/*
* Copyright (C) 2006 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.android.browser.view;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.PointF;
import android.graphics.Rect;
import android.os.StrictMode;
import android.util.AttributeSet;
import android.view.FocusFinder;
import android.view.InputDevice;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewDebug;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.accessibility.AccessibilityEvent;
import android.view.accessibility.AccessibilityNodeInfo;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.OverScroller;
import android.widget.TextView;
import com.android.internal.R;
import java.util.List;
/**
* Layout container for a view hierarchy that can be scrolled by the user,
* allowing it to be larger than the physical display. A ScrollView
* is a {@link FrameLayout}, meaning you should place one child in it
* containing the entire contents to scroll; this child may itself be a layout
* manager with a complex hierarchy of objects. A child that is often used
* is a {@link LinearLayout} in a vertical orientation, presenting a vertical
* array of top-level items that the user can scroll through.
*
* <p>The {@link TextView} class also
* takes care of its own scrolling, so does not require a ScrollView, but
* using the two together is possible to achieve the effect of a text view
* within a larger container.
*
* <p>ScrollView only supports vertical scrolling.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public class ScrollerView extends FrameLayout {
static final int ANIMATED_SCROLL_GAP = 250;
static final float MAX_SCROLL_FACTOR = 0.5f;
private long mLastScroll;
private final Rect mTempRect = new Rect();
protected OverScroller mScroller;
/**
* Position of the last motion event.
*/
private float mLastMotionY;
/**
* True when the layout has changed but the traversal has not come through yet.
* Ideally the view hierarchy would keep track of this for us.
*/
private boolean mIsLayoutDirty = true;
/**
* The child to give focus to in the event that a child has requested focus while the
* layout is dirty. This prevents the scroll from being wrong if the child has not been
* laid out before requesting focus.
*/
protected View mChildToScrollTo = null;
/**
* True if the user is currently dragging this ScrollView around. This is
* not the same as 'is being flinged', which can be checked by
* mScroller.isFinished() (flinging begins when the user lifts his finger).
*/
protected boolean mIsBeingDragged = false;
/**
* Determines speed during touch scrolling
*/
private VelocityTracker mVelocityTracker;
/**
* When set to true, the scroll view measure its child to make it fill the currently
* visible area.
*/
/* @ViewDebug.ExportedProperty(category = "layout") */
private boolean mFillViewport;
/**
* Whether arrow scrolling is animated.
*/
private boolean mSmoothScrollingEnabled = true;
private int mTouchSlop;
protected int mMinimumVelocity;
private int mMaximumVelocity;
private int mOverscrollDistance;
private int mOverflingDistance;
/**
* ID of the active pointer. This is used to retain consistency during
* drags/flings if multiple pointers are used.
*/
private int mActivePointerId = INVALID_POINTER;
/**
* The StrictMode "critical time span" objects to catch animation
* stutters. Non-null when a time-sensitive animation is
* in-flight. Must call finish() on them when done animating.
* These are no-ops on user builds.
*/
private StrictMode.Span mScrollStrictSpan = null; // aka "drag"
private StrictMode.Span mFlingStrictSpan = null;
/**
* Sentinel value for no current active pointer.
* Used by {@link #mActivePointerId}.
*/
private static final int INVALID_POINTER = -1;
/**
* orientation of the scrollview
*/
protected boolean mHorizontal;
protected boolean mIsOrthoDragged;
private float mLastOrthoCoord;
private View mDownView;
private PointF mDownCoords;
public ScrollerView(Context context) {
this(context, null);
}
public ScrollerView(Context context, AttributeSet attrs) {
this(context, attrs, com.android.internal.R.attr.scrollViewStyle);
}
public ScrollerView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
initScrollView();
TypedArray a =
context.obtainStyledAttributes(attrs, com.android.internal.R.styleable.ScrollView, defStyle, 0);
setFillViewport(a.getBoolean(R.styleable.ScrollView_fillViewport, false));
a.recycle();
}
private void initScrollView() {
mScroller = new OverScroller(getContext());
setFocusable(true);
setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
setWillNotDraw(false);
final ViewConfiguration configuration = ViewConfiguration.get(mContext);
mTouchSlop = configuration.getScaledTouchSlop();
mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
mOverscrollDistance = configuration.getScaledOverscrollDistance();
mOverflingDistance = configuration.getScaledOverflingDistance();
mDownCoords = new PointF();
}
public void setOrientation(int orientation) {
mHorizontal = (orientation == LinearLayout.HORIZONTAL);
requestLayout();
}
@Override
public boolean shouldDelayChildPressedState() {
return true;
}
@Override
protected float getTopFadingEdgeStrength() {
if (getChildCount() == 0) {
return 0.0f;
}
if (mHorizontal) {
final int length = getHorizontalFadingEdgeLength();
if (mScrollX < length) {
return mScrollX / (float) length;
}
} else {
final int length = getVerticalFadingEdgeLength();
if (mScrollY < length) {
return mScrollY / (float) length;
}
}
return 1.0f;
}
@Override
protected float getBottomFadingEdgeStrength() {
if (getChildCount() == 0) {
return 0.0f;
}
if (mHorizontal) {
final int length = getHorizontalFadingEdgeLength();
final int bottomEdge = getWidth() - mPaddingRight;
final int span = getChildAt(0).getRight() - mScrollX - bottomEdge;
if (span < length) {
return span / (float) length;
}
} else {
final int length = getVerticalFadingEdgeLength();
final int bottomEdge = getHeight() - mPaddingBottom;
final int span = getChildAt(0).getBottom() - mScrollY - bottomEdge;
if (span < length) {
return span / (float) length;
}
}
return 1.0f;
}
/**
* @return The maximum amount this scroll view will scroll in response to
* an arrow event.
