481 lines
19 KiB
Java
481 lines
19 KiB
Java
/*
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* Copyright (C) 2007 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.view;
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import android.graphics.Rect;
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import java.util.ArrayList;
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/**
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* The algorithm used for finding the next focusable view in a given direction
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* from a view that currently has focus.
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*/
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public class FocusFinder {
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private static ThreadLocal<FocusFinder> tlFocusFinder =
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new ThreadLocal<FocusFinder>() {
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protected FocusFinder initialValue() {
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return new FocusFinder();
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}
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};
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/**
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* Get the focus finder for this thread.
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*/
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public static FocusFinder getInstance() {
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return tlFocusFinder.get();
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}
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Rect mFocusedRect = new Rect();
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Rect mOtherRect = new Rect();
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Rect mBestCandidateRect = new Rect();
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// enforce thread local access
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private FocusFinder() {}
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/**
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* Find the next view to take focus in root's descendants, starting from the view
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* that currently is focused.
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* @param root Contains focused
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* @param focused Has focus now.
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* @param direction Direction to look.
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* @return The next focusable view, or null if none exists.
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*/
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public final View findNextFocus(ViewGroup root, View focused, int direction) {
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if (focused != null) {
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// check for user specified next focus
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View userSetNextFocus = focused.findUserSetNextFocus(root, direction);
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if (userSetNextFocus != null &&
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userSetNextFocus.isFocusable() &&
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(!userSetNextFocus.isInTouchMode() ||
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userSetNextFocus.isFocusableInTouchMode())) {
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return userSetNextFocus;
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}
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// fill in interesting rect from focused
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focused.getFocusedRect(mFocusedRect);
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root.offsetDescendantRectToMyCoords(focused, mFocusedRect);
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} else {
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// make up a rect at top left or bottom right of root
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switch (direction) {
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case View.FOCUS_RIGHT:
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case View.FOCUS_DOWN:
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final int rootTop = root.getScrollY();
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final int rootLeft = root.getScrollX();
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mFocusedRect.set(rootLeft, rootTop, rootLeft, rootTop);
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break;
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case View.FOCUS_LEFT:
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case View.FOCUS_UP:
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final int rootBottom = root.getScrollY() + root.getHeight();
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final int rootRight = root.getScrollX() + root.getWidth();
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mFocusedRect.set(rootRight, rootBottom,
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rootRight, rootBottom);
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break;
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}
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}
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return findNextFocus(root, focused, mFocusedRect, direction);
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}
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/**
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* Find the next view to take focus in root's descendants, searching from
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* a particular rectangle in root's coordinates.
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* @param root Contains focusedRect.
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* @param focusedRect The starting point of the search.
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* @param direction Direction to look.
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* @return The next focusable view, or null if none exists.
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*/
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public View findNextFocusFromRect(ViewGroup root, Rect focusedRect, int direction) {
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return findNextFocus(root, null, focusedRect, direction);
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}
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private View findNextFocus(ViewGroup root, View focused, Rect focusedRect, int direction) {
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ArrayList<View> focusables = root.getFocusables(direction);
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// initialize the best candidate to something impossible
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// (so the first plausible view will become the best choice)
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mBestCandidateRect.set(focusedRect);
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switch(direction) {
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case View.FOCUS_LEFT:
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mBestCandidateRect.offset(focusedRect.width() + 1, 0);
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break;
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case View.FOCUS_RIGHT:
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mBestCandidateRect.offset(-(focusedRect.width() + 1), 0);
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break;
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case View.FOCUS_UP:
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mBestCandidateRect.offset(0, focusedRect.height() + 1);
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break;
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case View.FOCUS_DOWN:
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mBestCandidateRect.offset(0, -(focusedRect.height() + 1));
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}
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View closest = null;
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int numFocusables = focusables.size();
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for (int i = 0; i < numFocusables; i++) {
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View focusable = focusables.get(i);
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// only interested in other non-root views
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if (focusable == focused || focusable == root) continue;
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// get visible bounds of other view in same coordinate system
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focusable.getDrawingRect(mOtherRect);
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root.offsetDescendantRectToMyCoords(focusable, mOtherRect);
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if (isBetterCandidate(direction, focusedRect, mOtherRect, mBestCandidateRect)) {
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mBestCandidateRect.set(mOtherRect);
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closest = focusable;
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}
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}
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return closest;
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}
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/**
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* Is rect1 a better candidate than rect2 for a focus search in a particular
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* direction from a source rect? This is the core routine that determines
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* the order of focus searching.
