/*
* 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.
*/
/*
* Revised 5/19/2010 by GORGES
* Now supports two-dimensional view scrolling
* http://GORGES.us
*/
package com.freerdp.freerdpcore.presentation;
import android.content.Context;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.view.FocusFinder;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.VelocityTracker;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.ViewParent;
import android.view.animation.AnimationUtils;
import android.widget.FrameLayout;
import android.widget.LinearLayout;
import android.widget.Scroller;
import android.widget.TextView;
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 TwoDScrollView
* 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>
* <p>The {@link TextView} class also
* takes care of its own scrolling, so does not require a TwoDScrollView, but
* using the two together is possible to achieve the effect of a text view
* within a larger container.
*/
public class ScrollView2D extends FrameLayout
{
static final int ANIMATED_SCROLL_GAP = 250;
static final float MAX_SCROLL_FACTOR = 0.5f;
private final Rect mTempRect = new Rect();
private ScrollView2DListener scrollView2DListener = null;
private long mLastScroll;
private Scroller mScroller;
private boolean scrollEnabled = true;
/**
* Flag to indicate that we are moving focus ourselves. This is so the
* code that watches for focus changes initiated outside this TwoDScrollView
* knows that it does not have to do anything.
*/
private boolean mTwoDScrollViewMovedFocus;
/**
* Position of the last motion event.
*/
private float mLastMotionY;
private float mLastMotionX;
/**
* 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.
*/
private View mChildToScrollTo = null;
/**
* True if the user is currently dragging this TwoDScrollView 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).
*/
private boolean mIsBeingDragged = false;
/**
* Determines speed during touch scrolling
*/
private VelocityTracker mVelocityTracker;
/**
* Whether arrow scrolling is animated.
*/
private int mTouchSlop;
private int mMinimumVelocity;
private int mMaximumVelocity;
public ScrollView2D(Context context)
{
super(context);
initTwoDScrollView();
}
public ScrollView2D(Context context, AttributeSet attrs)
{
super(context, attrs);
initTwoDScrollView();
}
public ScrollView2D(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
initTwoDScrollView();
}
@Override protected float getTopFadingEdgeStrength()
{
if (getChildCount() == 0)
{
return 0.0f;
}
final int length = getVerticalFadingEdgeLength();
if (getScrollY() < length)
{
return getScrollY() / (float)length;
}
return 1.0f;
}
@Override protected float getBottomFadingEdgeStrength()
{
if (getChildCount() == 0)
{
return 0.0f;
}
final int length = getVerticalFadingEdgeLength();
final int bottomEdge = getHeight() - getPaddingBottom();
final int span = getChildAt(0).getBottom() - getScrollY() - bottomEdge;
if (span < length)
{
return span / (float)length;
}
return 1.0f;
}
@Override protected float getLeftFadingEdgeStrength()
{
if (getChildCount() == 0)
{
return 0.0f;
}
final int length = getHorizontalFadingEdgeLength();
if (getScrollX() < length)
{
return getScrollX() / (float)length;
}
return 1.0f;
}
@Override protected float getRightFadingEdgeStrength()
{
if (getChildCount() == 0)
{
return 0.0f;
}
final int length = getHorizontalFadingEdgeLength();
final int rightEdge = getWidth() - getPaddingRight();
final int span = getChildAt(0).getRight() - getScrollX() - rightEdge;
if (span < length)
{
return span / (float)length;
}
return 1.0f;
}
/**
* Disable/Enable scrolling
*/
public void setScrollEnabled(boolean enable)
{
scrollEnabled = enable;
}
/**
* @return The maximum amount this scroll view will scroll in response to
* an arrow event.