*/
public int getMaxScrollAmount() {
return (int) (MAX_SCROLL_FACTOR * (mHorizontal
? (mRight - mLeft) : (mBottom - mTop)));
}
@Override
public void addView(View child) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child);
}
@Override
public void addView(View child, int index) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, index);
}
@Override
public void addView(View child, ViewGroup.LayoutParams params) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, params);
}
@Override
public void addView(View child, int index, ViewGroup.LayoutParams params) {
if (getChildCount() > 0) {
throw new IllegalStateException("ScrollView can host only one direct child");
}
super.addView(child, index, params);
}
/**
* @return Returns true this ScrollView can be scrolled
*/
private boolean canScroll() {
View child = getChildAt(0);
if (child != null) {
if (mHorizontal) {
return getWidth() < child.getWidth() + mPaddingLeft + mPaddingRight;
} else {
return getHeight() < child.getHeight() + mPaddingTop + mPaddingBottom;
}
}
return false;
}
/**
* Indicates whether this ScrollView's content is stretched to fill the viewport.
*
* @return True if the content fills the viewport, false otherwise.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public boolean isFillViewport() {
return mFillViewport;
}
/**
* Indicates this ScrollView whether it should stretch its content height to fill
* the viewport or not.
*
* @param fillViewport True to stretch the content's height to the viewport's
* boundaries, false otherwise.
*
* @attr ref android.R.styleable#ScrollView_fillViewport
*/
public void setFillViewport(boolean fillViewport) {
if (fillViewport != mFillViewport) {
mFillViewport = fillViewport;
requestLayout();
}
}
/**
* @return Whether arrow scrolling will animate its transition.
*/
public boolean isSmoothScrollingEnabled() {
return mSmoothScrollingEnabled;
}
/**
* Set whether arrow scrolling will animate its transition.
* @param smoothScrollingEnabled whether arrow scrolling will animate its transition
*/
public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) {
mSmoothScrollingEnabled = smoothScrollingEnabled;
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
if (!mFillViewport) {
return;
}
final int heightMode = MeasureSpec.getMode(heightMeasureSpec);
if (heightMode == MeasureSpec.UNSPECIFIED) {
return;
}
if (getChildCount() > 0) {
final View child = getChildAt(0);
if (mHorizontal) {
int width = getMeasuredWidth();
if (child.getMeasuredWidth() < width) {
final FrameLayout.LayoutParams lp = (LayoutParams) child
.getLayoutParams();
int childHeightMeasureSpec = getChildMeasureSpec(
heightMeasureSpec, mPaddingTop + mPaddingBottom,
lp.height);
width -= mPaddingLeft;
width -= mPaddingRight;
int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
width, MeasureSpec.EXACTLY);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
} else {
int height = getMeasuredHeight();
if (child.getMeasuredHeight() < height) {
final FrameLayout.LayoutParams lp = (LayoutParams) child
.getLayoutParams();
int childWidthMeasureSpec = getChildMeasureSpec(
widthMeasureSpec, mPaddingLeft + mPaddingRight,
lp.width);
height -= mPaddingTop;
height -= mPaddingBottom;
int childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
height, MeasureSpec.EXACTLY);
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
}
}
}
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
// Let the focused view and/or our descendants get the key first
return super.dispatchKeyEvent(event) || executeKeyEvent(event);
}
/**
* You can call this function yourself to have the scroll view perform
* scrolling from a key event, just as if the event had been dispatched to
* it by the view hierarchy.
*
* @param event The key event to execute.
* @return Return true if the event was handled, else false.
*/
public boolean executeKeyEvent(KeyEvent event) {
mTempRect.setEmpty();
if (!canScroll()) {
if (isFocused() && event.getKeyCode() != KeyEvent.KEYCODE_BACK) {
View currentFocused = findFocus();
if (currentFocused == this) currentFocused = null;
View nextFocused = FocusFinder.getInstance().findNextFocus(this,
currentFocused, View.FOCUS_DOWN);
return nextFocused != null
&& nextFocused != this
&& nextFocused.requestFocus(View.FOCUS_DOWN);
}
return false;
}
boolean handled = false;
if (event.getAction() == KeyEvent.ACTION_DOWN) {
switch (event.getKeyCode()) {
case KeyEvent.KEYCODE_DPAD_UP:
if (!event.isAltPressed()) {
handled = arrowScroll(View.FOCUS_UP);
} else {
handled = fullScroll(View.FOCUS_UP);
}
break;
case KeyEvent.KEYCODE_DPAD_DOWN:
if (!event.isAltPressed()) {
handled = arrowScroll(View.FOCUS_DOWN);
} else {
handled = fullScroll(View.FOCUS_DOWN);
}
break;
case KeyEvent.KEYCODE_SPACE:
pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN);
break;
}
}
return handled;
}
private boolean inChild(int x, int y) {
if (getChildCount() > 0) {
final int scrollY = mScrollY;
final View child = getChildAt(0);
return !(y < child.getTop() - scrollY
|| y >= child.getBottom() - scrollY
|| x < child.getLeft()
|| x >= child.getRight());
}
return false;
}
private void initOrResetVelocityTracker() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
} else {
mVelocityTracker.clear();
}
}
private void initVelocityTrackerIfNotExists() {
if (mVelocityTracker == null) {
mVelocityTracker = VelocityTracker.obtain();
}
}
private void recycleVelocityTracker() {
if (mVelocityTracker != null) {
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
@Override
public void requestDisallowInterceptTouchEvent(boolean disallowIntercept) {
if (disallowIntercept) {
recycleVelocityTracker();
}
super.requestDisallowInterceptTouchEvent(disallowIntercept);
}
@Override
public boolean onInterceptTouchEvent(MotionEvent ev) {
/*
* This method JUST determines whether we want to intercept the motion.
* If we return true, onMotionEvent will be called and we do the actual
* scrolling there.
*/
/*
* Shortcut the most recurring case: the user is in the dragging state
* and he is moving his finger. We want to intercept this motion.
*/
final int action = ev.getAction();
if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) {
return true;
}
if ((action == MotionEvent.ACTION_MOVE) && (mIsOrthoDragged)) {
return true;
}
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_MOVE: {
/*
* mIsBeingDragged == false, otherwise the shortcut would have
* caught it. Check whether the user has moved far enough from his
* original down touch.
*/
/*
* Locally do absolute value. mLastMotionY is set to the y value of
* the down event.
