【移動應用開發(fā)技術】Android中怎么利用Gallery實現(xiàn)幻燈片效果

【移動應用開發(fā)技術】Android中怎么利用Gallery實現(xiàn)幻燈片效果

今天就跟大家聊聊有關Android中怎么利用Gallery實現(xiàn)幻燈片效果，可能很多人都不太了解，為了讓大家更加了解，在下給大家總結了以下內(nèi)容，希望大家根據(jù)這篇文章可以有所收獲。（1）幻燈片效果的實現(xiàn)：自定義Gallery：DetailGallery.java可視界面：ImgSwitchActivity.java適配類：GalleryIndexAdapter.java1）自定義Gallery主要重寫onFling通過按下和松手的位置不同比較是向右移動還是向左移動，部分代碼如下：private

boolean

isScrollingLeft(MotionEvent

e1,

MotionEvent

e2)

{

return

e2.getX()

>

e1.getX();

}

@Override

public

boolean

onFling(MotionEvent

e1,

MotionEvent

e2,

float

velocityX,

float

velocityY)

{

int

kEvent;

if

(isScrollingLeft(e1,

e2))

{

kEvent

=

KeyEvent.KEYCODE_DPAD_LEFT;

}

else

{

kEvent

=

KeyEvent.KEYCODE_DPAD_RIGHT;

}

onKeyDown(kEvent,

null);

return

true;

}2）在適配類

GalleryIndexAdapter主要完成幻燈片的循環(huán)播放，在getCount里面返回值返回Integer.MAX_VALUE，然后在getView里面根據(jù)position與傳進來初始圖片個數(shù)進行余數(shù)計算得到每次循環(huán)到哪張圖片。部分代碼如下：@Override

public

int

getCount()

{

//

TODO

Auto-generated

method

stub

return

Integer.MAX_VALUE;

}

……

@Override

public

View

getView(int

position,

View

convertView,

ViewGroup

arg2)

{

//

TODO

Auto-generated

method

stub

ImageView

imageView

=

new

ImageView(context);

imageView.setBackgroundResource(imagList.get(position%imagList.size()));

imageView.setScaleType(ScaleType.FIT_XY);

imageView.setLayoutParams(new

Gallery.LayoutParams(Gallery.LayoutParams.FILL_PARENT

,

Gallery.LayoutParams.WRAP_CONTENT));

return

imageView;

}3）在可視界面里面實現(xiàn)邏輯控制，通過定時器定時刷新幻燈片，定時器通過定時發(fā)送消息，消息接受處理機制接收到消息之后，就模擬滑動事件，調(diào)用Gallery的onFling方法實現(xiàn)圖片自動切換效果。選擇按鈕的顯示效果（RadioButton）需要在Gallery的setOnItemSelectedListener進行處理。//定時器和事件處理5秒刷新一次幻燈片

/**

展示圖控制器，實現(xiàn)展示圖切換

*/

final

Handler

handler_gallery

=

new

Handler()

{

public

void

handleMessage(Message

msg)

{

/*

自定義屏幕按下的動作

*/

MotionEvent

e1

=

MotionEvent.obtain(SystemClock.uptimeMillis(),

SystemClock.uptimeMillis(),

MotionEvent.ACTION_UP,

89.333336f,

265.33334f,

0);

/*

自定義屏幕放開的動作

*/

MotionEvent

e2

=

MotionEvent.obtain(SystemClock.uptimeMillis(),

SystemClock.uptimeMillis(),

MotionEvent.ACTION_DOWN,

300.0f,

238.00003f,

0);

myGallery.onFling(e2,

e1,

-800,

0);

/*

給gallery添加按下和放開的動作，實現(xiàn)自動滑動

*/

super.handleMessage(msg);

}

};

protected

void

onResume()

{

autogallery();

super.onResume();

};

private

void

autogallery()

{

/*

設置定時器，每5秒自動切換展示圖

*/

Timer

time

=

new

Timer();

TimerTask

task

=

new

TimerTask()

{

@Override

public

void

run()

{

Message

m

=

new

Message();

handler_gallery.sendMessage(m);

}

};

time.schedule(task,

8000,

5000);

