Android入门第十三篇之Gallery + ImageSwitcher

本文来自http://blog.youkuaiyun.com/hellogv/，引用必须注明出处！

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:

view plain print ?

1. <?xmlversion="1.0"encoding="utf-8"?>
2. <RelativeLayoutxmlns:android="http://schemas.android.com/apk/res/android"
3. android:layout_width="match_parent"
4. android:layout_height="match_parent">
6. <ImageSwitcherandroid:id="@+id/switcher"
7. android:layout_width="match_parent"android:layout_height="match_parent"/>
9. <Galleryandroid:id="@+id/gallery"
10. android:background="#55000000"
11. android:layout_width="match_parent"
12. android:layout_alignParentBottom="true"
13. android:layout_alignParentLeft="true"
15. android:gravity="center_vertical"
16. android:spacing="16dp"android:layout_height="100dp"/>
17. </RelativeLayout>

程序的源码如下:

view plain print ?

1. packagecom.testImageView;
2. importjava.lang.reflect.Field;
3. importjava.util.ArrayList;
4. importandroid.app.Activity;
5. importandroid.content.Context;
6. importandroid.os.Bundle;
7. importandroid.view.MotionEvent;
8. importandroid.view.View;
9. importandroid.view.View.OnTouchListener;
10. importandroid.view.ViewGroup;
11. importandroid.view.animation.AnimationUtils;
12. importandroid.widget.AdapterView;
13. importandroid.widget.BaseAdapter;
14. importandroid.widget.Gallery;
15. importandroid.widget.ImageSwitcher;
16. importandroid.widget.ImageView;
17. importandroid.widget.AdapterView.OnItemSelectedListener;
18. importandroid.widget.Gallery.LayoutParams;
19. importandroid.widget.ViewSwitcher.ViewFactory;
20. publicclasstestImageViewextendsActivityimplementsViewFactory{
21. privateImageSwitcheris;
22. privateGallerygallery;
23. privateintdownX,upX;
24. privateArrayList<Integer>imgList=newArrayList<Integer>();//图像ID
26. @Override
27. protectedvoidonCreate(BundlesavedInstanceState){
28. //TODOAuto-generatedmethodstub
29. super.onCreate(savedInstanceState);
30. setContentView(R.layout.main);
31. //用反射机制来获取资源中的图片ID
32. Field[]fields=R.drawable.class.getDeclaredFields();
33. for(Fieldfield:fields)
34. {
35. if(!"icon".equals(field.getName()))//除了icon之外的图片
36. {
37. intindex=0;
38. try{
39. index=field.getInt(R.drawable.class);
40. }catch(IllegalArgumentExceptione){
41. //TODOAuto-generatedcatchblock
42. e.printStackTrace();
43. }catch(IllegalAccessExceptione){
44. //TODOAuto-generatedcatchblock
45. e.printStackTrace();
46. }
47. //保存图片ID
48. imgList.add(index);
49. }
50. }
52. //设置ImageSwitcher控件
53. is=(ImageSwitcher)findViewById(R.id.switcher);
54. is.setFactory(this);
55. is.setInAnimation(AnimationUtils.loadAnimation(this,
56. android.R.anim.fade_in));
57. is.setOutAnimation(AnimationUtils.loadAnimation(this,
58. android.R.anim.fade_out));
59. is.setOnTouchListener(newOnTouchListener(){
60. /*
61. *在ImageSwitcher控件上滑动可以切换图片
62. */
63. @Override
64. publicbooleanonTouch(Viewv,MotionEventevent){
65. if(event.getAction()==MotionEvent.ACTION_DOWN)
66. {
67. downX=(int)event.getX();//取得按下时的坐标
68. returntrue;
69. }
70. elseif(event.getAction()==MotionEvent.ACTION_UP)
71. {
72. upX=(int)event.getX();//取得松开时的坐标
73. intindex=0;
74. if(upX-downX>100)//从左拖到右，即看前一张
75. {
76. //如果是第一，则去到尾部
77. if(gallery.getSelectedItemPosition()==0)
78. index=gallery.getCount()-1;
79. else
80. index=gallery.getSelectedItemPosition()-1;
81. }
82. elseif(downX-upX>100)//从右拖到左，即看后一张
83. {
84. //如果是最后，则去到第一
85. if(gallery.getSelectedItemPosition()==(gallery.getCount()-1))
86. index=0;
87. else
88. index=gallery.getSelectedItemPosition()+1;
89. }
90. //改变gallery图片所选，自动触发ImageSwitcher的setOnItemSelectedListener
91. gallery.setSelection(index,true);
92. returntrue;
93. }
94. returnfalse;
95. }
97. });
99. //设置gallery控件
100. gallery=(Gallery)findViewById(R.id.gallery);
101. gallery.setAdapter(newImageAdapter(this));
102. gallery.setOnItemSelectedListener(newOnItemSelectedListener(){
103. @Override
104. publicvoidonItemSelected(AdapterView<?>arg0,Viewarg1,
105. intposition,longarg3){
106. is.setImageResource(imgList.get(position));
107. }
108. @Override
109. publicvoidonNothingSelected(AdapterView<?>arg0){
110. //TODOAuto-generatedmethodstub
111. }
113. });
114. }
115. //设置ImgaeSwitcher
116. @Override
117. publicViewmakeView(){
118. ImageViewi=newImageView(this);
119. i.setBackgroundColor(0xFF000000);
120. i.setScaleType(ImageView.ScaleType.CENTER);//居中
121. i.setLayoutParams(newImageSwitcher.LayoutParams(//自适应图片大小
122. LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
123. returni;
124. }
125. publicclassImageAdapterextendsBaseAdapter{
126. publicImageAdapter(Contextc){
127. mContext=c;
128. }
129. publicintgetCount(){
130. returnimgList.size();
131. }
132. publicObjectgetItem(intposition){
133. returnposition;
134. }
135. publiclonggetItemId(intposition){
136. returnposition;
137. }
138. publicViewgetView(intposition,ViewconvertView,ViewGroupparent){
139. ImageViewi=newImageView(mContext);
140. i.setImageResource(imgList.get(position));
141. i.setAdjustViewBounds(true);
142. i.setLayoutParams(newGallery.LayoutParams(
143. LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT));
144. returni;
145. }
146. privateContextmContext;
147. }
149. }