*/
final int activePointerId = mActivePointerId;
if (activePointerId == INVALID_POINTER) {
// If we don't have a valid id, the touch down wasn't on
// content.
break;
}
final int pointerIndex = ev.findPointerIndex(activePointerId);
final float y = mHorizontal ? ev.getX(pointerIndex) : ev
.getY(pointerIndex);
final int yDiff = (int) Math.abs(y - mLastMotionY);
if (yDiff > mTouchSlop) {
mIsBeingDragged = true;
mLastMotionY = y;
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
if (mScrollStrictSpan == null) {
mScrollStrictSpan = StrictMode
.enterCriticalSpan("ScrollView-scroll");
}
} else {
final float ocoord = mHorizontal ? ev.getY(pointerIndex) : ev
.getX(pointerIndex);
if (Math.abs(ocoord - mLastOrthoCoord) > mTouchSlop) {
mIsOrthoDragged = true;
mLastOrthoCoord = ocoord;
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
}
}
break;
}
case MotionEvent.ACTION_DOWN: {
final float y = mHorizontal ? ev.getX() : ev.getY();
mDownCoords.x = ev.getX();
mDownCoords.y = ev.getY();
if (!inChild((int) ev.getX(), (int) ev.getY())) {
mIsBeingDragged = false;
recycleVelocityTracker();
break;
}
/*
* Remember location of down touch. ACTION_DOWN always refers to
* pointer index 0.
*/
mLastMotionY = y;
mActivePointerId = ev.getPointerId(0);
initOrResetVelocityTracker();
mVelocityTracker.addMovement(ev);
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when being
* flinged.
*/
mIsBeingDragged = !mScroller.isFinished();
if (mIsBeingDragged && mScrollStrictSpan == null) {
mScrollStrictSpan = StrictMode
.enterCriticalSpan("ScrollView-scroll");
}
mIsOrthoDragged = false;
final float ocoord = mHorizontal ? ev.getY() : ev.getX();
mLastOrthoCoord = ocoord;
mDownView = findViewAt((int) ev.getX(), (int) ev.getY());
break;
}
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
/* Release the drag */
mIsBeingDragged = false;
mIsOrthoDragged = false;
mActivePointerId = INVALID_POINTER;
recycleVelocityTracker();
if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0,
getScrollRange())) {
invalidate();
}
break;
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mIsBeingDragged || mIsOrthoDragged;
}
@Override
public boolean onTouchEvent(MotionEvent ev) {
initVelocityTrackerIfNotExists();
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
switch (action & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN: {
mIsBeingDragged = getChildCount() != 0;
if (!mIsBeingDragged) {
return false;
}
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
// Remember where the motion event started
mLastMotionY = mHorizontal ? ev.getX() : ev.getY();
mActivePointerId = ev.getPointerId(0);
break;
}
case MotionEvent.ACTION_MOVE:
if (mIsOrthoDragged) {
// Scroll to follow the motion event
final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
final float x = ev.getX(activePointerIndex);
final float y = ev.getY(activePointerIndex);
if (isOrthoMove(x - mDownCoords.x, y - mDownCoords.y)) {
onOrthoDrag(mDownView, mHorizontal
? y - mDownCoords.y
: x - mDownCoords.x);
}
} else if (mIsBeingDragged) {
// Scroll to follow the motion event
final int activePointerIndex = ev.findPointerIndex(mActivePointerId);
final float y = mHorizontal ? ev.getX(activePointerIndex)
: ev.getY(activePointerIndex);
final int deltaY = (int) (mLastMotionY - y);
mLastMotionY = y;
final int oldX = mScrollX;
final int oldY = mScrollY;
final int range = getScrollRange();
if (mHorizontal) {
if (overScrollBy(deltaY, 0, mScrollX, 0, range, 0,
mOverscrollDistance, 0, true)) {
// Break our velocity if we hit a scroll barrier.
mVelocityTracker.clear();
}
} else {
if (overScrollBy(0, deltaY, 0, mScrollY, 0, range,
0, mOverscrollDistance, true)) {
// Break our velocity if we hit a scroll barrier.
mVelocityTracker.clear();
}
}
onScrollChanged(mScrollX, mScrollY, oldX, oldY);
final int overscrollMode = getOverScrollMode();
if (overscrollMode == OVER_SCROLL_ALWAYS ||
(overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) {
final int pulledToY = mHorizontal ? oldX + deltaY : oldY + deltaY;
if (pulledToY < 0) {
onPull(pulledToY);
} else if (pulledToY > range) {
onPull(pulledToY - range);
} else {
onPull(0);
}
}
}
break;
case MotionEvent.ACTION_UP:
final VelocityTracker vtracker = mVelocityTracker;
vtracker.computeCurrentVelocity(1000, mMaximumVelocity);
if (isOrthoMove(vtracker.getXVelocity(mActivePointerId),
vtracker.getYVelocity(mActivePointerId))
&& mMinimumVelocity < Math.abs((mHorizontal ? vtracker.getYVelocity()
: vtracker.getXVelocity()))) {
onOrthoFling(mDownView, mHorizontal ? vtracker.getYVelocity()
: vtracker.getXVelocity());
break;
}
if (mIsOrthoDragged) {
onOrthoDragFinished(mDownView);
mActivePointerId = INVALID_POINTER;
endDrag();
} else if (mIsBeingDragged) {
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialVelocity = mHorizontal
? (int) velocityTracker.getXVelocity(mActivePointerId)
: (int) velocityTracker.getYVelocity(mActivePointerId);
if (getChildCount() > 0) {
if ((Math.abs(initialVelocity) > mMinimumVelocity)) {
fling(-initialVelocity);
} else {
final int bottom = getScrollRange();
if (mHorizontal) {
if (mScroller.springBack(mScrollX, mScrollY, 0, bottom, 0, 0)) {
invalidate();
}
} else {
if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, bottom)) {
invalidate();
}
}
}
onPull(0);
}
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEvent.ACTION_CANCEL:
if (mIsOrthoDragged) {
onOrthoDragFinished(mDownView);
mActivePointerId = INVALID_POINTER;
endDrag();
} else if (mIsBeingDragged && getChildCount() > 0) {
if (mHorizontal) {
if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) {
invalidate();
}
} else {
if (mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange())) {
invalidate();
}
}
mActivePointerId = INVALID_POINTER;
endDrag();
}
break;
case MotionEvent.ACTION_POINTER_DOWN: {
final int index = ev.getActionIndex();
final float y = mHorizontal ? ev.getX(index) : ev.getY(index);
mLastMotionY = y;
mLastOrthoCoord = mHorizontal ? ev.getY(index) : ev.getX(index);
mActivePointerId = ev.getPointerId(index);
break;
}
case MotionEvent.ACTION_POINTER_UP:
onSecondaryPointerUp(ev);
mLastMotionY = mHorizontal
? ev.getX(ev.findPointerIndex(mActivePointerId))
: ev.getY(ev.findPointerIndex(mActivePointerId));
break;
}
return true;
}
protected View findViewAt(int x, int y) {
// subclass responsibility
return null;
}
protected void onPull(int delta) {
}
private void onSecondaryPointerUp(MotionEvent ev) {
final int pointerIndex = (ev.getAction() & MotionEvent.ACTION_POINTER_INDEX_MASK) >>
MotionEvent.ACTION_POINTER_INDEX_SHIFT;
final int pointerId = ev.getPointerId(pointerIndex);
if (pointerId == mActivePointerId) {
// This was our active pointer going up. Choose a new
// active pointer and adjust accordingly.