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* @param direction the direction (up, down, left, right)
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* @param source The source we are searching from
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* @param rect1 The candidate rectangle
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* @param rect2 The current best candidate.
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* @return Whether the candidate is the new best.
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*/
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boolean isBetterCandidate(int direction, Rect source, Rect rect1, Rect rect2) {
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// to be a better candidate, need to at least be a candidate in the first
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// place :)
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if (!isCandidate(source, rect1, direction)) {
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return false;
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}
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// we know that rect1 is a candidate.. if rect2 is not a candidate,
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// rect1 is better
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if (!isCandidate(source, rect2, direction)) {
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return true;
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}
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// if rect1 is better by beam, it wins
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if (beamBeats(direction, source, rect1, rect2)) {
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return true;
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}
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// if rect2 is better, then rect1 cant' be :)
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if (beamBeats(direction, source, rect2, rect1)) {
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return false;
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}
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// otherwise, do fudge-tastic comparison of the major and minor axis
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return (getWeightedDistanceFor(
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majorAxisDistance(direction, source, rect1),
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minorAxisDistance(direction, source, rect1))
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< getWeightedDistanceFor(
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majorAxisDistance(direction, source, rect2),
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minorAxisDistance(direction, source, rect2)));
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}
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/**
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* One rectangle may be another candidate than another by virtue of being
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* exclusively in the beam of the source rect.
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* @return Whether rect1 is a better candidate than rect2 by virtue of it being in src's
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* beam
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*/
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boolean beamBeats(int direction, Rect source, Rect rect1, Rect rect2) {
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final boolean rect1InSrcBeam = beamsOverlap(direction, source, rect1);
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final boolean rect2InSrcBeam = beamsOverlap(direction, source, rect2);
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// if rect1 isn't exclusively in the src beam, it doesn't win
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if (rect2InSrcBeam || !rect1InSrcBeam) {
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return false;
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}
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// we know rect1 is in the beam, and rect2 is not
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// if rect1 is to the direction of, and rect2 is not, rect1 wins.
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// for example, for direction left, if rect1 is to the left of the source
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// and rect2 is below, then we always prefer the in beam rect1, since rect2
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// could be reached by going down.
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if (!isToDirectionOf(direction, source, rect2)) {
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return true;
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}
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// for horizontal directions, being exclusively in beam always wins
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if ((direction == View.FOCUS_LEFT || direction == View.FOCUS_RIGHT)) {
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return true;
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}
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// for vertical directions, beams only beat up to a point:
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// now, as long as rect2 isn't completely closer, rect1 wins
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// e.g for direction down, completely closer means for rect2's top
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// edge to be closer to the source's top edge than rect1's bottom edge.
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return (majorAxisDistance(direction, source, rect1)
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< majorAxisDistanceToFarEdge(direction, source, rect2));
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}
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/**
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* Fudge-factor opportunity: how to calculate distance given major and minor
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* axis distances. Warning: this fudge factor is finely tuned, be sure to
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* run all focus tests if you dare tweak it.
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*/
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int getWeightedDistanceFor(int majorAxisDistance, int minorAxisDistance) {
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return 13 * majorAxisDistance * majorAxisDistance
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+ minorAxisDistance * minorAxisDistance;
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}
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/**
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* Is destRect a candidate for the next focus given the direction? This
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* checks whether the dest is at least partially to the direction of (e.g left of)
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* from source.
