CycleScrollView";

Context

mContext;

/**

*

Scroll

velocity.

*/

public

static

final

long

SCROLL_VELOCITY

=

50;

/**

*

Scroll

offset.

*/

public

static

final

int

SCROLL_OFFSET

=

-1;

/**

*

Touch

delay.

*/

public

static

final

long

TOUCH_DELAYMILLIS

=

2000;

/**

*

Fling

duration.

*/

public

static

final

int

FLING_DURATION

=

2000;

/**

*

Filing

max

velocity

x.

*/

public

static

final

int

MAX_VELOCITY_X

=

1000;

private

GestureDetector

detector;

private

Handler

mHandler;

private

Scroller

mScroller;

/**

*

Callback

interface

adapter

and

OnItemClick.

*/

private

CycleScrollAdapter<T>

mAdapter;

private

OnItemClickListener

mOnItemClickListener;

/**

*

Scroll

index

*/

private

int

mPreIndex;

private

int

mCurrentIndex;

private

int

mNextIndex;

private

View

mCurrentView;

private

View

mPreView;

private

View

mNextView;

private

float

mLastMotionX;

//

The

reLayout

is

false

can

not

invoke

onLayout.

private

boolean

reLayout

=

false;

//

If

the

item

count

more

than

screen

that

can

scroll.

private

boolean

canScroll

=

false;

//

A

flag

for

switch

current

view.

private

boolean

mCurrentViewAtLeft

=

true;

//

Fling

distance.

private

int

mFlingX

=

0;

private

boolean

isMoveAction

=

false;

private

int

defaultItemY

=

10;

private

int

maxItemCount

=

7;

private

int

initItemX

=

20;

/**

*

The

screen

width.

*/

private

int

screenWidth;

/**

*

Item

view

height.

*/

private

int

itemHeight;

/**

*

Item

view

width.

*/

private

int

itemWidth;

/**

*

Item

view

layout

x.

*/

private

int

itemX

=

getInitItemX();

/**

*

Item

view

layout

y.

*/

private

int

itemY

=

defaultItemY;

//

Auto

scroll

view

task.

private

final

Runnable

mScrollTask

=

new

Runnable()

{

@Override

public

void

run()

{

if

(canScroll)

{

scrollView(SCROLL_OFFSET);

mHandler.postDelayed(this,

SCROLL_VELOCITY);//

Loop

self.

}

}

};

public

CycleScrollView(Context

context)

{

super(context);

onCreate(context);

}

public

CycleScrollView(Context

context,

AttributeSet

attrs)

{

super(context,

attrs);

onCreate(context);

}

public

CycleScrollView(Context

context,

AttributeSet

attrs,

int

defStyle)

{

super(context,

attrs,

defStyle);

onCreate(context);

}

private

void

onCreate(Context

context)

{

mContext

=

context;

detector

=

new

GestureDetector(this);

mHandler

=

new

Handler();

mScroller

=

new

Scroller(context);

}

/**

*

Create

scroll

index.

*/

public

void

createIndex()

{

if

(canScroll)

{

mPreIndex

=

maxItemCount

-

1;

mCurrentIndex

=

0;

mNextIndex

=

1;

mPreView

=

getChildAt(mPreIndex);

mCurrentView

=

getChildAt(mCurrentIndex);

mNextView

=

getChildAt(mNextIndex);

}

}

/**

*

Set

item

click

callback.

*

*

@param

onItemClickListener

*

The

callback

*/

public

void

setOnItemClickListener(OnItemClickListener

onItemClickListener)

{

mOnItemClickListener

=

onItemClickListener;

}

/**

*

Set

itemAdapter

for

addItem

and

bindItem.

*

*

@param

itemAdapter

*/

public

void

setAdapter(CycleScrollAdapter<T>

adapter)

{

mAdapter

=

adapter;

}

/**

*

Start

auto

scroll.

*/

public

void

startScroll()

{

if

(canScroll)

{

mHandler.post(mScrollTask);

}

}

/**

*

Stop

auto

scroll

and

filing

scroll

task.

*/

public

void

stopScroll()

{

mHandler.removeCallbacks(mScrollTask);

}

/**

*

Delay

start

auto

scroll

task.

*/

public

void

delayStartScroll()

{

if

(canScroll)

{

mHandler.postDelayed(mScrollTask,

TOUCH_DELAYMILLIS);

}

}

@Override

protected

void

onMeasure(int

widthMeasureSpec,

int

heightMeasureSpec)

{

super.onMeasure(widthMeasureSpec,

heightMeasureSpec);

int

count

=

this.getChildCount();

for

(int

i

=

0;

i

<

count;

i++)

{

View

child

=

this.getChildAt(i);

child.measure(widthMeasureSpec,

heightMeasureSpec);

}

}

@Override

protected

void

onLayout(boolean

changed,

int

l,

int

t,

int

r,

int

b)

{

/**

*

On

layout

set

the

child

view

layout

by

x

y

width

and

height.