// TODO: Make this decision more intelligent.
final int newPointerIndex = pointerIndex == 0 ? 1 : 0;
mLastMotionY = mHorizontal ? ev.getX(newPointerIndex) : ev.getY(newPointerIndex);
mActivePointerId = ev.getPointerId(newPointerIndex);
if (mVelocityTracker != null) {
mVelocityTracker.clear();
}
mLastOrthoCoord = mHorizontal ? ev.getY(newPointerIndex)
: ev.getX(newPointerIndex);
}
}
@Override
public boolean onGenericMotionEvent(MotionEvent event) {
if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) {
switch (event.getAction()) {
case MotionEvent.ACTION_SCROLL: {
if (!mIsBeingDragged) {
if (mHorizontal) {
final float hscroll = event
.getAxisValue(MotionEvent.AXIS_HSCROLL);
if (hscroll != 0) {
final int delta = (int) (hscroll * getHorizontalScrollFactor());
final int range = getScrollRange();
int oldScrollX = mScrollX;
int newScrollX = oldScrollX - delta;
if (newScrollX < 0) {
newScrollX = 0;
} else if (newScrollX > range) {
newScrollX = range;
}
if (newScrollX != oldScrollX) {
super.scrollTo(newScrollX, mScrollY);
return true;
}
}
} else {
final float vscroll = event
.getAxisValue(MotionEvent.AXIS_VSCROLL);
if (vscroll != 0) {
final int delta = (int) (vscroll * getVerticalScrollFactor());
final int range = getScrollRange();
int oldScrollY = mScrollY;
int newScrollY = oldScrollY - delta;
if (newScrollY < 0) {
newScrollY = 0;
} else if (newScrollY > range) {
newScrollY = range;
}
if (newScrollY != oldScrollY) {
super.scrollTo(mScrollX, newScrollY);
return true;
}
}
}
}
}
}
}
return super.onGenericMotionEvent(event);
}
protected void onOrthoDrag(View draggedView, float distance) {
}
protected void onOrthoDragFinished(View draggedView) {
}
protected void onOrthoFling(View draggedView, float velocity) {
}
@Override
protected void onOverScrolled(int scrollX, int scrollY,
boolean clampedX, boolean clampedY) {
// Treat animating scrolls differently; see #computeScroll() for why.
if (!mScroller.isFinished()) {
mScrollX = scrollX;
mScrollY = scrollY;
invalidateParentIfNeeded();
if (mHorizontal && clampedX) {
mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0);
} else if (!mHorizontal && clampedY) {
mScroller.springBack(mScrollX, mScrollY, 0, 0, 0, getScrollRange());
}
} else {
super.scrollTo(scrollX, scrollY);
}
awakenScrollBars();
}
@Override
public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) {
super.onInitializeAccessibilityNodeInfo(info);
info.setScrollable(true);
}
@Override
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setScrollable(true);
}
@Override
public boolean dispatchPopulateAccessibilityEvent(AccessibilityEvent event) {
// Do not append text content to scroll events they are fired frequently
// and the client has already received another event type with the text.
if (event.getEventType() != AccessibilityEvent.TYPE_VIEW_SCROLLED) {
super.dispatchPopulateAccessibilityEvent(event);
}
return false;
}
private int getScrollRange() {
int scrollRange = 0;
if (getChildCount() > 0) {
View child = getChildAt(0);
if (mHorizontal) {
scrollRange = Math.max(0,
child.getWidth() - (getWidth() - mPaddingRight - mPaddingLeft));
} else {
scrollRange = Math.max(0,
child.getHeight() - (getHeight() - mPaddingBottom - mPaddingTop));
}
}
return scrollRange;
}
/**
* <p>
* Finds the next focusable component that fits in this View's bounds
* (excluding fading edges) pretending that this View's top is located at
* the parameter top.
* </p>
*
* @param topFocus look for a candidate at the top of the bounds if topFocus is true,
* or at the bottom of the bounds if topFocus is false
* @param top the top offset of the bounds in which a focusable must be
* found (the fading edge is assumed to start at this position)
* @param preferredFocusable the View that has highest priority and will be
* returned if it is within my bounds (null is valid)
* @return the next focusable component in the bounds or null if none can be found
*/
private View findFocusableViewInMyBounds(final boolean topFocus,
final int top, View preferredFocusable) {
/*
* The fading edge's transparent side should be considered for focus
* since it's mostly visible, so we divide the actual fading edge length
* by 2.
*/
final int fadingEdgeLength = (mHorizontal
? getHorizontalFadingEdgeLength()
: getVerticalFadingEdgeLength()) / 2;
final int topWithoutFadingEdge = top + fadingEdgeLength;
final int bottomWithoutFadingEdge = top + (mHorizontal ? getWidth() : getHeight()) - fadingEdgeLength;
if ((preferredFocusable != null)
&& ((mHorizontal ? preferredFocusable.getLeft() : preferredFocusable.getTop())
< bottomWithoutFadingEdge)
&& ((mHorizontal ? preferredFocusable.getRight() : preferredFocusable.getBottom()) > topWithoutFadingEdge)) {
return preferredFocusable;
}
return findFocusableViewInBounds(topFocus, topWithoutFadingEdge,
bottomWithoutFadingEdge);
}
/**
* <p>
* Finds the next focusable component that fits in the specified bounds.