*/
public int getMaxScrollAmountVertical()
{
return (int)(MAX_SCROLL_FACTOR * getHeight());
}
public int getMaxScrollAmountHorizontal()
{
return (int)(MAX_SCROLL_FACTOR * getWidth());
}
private void initTwoDScrollView()
{
mScroller = new Scroller(getContext());
setFocusable(true);
setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
setWillNotDraw(false);
final ViewConfiguration configuration = ViewConfiguration.get(getContext());
mTouchSlop = configuration.getScaledTouchSlop();
mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
}
@Override public void addView(View child)
{
if (getChildCount() > 0)
{
throw new IllegalStateException("TwoDScrollView can host only one direct child");
}
super.addView(child);
}
@Override public void addView(View child, int index)
{
if (getChildCount() > 0)
{
throw new IllegalStateException("TwoDScrollView 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("TwoDScrollView 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("TwoDScrollView can host only one direct child");
}
super.addView(child, index, params);
}
/**
* @return Returns true this TwoDScrollView can be scrolled
*/
private boolean canScroll()
{
if (!scrollEnabled)
return false;
View child = getChildAt(0);
if (child != null)
{
int childHeight = child.getHeight();
int childWidth = child.getWidth();
return (getHeight() < childHeight + getPaddingTop() + getPaddingBottom()) ||
(getWidth() < childWidth + getPaddingLeft() + getPaddingRight());
}
return false;
}
@Override public boolean dispatchKeyEvent(KeyEvent event)
{
// Let the focused view and/or our descendants get the key first
boolean handled = super.dispatchKeyEvent(event);
if (handled)
{
return true;
}
return 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())
{
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, false);
}
else
{
handled = fullScroll(View.FOCUS_UP, false);
}
break;
case KeyEvent.KEYCODE_DPAD_DOWN:
if (!event.isAltPressed())
{
handled = arrowScroll(View.FOCUS_DOWN, false);
}
else
{
handled = fullScroll(View.FOCUS_DOWN, false);
}
break;
case KeyEvent.KEYCODE_DPAD_LEFT:
if (!event.isAltPressed())
{
handled = arrowScroll(View.FOCUS_LEFT, true);
}
else
{
handled = fullScroll(View.FOCUS_LEFT, true);
}
break;
case KeyEvent.KEYCODE_DPAD_RIGHT:
if (!event.isAltPressed())
{
handled = arrowScroll(View.FOCUS_RIGHT, true);
}
else
{
handled = fullScroll(View.FOCUS_RIGHT, true);
}
break;
}
}
return handled;
}
@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 (!canScroll())
{
mIsBeingDragged = false;
return false;
}
final float y = ev.getY();
final float x = ev.getX();
switch (action)
{
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 yDiff = (int)Math.abs(y - mLastMotionY);
final int xDiff = (int)Math.abs(x - mLastMotionX);
if (yDiff > mTouchSlop || xDiff > mTouchSlop)
{
mIsBeingDragged = true;
}
break;
case MotionEvent.ACTION_DOWN:
/* Remember location of down touch */
mLastMotionY = y;
mLastMotionX = x;
/*
* If being flinged and user touches the screen, initiate drag;
* otherwise don't. mScroller.isFinished should be false when
* being flinged.
*/
mIsBeingDragged = !mScroller.isFinished();
break;
case MotionEvent.ACTION_CANCEL:
case MotionEvent.ACTION_UP:
/* Release the drag */
mIsBeingDragged = false;
break;
}
/*
* The only time we want to intercept motion events is if we are in the
* drag mode.
*/
return mIsBeingDragged;
}
@Override public boolean onTouchEvent(MotionEvent ev)
{
if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() != 0)
{
// Don't handle edge touches immediately -- they may actually belong to one of our
// descendants.
return false;
}
if (!canScroll())
{
return false;
}
if (mVelocityTracker == null)
{
mVelocityTracker = VelocityTracker.obtain();
}
mVelocityTracker.addMovement(ev);
final int action = ev.getAction();
final float y = ev.getY();
final float x = ev.getX();
switch (action)
{
case MotionEvent.ACTION_DOWN:
/*
* If being flinged and user touches, stop the fling. isFinished
* will be false if being flinged.