*/

if

(reLayout)

{//

Run

one

times.

for

(int

i

=

0;

i

<

getChildCount();

i++)

{

View

child

=

this.getChildAt(i);

child.setVisibility(View.VISIBLE);

child.layout(itemX,

getItemY(),

itemX

+

getItemWidth(),

getItemY()

+

getItemHeight());

itemX

+=

getItemMargin();

}

reLayout

=

!reLayout;

}

}

/**

*

When

fling

view

run

the

fling

task

scroll

view.

*/

@Override

public

boolean

onFling(MotionEvent

e1,

MotionEvent

e2,

float

velocityX,

float

velocityY)

{

if

(e1

==

null

||

e2

==

null)

{

return

false;

}

//

When

deltaX

and

velocityX

not

good

return

false.

if

(Math.abs(velocityX)

<

MAX_VELOCITY_X)

{

return

false;

}

//

Get

the

delta

x.

float

deltaX

=

(e1.getX()

-

e2.getX());

/**

*

If

can

fling

stop

other

scroll

task

at

first

,

delay

the

task

after

*

fling.

*/

mHandler.removeCallbacks(mScrollTask);

if

(canScroll)

{

mHandler.postDelayed(mScrollTask,

TOUCH_DELAYMILLIS

+

FLING_DURATION

-

1000);

}

/**

*

The

flingX

is

fling

distance.

*/

mFlingX

=

(int)

deltaX;

//

Start

scroll

with

fling

x.

mScroller.startScroll(0,

0,

mFlingX,

0,

FLING_DURATION);

return

false;

}

@Override

public

void

computeScroll()

{

if

(canScroll

&&

mSputeScrollOffset())

{

/**

*

The

Scroller.getCurrX()

approach

mFlingX

,

the

deltaX

more

and

*

more

small.

*/

int

deltaX

=

mFlingX

-

mScroller.getCurrX();

scrollView(-deltaX

/

10);

postInvalidate();

}

}

/**

*

When

touch

event

is

move

scroll

child

view.

*/

@Override

public

boolean

onTouchEvent(MotionEvent

ev)

{

//

Get

event

x,y

at

parent

view.

final

float

x

=

ev.getX();

/**

*

Get

event

x,y

at

screen.

*/

final

int

rawX

=

(int)

ev.getRawX();

final

int

rawY

=

(int)

ev.getRawY();

switch

(ev.getAction())

{

case

MotionEvent.ACTION_DOWN:

//

Reset

isMoveAction.

isMoveAction

=

false;

//

Get

motionX.

mLastMotionX

=

x;

break;

case

MotionEvent.ACTION_MOVE:

//

When

action

move

set

isMoveAction

true.

isMoveAction

=

true;

//

Only

support

one

pointer.

if

(ev.getPointerCount()

==

1)

{

//

Compute

delta

X.

int

deltaX

=

0;

deltaX

=

(int)

(x

-

mLastMotionX);

mLastMotionX

=

x;

//

When

canScroll

is

true,

scrollView

width

deltaX.

if

(canScroll)

{

scrollView(deltaX);

}

}

break;

case

MotionEvent.ACTION_UP:

/**

*

If

not

move

find

click

item

and

invoke

click

event.

*/

if

(!isMoveAction)

{

View

view

=

getClickItem(rawX,

rawY);

if

(view

!=

null)

{

mOnItemClickListener.onItemClick(Integer.valueOf(view

.getTag().toString()));

}

}

break;

}

return

this.detector.onTouchEvent(ev);

}

/**

*

Get

click

item

view

by

rawX

and

rawY.

*

@param

rawX

the

x

at

screen.

*

@param

rawY

the

y

at

screen.

*

@return

the

click

item

view.

*/

private

View

getClickItem(final

int

rawX,

final

int

rawY)

{

for

(int

i

=

0;

i

<

getChildCount();

i++)

{

View

child

=

getChildAt(i);

//

Get

item

view

rect.

Rect

rect

=

new

Rect();

child.getGlobalVisibleRect(rect);

//

If

click

point

on

the

item

view,

invoke

the

click

event.

if

(rect.contains(rawX,

rawY))

{

return

child;

}

}

return

null;

}

/**

*

Scroll

view

by

delta

x.

