Aandroid-ViewPager 源码分析
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public boolean executeKeyEvent(KeyEvent event) {
boolean handled = false;
if (event.getAction() == KeyEvent.ACTION_DOWN) {
switch (event.getKeyCode()) {
case KeyEvent.KEYCODE_DPAD_LEFT: // 左边.
handled = arrowScroll(FOCUS_LEFT); //
break;
case KeyEvent.KEYCODE_DPAD_RIGHT:
handled = arrowScroll(FOCUS_RIGHT); // 右边.
break;
case KeyEvent.KEYCODE_TAB: //
if (Build.VERSION.SDK_INT >= 11) {
// The focus finder had a bug handling FOCUS_FORWARD and FOCUS_BACKWARD
// before Android 3.0. Ignore the tab key on those devices.
if (KeyEventCompat.hasNoModifiers(event)) {
handled = arrowScroll(FOCUS_FORWARD);
} else if (KeyEventCompat.hasModifiers(event, KeyEvent.META_SHIFT_ON)) {
handled = arrowScroll(FOCUS_BACKWARD);
}
}
break;
}
}
return handled;
}
###
public boolean arrowScroll(int direction) {
View currentFocused = findFocus(); // 查找焦点.
if (currentFocused == this) { // 当前的焦点为 viewpager.
currentFocused = null;
} else if (currentFocused != null) { // page1, page2, page3... ...
boolean isChild = false;
//
for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup;
parent = parent.getParent()) {
if (parent == this) { // 如果又焦点的子控件的父亲是viewpager.
isChild = true;
break;
}
}
if (!isChild) {
// This would cause the focus search down below to fail in fun ways.
final StringBuilder sb = new StringBuilder();
sb.append(currentFocused.getClass().getSimpleName());
for (ViewParent parent = currentFocused.getParent(); parent instanceof ViewGroup;
parent = parent.getParent()) {
sb.append(" => ").append(parent.getClass().getSimpleName());
}
Log.e(TAG, "arrowScroll tried to find focus based on non-child " +
"current focused view " + sb.toString());
currentFocused = null; // 不是本viewpager内的焦点控件.
}
}
boolean handled = false;
// 获取 下一个焦点. 比如: NextFocusRight....
View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused,
direction);
if (nextFocused != null && nextFocused != currentFocused) {
if (direction == View.FOCUS_LEFT) { // 左边.
// If there is nothing to the left, or this is causing us to
// jump to the right, then what we really want to do is page left.
final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left;
final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left;
//
if (currentFocused != null && nextLeft >= currLeft) {
handled = pageLeft();
} else {
handled = nextFocused.requestFocus(); //
}
} else if (direction == View.FOCUS_RIGHT) {
// If there is nothing to the right, or this is causing us to
// jump to the left, then what we really want to do is page right.
final int nextLeft = getChildRectInPagerCoordinates(mTempRect, nextFocused).left;
final int currLeft = getChildRectInPagerCoordinates(mTempRect, currentFocused).left;
if (currentFocused != null && nextLeft <= currLeft) {
handled = pageRight(); // 向右边翻页.
} else {
handled = nextFocused.requestFocus();
}
}
} else if (direction == FOCUS_LEFT || direction == FOCUS_BACKWARD) {
// Trying to move left and nothing there; try to page.
handled = pageLeft();
} else if (direction == FOCUS_RIGHT || direction == FOCUS_FORWARD) {
// Trying to move right and nothing there; try to page.
handled = pageRight();
}
if (handled) {
playSoundEffect(SoundEffectConstants.getContantForFocusDirection(direction));
}
return handled;
}
###
boolean pageRight() {
if (mAdapter != null && mCurItem < (mAdapter.getCount()-1)) {
setCurrentItem(mCurItem+1, true); //
return true;
}
return false;
}
###
原文：http://my.oschina.net/hailongqiu/blog/372935
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