*/
if (!mScroller.isFinished())
{
mScroller.abortAnimation();
}
// Remember where the motion event started
mLastMotionY = y;
mLastMotionX = x;
break;
case MotionEvent.ACTION_MOVE:
// Scroll to follow the motion event
int deltaX = (int)(mLastMotionX - x);
int deltaY = (int)(mLastMotionY - y);
mLastMotionX = x;
mLastMotionY = y;
if (deltaX < 0)
{
if (getScrollX() < 0)
{
deltaX = 0;
}
}
else if (deltaX > 0)
{
final int rightEdge = getWidth() - getPaddingRight();
final int availableToScroll =
getChildAt(0).getRight() - getScrollX() - rightEdge;
if (availableToScroll > 0)
{
deltaX = Math.min(availableToScroll, deltaX);
}
else
{
deltaX = 0;
}
}
if (deltaY < 0)
{
if (getScrollY() < 0)
{
deltaY = 0;
}
}
else if (deltaY > 0)
{
final int bottomEdge = getHeight() - getPaddingBottom();
final int availableToScroll =
getChildAt(0).getBottom() - getScrollY() - bottomEdge;
if (availableToScroll > 0)
{
deltaY = Math.min(availableToScroll, deltaY);
}
else
{
deltaY = 0;
}
}
if (deltaY != 0 || deltaX != 0)
scrollBy(deltaX, deltaY);
break;
case MotionEvent.ACTION_UP:
final VelocityTracker velocityTracker = mVelocityTracker;
velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
int initialXVelocity = (int)velocityTracker.getXVelocity();
int initialYVelocity = (int)velocityTracker.getYVelocity();
if ((Math.abs(initialXVelocity) + Math.abs(initialYVelocity) > mMinimumVelocity) &&
getChildCount() > 0)
{
fling(-initialXVelocity, -initialYVelocity);
}
if (mVelocityTracker != null)
{
mVelocityTracker.recycle();
mVelocityTracker = null;
}
}
return true;
}
/**
* 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.
*
* @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 (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,
final boolean leftFocus, final int left,
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 verticalFadingEdgeLength = getVerticalFadingEdgeLength() / 2;
final int topWithoutFadingEdge = top + verticalFadingEdgeLength;
final int bottomWithoutFadingEdge = top + getHeight() - verticalFadingEdgeLength;
final int horizontalFadingEdgeLength = getHorizontalFadingEdgeLength() / 2;
final int leftWithoutFadingEdge = left + horizontalFadingEdgeLength;
final int rightWithoutFadingEdge = left + getWidth() - horizontalFadingEdgeLength;
if ((preferredFocusable != null) &&
(preferredFocusable.getTop() < bottomWithoutFadingEdge) &&
(preferredFocusable.getBottom() > topWithoutFadingEdge) &&
(preferredFocusable.getLeft() < rightWithoutFadingEdge) &&
(preferredFocusable.getRight() > leftWithoutFadingEdge))
{
return preferredFocusable;
}
return findFocusableViewInBounds(topFocus, topWithoutFadingEdge, bottomWithoutFadingEdge,
leftFocus, leftWithoutFadingEdge, rightWithoutFadingEdge);
}
/**
* 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, boolean leftFocus,
int left, int right)
{
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 = view.getTop();
int viewBottom = view.getBottom();
int viewLeft = view.getLeft();
int viewRight = view.getRight();
if (top < viewBottom && viewTop < bottom && left < viewRight && viewLeft < right)
{
/*
* the focusable is in the target area, it is a candidate for
* focusing
*/
final boolean viewIsFullyContained = (top < viewTop) && (viewBottom < bottom) &&
(left < viewLeft) && (viewRight < right);
if (focusCandidate == null)
{
/* No candidate, take this one */
focusCandidate = view;
foundFullyContainedFocusable = viewIsFullyContained;
}
else
{
final boolean viewIsCloserToVerticalBoundary =
(topFocus && viewTop < focusCandidate.getTop()) ||
(!topFocus && viewBottom > focusCandidate.getBottom());
final boolean viewIsCloserToHorizontalBoundary =
(leftFocus && viewLeft < focusCandidate.getLeft()) ||
(!leftFocus && viewRight > focusCandidate.getRight());
if (foundFullyContainedFocusable)
{
if (viewIsFullyContained && viewIsCloserToVerticalBoundary &&
viewIsCloserToHorizontalBoundary)
{
/*
* 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 (viewIsCloserToVerticalBoundary && viewIsCloserToHorizontalBoundary)
{
/*
* Partially contained view beats another partially
* contained view if it's closer
*/
focusCandidate = view;
}
}
}
}
}
return focusCandidate;
}
/**
* <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 horizontal)
{
if (!horizontal)
{
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();
mTempRect.top = mTempRect.bottom - height;
}
}
return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom, 0, 0, 0);
}
else
{
boolean right = direction == View.FOCUS_DOWN;
int width = getWidth();
mTempRect.left = 0;
mTempRect.right = width;
if (right)