*

*

@param

deltaX

*

The

scroll

distance.

*/

private

void

scrollView(int

deltaX)

{

//

Move

child

view

by

deltaX.

moveChildView(deltaX);

//

After

move

change

index.

if

(deltaX

<

0)

{//

move

left

//

If

current

at

right

switch

current

view

to

left.

switchCurrentViewToLeft();

//

change

previous

current

next

index.

moveToNext();

}

else

{//

move

right

//

If

current

at

left

switch

current

view

to

right.

switchCurrentViewToRight();

//

change

previous

current

next

index.

moveToPre();

}

invalidate();

}

/**

*

Move

view

by

delta

x.

*

*

@param

deltaX

*

The

move

distance.

*/

private

void

moveChildView(int

deltaX)

{

for

(int

i

=

0;

i

<

getChildCount();

i++)

{

View

child

=

getChildAt(i);

child.layout(child.getLeft()

+

deltaX,

child.getTop(),

child.getRight()

+

deltaX,

child.getBottom());

}

}

/**

*

Current

event

is

move

to

left,

if

current

view

at

right

switch

current

*

view

to

left.

*/

private

void

switchCurrentViewToLeft()

{

if

(!mCurrentViewAtLeft)

{

mPreIndex

=

mCurrentIndex;

mCurrentIndex

=

mNextIndex;

mNextIndex++;

if

(mNextIndex

>

maxItemCount

-

1)

{

mNextIndex

=

0;

}

mCurrentView

=

getChildAt(mCurrentIndex);

mPreView

=

getChildAt(mPreIndex);

mNextView

=

getChildAt(mNextIndex);

mCurrentViewAtLeft

=

!mCurrentViewAtLeft;

}

}

/**

*

Current

event

is

move

to

right,

if

current

view

at

left

switch

current

*

view

to

right.

*/

private

void

switchCurrentViewToRight()

{

if

(mCurrentViewAtLeft)

{

mNextIndex

=

mCurrentIndex;

mCurrentIndex

=

mPreIndex;

mPreIndex--;

if

(mPreIndex

<

0)

{

mPreIndex

=

maxItemCount

-

1;

}

mCurrentView

=

getChildAt(mCurrentIndex);

mPreView

=

getChildAt(mPreIndex);

mNextView

=

getChildAt(mNextIndex);

mCurrentViewAtLeft

=

!mCurrentViewAtLeft;

}

}

/**

*

Current

event

is

move

to

left,if

current

view

move

out

of

screen

move

the

*

current

view

to

right

and

reBind

the

item

change

index.

*/

private

void

moveToNext()

{

if

(mCurrentView.getRight()

<

0)

{

mCurrentView.layout(mPreView.getLeft()

+

getItemMargin(),

getItemY(),

mPreView.getLeft()

+

getItemMargin()

+

getItemWidth(),

getItemY()

+

getItemHeight());

if

(mCurrentView.getTag()

!=

null)

{

int

listIndex

=

(Integer)

mCurrentView.getTag();

int

index

=

(listIndex

+

maxItemCount)

%

mAdapter.getCount();

mAdapter.bindView(mCurrentView,

mAdapter.get(index));

mCurrentView.setTag(index);

}

mPreIndex

=

mCurrentIndex;

mCurrentIndex

=

mNextIndex;

mNextIndex++;

if

(mNextIndex

>

maxItemCount

-

1)

{

mNextIndex

=

0;

}

mCurrentView

=

getChildAt(mCurrentIndex);

mPreView

=

getChildAt(mPreIndex);

mNextView

=

getChildAt(mNextIndex);

moveToNext();

}

}

/**

*

Current

event

is

move

to

right,if

current

view

move

out

of

screen

move

*

the

current

view

to

left

and

reBind

the

item

change

index.

*/

private

void

moveToPre()

{

if

(mCurrentView.getLeft()

>

getScreenWidth())

{

mCurrentView.layout(mNextView.getLeft()

-

getItemMargin(),

getItemY(),

mNextView.getLeft()

-

getItemMargin()

+

getItemWidth(),

getItemY()

+

getItemHeight());

if

(mCurrentView.getTag()

!=

null)

{

int

listIndex

=

(Integer)

mCurrentView.getTag();

int

index

=

(listIndex

-

maxItemCount

+

mAdapter.getCount())

%

mAdapter.getCount();

mAdapter.bindView(mCurrentView,

mAdapter.get(index));

mCurrentView.setTag(index);

}

mNextIndex

=

mCurrentIndex;

mCurrentIndex

=

mPreIndex;

mPreIndex--;

if

(mPreIndex

<

0)

