1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/mobile/android/base/gfx/Axis.java Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,417 @@
1.4 +/* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
1.5 + * This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +package org.mozilla.gecko.gfx;
1.10 +
1.11 +import java.util.HashMap;
1.12 +import java.util.Map;
1.13 +
1.14 +import org.mozilla.gecko.GeckoAppShell;
1.15 +import org.mozilla.gecko.PrefsHelper;
1.16 +import org.mozilla.gecko.util.FloatUtils;
1.17 +
1.18 +import android.util.Log;
1.19 +import android.view.View;
1.20 +
1.21 +/**
1.22 + * This class represents the physics for one axis of movement (i.e. either
1.23 + * horizontal or vertical). It tracks the different properties of movement
1.24 + * like displacement, velocity, viewport dimensions, etc. pertaining to
1.25 + * a particular axis.
1.26 + */
1.27 +abstract class Axis {
1.28 + private static final String LOGTAG = "GeckoAxis";
1.29 +
1.30 + private static final String PREF_SCROLLING_FRICTION_SLOW = "ui.scrolling.friction_slow";
1.31 + private static final String PREF_SCROLLING_FRICTION_FAST = "ui.scrolling.friction_fast";
1.32 + private static final String PREF_SCROLLING_MAX_EVENT_ACCELERATION = "ui.scrolling.max_event_acceleration";
1.33 + private static final String PREF_SCROLLING_OVERSCROLL_DECEL_RATE = "ui.scrolling.overscroll_decel_rate";
1.34 + private static final String PREF_SCROLLING_OVERSCROLL_SNAP_LIMIT = "ui.scrolling.overscroll_snap_limit";
1.35 + private static final String PREF_SCROLLING_MIN_SCROLLABLE_DISTANCE = "ui.scrolling.min_scrollable_distance";
1.36 +
1.37 + // This fraction of velocity remains after every animation frame when the velocity is low.
1.38 + private static float FRICTION_SLOW;
1.39 + // This fraction of velocity remains after every animation frame when the velocity is high.
1.40 + private static float FRICTION_FAST;
1.41 + // Below this velocity (in pixels per frame), the friction starts increasing from FRICTION_FAST
1.42 + // to FRICTION_SLOW.
1.43 + private static float VELOCITY_THRESHOLD;
1.44 + // The maximum velocity change factor between events, per ms, in %.
1.45 + // Direction changes are excluded.
1.46 + private static float MAX_EVENT_ACCELERATION;
1.47 +
1.48 + // The rate of deceleration when the surface has overscrolled.
1.49 + private static float OVERSCROLL_DECEL_RATE;
1.50 + // The percentage of the surface which can be overscrolled before it must snap back.
1.51 + private static float SNAP_LIMIT;
1.52 +
1.53 + // The minimum amount of space that must be present for an axis to be considered scrollable,
1.54 + // in pixels.
1.55 + private static float MIN_SCROLLABLE_DISTANCE;
1.56 +
1.57 + private static float getFloatPref(Map<String, Integer> prefs, String prefName, int defaultValue) {
1.58 + Integer value = (prefs == null ? null : prefs.get(prefName));
1.59 + return (float)(value == null || value < 0 ? defaultValue : value) / 1000f;
1.60 + }
1.61 +
1.62 + private static int getIntPref(Map<String, Integer> prefs, String prefName, int defaultValue) {
1.63 + Integer value = (prefs == null ? null : prefs.get(prefName));
1.64 + return (value == null || value < 0 ? defaultValue : value);
1.65 + }
1.66 +
1.67 + static void initPrefs() {
1.68 + final String[] prefs = { PREF_SCROLLING_FRICTION_FAST,