* </p>
*
* @param topFocus look for a candidate is the one at the top of the bounds
* if topFocus is true, or at the bottom of the bounds if topFocus is
* false
* @param top the top offset of the bounds in which a focusable must be
* found
* @param bottom the bottom offset of the bounds in which a focusable must
* be found
* @return the next focusable component in the bounds or null if none can
* be found
*/
private View findFocusableViewInBounds(boolean topFocus, int top, int bottom) {
List<View> focusables = getFocusables(View.FOCUS_FORWARD);
View focusCandidate = null;
/*
* A fully contained focusable is one where its top is below the bound's
* top, and its bottom is above the bound's bottom. A partially
* contained focusable is one where some part of it is within the
* bounds, but it also has some part that is not within bounds. A fully contained
* focusable is preferred to a partially contained focusable.
*/
boolean foundFullyContainedFocusable = false;
int count = focusables.size();
for (int i = 0; i < count; i++) {
View view = focusables.get(i);
int viewTop = mHorizontal ? view.getLeft() : view.getTop();
int viewBottom = mHorizontal ? view.getRight() : view.getBottom();
if (top < viewBottom && viewTop < bottom) {
/*
* the focusable is in the target area, it is a candidate for
* focusing
*/
final boolean viewIsFullyContained = (top < viewTop) &&
(viewBottom < bottom);
if (focusCandidate == null) {
/* No candidate, take this one */
focusCandidate = view;
foundFullyContainedFocusable = viewIsFullyContained;
} else {
final int ctop = mHorizontal ? focusCandidate.getLeft() : focusCandidate.getTop();
final int cbot = mHorizontal ? focusCandidate.getRight() : focusCandidate.getBottom();
final boolean viewIsCloserToBoundary =
(topFocus && viewTop < ctop) ||
(!topFocus && viewBottom > cbot);
if (foundFullyContainedFocusable) {
if (viewIsFullyContained && viewIsCloserToBoundary) {
/*
* We're dealing with only fully contained views, so
* it has to be closer to the boundary to beat our
* candidate
*/
focusCandidate = view;
}
} else {
if (viewIsFullyContained) {
/* Any fully contained view beats a partially contained view */
focusCandidate = view;
foundFullyContainedFocusable = true;
} else if (viewIsCloserToBoundary) {
/*
* Partially contained view beats another partially
* contained view if it's closer
*/
focusCandidate = view;
}
}
}
}
}
return focusCandidate;
}
// i was here
/**
* <p>Handles scrolling in response to a "page up/down" shortcut press. This
* method will scroll the view by one page up or down and give the focus
* to the topmost/bottommost component in the new visible area. If no
* component is a good candidate for focus, this scrollview reclaims the
* focus.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go one page up or
* {@link android.view.View#FOCUS_DOWN} to go one page down
* @return true if the key event is consumed by this method, false otherwise
*/
public boolean pageScroll(int direction) {
boolean down = direction == View.FOCUS_DOWN;
int height = getHeight();
if (down) {
mTempRect.top = getScrollY() + height;
int count = getChildCount();
if (count > 0) {
View view = getChildAt(count - 1);
if (mTempRect.top + height > view.getBottom()) {
mTempRect.top = view.getBottom() - height;
}
}
} else {
mTempRect.top = getScrollY() - height;
if (mTempRect.top < 0) {
mTempRect.top = 0;
}
}
mTempRect.bottom = mTempRect.top + height;
return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
}
/**
* <p>Handles scrolling in response to a "home/end" shortcut press. This
* method will scroll the view to the top or bottom and give the focus
* to the topmost/bottommost component in the new visible area. If no
* component is a good candidate for focus, this scrollview reclaims the
* focus.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go the top of the view or
* {@link android.view.View#FOCUS_DOWN} to go the bottom
* @return true if the key event is consumed by this method, false otherwise
*/
public boolean fullScroll(int direction) {
boolean down = direction == View.FOCUS_DOWN;
int height = getHeight();
mTempRect.top = 0;
mTempRect.bottom = height;
if (down) {
int count = getChildCount();
if (count > 0) {
View view = getChildAt(count - 1);
mTempRect.bottom = view.getBottom() + mPaddingBottom;
mTempRect.top = mTempRect.bottom - height;
}
}
return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom);
}
/**
* <p>Scrolls the view to make the area defined by <code>top</code> and
* <code>bottom</code> visible. This method attempts to give the focus
* to a component visible in this area. If no component can be focused in
* the new visible area, the focus is reclaimed by this ScrollView.</p>
*
* @param direction the scroll direction: {@link android.view.View#FOCUS_UP}
* to go upward, {@link android.view.View#FOCUS_DOWN} to downward
* @param top the top offset of the new area to be made visible
* @param bottom the bottom offset of the new area to be made visible
* @return true if the key event is consumed by this method, false otherwise
*/
private boolean scrollAndFocus(int direction, int top, int bottom) {
boolean handled = true;
int height = getHeight();
int containerTop = getScrollY();
int containerBottom = containerTop + height;
boolean up = direction == View.FOCUS_UP;
View newFocused = findFocusableViewInBounds(up, top, bottom);
if (newFocused == null) {
newFocused = this;
}
if (top >= containerTop && bottom <= containerBottom) {
handled = false;
} else {
int delta = up ? (top - containerTop) : (bottom - containerBottom);
doScrollY(delta);
}
if (newFocused != findFocus()) newFocused.requestFocus(direction);
return handled;
}
/**
* Handle scrolling in response to an up or down arrow click.