{

mPreIndex

=

maxItemCount

-

1;

}

mCurrentView

=

getChildAt(mCurrentIndex);

mPreView

=

getChildAt(mPreIndex);

mNextView

=

getChildAt(mNextIndex);

moveToPre();

}

}

@Override

public

boolean

onDown(MotionEvent

e)

{

return

true;

}

@Override

public

void

onShowPress(MotionEvent

e)

{

}

@Override

public

boolean

onSingleTapUp(MotionEvent

e)

{

return

false;

}

@Override

public

boolean

onScroll(MotionEvent

e1,

MotionEvent

e2,

float

distanceX,

float

distanceY)

{

return

false;

}

@Override

public

void

onLongPress(MotionEvent

e)

{

}

public

int

getMaxItemCount()

{

return

maxItemCount;

}

public

void

setMaxItemCount(int

maxItemCount)

{

this.maxItemCount

=

maxItemCount;

}

public

void

setReLayout(boolean

reLayout)

{

this.reLayout

=

reLayout;

}

public

void

setCanScroll(boolean

canScroll)

{

this.canScroll

=

canScroll;

}

public

int

getItemX()

{

return

itemX;

}

public

void

setItemX(int

itemX)

{

this.itemX

=

itemX;

}

public

int

getItemY()

{

return

itemY;

}

public

void

setItemY(int

itemY)

{

this.itemY

=

itemY;

}

public

int

getItemWidth()

{

return

itemWidth;

}

public

void

setItemWidth(int

itemWidth)

{

this.itemWidth

=

itemWidth;

}

public

int

getItemHeight()

{

return

itemHeight;

}

public

void

setItemHeight(int

itemHeight)

{

this.itemHeight

=

itemHeight;

}

public

int

getItemMargin()

{

return

(screenWidth

-

itemWidth

*

(maxItemCount

-

1)

-

initItemX

*

2)/(maxItemCount

-

2)

+

itemWidth;

}

public

int

getScreenWidth()

{

return

screenWidth;

}

public

void

setScreenWidth(int

screenWidth)

{

this.screenWidth

=

screenWidth;

}

public

int

getInitItemX()

{

return

initItemX;

}

public

void

setInitItemX(int

initItemX)

{

this.initItemX

=

initItemX;

}

/**

*

The

interface

for

item

click

callback.

*/

interface

OnItemClickListener

{

public

boolean

onItemClick(int

position);

}

}CycleScrollAdapter.javapackage

com.example.test;

import

java.util.List;

import

android.app.Activity;

import

android.content.Context;

import

android.util.DisplayMetrics;

import

android.view.View;

public

abstract

class

CycleScrollAdapter<T>

{

private

List<T>

list;

private

CycleScrollView<T>

mCycleScrollView;

Context

mContext;

/**

*

Initial

CycleScrollAdapter

bind

list

to

view.

*

*

@param

list

*

The

list

data.

*

@param

cycleScrollView

*

The

CycleScrollView.

*

@param

context

*

The

Context.

*/

public

CycleScrollAdapter(List<T>

list,

CycleScrollView<T>

cycleScrollView,

Context

context)

{

this.list

=

list;

mContext

=

context;

mCycleScrollView

=

cycleScrollView;

mCycleScrollView.setAdapter(this);

GetScreenWidthPixels();

initView(list);

}

/**

*

Get

screen

width

pixels.

*/

private

void

GetScreenWidthPixels()

{

DisplayMetrics

dm

=

new

DisplayMetrics();

Activity

a

=

(Activity)

mContext;

a.getWindowManager().getDefaultDisplay().getMetrics(dm);

mCycleScrollView.setScreenWidth(dm.widthPixels);

}

/**

*

Bind

list

to

view.

*

*

@param

list

*

The

list

data.

*/

protected

void

initView(List<T>

list)

{

if

(list

==

null

||

list.size()

==

0)

{

return;

}

//

Clear

all

view

from

ViewGroup

at

first.

mCycleScrollView.removeAllViewsInLayout();

//

Loop

list.

for

(int

i

=

0;

i

<

list.size();

i++)

{

/**

*

If

list

size

more

than

MaxItemCount

break

the

loop,

only

create

*

view

count

is

MaxItemCount.

*/

if

(i

==

mCycleScrollView.getMaxItemCount())

{

break;

}

/**

*

If

list

size

less

than

MaxItemCount

at

the

last

loop

reLayout

*

otherwise

at

the

MaxItemCount

index

reLayout.

