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Diffstat (limited to 'src/com/android/browser/view/HorizontalScrollView.java')
| -rw-r--r-- | src/com/android/browser/view/HorizontalScrollView.java | 1453 |
1 files changed, 1453 insertions, 0 deletions
diff --git a/src/com/android/browser/view/HorizontalScrollView.java b/src/com/android/browser/view/HorizontalScrollView.java new file mode 100644 index 0000000..2da9058 --- /dev/null +++ b/src/com/android/browser/view/HorizontalScrollView.java @@ -0,0 +1,1453 @@ +/* + * Copyright (C) 2009 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 com.android.internal.R; + +import android.content.Context; +import android.content.res.Resources; +import android.content.res.TypedArray; +import android.graphics.Canvas; +import android.graphics.Rect; +import android.graphics.drawable.Drawable; +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.animation.AnimationUtils; +import android.widget.EdgeGlow; +import android.widget.FrameLayout; +import android.widget.OverScroller; + +import java.util.List; + +// copied from frameworks to allow for customizations +public class HorizontalScrollView extends FrameLayout { + + private static final int ANIMATED_SCROLL_GAP = 250; + + private static final float MAX_SCROLL_FACTOR = 0.5f; + + + private long mLastScroll; + + private final Rect mTempRect = new Rect(); + protected OverScroller mScroller; + private EdgeGlow mEdgeGlowLeft; + private EdgeGlow mEdgeGlowRight; + + /** + * Position of the last motion event. + */ + 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 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; + private 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; + + /** + * Sentinel value for no current active pointer. + * Used by {@link #mActivePointerId}. + */ + private static final int INVALID_POINTER = -1; + + public HorizontalScrollView(Context context) { + this(context, null); + } + + public HorizontalScrollView(Context context, AttributeSet attrs) { + this(context, attrs, com.android.internal.R.attr.horizontalScrollViewStyle); + } + + public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { + super(context, attrs, defStyle); + initScrollView(); + + TypedArray a = context.obtainStyledAttributes(attrs, + android.R.styleable.HorizontalScrollView, defStyle, 0); + + setFillViewport(a.getBoolean(android.R.styleable.HorizontalScrollView_fillViewport, false)); + + a.recycle(); + } + + @Override + protected float getLeftFadingEdgeStrength() { + return 0.0f; + } + + @Override + protected float getRightFadingEdgeStrength() { + return 0.0f; + } + + /** + * @return The maximum amount this scroll view will scroll in response to + * an arrow event. + */ + public int getMaxScrollAmount() { + return (int) (MAX_SCROLL_FACTOR * (mRight - mLeft)); + } + + + 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(); + } + + @Override + public void addView(View child) { + if (getChildCount() > 0) { + throw new IllegalStateException("HorizontalScrollView can host only one direct child"); + } + + super.addView(child); + } + + @Override + public void addView(View child, int index) { + if (getChildCount() > 0) { + throw new IllegalStateException("HorizontalScrollView 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("HorizontalScrollView 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("HorizontalScrollView can host only one direct child"); + } + + super.addView(child, index, params); + } + + /** + * @return Returns true this HorizontalScrollView can be scrolled + */ + private boolean canScroll() { + View child = getChildAt(0); + if (child != null) { + int childWidth = child.getWidth(); + return getWidth() < childWidth + mPaddingLeft + mPaddingRight ; + } + return false; + } + + /** + * Indicates whether this HorizontalScrollView's content is stretched to + * fill the viewport. + * + * @return True if the content fills the viewport, false otherwise. + * + * @attr ref android.R.styleable#HorizontalScrollView_fillViewport + */ + public