{
int count = getChildCount();
if (count > 0)
{
View view = getChildAt(count - 1);
mTempRect.right = view.getBottom();
mTempRect.left = mTempRect.right - width;
}
}
return scrollAndFocus(0, 0, 0, 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 directionY, int top, int bottom, int directionX, int left,
int right)
{
boolean handled = true;
int height = getHeight();
int containerTop = getScrollY();
int containerBottom = containerTop + height;
boolean up = directionY == View.FOCUS_UP;
int width = getWidth();
int containerLeft = getScrollX();
int containerRight = containerLeft + width;
boolean leftwards = directionX == View.FOCUS_UP;
View newFocused = findFocusableViewInBounds(up, top, bottom, leftwards, left, right);
if (newFocused == null)
{
newFocused = this;
}
if ((top >= containerTop && bottom <= containerBottom) ||
(left >= containerLeft && right <= containerRight))
{
handled = false;
}
else
{
int deltaY = up ? (top - containerTop) : (bottom - containerBottom);
int deltaX = leftwards ? (left - containerLeft) : (right - containerRight);
doScroll(deltaX, deltaY);
}
if (newFocused != findFocus() && newFocused.requestFocus(directionY))
{
mTwoDScrollViewMovedFocus = true;
mTwoDScrollViewMovedFocus = false;
}
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, boolean horizontal)
{
View currentFocused = findFocus();
if (currentFocused == this)
currentFocused = null;
View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction);
final int maxJump =
horizontal ? getMaxScrollAmountHorizontal() : getMaxScrollAmountVertical();
if (!horizontal)
{
if (nextFocused != null)
{
nextFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(nextFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScroll(0, 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();
if (daBottom - screenBottom < maxJump)
{
scrollDelta = daBottom - screenBottom;
}
}
}
if (scrollDelta == 0)
{
return false;
}
doScroll(0, direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta);
}
}
else
{
if (nextFocused != null)
{
nextFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(nextFocused, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScroll(scrollDelta, 0);
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();
if (daBottom - screenBottom < maxJump)
{
scrollDelta = daBottom - screenBottom;
}
}
}
if (scrollDelta == 0)
{
return false;
}
doScroll(direction == View.FOCUS_DOWN ? scrollDelta : -scrollDelta, 0);
}
}
return true;
}
/**
* Smooth scroll by a Y delta
*
* @param delta the number of pixels to scroll by on the Y axis
*/
private void doScroll(int deltaX, int deltaY)
{
if (deltaX != 0 || deltaY != 0)
{
smoothScrollBy(deltaX, deltaY);
}
}
/**
* 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)
{
long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll;
if (duration > ANIMATED_SCROLL_GAP)
{
mScroller.startScroll(getScrollX(), getScrollY(), dx, dy);
awakenScrollBars(mScroller.getDuration());
invalidate();
}
else
{
if (!mScroller.isFinished())
{
mScroller.abortAnimation();
}
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 - getScrollX(), y - getScrollY());
}
/**
* <p>The scroll range of a scroll view is the overall height of all of its
* children.</p>
*/
@Override protected int computeVerticalScrollRange()
{
int count = getChildCount();
return count == 0 ? getHeight() : (getChildAt(0)).getBottom();
}
@Override protected int computeHorizontalScrollRange()
{
int count = getChildCount();
return count == 0 ? getWidth() : (getChildAt(0)).getRight();
}
@Override
protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec)
{
ViewGroup.LayoutParams lp = child.getLayoutParams();
int childWidthMeasureSpec;
int childHeightMeasureSpec;
childWidthMeasureSpec = getChildMeasureSpec(parentWidthMeasureSpec,
getPaddingLeft() + getPaddingRight(), 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();
final int childWidthMeasureSpec =
MeasureSpec.makeMeasureSpec(lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED);
final int 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 = getScrollX();
int oldY = getScrollY();
int x = mScroller.getCurrX();
int y = mScroller.getCurrY();
if (getChildCount() > 0)
{
View child = getChildAt(0);
scrollTo(
clamp(x, getWidth() - getPaddingRight() - getPaddingLeft(), child.getWidth()),
clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(),
child.getHeight()));
}
else
{
scrollTo(x, y);
}
if (oldX != getScrollX() || oldY != getScrollY())
{
onScrollChanged(getScrollX(), getScrollY(), oldX, oldY);
}
// Keep on drawing until the animation has finished.