*/

if

(i

==

list.size()

-

1

||

i

==

mCycleScrollView.getMaxItemCount()

-

1)

{

mCycleScrollView.setItemX(mCycleScrollView.getInitItemX());

mCycleScrollView.setReLayout(true);

}

add(list.get(i),

i);

}

/**

*

If

list

count

more

than

MaxItemCount

the

view

can

scroll

otherwise

*

can

not

scroll.

*/

if

(list.size()

>=

mCycleScrollView.getMaxItemCount())

{

mCycleScrollView.setCanScroll(true);

}

else

{

mCycleScrollView.setCanScroll(false);

}

/**

*

If

list

count

more

than

MaxItemCount

reBuild

index.

*/

mCycleScrollView.createIndex();

}

/**

*

Get

list

size.

*

*

@return

The

list

size.

*/

public

int

getCount()

{

return

list.size();

}

/**

*

Returns

the

element

at

the

specified

location

in

this

*

*

@param

index

*

the

index

of

the

element

to

return.

*

@return

the

element

at

the

specified

location.

*/

public

T

get(int

index)

{

return

list.get(index);

}

/**

*

Adds

the

specified

object

at

the

end

of

this

and

refresh

view.

*

*

@param

t

*

the

object

to

add.

*/

public

void

addItem(T

t)

{

list.add(t);

initView(list);

}

/**

*

Removes

the

first

occurrence

of

the

specified

object

from

this

and

*

refresh

view.

*

*

@param

t

*

the

object

to

remove.

*/

public

void

removeItem(T

t)

{

list.remove(t);

initView(list);

}

/**

*

Add

the

specified

view

to

the

index.

*

*

@param

t

*

The

data

to

add.

*

@param

index

*

the

index.

*/

private

void

add(T

t,

int

index)

{

View

view

=

getView(t);

ComputeItemSize(view);

mCycleScrollView.addView(view);

view.setTag(index);

}

/**

*

If

item

size

is

null

compute

item

size.

*

*

@param

view

*

the

item

view.

*/

private

void

ComputeItemSize(View

view)

{

if

(mCycleScrollView.getItemWidth()

==

0

||

mCycleScrollView.getItemHeight()

==

0)

{

int

w

=

View.MeasureSpec.makeMeasureSpec(0,

View.MeasureSpec.UNSPECIFIED);

int

h

=

View.MeasureSpec.makeMeasureSpec(0,

View.MeasureSpec.UNSPECIFIED);

view.measure(w,

h);

int

height

=

view.getMeasuredHeight();

int

width

=

view.getMeasuredWidth();

mCycleScrollView.setItemHeight(height);

mCycleScrollView.setItemWidth(width);

}

}

/**

*

Get

item

view.

*

*

@param

t

*

the

data

need

bind

to

view.

*

@return

the

view.

*/

public

abstract

View

getView(T

t);

/**

*

Bind

the

item

to

view.

*

*

@param

child

*

the

item

view

need

bind.

*

@param

t

*

the

item.

*/

public

abstract

void

bindView(View

child,

T

t);

}以上两个是核心类，下面是测试代码。实现CycleScrollAdapterAppCycleScrollAdapter.java绑定视图和应用数据package

com.example.test;

import

java.util.List;

import

android.content.Context;

import

android.content.pm.PackageInfo;

import

android.view.View;

import

android.widget.ImageView;

import

android.widget.TextView;

public

class

AppCycleScrollAdapter

extends

CycleScrollAdapter<PackageInfo>

{

public

AppCycleScrollAdapter(List<PackageInfo>

list,

CycleScrollView<PackageInfo>

cycleScrollView,

Context

context)

{

super(list,

cycleScrollView,

context);

}

@Override

protected

void

initView(List<PackageInfo>

list)

{

super.initView(list);

}

@Override

public

void

bindView(View

child,

PackageInfo

pi)

{

ImageView

image

=

(ImageView)

child.findViewById(R.id.item_image);

TextView

text

=

(TextView)

child.findViewById(R.id.item_text);

image.setImageDrawable(pi.applicationInfo.loadIcon(mContext

.getPackageManager()));

text.setText(pi.applicationInfo.loadLabel(mContext.getPackageManager()));

}

@Override

public

View

getView(PackageInfo

pi)

{

View

view

=

View.inflate(mContext,

R.layout.view_item,

null);

//

inflate

APP

icon

view

ImageView

image

=

(ImageView)

view.findViewById(R.id.item_image);

//

inflate

APP

name

view

TextView

text

=

(TextView)

view.findViewById(R.id.item_text);

image.setImageDrawable(pi.applicationInfo.loadIcon(mContext

.getPackageManager()));

text.setText(pi.applicationInfo.loadLabel(mContext.getPackageManager()));

ret