*
* @param direction The direction corresponding to the arrow key that was
* pressed
* @return True if we consumed the event, false otherwise
*/
public boolean arrowScroll(int direction) {
View currentFocused = findFocus();
if (currentFocused == this) currentFocused = null;
View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);
final int maxJump = getMaxScrollAmount();
if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump, getHeight())) {
nextFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(nextFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScrollY(scrollDelta);
nextFocused.requestFocus(direction);
} else {
// no new focus
int scrollDelta = maxJump;
if (direction == View.FOCUS_UP && getScrollY() < scrollDelta) {
scrollDelta = getScrollY();
} else if (direction == View.FOCUS_DOWN) {
if (getChildCount() > 0) {
int daBottom = getChildAt(0).getBottom();
int screenBottom = getScrollY() + getHeight() - mPaddingBottom;
if (daBottom - screenBottom < maxJump) {
scrollDelta = daBottom - screenBottom;
}
}
}
if (scrollDelta == 0) {
return false;
}
doScrollY(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
}
if (currentFocused != null && currentFocused.isFocused()
&& isOffScreen(currentFocused)) {
// previously focused item still has focus and is off screen, give
// it up (take it back to ourselves)
// (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are
// sure to
// get it)
final int descendantFocusability = getDescendantFocusability(); // save
setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
requestFocus();
setDescendantFocusability(descendantFocusability); // restore
}
return true;
}
private boolean isOrthoMove(float moveX, float moveY) {
return mHorizontal && Math.abs(moveY) > Math.abs(moveX)
|| !mHorizontal && Math.abs(moveX) > Math.abs(moveY);
}
/**
* @return whether the descendant of this scroll view is scrolled off
* screen.
*/
private boolean isOffScreen(View descendant) {
if (mHorizontal) {
return !isWithinDeltaOfScreen(descendant, getWidth(), 0);
} else {
return !isWithinDeltaOfScreen(descendant, 0, getHeight());
}
}
/**
* @return whether the descendant of this scroll view is within delta
* pixels of being on the screen.
*/
private boolean isWithinDeltaOfScreen(View descendant, int delta, int height) {
descendant.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(descendant, mTempRect);
if (mHorizontal) {
return (mTempRect.right + delta) >= getScrollX()
&& (mTempRect.left - delta) <= (getScrollX() + height);
} else {
return (mTempRect.bottom + delta) >= getScrollY()
&& (mTempRect.top - delta) <= (getScrollY() + height);
}
}
/**
* Smooth scroll by a Y delta
*
* @param delta the number of pixels to scroll by on the Y axis
*/
private void doScrollY(int delta) {
if (delta != 0) {
if (mSmoothScrollingEnabled) {
if (mHorizontal) {
smoothScrollBy(0, delta);
} else {
smoothScrollBy(delta, 0);
}
} else {
if (mHorizontal) {
scrollBy(0, delta);
} else {
scrollBy(delta, 0);
}
}
}
}
/**
* Like {@link View#scrollBy}, but scroll smoothly instead of immediately.
*
* @param dx the number of pixels to scroll by on the X axis
* @param dy the number of pixels to scroll by on the Y axis
*/
public final void smoothScrollBy(int dx, int dy) {
if (getChildCount() == 0) {
// Nothing to do.
return;
}
long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
if (duration > ANIMATED_SCROLL_GAP) {
if (mHorizontal) {
final int width = getWidth() - mPaddingRight - mPaddingLeft;
final int right = getChildAt(0).getWidth();
final int maxX = Math.max(0, right - width);
final int scrollX = mScrollX;
dx = Math.max(0, Math.min(scrollX + dx, maxX)) - scrollX;
mScroller.startScroll(scrollX, mScrollY, dx, 0);
} else {
final int height = getHeight() - mPaddingBottom - mPaddingTop;
final int bottom = getChildAt(0).getHeight();
final int maxY = Math.max(0, bottom - height);
final int scrollY = mScrollY;
dy = Math.max(0, Math.min(scrollY + dy, maxY)) - scrollY;
mScroller.startScroll(mScrollX, scrollY, 0, dy);
}
invalidate();
} else {
if (!mScroller.isFinished()) {
mScroller.abortAnimation();
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
scrollBy(dx, dy);
}
mLastScroll = AnimationUtils.currentAnimationTimeMillis();
}
/**
* Like {@link #scrollTo}, but scroll smoothly instead of immediately.
*
* @param x the position where to scroll on the X axis
* @param y the position where to scroll on the Y axis
*/
public final void smoothScrollTo(int x, int y) {
smoothScrollBy(x - mScrollX, y - mScrollY);
}
/**
* <p>
* The scroll range of a scroll view is the overall height of all of its
* children.
* </p>
*/
@Override
protected int computeVerticalScrollRange() {
if (mHorizontal) {
return super.computeVerticalScrollRange();
}
final int count = getChildCount();
final int contentHeight = getHeight() - mPaddingBottom - mPaddingTop;
if (count == 0) {
return contentHeight;
}
int scrollRange = getChildAt(0).getBottom();
final int scrollY = mScrollY;
final int overscrollBottom = Math.max(0, scrollRange - contentHeight);
if (scrollY < 0) {
scrollRange -= scrollY;
} else if (scrollY > overscrollBottom) {
scrollRange += scrollY - overscrollBottom;
}
return scrollRange;
}
/**
* <p>
* The scroll range of a scroll view is the overall height of all of its
* children.
* </p>
*/
@Override
protected int computeHorizontalScrollRange() {
if (!mHorizontal) {
return super.computeHorizontalScrollRange();
}
final int count = getChildCount();
final int contentWidth = getWidth() - mPaddingRight - mPaddingLeft;
if (count == 0) {
return contentWidth;
}
int scrollRange = getChildAt(0).getRight();
final int scrollX = mScrollX;
final int overscrollBottom = Math.max(0, scrollRange - contentWidth);
if (scrollX < 0) {
scrollRange -= scrollX;
} else if (scrollX > overscrollBottom) {
scrollRange += scrollX - overscrollBottom;
}
return scrollRange;
}
@Override
protected int computeVerticalScrollOffset() {
return Math.max(0, super.computeVerticalScrollOffset());
}
@Override
protected int computeHorizontalScrollOffset() {
return Math.max(0, super.computeHorizontalScrollOffset());
}
@Override
protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) {
ViewGroup.LayoutParams lp = child.getLayoutParams();
int childWidthMeasureSpec;
int childHeightMeasureSpec;
if (mHorizontal) {
childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop
+ mPaddingBottom, lp.height);
childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
} else {
childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec, mPaddingLeft
+ mPaddingRight, lp.width);
childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed,
int parentHeightMeasureSpec, int heightUsed) {
final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();
int childWidthMeasureSpec;
int childHeightMeasureSpec;
if (mHorizontal) {
childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec,
mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin
+ heightUsed, lp.height);
childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(
lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);
} else {
childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
mPaddingLeft + mPaddingRight + lp.leftMargin + lp.rightMargin
+ widthUsed, lp.width);
childHeightMeasureSpec = MeasureSpec.makeMeasureSpec(
lp.topMargin + lp.bottomMargin, MeasureSpec.UNSPECIFIED);
}
child.measure(childWidthMeasureSpec, childHeightMeasureSpec);
}
@Override
public void computeScroll() {
if (mScroller.computeScrollOffset()) {
// This is called at drawing time by ViewGroup. We don't want to
// re-show the scrollbars at this point, which scrollTo will do,
// so we replicate most of scrollTo here.