postInvalidate();
}
}
/**
* 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 TwoDScrollView coordinates */
offsetDescendantRectToMyCoords(child, mTempRect);
int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
if (scrollDelta != 0)
{
scrollBy(0, scrollDelta);
}
}
/**
* 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)
{
scrollBy(0, delta);
}
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 (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;
}
@Override public void requestChildFocus(View child, View focused)
{
if (!mTwoDScrollViewMovedFocus)
{
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.
* <p>
* 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 (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;
}
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 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(getScrollX(), getScrollY());
}
@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.
currentFocused.getDrawingRect(mTempRect);
offsetDescendantRectToMyCoords(currentFocused, mTempRect);
int scrollDeltaX = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
int scrollDeltaY = computeScrollDeltaToGetChildRectOnScreen(mTempRect);
doScroll(scrollDeltaX, scrollDeltaY);
}
/**
* 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/curor is moving down the screen,
* which means we want to scroll towards the top.
*/
public void fling(int velocityX, int velocityY)
{
if (getChildCount() > 0)
{
int height = getHeight() - getPaddingBottom() - getPaddingTop();
int bottom = getChildAt(0).getHeight();
int width = getWidth() - getPaddingRight() - getPaddingLeft();
int right = getChildAt(0).getWidth();
mScroller.fling(getScrollX(), getScrollY(), velocityX, velocityY, 0, right - width, 0,
bottom - height);
final boolean movingDown = velocityY > 0;
final boolean movingRight = velocityX > 0;
View newFocused = findFocusableViewInMyBounds(
movingRight, mScroller.getFinalX(), movingDown, mScroller.getFinalY(), findFocus());
if (newFocused == null)
{
newFocused = this;
}
if (newFocused != findFocus() &&
newFocused.requestFocus(movingDown ? View.FOCUS_DOWN : View.FOCUS_UP))
{
mTwoDScrollViewMovedFocus = true;
mTwoDScrollViewMovedFocus = false;
}
awakenScrollBars(mScroller.getDuration());
invalidate();
}
}
/**
* {@inheritDoc}
* <p>
* <p>This version also clamps the scrolling to the bounds of our child.
*/
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() - getPaddingRight() - getPaddingLeft(), child.getWidth());
y = clamp(y, getHeight() - getPaddingBottom() - getPaddingTop(), child.getHeight());
if (x != getScrollX() || y != getScrollY())
{
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;
}
public void setScrollViewListener(ScrollView2DListener scrollViewListener)
{
this.scrollView2DListener = scrollViewListener;
}
@Override protected void onScrollChanged(int x, int y, int oldx, int oldy)
{
super.onScrollChanged(x, y, oldx, oldy);
if (scrollView2DListener != null)
{
scrollView2DListener.onScrollChanged(this, x, y, oldx, oldy);
}
}
// interface to receive notifications when the view is scrolled
public interface ScrollView2DListener {
abstract void onScrollChanged(ScrollView2D scrollView, int x, int y, int oldx, int oldy);
}
}