public void setDisplayedViewIndex(int i) {
if (0 <= i && i < mAdapter.getCount()) {
onMoveOffChild(mCurrent);
mCurrent = i;
onMoveToChild(i);
mResetLayout = true;
requestLayout();
}
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
View cv = mChildViews.get(mCurrent);
Point cvOffset;
if (!mResetLayout) {
// Move to next or previous if current is sufficiently off center
if (cv != null) {
cvOffset = subScreenSizeOffset(cv);
// cv.getRight() may be out of date with the current scale
// so add left to the measured width for the correct position
if (cv.getLeft() + cv.getMeasuredWidth() + cvOffset.x + GAP / 2 + mXScroll < getWidth() / 2
&& mCurrent + 1 < mAdapter.getCount()) {
postUnsettle(cv);
// post to invoke test for end of animation
// where we must set hq area for the new current view
post(this);
onMoveOffChild(mCurrent);
mCurrent++;
onMoveToChild(mCurrent);
}
if (cv.getLeft() - cvOffset.x - GAP / 2 + mXScroll >= getWidth() / 2 && mCurrent > 0) {
postUnsettle(cv);
// post to invoke test for end of animation
// where we must set hq area for the new current view
post(this);
onMoveOffChild(mCurrent);
mCurrent--;
onMoveToChild(mCurrent);
}
}
// Remove not needed children and hold them for reuse
int numChildren = mChildViews.size();
int childIndices[] = new int[numChildren];
for (int i = 0; i < numChildren; i++) childIndices[i] = mChildViews.keyAt(i);
for (int i = 0; i < numChildren; i++) {
int ai = childIndices[i];
if (ai < mCurrent - 1 || ai > mCurrent + 1) {
View v = mChildViews.get(ai);
onNotInUse(v);
mViewCache.add(v);
removeViewInLayout(v);
mChildViews.remove(ai);
}
}
} else {
mResetLayout = false;
mXScroll = mYScroll = 0;
// Remove all children and hold them for reuse
int numChildren = mChildViews.size();
for (int i = 0; i < numChildren; i++) {
View v = mChildViews.valueAt(i);
onNotInUse(v);
mViewCache.add(v);
removeViewInLayout(v);
}
mChildViews.clear();
// post to ensure generation of hq area
post(this);
}
// Ensure current view is present
int cvLeft, cvRight, cvTop, cvBottom;
boolean notPresent = (mChildViews.get(mCurrent) == null);
cv = getOrCreateChild(mCurrent);
// When the view is sub-screen-size in either dimension we
// offset it to center within the screen area, and to keep
// the views spaced out
cvOffset = subScreenSizeOffset(cv);
if (notPresent) {
// Main item not already present. Just place it top left
cvLeft = cvOffset.x;
cvTop = cvOffset.y;
} else {
// Main item already present. Adjust by scroll offsets
cvLeft = cv.getLeft() + mXScroll;
cvTop = cv.getTop() + mYScroll;
}
// Scroll values have been accounted for
mXScroll = mYScroll = 0;
cvRight = cvLeft + cv.getMeasuredWidth();
cvBottom = cvTop + cv.getMeasuredHeight();
if (!mUserInteracting && mScroller.isFinished()) {
Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
cvRight += corr.x;
cvLeft += corr.x;
cvTop += corr.y;
cvBottom += corr.y;
} else if (cv.getMeasuredHeight() <= getHeight()) {
// When the current view is as small as the screen in height, clamp
// it vertically
Point corr = getCorrection(getScrollBounds(cvLeft, cvTop, cvRight, cvBottom));
cvTop += corr.y;
cvBottom += corr.y;
}
cv.layout(cvLeft, cvTop, cvRight, cvBottom);
if (mCurrent > 0) {
View lv = getOrCreateChild(mCurrent - 1);
Point leftOffset = subScreenSizeOffset(lv);
int gap = leftOffset.x + GAP + cvOffset.x;
lv.layout(
cvLeft - lv.getMeasuredWidth() - gap,
(cvBottom + cvTop - lv.getMeasuredHeight()) / 2,
cvLeft - gap,
(cvBottom + cvTop + lv.getMeasuredHeight()) / 2);
}
if (mCurrent + 1 < mAdapter.getCount()) {
View rv = getOrCreateChild(mCurrent + 1);
Point rightOffset = subScreenSizeOffset(rv);
int gap = cvOffset.x + GAP + rightOffset.x;
rv.layout(
cvRight + gap,
(cvBottom + cvTop - rv.getMeasuredHeight()) / 2,
cvRight + rv.getMeasuredWidth() + gap,
(cvBottom + cvTop + rv.getMeasuredHeight()) / 2);
}
invalidate();
}
