Android入门户十三篇之Gallery + ImageSwitcher

Android入门第十三篇之Gallery + ImageSwitcher

上次讲了如何使用Gallery控件，这次就讲Gallery 与ImageSwitcher的结合使用，本文实现一个简单的浏览图片的功能。先贴出程序运行截图：

除了Gallery可以拖拉切换图片，我在ImageSwitcher控件加入了setOnTouchListener事件实现，使得ImageSwitcher也可以在拖拉中切换图片。本例子依然使用JAVA的反射机制来自动读取资源中的图片。

?

main.xml的源码如下:

<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent"> <ImageSwitcher android:id="@+id/switcher" android:layout_width="match_parent" android:layout_height="match_parent"/> <Gallery android:id="@+id/gallery" android:background="#55000000" android:layout_width="match_parent" android:layout_alignParentBottom="true" android:layout_alignParentLeft="true" android:gravity="center_vertical" android:spacing="16dp" android:layout_height="100dp"/></RelativeLayout>

?

程序的源码如下:

view plaincopy to clipboardprint?

1. package?com.testImageView;??import?java.lang.reflect.Field;??
2. import?java.util.ArrayList;??import?android.app.Activity;??
3. import?android.content.Context;??import?android.os.Bundle;??
4. import?android.view.MotionEvent;??import?android.view.View;??
5. import?android.view.View.OnTouchListener;??import?android.view.ViewGroup;??
6. import?android.view.animation.AnimationUtils;??import?android.widget.AdapterView;??
7. import?android.widget.BaseAdapter;??import?android.widget.Gallery;??
8. import?android.widget.ImageSwitcher;??import?android.widget.ImageView;??
9. import?android.widget.AdapterView.OnItemSelectedListener;??import?android.widget.Gallery.LayoutParams;??
10. import?android.widget.ViewSwitcher.ViewFactory;??public?class?testImageView?extends?Activity?implements?ViewFactory?{??
11. ????private?ImageSwitcher?is;??????private?Gallery?gallery;??
12. ????private?int?downX,upX;??????private?ArrayList<Integer>?imgList=new?ArrayList<Integer>();//图像ID??
13. ??????????@Override??
14. ????protected?void?onCreate(Bundle?savedInstanceState)?{??????????//?TODO?Auto-generated?method?stub??
15. ????????super.onCreate(savedInstanceState);??????????setContentView(R.layout.main);??
16. ????????//用反射机制来获取资源中的图片ID??????????Field[]?fields?=?R.drawable.class.getDeclaredFields();??
17. ????????for?(Field?field?:?fields)??????????{??
18. ????????????if?(!"icon".equals(field.getName()))//除了icon之外的图片??????????????{?????
19. ????????????????int?index?=?0;??????????????????try?{??
20. ????????????????????index?=?field.getInt(R.drawable.class);??????????????????}?catch?(IllegalArgumentException?e)?{??
21. ????????????????????//?TODO?Auto-generated?catch?block??????????????????????e.printStackTrace();??
22. ????????????????}?catch?(IllegalAccessException?e)?{??????????????????????//?TODO?Auto-generated?catch?block??
23. ????????????????????e.printStackTrace();??????????????????}??
24. ????????????????//保存图片ID??????????????????imgList.add(index);??
25. ????????????}??????????}??
26. ??????????????????//设置ImageSwitcher控件??
27. ????????is?=?(ImageSwitcher)?findViewById(R.id.switcher);??????????is.setFactory(this);??
28. ????????is.setInAnimation(AnimationUtils.loadAnimation(this,??????????????????android.R.anim.fade_in));??
29. ????????is.setOutAnimation(AnimationUtils.loadAnimation(this,??????????????????android.R.anim.fade_out));??
30. ????????is.setOnTouchListener(new?OnTouchListener(){??????????????/*?
31. ?????????????*?在ImageSwitcher控件上滑动可以切换图片??????????????*/??
32. ????????????@Override??????????????public?boolean?onTouch(View?v,?MotionEvent?event)?{??
33. ????????????????if(event.getAction()==MotionEvent.ACTION_DOWN)??????????????????{??
34. ????????????????????downX=(int)?event.getX();//取得按下时的坐标??????????????????????return?true;??
35. ????????????????}??????????????????else?if(event.getAction()==MotionEvent.ACTION_UP)??
36. ????????????????{??????????????????????upX=(int)?event.getX();//取得松开时的坐标??
37. ????????????????????int?index=0;??????????????????????if(upX-downX>100)//从左拖到右，即看前一张??
38. ????????????????????{??????????????????????????//如果是第一，则去到尾部??
39. ????????????????????????if(gallery.getSelectedItemPosition()==0)?????????????????????????????index=gallery.getCount()-1;??
40. ????????????????????????else??????????????????????????????index=gallery.getSelectedItemPosition()-1;??
41. ????????????????????}??????????????????????else?if(downX-upX>100)//从右拖到左，即看后一张??
42. ????????????????????{??????????????????????????//如果是最后，则去到第一??
43. ????????????????????????if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))??????????????????????????????index=0;??
44. ????????????????????????else??????????????????????????????index=gallery.getSelectedItemPosition()+1;??
45. ????????????????????}??????????????????????//改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener??
46. ????????????????????gallery.setSelection(index,?true);??????????????????????return?true;??
47. ????????????????}??????????????????return?false;??
48. ????????????}????????????????
49. ????????});????????????
50. ????????//设置gallery控件??????????gallery?=?(Gallery)?findViewById(R.id.gallery);??
51. ????????gallery.setAdapter(new?ImageAdapter(this));??????????gallery.setOnItemSelectedListener(new?OnItemSelectedListener(){??
52. ????????????@Override??????????????public?void?onItemSelected(AdapterView<?>?arg0,?View?arg1,??
53. ????????????????????int?position,?long?arg3)?{??????????????????is.setImageResource(imgList.get(position));??
54. ????????????}??????????????@Override??
55. ????????????public?void?onNothingSelected(AdapterView<?>?arg0)?{??????????????????//?TODO?Auto-generated?method?stub??
56. ????????????}????????????????
57. ????????});??????}??
58. ????//设置ImgaeSwitcher??????@Override??
59. ????public?View?makeView()?{??????????ImageView?i?=?new?ImageView(this);??
60. ????????i.setBackgroundColor(0xFF000000);??????????i.setScaleType(ImageView.ScaleType.CENTER);//居中??
61. ????????i.setLayoutParams(new?ImageSwitcher.LayoutParams(//自适应图片大小??????????????????LayoutParams.FILL_PARENT,?LayoutParams.FILL_PARENT));??
62. ????????return?i;??????}??
63. ????public?class?ImageAdapter?extends?BaseAdapter?{??????????public?ImageAdapter(Context?c)?{??
64. ????????????mContext?=?c;??????????}??
65. ????????public?int?getCount()?{??????????????return?imgList.size();??
66. ????????}??????????public?Object?getItem(int?position)?{??
67. ????????????return?position;??????????}??
68. ????????public?long?getItemId(int?position)?{??????????????return?position;??
69. ????????}??????????public?View?getView(int?position,?View?convertView,?ViewGroup?parent)?{??
70. ????????????ImageView?i?=?new?ImageView(mContext);??????????????i.setImageResource(imgList.get(position));??
71. ????????????i.setAdjustViewBounds(true);??????????????i.setLayoutParams(new?Gallery.LayoutParams(??
72. ????????????????????LayoutParams.WRAP_CONTENT,?LayoutParams.WRAP_CONTENT));??????????????return?i;??
73. ????????}??????????private?Context?mContext;??
74. ????}????
75. }?