/* * Copyright (C) 2007 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 android.view; import android.graphics.Rect; import java.util.ArrayList; import java.util.Collections; import java.util.Comparator; /** * The algorithm used for finding the next focusable view in a given direction * from a view that currently has focus. */ public class FocusFinder { private static final ThreadLocal tlFocusFinder = new ThreadLocal() { @Override protected FocusFinder initialValue() { return new FocusFinder(); } }; /** * Get the focus finder for this thread. */ public static FocusFinder getInstance() { return tlFocusFinder.get(); } final Rect mFocusedRect = new Rect(); final Rect mOtherRect = new Rect(); final Rect mBestCandidateRect = new Rect(); final SequentialFocusComparator mSequentialFocusComparator = new SequentialFocusComparator(); private final ArrayList mTempList = new ArrayList(); // enforce thread local access private FocusFinder() {} /** * Find the next view to take focus in root's descendants, starting from the view * that currently is focused. * @param root Contains focused. Cannot be null. * @param focused Has focus now. * @param direction Direction to look. * @return The next focusable view, or null if none exists. */ public final View findNextFocus(ViewGroup root, View focused, int direction) { return findNextFocus(root, focused, null, direction); } /** * Find the next view to take focus in root's descendants, searching from * a particular rectangle in root's coordinates. * @param root Contains focusedRect. Cannot be null. * @param focusedRect The starting point of the search. * @param direction Direction to look. * @return The next focusable view, or null if none exists. */ public View findNextFocusFromRect(ViewGroup root, Rect focusedRect, int direction) { mFocusedRect.set(focusedRect); return findNextFocus(root, null, mFocusedRect, direction); } private View findNextFocus(ViewGroup root, View focused, Rect focusedRect, int direction) { View next = null; if (focused != null) { next = findNextUserSpecifiedFocus(root, focused, direction); } if (next != null) { return next; } ArrayList focusables = mTempList; try { focusables.clear(); root.addFocusables(focusables, direction); if (!focusables.isEmpty()) { next = findNextFocus(root, focused, focusedRect, direction, focusables); } } finally { focusables.clear(); } return next; } private View findNextUserSpecifiedFocus(ViewGroup root, View focused, int direction) { // check for user specified next focus View userSetNextFocus = focused.findUserSetNextFocus(root, direction); if (userSetNextFocus != null && userSetNextFocus.isFocusable() && (!userSetNextFocus.isInTouchMode() || userSetNextFocus.isFocusableInTouchMode())) { return userSetNextFocus; } return null; } private View findNextFocus(ViewGroup root, View focused, Rect focusedRect, int direction, ArrayList focusables) { if (focused != null) { if (focusedRect == null) { focusedRect = mFocusedRect; } // fill in interesting rect from focused focused.getFocusedRect(focusedRect); root.offsetDescendantRectToMyCoords(focused, focusedRect); } else { if (focusedRect == null) { focusedRect = mFocusedRect; // make up a rect at top left or bottom right of root switch (direction) { case View.FOCUS_RIGHT: case View.FOCUS_DOWN: setFocusTopLeft(root, focusedRect); break; case View.FOCUS_FORWARD: if (root.isLayoutRtl()) { setFocusBottomRight(root, focusedRect); } else { setFocusTopLeft(root, focusedRect); } break; case View.FOCUS_LEFT: case View.FOCUS_UP: setFocusBottomRight(root, focusedRect); break; case View.FOCUS_BACKWARD: if (root.isLayoutRtl()) { setFocusTopLeft(root, focusedRect); } else { setFocusBottomRight(root, focusedRect); break; } } } } switch (direction) { case View.FOCUS_FORWARD: case View.FOCUS_BACKWARD: return findNextFocusInRelativeDirection(focusables, root, focused, focusedRect, direction); case View.FOCUS_UP: case View.FOCUS_DOWN: case View.FOCUS_LEFT: case View.FOCUS_RIGHT: return findNextFocusInAbsoluteDirection(focusables, root, focused, focusedRect, direction); default: throw new IllegalArgumentException("Unknown direction: " + direction); } } private View findNextFocusInRelativeDirection(ArrayList focusables, ViewGroup root, View focused, Rect focusedRect, int direction) { try { // Note: This sort is stable. mSequentialFocusComparator.setRoot(root); Collections.sort(focusables, mSequentialFocusComparator); } finally { mSequentialFocusComparator.recycle(); } final int count = focusables.size(); switch (direction) { case View.FOCUS_FORWARD: return getForwardFocusable(root, focused, focusables, count); case View.FOCUS_BACKWARD: return getBackwardFocusable(root, focused, focusables, count); } return focusables.get(count - 1); } private void setFocusBottomRight(ViewGroup root, Rect focusedRect) { final int rootBottom = root.getScrollY() + root.getHeight(); final int rootRight = root.getScrollX() + root.getWidth(); focusedRect.set(rootRight, rootBottom, rootRight, rootBottom); } private void setFocusTopLeft(ViewGroup root, Rect focusedRect) { final int rootTop = root.getScrollY(); final int rootLeft = root.getScrollX(); focusedRect.set(rootLeft, rootTop, rootLeft, rootTop); } View findNextFocusInAbsoluteDirection(ArrayList focusables, ViewGroup root, View focused, Rect focusedRect, int direction) { // initialize the best candidate to something impossible // (so the first plausible view will become the best choice) mBestCandidateRect.set(focusedRect); switch(direction) { case View.FOCUS_LEFT: mBestCandidateRect.offset(focusedRect.width() + 1, 0); break; case View.FOCUS_RIGHT: mBestCandidateRect.offset(-(focusedRect.width() + 1), 0); break; case View.FOCUS_UP: mBestCandidateRect.offset(0, focusedRect.height() + 1); break; case View.FOCUS_DOWN: mBestCandidateRect.offset(0, -(focusedRect.height() + 1)); } View closest = null; int numFocusables = focusables.size(); for (int i = 0; i < numFocusables; i++) { View focusable = focusables.get(i); // only interested in other non-root views if (focusable == focused || focusable == root) continue; // get focus bounds of other view in same coordinate system focusable.getFocusedRect(mOtherRect); root.offsetDescendantRectToMyCoords(focusable, mOtherRect); if (isBetterCandidate(direction, focusedRect, mOtherRect, mBestCandidateRect)) { mBestCandidateRect.set(mOtherRect); closest = focusable; } } return closest; } private static View getForwardFocusable(ViewGroup root, View focused, ArrayList focusables, int count) { return (root.isLayoutRtl()) ? getPreviousFocusable(focused, focusables, count) : getNextFocusable(focused, focusables, count); } private static View getNextFocusable(View focused, ArrayList focusables, int count) { if (focused != null) { int position = focusables.lastIndexOf(focused); if (position >= 0 && position + 1 < count) { return focusables.get(position + 1); } } if (!focusables.isEmpty()) { return focusables.get(0); } return null; } private static View getBackwardFocusable(ViewGroup root, View focused, ArrayList focusables, int count) { return (root.isLayoutRtl()) ? getNextFocusable(focused, focusables, count) : getPreviousFocusable(focused, focusables, count); } private static View getPreviousFocusable(View focused, ArrayList focusables, int count) { if (focused != null) { int position = focusables.indexOf(focused); if (position > 0) { return focusables.get(position - 1); } } if (!focusables.isEmpty()) { return focusables.get(count - 1); } return null; } /** * Is rect1 a better candidate than rect2 for a focus search in a particular * direction from a source rect? This is the core routine that determines * the order of focus searching. * @param direction the direction (up, down, left, right) * @param source The source we are searching from * @param rect1 The candidate rectangle * @param rect2 The current best candidate. * @return Whether the candidate is the new best. */ boolean isBetterCandidate(int direction, Rect source, Rect rect1, Rect rect2) { // to be a better candidate, need to at least be a candidate in the first // place :) if (!isCandidate(source, rect1, direction)) { return false; } // we know that rect1 is a candidate.. if rect2 is not a candidate, // rect1 is better if (!isCandidate(source, rect2, direction)) { return true; } // if rect1 is better by beam, it wins if (beamBeats(direction, source, rect1, rect2)) { return true; } // if rect2 is better, then rect1 cant' be :) if (beamBeats(direction, source, rect2, rect1)) { return false; } // otherwise, do fudge-tastic comparison of the major and minor axis return (getWeightedDistanceFor( majorAxisDistance(direction, source, rect1), minorAxisDistance(direction, source, rect1)) < getWeightedDistanceFor( majorAxisDistance(direction, source, rect2), minorAxisDistance(direction, source, rect2))); } /** * One rectangle may be another candidate than another by virtue of being * exclusively in the beam of the source rect. * @return Whether rect1 is a better candidate than rect2 by virtue of it being in src's * beam */ boolean beamBeats(int direction, Rect source, Rect rect1, Rect rect2) { final boolean rect1InSrcBeam = beamsOverlap(direction, source, rect1); final boolean rect2InSrcBeam = beamsOverlap(direction, source, rect2); // if rect1 isn't exclusively in the src beam, it doesn't win if (rect2InSrcBeam || !rect1InSrcBeam) { return false; } // we know rect1 is in the beam, and rect2 is not // if rect1 is to the direction of, and