//
// It's a little odd to call onScrollChanged from inside the drawing.
//
// It is, except when you remember that computeScroll() is used to
// animate scrolling. So unless we want to defer the onScrollChanged()
// until the end of the animated scrolling, we don't really have a
// choice here.
//
// I agree. The alternative, which I think would be worse, is to post
// something and tell the subclasses later. This is bad because there
// will be a window where mScrollX/Y is different from what the app
// thinks it is.
//
int oldX = mScrollX;
int oldY = mScrollY;
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (oldX != x || oldY != y) {
if (mHorizontal) {
overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0,
mOverflingDistance, 0, false);
} else {
overScrollBy(x - oldX, y - oldY, oldX, oldY, 0, getScrollRange(),
0, mOverflingDistance, false);
}
onScrollChanged(mScrollX, mScrollY, oldX, oldY);
}
awakenScrollBars();
// Keep on drawing until the animation has finished.
postInvalidate();
} else {
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
}
/**
* Scrolls the view to the given child.
*
* @param child the View to scroll to
*/
private void scrollToChild(View child) {
child.getDrawingRect(mTempRect);
/* Offset from child's local coordinates to ScrollView coordinates */
offsetDescendantRectToMyCoords(child, mTempRect);
scrollToChildRect(mTempRect, true);
}
/**
* If rect is off screen, scroll just enough to get it (or at least the
* first screen size chunk of it) on screen.
*
* @param rect The rectangle.
* @param immediate True to scroll immediately without animation
* @return true if scrolling was performed
*/
private boolean scrollToChildRect(Rect rect, boolean immediate) {
final int delta = computeScrollDeltaToGetChildRectOnScreen(rect);
final boolean scroll = delta != 0;
if (scroll) {
if (immediate) {
if (mHorizontal) {
scrollBy(delta, 0);
} else {
scrollBy(0, delta);
}
} else {
if (mHorizontal) {
smoothScrollBy(delta, 0);
} else {
smoothScrollBy(0, delta);
}
}
}
return scroll;
}
/**
* Compute the amount to scroll in the Y direction in order to get
* a rectangle completely on the screen (or, if taller than the screen,
* at least the first screen size chunk of it).
*
* @param rect The rect.
* @return The scroll delta.
*/
protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) {
if (mHorizontal) {
return computeScrollDeltaToGetChildRectOnScreenHorizontal(rect);
} else {
return computeScrollDeltaToGetChildRectOnScreenVertical(rect);
}
}
private int computeScrollDeltaToGetChildRectOnScreenVertical(Rect rect) {
if (getChildCount() == 0) return 0;
int height = getHeight();
int screenTop = getScrollY();
int screenBottom = screenTop + height;
int fadingEdge = getVerticalFadingEdgeLength();
// leave room for top fading edge as long as rect isn't at very top
if (rect.top > 0) {
screenTop += fadingEdge;
}
// leave room for bottom fading edge as long as rect isn't at very bottom
if (rect.bottom < getChildAt(0).getHeight()) {
screenBottom -= fadingEdge;
}
int scrollYDelta = 0;
if (rect.bottom > screenBottom && rect.top > screenTop) {
// need to move down to get it in view: move down just enough so
// that the entire rectangle is in view (or at least the first
// screen size chunk).
if (rect.height() > height) {
// just enough to get screen size chunk on
scrollYDelta += (rect.top - screenTop);
} else {
// get entire rect at bottom of screen
scrollYDelta += (rect.bottom - screenBottom);
}
// make sure we aren't scrolling beyond the end of our content
int bottom = getChildAt(0).getBottom();
int distanceToBottom = bottom - screenBottom;
scrollYDelta = Math.min(scrollYDelta, distanceToBottom);
} else if (rect.top < screenTop && rect.bottom < screenBottom) {
// need to move up to get it in view: move up just enough so that
// entire rectangle is in view (or at least the first screen
// size chunk of it).
if (rect.height() > height) {
// screen size chunk
scrollYDelta -= (screenBottom - rect.bottom);
} else {
// entire rect at top
scrollYDelta -= (screenTop - rect.top);
}
// make sure we aren't scrolling any further than the top our content
scrollYDelta = Math.max(scrollYDelta, -getScrollY());
}
return scrollYDelta;
}
private int computeScrollDeltaToGetChildRectOnScreenHorizontal(Rect rect) {
if (getChildCount() == 0) return 0;
int width = getWidth();
int screenLeft = getScrollX();
int screenRight = screenLeft + width;
int fadingEdge = getHorizontalFadingEdgeLength();
// leave room for left fading edge as long as rect isn't at very left
if (rect.left > 0) {
screenLeft += fadingEdge;
}
// leave room for right fading edge as long as rect isn't at very right
if (rect.right < getChildAt(0).getWidth()) {
screenRight -= fadingEdge;
}
int scrollXDelta = 0;
if (rect.right > screenRight && rect.left > screenLeft) {
// need to move right to get it in view: move right just enough so
// that the entire rectangle is in view (or at least the first
// screen size chunk).