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*
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* Includes an edge case for an empty rect (which is used in some cases when
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* searching from a point on the screen).
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*/
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boolean isCandidate(Rect srcRect, Rect destRect, int direction) {
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switch (direction) {
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case View.FOCUS_LEFT:
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return (srcRect.right > destRect.right || srcRect.left >= destRect.right)
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&& srcRect.left > destRect.left;
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case View.FOCUS_RIGHT:
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return (srcRect.left < destRect.left || srcRect.right <= destRect.left)
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&& srcRect.right < destRect.right;
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case View.FOCUS_UP:
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return (srcRect.bottom > destRect.bottom || srcRect.top >= destRect.bottom)
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&& srcRect.top > destRect.top;
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case View.FOCUS_DOWN:
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return (srcRect.top < destRect.top || srcRect.bottom <= destRect.top)
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&& srcRect.bottom < destRect.bottom;
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* Do the "beams" w.r.t the given direcition's axos of rect1 and rect2 overlap?
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* @param direction the direction (up, down, left, right)
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* @param rect1 The first rectangle
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* @param rect2 The second rectangle
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* @return whether the beams overlap
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*/
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boolean beamsOverlap(int direction, Rect rect1, Rect rect2) {
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switch (direction) {
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case View.FOCUS_LEFT:
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case View.FOCUS_RIGHT:
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return (rect2.bottom >= rect1.top) && (rect2.top <= rect1.bottom);
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case View.FOCUS_UP:
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case View.FOCUS_DOWN:
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return (rect2.right >= rect1.left) && (rect2.left <= rect1.right);
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* e.g for left, is 'to left of'
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*/
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boolean isToDirectionOf(int direction, Rect src, Rect dest) {
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switch (direction) {
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case View.FOCUS_LEFT:
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return src.left >= dest.right;
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case View.FOCUS_RIGHT:
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return src.right <= dest.left;
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case View.FOCUS_UP:
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return src.top >= dest.bottom;
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case View.FOCUS_DOWN:
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return src.bottom <= dest.top;
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* @return The distance from the edge furthest in the given direction
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* of source to the edge nearest in the given direction of dest. If the
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* dest is not in the direction from source, return 0.
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*/
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static int majorAxisDistance(int direction, Rect source, Rect dest) {
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return Math.max(0, majorAxisDistanceRaw(direction, source, dest));
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}
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static int majorAxisDistanceRaw(int direction, Rect source, Rect dest) {
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switch (direction) {
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case View.FOCUS_LEFT:
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return source.left - dest.right;
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case View.FOCUS_RIGHT:
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return dest.left - source.right;
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case View.FOCUS_UP:
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return source.top - dest.bottom;
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case View.FOCUS_DOWN:
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return dest.top - source.bottom;
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* @return The distance along the major axis w.r.t the direction from the
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* edge of source to the far edge of dest. If the
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* dest is not in the direction from source, return 1 (to break ties with
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* {@link #majorAxisDistance}).
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*/
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static int majorAxisDistanceToFarEdge(int direction, Rect source, Rect dest) {
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return Math.max(1, majorAxisDistanceToFarEdgeRaw(direction, source, dest));
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}
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static int majorAxisDistanceToFarEdgeRaw(int direction, Rect source, Rect dest) {
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switch (direction) {
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case View.FOCUS_LEFT:
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return source.left - dest.left;
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case View.FOCUS_RIGHT:
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return dest.right - source.right;
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case View.FOCUS_UP:
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return source.top - dest.top;
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case View.FOCUS_DOWN:
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return dest.bottom - source.bottom;
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* Find the distance on the minor axis w.r.t the direction to the nearest
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* edge of the destination rectange.
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* @param direction the direction (up, down, left, right)
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* @param source The source rect.
