Android重写ViewPager修改滑动灵敏度

谁借莪１个温暖的怀抱￠ 2022-05-13 05:50 291阅读 0赞

使用ViewPager作为一个页面进行切换，里面可以存放很多View，但有时在操作View时不小心滑动一下就有可能跳到下一页，这并不是我们想要的，这里就需要重写ViewPager修改它的滑动条件

效果图

![SouthEast][]

程序目录结构

![SouthEast 1][]

BTViewPager.java

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1.  **package**com.example.viewpagerdemo;
2.  
3.  **import**android.content.Context;
4.  **import**android.support.v4.view.ViewPager;
5.  **import**android.util.AttributeSet;
6.  **import**android.util.Log;
7.  **import**android.view.MotionEvent;
8.  **import**android.widget.Scroller;
9.  
10. /\*\*
11. \*解决ViewPager滑动过于灵敏，只有滑动距离大于100才滑到另一页
12. \*
13. \*@authorAdministrator
14. \*
15. \*/
16. **public****class**BTViewPager**extends**ViewPager\{ 
17. 
18. **private****static****final**StringTAG="dzt\_pager";
19. **private****static****final****int**MOVE\_LIMITATION=100;//触发移动的像素距离
20. **private****float**mLastMotionX;//手指触碰屏幕的最后一次x坐标
21. **private****int**mCurScreen;
22. 
23. **private**ScrollermScroller;//滑动控件
24. 
25. **public**BTViewPager(Contextcontext)\{ 
26. **super**(context);
27. //TODOAuto-generatedconstructorstub
28. init(context);
29. \}
30. 
31. **public**BTViewPager(Contextcontext,AttributeSetattrs)\{ 
32. **super**(context,attrs);
33. //TODOAuto-generatedconstructorstub
34. init(context);
35. \}
36. 
37. **private****void**init(Contextcontext)\{ 
38. mScroller=**new**Scroller(context);
39. mCurScreen=0;//默认设置显示第一个VIEW
40. \}
41. 
42. @Override
43. **public****boolean**onTouchEvent(MotionEventevent)\{ 
44. //TODOAuto-generatedmethodstub
45. 
46. **final****int**action=event.getAction();
47. **final****float**x=event.getX();
48. **switch**(action)\{ 
49. **case**MotionEvent.ACTION\_DOWN:
50. Log.d(TAG,"\[BTViewPager->\]onTouchEventACTION\_DOWN");
51. mLastMotionX=x;
52. **break**;
53. **case**MotionEvent.ACTION\_MOVE:
54. Log.d(TAG,"\[BTViewPager->\]onTouchEventACTION\_MOVE");
55. **break**;
56. **case**MotionEvent.ACTION\_UP:
57. Log.d(TAG,"Item="\+getCurrentItem()+"count="
58. \+getChildCount());
59. 
60. **if**(Math.abs(x-mLastMotionX)<MOVE\_LIMITATION)\{ 
61. //snapToDestination();//跳到指定页
62. snapToScreen(getCurrentItem());
63. **return****true**;
64. \}
65. **break**;
66. **default**:
67. **break**;
68. \}
69. Log.d(TAG,"\[BTViewPager->\]onTouchEvent--end");
70. **return****super**.onTouchEvent(event);
71. \}
72. 
73. @Override
74. **public****void**computeScroll()\{ 
75. //TODOAuto-generatedmethodstub
76. Log.d(TAG,"\[BTViewPager->\]computeScroll");
77. **super**.computeScroll();
78. 
79. **if**(mScroller.computeScrollOffset())\{ 
80. Log.d(TAG,
81. "\[BTViewPager->\]computeScrollx="\+mScroller.getCurrX());
82. scrollTo(mScroller.getCurrX(),mScroller.getCurrY());
83. invalidate();
84. \}
85. 
86. \}
87. 
88. /\*\*
89. \*根据滑动的距离判断移动到第几个视图
90. \*/