rect2 is not, rect1 wins. // for example, for direction left, if rect1 is to the left of the source // and rect2 is below, then we always prefer the in beam rect1, since rect2 // could be reached by going down. if (!isToDirectionOf(direction, source, rect2)) { return true; } // for horizontal directions, being exclusively in beam always wins if ((direction == View.FOCUS_LEFT || direction == View.FOCUS_RIGHT)) { return true; } // for vertical directions, beams only beat up to a point: // now, as long as rect2 isn't completely closer, rect1 wins // e.g for direction down, completely closer means for rect2's top // edge to be closer to the source's top edge than rect1's bottom edge. return (majorAxisDistance(direction, source, rect1) < majorAxisDistanceToFarEdge(direction, source, rect2)); } /** * Fudge-factor opportunity: how to calculate distance given major and minor * axis distances. Warning: this fudge factor is finely tuned, be sure to * run all focus tests if you dare tweak it. */ int getWeightedDistanceFor(int majorAxisDistance, int minorAxisDistance) { return 13 * majorAxisDistance * majorAxisDistance + minorAxisDistance * minorAxisDistance; } /** * Is destRect a candidate for the next focus given the direction? This * checks whether the dest is at least partially to the direction of (e.g left of) * from source. * * Includes an edge case for an empty rect (which is used in some cases when * searching from a point on the screen). */ boolean isCandidate(Rect srcRect, Rect destRect, int direction) { switch (direction) { case View.FOCUS_LEFT: return (srcRect.right > destRect.right || srcRect.left >= destRect.right) && srcRect.left > destRect.left; case View.FOCUS_RIGHT: return (srcRect.left < destRect.left || srcRect.right <= destRect.left) && srcRect.right < destRect.right; case View.FOCUS_UP: return (srcRect.bottom > destRect.bottom || srcRect.top >= destRect.bottom) && srcRect.top > destRect.top; case View.FOCUS_DOWN: return (srcRect.top < destRect.top || srcRect.bottom <= destRect.top) && srcRect.bottom < destRect.bottom; } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * Do the "beams" w.r.t the given direction's axis of rect1 and rect2 overlap? * @param direction the direction (up, down, left, right) * @param rect1 The first rectangle * @param rect2 The second rectangle * @return whether the beams overlap */ boolean beamsOverlap(int direction, Rect rect1, Rect rect2) { switch (direction) { case View.FOCUS_LEFT: case View.FOCUS_RIGHT: return (rect2.bottom >= rect1.top) && (rect2.top <= rect1.bottom); case View.FOCUS_UP: case View.FOCUS_DOWN: return (rect2.right >= rect1.left) && (rect2.left <= rect1.right); } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * e.g for left, is 'to left of' */ boolean isToDirectionOf(int direction, Rect src, Rect dest) { switch (direction) { case View.FOCUS_LEFT: return src.left >= dest.right; case View.FOCUS_RIGHT: return src.right <= dest.left; case View.FOCUS_UP: return src.top >= dest.bottom; case View.FOCUS_DOWN: return src.bottom <= dest.top; } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * @return The distance from the edge furthest in the given direction * of source to the edge nearest in the given direction of dest. If the * dest is not in the direction from source, return 0. */ static int majorAxisDistance(int direction, Rect source, Rect dest) { return Math.max(0, majorAxisDistanceRaw(direction, source, dest)); } static int majorAxisDistanceRaw(int direction, Rect source, Rect dest) { switch (direction) { case View.FOCUS_LEFT: return source.left - dest.right; case View.FOCUS_RIGHT: return dest.left - source.right; case View.FOCUS_UP: return source.top - dest.bottom; case View.FOCUS_DOWN: return dest.top - source.bottom; } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * @return The distance along the major axis w.r.t the direction from the * edge of source to the far edge of dest. If the * dest is not in the direction from source, return 1 (to break ties with * {@link #majorAxisDistance}). */ static int majorAxisDistanceToFarEdge(int direction, Rect source, Rect dest) { return Math.max(1, majorAxisDistanceToFarEdgeRaw(direction, source, dest)); } static int majorAxisDistanceToFarEdgeRaw(int direction, Rect source, Rect dest) { switch (direction) { case View.FOCUS_LEFT: return source.left - dest.left; case View.FOCUS_RIGHT: return dest.right - source.right; case View.FOCUS_UP: return source.top - dest.top; case View.FOCUS_DOWN: return dest.bottom - source.bottom; } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * Find the distance on the minor axis w.r.t the direction to the nearest * edge of the destination rectangle. * @param direction the direction (up, down, left, right) * @param source The source rect. * @param dest The destination rect. * @return The distance. */ static int minorAxisDistance(int direction, Rect source, Rect dest) { switch (direction) { case View.FOCUS_LEFT: case View.FOCUS_RIGHT: // the distance between the center verticals return Math.abs( ((source.top + source.height() / 2) - ((dest.top + dest.height() / 2)))); case View.FOCUS_UP: case View.FOCUS_DOWN: // the distance between the center horizontals return Math.abs( ((source.left + source.width() / 2) - ((dest.left + dest.width() / 2)))); } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * Find the nearest touchable view to the specified view. * * @param root The root of the tree in which to search * @param x X coordinate from which to start the search * @param y Y coordinate from which to start the search * @param direction Direction to look * @param deltas Offset from the to the edge of the nearest view. Note that this array * may already be populated with values. * @return The nearest touchable view, or null if none exists. */ public View findNearestTouchable(ViewGroup root, int x, int y, int direction, int[] deltas) { ArrayList touchables = root.getTouchables(); int minDistance = Integer.MAX_VALUE; View closest = null; int numTouchables = touchables.size(); int edgeSlop = ViewConfiguration.get(root.mContext).getScaledEdgeSlop(); Rect closestBounds = new Rect(); Rect touchableBounds = mOtherRect; for (int i = 0; i < numTouchables; i++) { View touchable = touchables.get(i); // get visible bounds of other view in same coordinate system touchable.getDrawingRect(touchableBounds); root.offsetRectBetweenParentAndChild(touchable, touchableBounds, true, true); if (!isTouchCandidate(x, y, touchableBounds, direction)) { continue; } int distance = Integer.MAX_VALUE; switch (direction) { case View.FOCUS_LEFT: distance = x - touchableBounds.right + 1; break; case View.FOCUS_RIGHT: distance = touchableBounds.left; break; case View.FOCUS_UP: distance = y - touchableBounds.bottom + 1; break; case View.FOCUS_DOWN: distance = touchableBounds.top; break; } if (distance < edgeSlop) { // Give preference to innermost views if (closest == null || closestBounds.contains(touchableBounds) || (!touchableBounds.contains(closestBounds) && distance < minDistance)) { minDistance = distance; closest = touchable; closestBounds.set(touchableBounds); switch (direction) { case View.FOCUS_LEFT: deltas[0] = -distance; break; case View.FOCUS_RIGHT: deltas[0] = distance; break; case View.FOCUS_UP: deltas[1] = -distance; break; case View.FOCUS_DOWN: deltas[1] = distance; break; } } } } return closest; } /** * Is destRect a candidate for the next touch given the direction? */ private boolean isTouchCandidate(int x, int y, Rect destRect, int direction) { switch (direction) { case View.FOCUS_LEFT: return destRect.left <= x && destRect.top <= y && y <= destRect.bottom; case View.FOCUS_RIGHT: return destRect.left >= x && destRect.top <= y && y <= destRect.bottom; case View.FOCUS_UP: return destRect.top <= y && destRect.left <= x && x <= destRect.right; case View.FOCUS_DOWN: return destRect.top >= y && destRect.left <= x && x <= destRect.right; } throw new IllegalArgumentException("direction must be one of " + "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}."); } /** * Sorts views according to their visual layout and geometry for default tab order. * This is used for sequential focus traversal. */ private static final class SequentialFocusComparator implements Comparator { private final Rect mFirstRect = new Rect(); private final Rect mSecondRect = new Rect(); private ViewGroup mRoot; public void recycle() { mRoot = null; } public void setRoot(ViewGroup root) { mRoot = root; } public int compare(View first, View second) { if (first == second) { return 0; } getRect(first, mFirstRect); getRect(second, mSecondRect); if (mFirstRect.top < mSecondRect.top) { return -1; } else if (mFirstRect.top > mSecondRect.top) { return 1; } else if (mFirstRect.left < mSecondRect.left) { return -1; } else if (mFirstRect.left > mSecondRect.left) { return 1; } else if (mFirstRect.bottom < mSecondRect.bottom) { return -1; } else if (mFirstRect.bottom > mSecondRect.bottom) { return 1; } else if (mFirstRect.right < mSecondRect.right) { return -1; } else if (mFirstRect.right > mSecondRect.right) { return 1; } else { // The view are distinct but completely coincident so we consider // them equal for our purposes. Since the sort is stable, this // means that the views will retain their layout order relative to one another. return 0; } } private void getRect(View view, Rect rect) { view.getDrawingRect(rect); mRoot.offsetDescendantRectToMyCoords(view, rect); } } }