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* @param dest The destination rect.
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* @return The distance.
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*/
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static int minorAxisDistance(int direction, Rect source, Rect dest) {
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switch (direction) {
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case View.FOCUS_LEFT:
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case View.FOCUS_RIGHT:
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// the distance between the center verticals
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return Math.abs(
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((source.top + source.height() / 2) -
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((dest.top + dest.height() / 2))));
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case View.FOCUS_UP:
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case View.FOCUS_DOWN:
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// the distance between the center horizontals
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return Math.abs(
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((source.left + source.width() / 2) -
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((dest.left + dest.width() / 2))));
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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/**
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* Find the nearest touchable view to the specified view.
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*
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* @param root The root of the tree in which to search
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* @param x X coordinate from which to start the search
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* @param y Y coordinate from which to start the search
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* @param direction Direction to look
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* @param deltas Offset from the <x, y> to the edge of the nearest view. Note that this array
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* may already be populated with values.
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* @return The nearest touchable view, or null if none exists.
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*/
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public View findNearestTouchable(ViewGroup root, int x, int y, int direction, int[] deltas) {
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ArrayList<View> touchables = root.getTouchables();
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int minDistance = Integer.MAX_VALUE;
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View closest = null;
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int numTouchables = touchables.size();
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int edgeSlop = ViewConfiguration.get(root.mContext).getScaledEdgeSlop();
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Rect closestBounds = new Rect();
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Rect touchableBounds = mOtherRect;
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for (int i = 0; i < numTouchables; i++) {
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View touchable = touchables.get(i);
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// get visible bounds of other view in same coordinate system
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touchable.getDrawingRect(touchableBounds);
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root.offsetRectBetweenParentAndChild(touchable, touchableBounds, true, true);
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if (!isTouchCandidate(x, y, touchableBounds, direction)) {
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continue;
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}
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int distance = Integer.MAX_VALUE;
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switch (direction) {
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case View.FOCUS_LEFT:
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distance = x - touchableBounds.right + 1;
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break;
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case View.FOCUS_RIGHT:
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distance = touchableBounds.left;
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break;
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case View.FOCUS_UP:
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distance = y - touchableBounds.bottom + 1;
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break;
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case View.FOCUS_DOWN:
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distance = touchableBounds.top;
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break;
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}
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if (distance < edgeSlop) {
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// Give preference to innermost views
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if (closest == null ||
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closestBounds.contains(touchableBounds) ||
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(!touchableBounds.contains(closestBounds) && distance < minDistance)) {
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minDistance = distance;
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closest = touchable;
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closestBounds.set(touchableBounds);
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switch (direction) {
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case View.FOCUS_LEFT:
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deltas[0] = -distance;
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break;
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case View.FOCUS_RIGHT:
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deltas[0] = distance;
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break;
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case View.FOCUS_UP:
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deltas[1] = -distance;
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break;
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case View.FOCUS_DOWN:
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deltas[1] = distance;
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break;
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}
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}
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}
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}
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return closest;
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}
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/**
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* Is destRect a candidate for the next touch given the direction?
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*/
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private boolean isTouchCandidate(int x, int y, Rect destRect, int direction) {
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switch (direction) {
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case View.FOCUS_LEFT:
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return destRect.left <= x && destRect.top <= y && y <= destRect.bottom;
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case View.FOCUS_RIGHT:
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return destRect.left >= x && destRect.top <= y && y <= destRect.bottom;
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case View.FOCUS_UP:
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return destRect.top <= y && destRect.left <= x && x <= destRect.right;
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case View.FOCUS_DOWN:
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return destRect.top >= y && destRect.left <= x && x <= destRect.right;
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}
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throw new IllegalArgumentException("direction must be one of "
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+ "{FOCUS_UP, FOCUS_DOWN, FOCUS_LEFT, FOCUS_RIGHT}.");
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}
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}
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