boolean isFillViewport() { + return mFillViewport; + } + + /** + * Indicates this HorizontalScrollView whether it should stretch its content width + * to fill the viewport or not. + * + * @param fillViewport True to stretch the content's width to the viewport's + * boundaries, false otherwise. + * + * @attr ref android.R.styleable#HorizontalScrollView_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 widthMode = MeasureSpec.getMode(widthMeasureSpec); + if (widthMode == MeasureSpec.UNSPECIFIED) { + return; + } + + if (getChildCount() > 0) { + final View child = getChildAt(0); + 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); + } + } + } + + @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()) { + View currentFocused = findFocus(); + if (currentFocused == this) currentFocused = null; + View nextFocused = FocusFinder.getInstance().findNextFocus(this, + currentFocused, View.FOCUS_RIGHT); + return nextFocused != null && nextFocused != this && + nextFocused.requestFocus(View.FOCUS_RIGHT); + } + return false; + } + + boolean handled = false; + if (event.getAction() == KeyEvent.ACTION_DOWN) { + switch (event.getKeyCode()) { + case KeyEvent.KEYCODE_DPAD_LEFT: + if (!event.isAltPressed()) { + handled = arrowScroll(View.FOCUS_LEFT); + } else { + handled = fullScroll(View.FOCUS_LEFT); + } + break; + case KeyEvent.KEYCODE_DPAD_RIGHT: + if (!event.isAltPressed()) { + handled = arrowScroll(View.FOCUS_RIGHT); + } else { + handled = fullScroll(View.FOCUS_RIGHT); + } + break; + case KeyEvent.KEYCODE_SPACE: + pageScroll(event.isShiftPressed() ? View.FOCUS_LEFT : View.FOCUS_RIGHT); + break; + } + } + + return handled; + } + + private boolean inChild(int x, int y) { + if (getChildCount() > 0) { + final int scrollX = mScrollX; + final View child = getChildAt(0); + return !(y < child.getTop() + || y >= child.getBottom() + || x < child.getLeft() - scrollX + || x >= child.getRight() - scrollX); + } + return false; + } + + @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; + } + + 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. mLastMotionX is set to the x 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 x = ev.getX(pointerIndex); + final int xDiff = (int) Math.abs(x - mLastMotionX); + if (xDiff > mTouchSlop) { + mIsBeingDragged = true; + mLastMotionX = x; + if (mParent != null) mParent.requestDisallowInterceptTouchEvent(true); + } + break; + } + + case MotionEvent.ACTION_DOWN: { + final float x = ev.getX(); + if (!inChild((int) x, (int) ev.getY())) { + mIsBeingDragged = false; + break; + } + + /* + * Remember location of down touch. + * ACTION_DOWN always refers to pointer index 0. + */ + mLastMotionX = x; + mActivePointerId = ev.getPointerId(0); + + /* + * 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; + mActivePointerId = INVALID_POINTER; + if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { + invalidate(); + } + break; + case MotionEvent.ACTION_POINTER_DOWN: { + final int index = ev.getActionIndex(); + mLastMotionX = ev.getX(index); + mActivePointerId = ev.getPointerId(index); + break; + } + case MotionEvent.ACTION_POINTER_UP: + onSecondaryPointerUp(ev); + mLastMotionX = ev.getX(ev.findPointerIndex(mActivePointerId)); + 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 (mVelocityTracker == null) { + mVelocityTracker = VelocityTracker.obtain(); + } + 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(); + } + + // Remember where the motion event started + mLastMotionX = ev.getX(); + mActivePointerId = ev.getPointerId(0); + break; + } + case MotionEvent.ACTION_MOVE: + if (mIsBeingDragged) { + // Scroll to follow the motion event + final int activePointerIndex = ev.findPointerIndex(mActivePointerId); + final float x = ev.getX(activePointerIndex); + final int deltaX = (int) (mLastMotionX - x); + mLastMotionX = x; + + final int oldX = mScrollX; + final int oldY = mScrollY; + final int range = getScrollRange(); + if (overScrollBy(deltaX, 0, mScrollX, 0, range, 0, + mOverscrollDistance, 0, 