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Fixing PagedView bad snap-back decisions

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-> There was some code that was causing pages to snap back
   much to the original page much too frequently.

Change-Id: Ibd02ac634c737887a2bcfd7096882c95c51087f1
This commit is contained in:
Adam Cohen
2011-11-18 12:03:48 -08:00
parent bad24941cd
commit 00481b3ed3
1 changed files with 9 additions and 8 deletions
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src/com/android/launcher2/PagedView.java
+9 -8
View File
@@ -61,8 +61,6 @@ public abstract class PagedView extends ViewGroup {
// the min drag distance for a fling to register, to prevent random page shifts
private static final int MIN_LENGTH_FOR_FLING = 25;
// The min drag distance to trigger a page shift (regardless of velocity)
private static final int MIN_LENGTH_FOR_MOVE = 200;
private static final int PAGE_SNAP_ANIMATION_DURATION = 550;
protected static final float NANOTIME_DIV = 1000000000.0f;
@@ -72,6 +70,8 @@ public abstract class PagedView extends ViewGroup {
private static final int MINIMUM_SNAP_VELOCITY = 2200;
private static final int MIN_FLING_VELOCITY = 250;
private static final float RETURN_TO_ORIGINAL_PAGE_THRESHOLD = 0.33f;
// The page is moved more than halfway, automatically move to the next page on touch up.
private static final float SIGNIFICANT_MOVE_THRESHOLD = 0.4f;
// the velocity at which a fling gesture will cause us to snap to the next page
protected int mSnapVelocity = 500;
@@ -1205,24 +1205,25 @@ public abstract class PagedView extends ViewGroup {
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int velocityX = (int) velocityTracker.getXVelocity(activePointerId);
final int deltaX = (int) (x - mDownMotionX);
boolean isSignificantMove = Math.abs(deltaX) > MIN_LENGTH_FOR_MOVE;
final int pageWidth = getScaledMeasuredWidth(getPageAt(mCurrentPage));
boolean isSignificantMove = Math.abs(deltaX) > pageWidth *
SIGNIFICANT_MOVE_THRESHOLD;
final int snapVelocity = mSnapVelocity;
mTotalMotionX += Math.abs(mLastMotionX + mLastMotionXRemainder - x);
boolean isFling = mTotalMotionX > MIN_LENGTH_FOR_FLING &&
Math.abs(velocityX) > snapVelocity;
// In the case that the page is moved far to one direction and then is flung
// in the opposite direction, we use a threshold to determine whether we should
// just return to the starting page, or if we should skip one further.
boolean returnToOriginalPage = false;
final int pageWidth = getScaledMeasuredWidth(getPageAt(mCurrentPage));
if (Math.abs(deltaX) > pageWidth * RETURN_TO_ORIGINAL_PAGE_THRESHOLD &&
Math.signum(velocityX) != Math.signum(deltaX)) {
Math.signum(velocityX) != Math.signum(deltaX) && isFling) {
returnToOriginalPage = true;
}
boolean isFling = mTotalMotionX > MIN_LENGTH_FOR_FLING &&
Math.abs(velocityX) > snapVelocity;
int finalPage;
// We give flings precedence over large moves, which is why we short-circuit our
// test for a large move if a fling has been registered. That is, a large