}

//指示按鈕和gallery初始化過程以及事件監(jiān)聽添加過程

//初始化

void

init(){

myGallery

=

(DetailGallery)findViewById(R.id.myGallery);

gallery_points

=

(RadioGroup)

this.findViewById(R.id.galleryRaidoGroup);

ArrayList<Integer>

list

=

new

ArrayList<Integer>();

list.add(R.drawable.banner1);

list.add(R.drawable.banner2);

list.add(R.drawable.banner3);

list.add(R.drawable.banner4);

GalleryIndexAdapter

adapter

=

new

GalleryIndexAdapter(list,

context);

myGallery.setAdapter(adapter);

//設置小按鈕

gallery_point

=

new

RadioButton[list.size()];

for

(int

i

=

0;

i

<

gallery_point.length;

i++)

{

layout

=

(LinearLayout)

inflater.inflate(R.layout.gallery_icon,

null);

gallery_point[i]

=

(RadioButton)

layout.findViewById(R.id.gallery_radiobutton);

gallery_point[i].setId(i);/*

設置指示圖按鈕ID

*/

int

wh

=

Tool.dp2px(context,

10);

RadioGroup.LayoutParams

layoutParams

=

new

RadioGroup.LayoutParams(wh,

wh);

//

設置指示圖大小

gallery_point[i].setLayoutParams(layoutParams);

layoutParams.setMargins(4,

0,

4,

0);//

設置指示圖margin值

gallery_point[i].setClickable(false);/*

設置指示圖按鈕不能點擊

*/

layout.removeView(gallery_point[i]);//一個子視圖不能指定了多個父視圖

gallery_points.addView(gallery_point[i]);/*

把已經(jīng)初始化的指示圖動態(tài)添加到指示圖的RadioGroup中

*/

}

}

//添加事件

void

addEvn(){

myGallery.setOnItemSelectedListener(new

OnItemSelectedListener()

{

@Override

public

void

onItemSelected(AdapterView<?>

arg0,

View

arg1,

int

arg2,

long

arg3)

{

//

TODO

Auto-generated

method

stub

gallery_points.check(gallery_point[arg2%gallery_point.length].getId());

}

@Override

public

void

onNothingSelected(AdapterView<?>

arg0)

{

//

TODO

Auto-generated

method

stub

}

});

}（2）商品圖片滑動實現(xiàn)過程：圖片滑動效果和上面的幻燈片效果非常的類似，只是在邏輯處理和界面上有一些小小的區(qū)別。1）適配器類GalleryAdapter.java上面進行了圖片縮放處理，節(jié)省了內(nèi)存開銷，又可把圖片按照自己的要求縮放。//由于是測試case，所以圖片都是寫死的為了區(qū)別，在position

=

1的時候換了一張圖片

public

View

getView(int

position,

View

convertView,

ViewGroup

parent)

{

//

TODO

Auto-generated

method

stub

ImageView

imageView

=

(ImageView)

LayoutInflater.from(context).inflate(R.layout.img,

null);

Bitmap

bitmap

=

null;

try

{

if(position

==

1

){

bitmap

=

BitmapFactory.decodeStream(assetManager.open("xpic11247_s.jpg"));

imageView.setTag("xpic11247_s.jpg");

}

else{

bitmap

=

BitmapFactory.decodeStream(assetManager.open("item0_pic.jpg"));

imageView.setTag("item0_pic.jpg");

}

}

catch

(IOException

e)

{

//

TODO

Auto-generated

catch

block

e.printStackTrace();

}

//

加載圖片之前進行縮放

int

width

=

bitmap.getWidth();

int

height

=

bitmap.getHeight();

float

newHeight

=

200;

float

newWidth

=

width*newHeight/height;

float

scaleWidth

=

((float)

newWidth)

/

width;

float

scaleHeight

=

((float)

newHeight)

/

height;

//

取得想要縮放的matrix參數(shù)

Matrix

matrix

=

new

Matrix();

matrix.postScale(scaleWidth,

scaleHeight);

//

得到新的圖片

Bitmap

newbm

=

Bitmap.createBitmap(bitmap,

0,

0,

width,

height,

matrix,

true);

System.out.println(newbm.getHeight()+""+newbm.getWidth());