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 pulledToX = oldX + deltaX; + if (pulledToX < 0) { + mEdgeGlowLeft.onPull((float) deltaX / getWidth()); + if (!mEdgeGlowRight.isFinished()) { + mEdgeGlowRight.onRelease(); + } + } else if (pulledToX > range) { + mEdgeGlowRight.onPull((float) deltaX / getWidth()); + if (!mEdgeGlowLeft.isFinished()) { + mEdgeGlowLeft.onRelease(); + } + } + if (mEdgeGlowLeft != null + && (!mEdgeGlowLeft.isFinished() || !mEdgeGlowRight.isFinished())) { + invalidate(); + } + } + } + break; + case MotionEvent.ACTION_UP: + if (mIsBeingDragged) { + final VelocityTracker velocityTracker = mVelocityTracker; + velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); + int initialVelocity = (int) velocityTracker.getXVelocity(mActivePointerId); + + if (getChildCount() > 0) { + if ((Math.abs(initialVelocity) > mMinimumVelocity)) { + fling(-initialVelocity); + } else { + final int right = getScrollRange(); + if (mScroller.springBack(mScrollX, mScrollY, 0, right, 0, 0)) { + invalidate(); + } + } + } + + mActivePointerId = INVALID_POINTER; + mIsBeingDragged = false; + + if (mVelocityTracker != null) { + mVelocityTracker.recycle(); + mVelocityTracker = null; + } + if (mEdgeGlowLeft != null) { + mEdgeGlowLeft.onRelease(); + mEdgeGlowRight.onRelease(); + } + } + break; + case MotionEvent.ACTION_CANCEL: + if (mIsBeingDragged && getChildCount() > 0) { + if (mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0)) { + invalidate(); + } + mActivePointerId = INVALID_POINTER; + mIsBeingDragged = false; + if (mVelocityTracker != null) { + mVelocityTracker.recycle(); + mVelocityTracker = null; + } + if (mEdgeGlowLeft != null) { + mEdgeGlowLeft.onRelease(); + mEdgeGlowRight.onRelease(); + } + } + break; + case MotionEvent.ACTION_POINTER_UP: + onSecondaryPointerUp(ev); + break; + } + return true; + } + + 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; + mLastMotionX = ev.getX(newPointerIndex); + mActivePointerId = ev.getPointerId(newPointerIndex); + if (mVelocityTracker != null) { + mVelocityTracker.clear(); + } + } + } + + @Override + public boolean onGenericMotionEvent(MotionEvent event) { + if ((event.getSource() & InputDevice.SOURCE_CLASS_POINTER) != 0) { + switch (event.getAction()) { + case MotionEvent.ACTION_SCROLL: { + if (!mIsBeingDragged) { + final float hscroll; + if ((event.getMetaState() & KeyEvent.META_SHIFT_ON) != 0) { + hscroll = -event.getAxisValue(MotionEvent.AXIS_VSCROLL); + } else { + 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; + } + } + } + } + } + } + return super.onGenericMotionEvent(event); + } + + @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 (clampedX) { + mScroller.springBack(mScrollX, mScrollY, 0, getScrollRange(), 0, 0); + } + } else { + super.scrollTo(scrollX, scrollY); + } + awakenScrollBars(); + } + + private int getScrollRange() { + int scrollRange = 0; + if (getChildCount() > 0) { + View child = getChildAt(0); + scrollRange = Math.max(0, + child.getWidth() - (getWidth() - mPaddingLeft - mPaddingRight)); + } + return scrollRange; + } + + /** + * <p> + * Finds the next focusable component that fits in this View's bounds + * (excluding fading edges) pretending that this View's left is located at + * the parameter left. + * </p> + * + * @param leftFocus look for a candidate is the one at the left of the bounds + * if leftFocus is true, or at the right of the bounds if leftFocus + * is false + * @param left the left 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 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 fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; + final int leftWithoutFadingEdge = left + fadingEdgeLength; + final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; + + if ((preferredFocusable != null) + && (preferredFocusable.getLeft() < rightWithoutFadingEdge) + && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { + return preferredFocusable; + } + + return findFocusableViewInBounds(leftFocus, leftWithoutFadingEdge, + rightWithoutFadingEdge); + } + + /** + * <p> + * Finds