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tweak snap scroll

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WebView.mHeldMotionless should only be set to MOTIONLESS_FALSE
if some scrolling occurs, even in the case where motion is discarded
by snap-scroll mode.

Refactoring the code allows the code to be smaller, and provides
a single point where scrollBy() is called while dragging.

This doesn't change the snap-scroll logic in any way.

related to http://b/issue?id=2092446
This commit is contained in:
Cary Clark
2009-10-14 14:53:37 -04:00
parent 5af4cf47b9
commit ac492e181a
1 changed files with 33 additions and 46 deletions
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79
core/java/android/webkit/WebView.java
View File

@@ -543,11 +543,10 @@ public class WebView extends AbsoluteLayout
private boolean mUserScroll = false;
private int mSnapScrollMode = SNAP_NONE;
private static final int SNAP_NONE = 1;
private static final int SNAP_X = 2;
private static final int SNAP_Y = 3;
private static final int SNAP_X_LOCK = 4;
private static final int SNAP_Y_LOCK = 5;
private static final int SNAP_NONE = 0;
private static final int SNAP_LOCK = 1; // not a separate state
private static final int SNAP_X = 2; // may be combined with SNAP_LOCK
private static final int SNAP_Y = 4; // may be combined with SNAP_LOCK
private boolean mSnapPositive;
// Used to match key downs and key ups
@@ -3914,11 +3913,6 @@ public class WebView extends AbsoluteLayout
if (Math.abs(fDeltaX) < 1.0f && Math.abs(fDeltaY) < 1.0f) {
keepScrollBarsVisible = done = true;
} else {
if (mHeldMotionless != MOTIONLESS_FALSE) {
mPrivateHandler.removeMessages(DRAG_HELD_MOTIONLESS);
mPrivateHandler.removeMessages(AWAKEN_SCROLL_BARS);
mHeldMotionless = MOTIONLESS_FALSE;
}
if (mSnapScrollMode == SNAP_X || mSnapScrollMode == SNAP_Y) {
int ax = Math.abs(deltaX);
int ay = Math.abs(deltaY);
@@ -3929,54 +3923,47 @@ public class WebView extends AbsoluteLayout
mSnapScrollMode = SNAP_NONE;
}
// reverse direction means lock in the snap mode
if ((ax > MAX_SLOPE_FOR_DIAG * ay) &&
((mSnapPositive &&
deltaX < -mMinLockSnapReverseDistance)
|| (!mSnapPositive &&
deltaX > mMinLockSnapReverseDistance))) {
mSnapScrollMode = SNAP_X_LOCK;
if (ax > MAX_SLOPE_FOR_DIAG * ay &&
(mSnapPositive
? deltaX < -mMinLockSnapReverseDistance
: deltaX > mMinLockSnapReverseDistance)) {
mSnapScrollMode |= SNAP_LOCK;
}
} else {
// radical change means getting out of snap mode
if ((ax > MAX_SLOPE_FOR_DIAG * ay)
if (ax > MAX_SLOPE_FOR_DIAG * ay
&& ax > MIN_BREAK_SNAP_CROSS_DISTANCE) {
mSnapScrollMode = SNAP_NONE;
}
// reverse direction means lock in the snap mode
if ((ay > MAX_SLOPE_FOR_DIAG * ax) &&
((mSnapPositive &&
deltaY < -mMinLockSnapReverseDistance)
|| (!mSnapPositive &&
deltaY > mMinLockSnapReverseDistance))) {
mSnapScrollMode = SNAP_Y_LOCK;
if (ay > MAX_SLOPE_FOR_DIAG * ax &&
(mSnapPositive
? deltaY < -mMinLockSnapReverseDistance
: deltaY > mMinLockSnapReverseDistance)) {
mSnapScrollMode |= SNAP_LOCK;
}
}
}
if (mSnapScrollMode == SNAP_X
|| mSnapScrollMode == SNAP_X_LOCK) {
if (deltaX == 0) {
// keep the scrollbar on the screen even there is no
// scroll
keepScrollBarsVisible = true;
if (mSnapScrollMode != SNAP_NONE) {
if ((mSnapScrollMode & SNAP_X) == SNAP_X) {
deltaY = 0;
} else {
scrollBy(deltaX, 0);
deltaX = 0;
}
mLastTouchX = x;
} else if (mSnapScrollMode == SNAP_Y
|| mSnapScrollMode == SNAP_Y_LOCK) {
if (deltaY == 0) {
// keep the scrollbar on the screen even there is no
// scroll
keepScrollBarsVisible = true;
} else {
scrollBy(0, deltaY);
}
mLastTouchY = y;
} else {
}
if ((deltaX | deltaY) != 0) {
scrollBy(deltaX, deltaY);
mLastTouchX = x;
mLastTouchY = y;
if (deltaX != 0) {
mLastTouchX = x;
}
if (deltaY != 0) {
mLastTouchY = y;
}
mHeldMotionless = MOTIONLESS_FALSE;
} else {
// keep the scrollbar on the screen even there is no
// scroll
keepScrollBarsVisible = true;
}
mLastTouchTime = eventTime;
mUserScroll = true;
@@ -4412,7 +4399,7 @@ public class WebView extends AbsoluteLayout
int vy = (int) mVelocityTracker.getYVelocity();
if (mSnapScrollMode != SNAP_NONE) {
if (mSnapScrollMode == SNAP_X || mSnapScrollMode == SNAP_X_LOCK) {
if ((mSnapScrollMode & SNAP_X) == SNAP_X) {
vy = 0;
} else {
vx = 0;