if (rect.width() > width) {
// just enough to get screen size chunk on
scrollXDelta += (rect.left - screenLeft);
} else {
// get entire rect at right of screen
scrollXDelta += (rect.right - screenRight);
}
// make sure we aren't scrolling beyond the end of our content
int right = getChildAt(0).getRight();
int distanceToRight = right - screenRight;
scrollXDelta = Math.min(scrollXDelta, distanceToRight);
} else if (rect.left < screenLeft && rect.right < screenRight) {
// need to move right to get it in view: move right just enough so that
// entire rectangle is in view (or at least the first screen
// size chunk of it).
if (rect.width() > width) {
// screen size chunk
scrollXDelta -= (screenRight - rect.right);
} else {
// entire rect at left
scrollXDelta -= (screenLeft - rect.left);
}
// make sure we aren't scrolling any further than the left our content
scrollXDelta = Math.max(scrollXDelta, -getScrollX());
}
return scrollXDelta;
}
@Override
public void requestChildFocus(View child, View focused) {
if (!mIsLayoutDirty) {
scrollToChild(focused);
} else {
// The child may not be laid out yet, we can't compute the scroll yet
mChildToScrollTo = focused;
}
super.requestChildFocus(child, focused);
}
/**
* When looking for focus in children of a scroll view, need to be a little
* more careful not to give focus to something that is scrolled off screen.
*
* This is more expensive than the default {@link android.view.ViewGroup}
* implementation, otherwise this behavior might have been made the default.
*/
@Override
protected boolean onRequestFocusInDescendants(int direction,
Rect previouslyFocusedRect) {
// convert from forward / backward notation to up / down / left / right
// (ugh).
if (mHorizontal) {
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_RIGHT;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_LEFT;
}
} else {
if (direction == View.FOCUS_FORWARD) {
direction = View.FOCUS_DOWN;
} else if (direction == View.FOCUS_BACKWARD) {
direction = View.FOCUS_UP;
}
}
final View nextFocus = previouslyFocusedRect == null ?
FocusFinder.getInstance().findNextFocus(this, null, direction) :
FocusFinder.getInstance().findNextFocusFromRect(this,
previouslyFocusedRect, direction);
if (nextFocus == null) {
return false;
}
if (isOffScreen(nextFocus)) {
return false;
}
return nextFocus.requestFocus(direction, previouslyFocusedRect);
}
@Override
public boolean requestChildRectangleOnScreen(View child, Rect rectangle,
boolean immediate) {
// offset into coordinate space of this scroll view
rectangle.offset(child.getLeft() - child.getScrollX(),
child.getTop() - child.getScrollY());
return scrollToChildRect(rectangle, immediate);
}
@Override
public void requestLayout() {
mIsLayoutDirty = true;
super.requestLayout();
}
@Override
protected void onDetachedFromWindow() {
super.onDetachedFromWindow();
if (mScrollStrictSpan != null) {
mScrollStrictSpan.finish();
mScrollStrictSpan = null;
}
if (mFlingStrictSpan != null) {
mFlingStrictSpan.finish();
mFlingStrictSpan = null;
}
}
@Override
protected void onLayout(boolean changed, int l, int t, int r, int b) {
super.onLayout(changed, l, t, r, b);
mIsLayoutDirty = false;
// Give a child focus if it needs it
if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) {
scrollToChild(mChildToScrollTo);
}
mChildToScrollTo = null;
// Calling this with the present values causes it to re-clam them
scrollTo(mScrollX, mScrollY);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
View currentFocused = findFocus();
if (null == currentFocused || this == currentFocused)
return;
// If the currently-focused view was visible on the screen when the
// screen was at the old height, then scroll the screen to make that
// view visible with the new screen height.
if (isWithinDeltaOfScreen(currentFocused, 0, oldh)) {
currentFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(currentFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScrollY(scrollDelta);
}
}
/**
* Return true if child is an descendant of parent, (or equal to the parent).
*/
private boolean isViewDescendantOf(View child, View parent) {
if (child == parent) {
return true;
}
final ViewParent theParent = child.getParent();
return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent);
}
/**
* Fling the scroll view
*
* @param velocityY The initial velocity in the Y direction. Positive
* numbers mean that the finger/cursor is moving down the screen,
* which means we want to scroll towards the top.
*/
public void fling(int velocityY) {
if (getChildCount() > 0) {
if (mHorizontal) {
int width = getWidth() - mPaddingRight - mPaddingLeft;
int right = getChildAt(0).getWidth();
mScroller.fling(mScrollX, mScrollY, velocityY, 0,
0, Math.max(0, right - width), 0, 0, width/2, 0);
} else {
int height = getHeight() - mPaddingBottom - mPaddingTop;
int bottom = getChildAt(0).getHeight();
mScroller.fling(mScrollX, mScrollY, 0, velocityY, 0, 0, 0,
Math.max(0, bottom - height), 0, height/2);
}
if (mFlingStrictSpan == null) {
mFlingStrictSpan = StrictMode.enterCriticalSpan("ScrollView-fling");
}
invalidate();
}
}
private void endDrag() {
mIsBeingDragged = false;
mIsOrthoDragged = false;
mDownView = null;
recycleVelocityTracker();
if (mScrollStrictSpan != null) {
mScrollStrictSpan.finish();
mScrollStrictSpan = null;
}
}
/**
* {@inheritDoc}
*
* <p>This version also clamps the scrolling to the bounds of our child.
*/
@Override
public void scrollTo(int x, int y) {
// we rely on the fact the View.scrollBy calls scrollTo.
if (getChildCount() > 0) {
View child = getChildAt(0);
x = clamp(x, getWidth() - mPaddingRight - mPaddingLeft, child.getWidth());
y = clamp(y, getHeight() - mPaddingBottom - mPaddingTop, child.getHeight());
if (x != mScrollX || y != mScrollY) {
super.scrollTo(x, y);
}
}
}
private int clamp(int n, int my, int child) {
if (my >= child || n < 0) {
/* my >= child is this case:
* |--------------- me ---------------|
* |------ child ------|
* or
* |--------------- me ---------------|
* |------ child ------|
* or
* |--------------- me ---------------|
* |------ child ------|
*
* n < 0 is this case:
* |------ me ------|
* |-------- child --------|
* |-- mScrollX --|
*/
return 0;
}
if ((my+n) > child) {
/* this case:
* |------ me ------|
* |------ child ------|
* |-- mScrollX --|
*/
return child-my;
}
return n;
}
}