the next focusable component that fits in the specified bounds. + * </p> + * + * @param leftFocus look for a candidate is the one at the left of the bounds + * if leftFocus is true, or at the right of the bounds if + * leftFocus is false + * @param left the left offset of the bounds in which a focusable must be + * found + * @param right the right 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 leftFocus, int left, int right) { + + List<View> focusables = getFocusables(View.FOCUS_FORWARD); + View focusCandidate = null; + + /* + * A fully contained focusable is one where its left is below the bound's + * left, and its right is above the bound's right. 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 viewLeft = view.getLeft(); + int viewRight = view.getRight(); + + if (left < viewRight && viewLeft < right) { + /* + * the focusable is in the target area, it is a candidate for + * focusing + */ + + final boolean viewIsFullyContained = (left < viewLeft) && + (viewRight < right); + + if (focusCandidate == null) { + /* No candidate, take this one */ + focusCandidate = view; + foundFullyContainedFocusable = viewIsFullyContained; + } else { + final boolean viewIsCloserToBoundary = + (leftFocus && viewLeft < focusCandidate.getLeft()) || + (!leftFocus && viewRight > focusCandidate.getRight()); + + 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; + } + + /** + * <p>Handles scrolling in response to a "page up/down" shortcut press. This + * method will scroll the view by one page left or right and give the focus + * to the leftmost/rightmost 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_LEFT} + * to go one page left or {@link android.view.View#FOCUS_RIGHT} + * to go one page right + * @return true if the key event is consumed by this method, false otherwise + */ + public boolean pageScroll(int direction) { + boolean right = direction == View.FOCUS_RIGHT; + int width = getWidth(); + + if (right) { + mTempRect.left = getScrollX() + width; + int count = getChildCount(); + if (count > 0) { + View view = getChildAt(0); + if (mTempRect.left + width > view.getRight()) { + mTempRect.left = view.getRight() - width; + } + } + } else { + mTempRect.left = getScrollX() - width; + if (mTempRect.left < 0) { + mTempRect.left = 0; + } + } + mTempRect.right = mTempRect.left + width; + + return scrollAndFocus(direction, mTempRect.left, mTempRect.right); + } + + /** + * <p>Handles scrolling in response to a "home/end" shortcut press. This + * method will scroll the view to the left or right and give the focus + * to the leftmost/rightmost 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_LEFT} + * to go the left of the view or {@link android.view.View#FOCUS_RIGHT} + * to go the right + * @return true if the key event is consumed by this method, false otherwise + */ + public boolean fullScroll(int direction) { + boolean right = direction == View.FOCUS_RIGHT; + int width = getWidth(); + + mTempRect.left = 0; + mTempRect.right = width; + + if (right) { + int count = getChildCount(); + if (count > 0) { + View view = getChildAt(0); + mTempRect.right = view.getRight(); + mTempRect.left = mTempRect.right - width; + } + } + + return scrollAndFocus(direction, mTempRect.left, mTempRect.right); + } + + /** + * <p>Scrolls the view to make the area defined by <code>left</code> and + * <code>right</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_LEFT} + * to go left {@link android.view.View#FOCUS_RIGHT} to right + * @param left the left offset of the new area to be made visible + * @param right the right 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 left, int right) { + boolean handled = true; + + int width = getWidth(); + int containerLeft = getScrollX(); + int containerRight = containerLeft + width; + boolean goLeft = direction == View.FOCUS_LEFT; + + View newFocused = findFocusableViewInBounds(goLeft, left, right); + if (newFocused == null) { + newFocused = this; + } + + if (left >= containerLeft && right <= containerRight) { + handled = false; + } else { + int delta = goLeft ? (left - containerLeft) : (right - containerRight); + doScrollX(delta); + } + + if (newFocused != findFocus()) newFocused.requestFocus(direction); + + return handled; + } + + /** + * Handle scrolling in response to a left or right 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)) { + nextFocused.getDrawingRect(mTempRect); + offsetDescendantRectToMyCoords(nextFocused, mTempRect); + int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); + doScrollX(scrollDelta); + nextFocused.requestFocus(direction); + } else { + // no new focus + int scrollDelta = maxJump; + + if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { + scrollDelta = getScrollX(); + } else if (direction == View.FOCUS_RIGHT && getChildCount() > 0) { + + int daRight = getChildAt(0).getRight(); + + int screenRight = getScrollX() + getWidth(); + + if (daRight - screenRight < maxJump) { + scrollDelta = daRight - screenRight; + } + } + if (scrollDelta == 0) { + return false; + } + doScrollX(direction == View.FOCUS_RIGHT ? 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; + } + + /** + * @return whether the descendant of this scroll view is scrolled off + * screen. + */ + private boolean isOffScreen(View descendant) { + return !isWithinDeltaOfScreen(descendant, 0); + } + + /** + * @return whether the descendant of this scroll view is within delta + * pixels of being on the screen. + */ + private boolean isWithinDeltaOfScreen(View descendant, int delta) { + descendant.getDrawingRect(mTempRect); + offsetDescendantRectToMyCoords(descendant, mTempRect); + + return (mTempRect.right + delta) >= getScrollX() + && (mTempRect.left - delta) <= (getScrollX() + getWidth()); + } + + /** + * Smooth scroll by a X delta + * + * @param delta the number of pixels to scroll by on the X axis + */ + private void doScrollX(int delta) { + if (delta != 0) { + if (mSmoothScrollingEnabled) { + smoothScrollBy(delta, 0); + } 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) { + 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); + 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 - mScrollX, y - mScrollY); + } + + /** + * <p>The scroll range of a scroll view is the overall width of all of its + * children.</p> + */ + @Override + protected int computeHorizontalScrollRange() { + final int count = getChildCount(); + final int contentWidth = getWidth() - mPaddingLeft - mPaddingRight; + if (count == 0) { + return contentWidth; + } + + int scrollRange = getChildAt(0).getRight(); + final int scrollX = mScrollX; + final int overscrollRight = Math.max(0, scrollRange - contentWidth); + if (scrollX < 0) { + scrollRange -= scrollX; + } else if (scrollX > overscrollRight) { + scrollRange += scrollX - overscrollRight; + } + + return scrollRange; + } + + @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; + + childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, mPaddingTop + + mPaddingBottom, lp.height); + + childWidthMeasureSpec = 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 childHeightMeasureSpec = getChildMeasureSpec(parentHeightMeasureSpec, + mPaddingTop + mPaddingBottom + lp.topMargin + lp.bottomMargin + + heightUsed, lp.height); + final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec( + lp.leftMargin + lp.rightMargin, 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) { + overScrollBy(x - oldX, y - oldY, oldX, oldY, getScrollRange(), 0, + mOverflingDistance, 0, false); + onScrollChanged(mScrollX, mScrollY, oldX, oldY); + + final int range = getScrollRange(); + final int overscrollMode = getOverScrollMode(); + if (overscrollMode == OVER_SCROLL_ALWAYS || + (overscrollMode == OVER_SCROLL_IF_CONTENT_SCROLLS && range > 0)) { + if (x < 0 && oldX >= 0) { + mEdgeGlowLeft.onAbsorb((int) mScroller.getCurrVelocity()); + } else if (x > range && oldX <= range) { + mEdgeGlowRight.onAbsorb((int) mScroller.getCurrVelocity()); + } + } + } + awakenScrollBars(); + + // 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 