【移动应用开发技术】Android中怎么利用Gallery实现幻灯片效果

【移动应用开发技术】Android中怎么利用Gallery实现幻灯片效果

今天就跟大家聊聊有关Android中怎么利用Gallery实现幻灯片效果，可能很多人都不太了解，为了让大家更加了解，在下给大家总结了以下内容，希望大家根据这篇文章可以有所收获。（1）幻灯片效果的实现：自定义Gallery：DetailGallery.java可视界面：ImgSwitchActivity.java适配类：GalleryIndexAdapter.java1）自定义Gallery主要重写onFling通过按下和松手的位置不同比较是向右移动还是向左移动，部分代码如下：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）在适配类

GalleryIndexAdapter主要完成幻灯片的循环播放，在getCount里面返回值返回Integer.MAX_VALUE，然后在getView里面根据position与传进来初始图片个数进行余数计算得到每次循环到哪张图片。部分代码如下：@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）在可视界面里面实现逻辑控制，通过定时器定时刷新幻灯片，定时器通过定时发送消息，消息接受处理机制接收到消息之后，就模拟滑动事件，调用Gallery的onFling方法实现图片自动切换效果。选择按钮的显示效果（RadioButton）需要在Gallery的setOnItemSelectedListener进行处理。//定时器和事件处理5秒刷新一次幻灯片

/**

展示图控制器，实现展示图切换

*/

final

Handler

handler_gallery

=

new

Handler()

{

public

void

handleMessage(Message

msg)

{

/*

自定义屏幕按下的动作

*/

MotionEvent

e1

=

MotionEvent.obtain(SystemClock.uptimeMillis(),

SystemClock.uptimeMillis(),

MotionEvent.ACTION_UP,

89.333336f,

265.33334f,

0);

/*

自定义屏幕放开的动作

*/

MotionEvent

e2

=

MotionEvent.obtain(SystemClock.uptimeMillis(),

SystemClock.uptimeMillis(),

MotionEvent.ACTION_DOWN,

300.0f,

238.00003f,

0);

myGallery.onFling(e2,

e1,

-800,

0);

/*

给gallery添加按下和放开的动作，实现自动滑动

*/

super.handleMessage(msg);

}

};

protected

void

onResume()

{

autogallery();

super.onResume();

};

private

void

autogallery()

{

/*

设置定时器，每5秒自动切换展示图

*/

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);

}

//指示按钮和gallery初始化过程以及事件监听添加过程

//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);

//设置小按钮

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);/*

设置指示图按钮ID

*/

int

wh

=

Tool.dp2px(context,

10);

RadioGroup.LayoutParams

layoutParams

=

new

RadioGroup.LayoutParams(wh,

wh);

//

设置指示图大小

gallery_point[i].setLayoutParams(layoutParams);

layoutParams.setMargins(4,

0,

4,

0);//

设置指示图margin值

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

设置指示图按钮不能点击

*/

layout.removeView(gallery_point[i]);//一个子视图不能指定了多个父视图

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

把已经初始化的指示图动态添加到指示图的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）商品图片滑动实现过程：图片滑动效果和上面的幻灯片效果非常的类似，只是在逻辑处理和界面上有一些小小的区别。1）适配器类GalleryAdapter.java上面进行了图片缩放处理，节省了内存开销，又可把图片按照自己的要求缩放。//由于是测试case，所以图片都是写死的为了区别，在position

=

1的时候换了一张图片

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();

}

//

加载图片之前进行缩放

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;

//

取得想要缩放的matrix参数

Matrix

matrix

=

new

Matrix();

matrix.postScale(scaleWidth,

scaleHeight);

//

得到新的图片

Bitmap

newbm

=

Bitmap.createBitmap(bitmap,

0,

0,

width,

height,

matrix,

true);

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