requestFocus() 与 requestFocusFromTouch() 方法的区别
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android中设置控件获得焦点
标签: androidbutton
2011-12-01 17:15 55277人阅读 评论(3)收藏 举报
版权声明:本文为博主原创文章,未经博主允许不得转载。
Android中,要使控件获得焦点,需要先setFocus,再requestFocus。
以Button为例:
btn.setFocusable(true);
btn.setFocusableInTouchMode(true);
btn.requestFocus();
btn.requestFocusFromTouch();
//获得失去焦点的监听器
btn.setOnFocusChangeListener(new OnFocusChangeListener() {
@Override
public void onFocusChange(View v, boolean hasFocus) {
// TODO Auto-generated method stub
if (hasFocus) {
btn_box.setBackgroundResource(R.drawable.book_green);
}else {
btn_box.setBackgroundResource(R.drawable.book);
}
}
});
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requestFocus() 与 requestFocusFromTouch() 方法的区别
2015-05-04 23:26 3077人阅读 评论(0)收藏 举报
分类:
Android(46)
版权声明:本文为博主原创文章,未经博主允许不得转载。
两个方法都是获取焦点:
requestFocus() 源码如下:
[java] view plaincopy
print?
- /**
- * Call this to try to give focus to a specific view or to one of its descendants
- * and give it hints about the direction and a specific rectangle that the focus
- * is coming from. The rectangle can help give larger views a finer grained hint
- * about where focus is coming from, and therefore, where to show selection, or
- * forward focus change internally.
- *
- * @return Whether this view or one of its descendants actually took focus.
- */
- public boolean requestFocus(int direction, Rect previouslyFocusedRect) {
- // need to be focusable
- if ((mViewFlags & FOCUSABLE_MASK) != FOCUSABLE ||
- (mViewFlags & VISIBILITY_MASK) != VISIBLE) {
- return false;
- }
- // need to be focusable in touch mode if in touch mode
- if (isInTouchMode() &&
- (FOCUSABLE_IN_TOUCH_MODE != (mViewFlags & FOCUSABLE_IN_TOUCH_MODE))) {
- return false;
- }
- // need to not have any parents blocking us
- if (hasAncestorThatBlocksDescendantFocus()) {
- return false;
- }
- handleFocusGainInternal(direction, previouslyFocusedRect);
- return true;
- }
http://blog.csdn.net/wangbole/article/details/45488787
http://blog.csdn.net/wangbole/article/details/45488787
requestFocusFromTouch() 源码如下:
[java] view plaincopy
print?
- /**
- * Call this to try to give focus to a specific view or to one of its descendants. This is a
- * special variant of {@link #requestFocus() } that will allow views that are not focuable in
- * touch mode to request focus when they are touched.
- *
- * @return Whether this view or one of its descendants actually took focus.
- *
- * @see #isInTouchMode()
- *
- */
- public final boolean requestFocusFromTouch() {
- // Leave touch mode if we need to
- if (isInTouchMode()) {
- ViewRootImpl viewRoot = getViewRootImpl();
- if (viewRoot != null) {
- viewRoot.ensureTouchMode(false);
- }
- }
- return requestFocus(View.FOCUS_DOWN);
- }
从代码中可以看出:
requestFocus() 方法在三种情况下获取焦点不能生效。
1)对应的View不支持Focus;
2) 对应的View支持Focus,但是不支持在Touch模式下的Focus;
3) 对应的View其祖先View 设置了FOCUS_BLOCK_DESCENDANTS 标志, 阻止其子View获取焦点。
而requestFocusFromTouch() 方法设计的目的就是解决requestFocus() 在第二种不能获得焦点的情况下,Touch模式下不支持焦点,也能够获得焦点使用的。
Baidu Button BEGIN
Baidu Button END 172.16.140.12 Baidu Button BEGIN Baidu Button END
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