ScrollView coordinates */ + offsetDescendantRectToMyCoords(child, mTempRect); + + int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); + + if (scrollDelta != 0) { + scrollBy(scrollDelta, 0); + } + } + + /** + * 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 + */ + protected boolean scrollToChildRect(Rect rect, boolean immediate) { + final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); + final boolean scroll = delta != 0; + if (scroll) { + if (immediate) { + scrollBy(delta, 0); + } else { + smoothScrollBy(delta, 0); + } + } + return scroll; + } + + /** + * Compute the amount to scroll in the X 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 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 (direction == View.FOCUS_FORWARD) { + direction = View.FOCUS_RIGHT; + } else if (direction == View.FOCUS_BACKWARD) { + direction = View.FOCUS_LEFT; + } + + 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 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; + + final int maxJump = mRight - mLeft; + + if (isWithinDeltaOfScreen(currentFocused, maxJump)) { + currentFocused.getDrawingRect(mTempRect); + offsetDescendantRectToMyCoords(currentFocused, mTempRect); + int scrollDelta = computeScrollDeltaToGetChildRectOnScreen(mTempRect); + doScrollX(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 velocityX The initial velocity in the X direction. Positive + * numbers mean that the finger/curor is moving down the screen, + * which means we want to scroll towards the left. + */ + public void fling(int velocityX) { + if (getChildCount() > 0) { + int width = getWidth() - mPaddingRight - mPaddingLeft; + int right = getChildAt(0).getWidth(); + + mScroller.fling(mScrollX, mScrollY, velocityX, 0, 0, + Math.max(0, right - width), 0, 0, width/2, 0); + + final boolean movingRight = velocityX > 0; + + View currentFocused = findFocus(); + View newFocused = findFocusableViewInMyBounds(movingRight, + mScroller.getFinalX(), currentFocused); + + if (newFocused == null) { + newFocused = this; + } + + if (newFocused != currentFocused) { + newFocused.requestFocus(movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT); + } + + invalidate(); + } + } + + /** + * {@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); + } + } + } + + @Override + public void setOverScrollMode(int mode) { + if (mode != OVER_SCROLL_NEVER) { + if (mEdgeGlowLeft == null) { + Context context = getContext(); + final Resources res = context.getResources(); + final Drawable edge = res.getDrawable(R.drawable.overscroll_edge); + final Drawable glow = res.getDrawable(R.drawable.overscroll_glow); + mEdgeGlowLeft = new EdgeGlow(context, edge, glow); + mEdgeGlowRight = new EdgeGlow(context, edge, glow); + } + } else { + mEdgeGlowLeft = null; + mEdgeGlowRight = null; + } + super.setOverScrollMode(mode); + } + + @SuppressWarnings({"SuspiciousNameCombination"}) + @Override + public void draw(Canvas canvas) { + super.draw(canvas); + if (mEdgeGlowLeft != null) { + final int scrollX = mScrollX; + if (!mEdgeGlowLeft.isFinished()) { + final int restoreCount = canvas.save(); + final int height = getHeight() - mPaddingTop - mPaddingBottom; + + canvas.rotate(270); + canvas.translate(-height + mPaddingTop, Math.min(0, scrollX)); + mEdgeGlowLeft.setSize(height, getWidth()); + if (mEdgeGlowLeft.draw(canvas)) { + invalidate(); + } + canvas.restoreToCount(restoreCount); + } + if (!mEdgeGlowRight.isFinished()) { + final int restoreCount = canvas.save(); + final int width = getWidth(); + final int height = getHeight() - mPaddingTop - mPaddingBottom; + + canvas.rotate(90); + canvas.translate(-mPaddingTop, + -(Math.max(getScrollRange(), scrollX) + width)); + mEdgeGlowRight.setSize(height, width); + if (mEdgeGlowRight.draw(canvas)) { + invalidate(); + } + canvas.restoreToCount(restoreCount); + } + } + } + + private int clamp(int n, int my, int child) { + if (my >= child || n < 0) { + return 0; + } + if ((my + n) > child) { + return child - my; + } + return n; + } +} |