91. **public****void**snapToDestination()\{ 
92. **final****int**screenWidth=getWidth();
93. **final****int**destScreen=(getScrollX()+screenWidth/2)/screenWidth;
94. Log.d(TAG,"\[BTViewPager->\]snapToDestinationscreenWidth="
95. \+screenWidth+"destScreen="\+destScreen);
96. snapToScreen(destScreen);
97. \}
98. 
99. /\*\*
100. \*滚动到制定的视图
101. \*
102. \*@paramwhichScreen
103. \*视图下标
104. \*/
105. **public****void**snapToScreen(**int**whichScreen)\{ 
106. //whichScreen=Math.max(0,Math.min(whichScreen,getChildCount()-
107. //1));
108. **if**(getScrollX()!=(whichScreen\*getWidth()))\{ 
109. 
110. **final****int**delta=whichScreen\*getWidth()-getScrollX();
111. Log.d(TAG,"\[BTViewPager->\]snapToScreen-whichScreen="
112. \+whichScreen+"delta="\+delta+"scrollX="
113. \+getScrollX());
114. mScroller.startScroll(getScrollX(),0,delta,0,
115. Math.abs(delta)\*2);
116. mCurScreen=whichScreen;
117. invalidate();
118. \}
119. \}
120. 
121. /\*\*
122. \*用于拦截手势事件的，每个手势事件都会先调用这个方法。Layout里的onInterceptTouchEvent默认返回值是false,
123. \*这样touch事件会传递到childview控件，如果返回false子控件可以响应，否则了控件不响应，这里主要是拦截子控件的响应，
124. \*对ViewGroup不管返回值是什么都会执行onTouchEvent
125. \*/
126. @Override
127. **public****boolean**onInterceptTouchEvent(MotionEventarg0)\{ 
128. //TODOAuto-generatedmethodstub
129. Log.d(TAG,"\[BTViewPager->\]onInterceptTouchEvent");
130. **final****int**action=arg0.getAction();
131. **final****float**x=arg0.getX();
132. **switch**(action)\{ 
133. **case**MotionEvent.ACTION\_DOWN:
134. Log.d(TAG,"onInterceptTouchEvent---ACTION\_DOWN");
135. mLastMotionX=x;
136. **break**;
137. **case**MotionEvent.ACTION\_MOVE:
138. Log.d(TAG,"onInterceptTouchEvent---ACTION\_MOVE");
139. **break**;
140. **case**MotionEvent.ACTION\_UP:
141. Log.d(TAG,"onInterceptTouchEvent---ACTION\_UP");
142. **break**;
143. **default**:
144. **break**;
145. \}
146. **return****super**.onInterceptTouchEvent(arg0);
147. \}
148. \}

只要是在onTouchEvent的UP中处理滑动的条件

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1.  **if**(Math.abs(x-mLastMotionX)<MOVE\_LIMITATION)\{ 
2.  //snapToDestination();//跳到指定页
3.  snapToScreen(getCurrentItem());
4.  **return****true**;
5.  \}

只有滑动的距离大于100才进行上下页处理，否则就停在当前页，当前页使用getCurrentItem()获取， 有一点要注意在ViewPager中getChildCount()获取的值是错误的，不清楚是什么原因，在ViewGroup中是有效的，这个可能要查看ViewPager源码才能弄清楚是什么原因，有知道的朋友可以告知我！  
完整Demo： [http://download.csdn.net/detail/deng0zhaotai/7384637][http_download.csdn.net_detail_deng0zhaotai_7384637]

[SouthEast]: /images/20220513/dfe6b8cf07194906b0f794b173554a6c.png
[SouthEast 1]: /images/20220513/4e9d20541c144dbb9698db780f894ecb.png
[view plain]: http://blog.csdn.net/deng0zhaotai/article/details/26577711#
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[CODE_CODE]: https://code.csdn.net/snippets/358066
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