1.69 + PREF_SCROLLING_FRICTION_SLOW,
1.70 + PREF_SCROLLING_MAX_EVENT_ACCELERATION,
1.71 + PREF_SCROLLING_OVERSCROLL_DECEL_RATE,
1.72 + PREF_SCROLLING_OVERSCROLL_SNAP_LIMIT,
1.73 + PREF_SCROLLING_MIN_SCROLLABLE_DISTANCE };
1.74 +
1.75 + PrefsHelper.getPrefs(prefs, new PrefsHelper.PrefHandlerBase() {
1.76 + Map<String, Integer> mPrefs = new HashMap<String, Integer>();
1.77 +
1.78 + @Override public void prefValue(String name, int value) {
1.79 + mPrefs.put(name, value);
1.80 + }
1.81 +
1.82 + @Override public void finish() {
1.83 + setPrefs(mPrefs);
1.84 + }
1.85 + });
1.86 + }
1.87 +
1.88 + static final float MS_PER_FRAME = 1000.0f / 60.0f;
1.89 + static final long NS_PER_FRAME = Math.round(1000000000f / 60f);
1.90 + private static final float FRAMERATE_MULTIPLIER = (1000f/60f) / MS_PER_FRAME;
1.91 + private static final int FLING_VELOCITY_POINTS = 8;
1.92 +
1.93 + // The values we use for friction are based on a 16.6ms frame, adjust them to currentNsPerFrame:
1.94 + static float getFrameAdjustedFriction(float baseFriction, long currentNsPerFrame) {
1.95 + float framerateMultiplier = (float)currentNsPerFrame / NS_PER_FRAME;
1.96 + return (float)Math.pow(Math.E, (Math.log(baseFriction) / framerateMultiplier));
1.97 + }
1.98 +
1.99 + static void setPrefs(Map<String, Integer> prefs) {
1.100 + FRICTION_SLOW = getFloatPref(prefs, PREF_SCROLLING_FRICTION_SLOW, 850);
1.101 + FRICTION_FAST = getFloatPref(prefs, PREF_SCROLLING_FRICTION_FAST, 970);
1.102 + VELOCITY_THRESHOLD = 10 / FRAMERATE_MULTIPLIER;
1.103 + MAX_EVENT_ACCELERATION = getFloatPref(prefs, PREF_SCROLLING_MAX_EVENT_ACCELERATION, GeckoAppShell.getDpi() > 300 ? 100 : 40);
1.104 + OVERSCROLL_DECEL_RATE = getFloatPref(prefs, PREF_SCROLLING_OVERSCROLL_DECEL_RATE, 40);
1.105 + SNAP_LIMIT = getFloatPref(prefs, PREF_SCROLLING_OVERSCROLL_SNAP_LIMIT, 300);
1.106 + MIN_SCROLLABLE_DISTANCE = getFloatPref(prefs, PREF_SCROLLING_MIN_SCROLLABLE_DISTANCE, 500);
1.107 + Log.i(LOGTAG, "Prefs: " + FRICTION_SLOW + "," + FRICTION_FAST + "," + VELOCITY_THRESHOLD + ","
1.108 + + MAX_EVENT_ACCELERATION + "," + OVERSCROLL_DECEL_RATE + "," + SNAP_LIMIT + "," + MIN_SCROLLABLE_DISTANCE);
1.109 + }
1.110 +
1.111 + static {
1.112 + // set the scrolling parameters to default values on startup
1.113 + setPrefs(null);
1.114 + }
1.115 +
1.116 + private enum FlingStates {
1.117 + STOPPED,
1.118 + PANNING,
1.119 + FLINGING,
1.120 + }
1.121 +
1.122 + private enum Overscroll {
1.123 + NONE,
1.124 + MINUS, // Overscrolled in the negative direction
1.125 + PLUS, // Overscrolled in the positive direction
1.126 + BOTH, // Overscrolled in both directions (page is zoomed to smaller than screen)
1.127 + }
1.128 +
1.129 + private final SubdocumentScrollHelper mSubscroller;
1.130 +
1.131 + private int mOverscrollMode; /* Default to only overscrolling if we're allowed to scroll in a direction */
1.132 + private float mFirstTouchPos; /* Position of the first touch event on the current drag. */
1.133 + private float mTouchPos; /* Position of the most recent touch event on the current drag. */
1.134 + private float mLastTouchPos; /* Position of the touch event before touchPos. */
1.135 + private float mVelocity; /* Velocity in this direction; pixels per animation frame. */
1.136 + private float[] mRecentVelocities; /* Circular buffer of recent velocities since last touch start. */
1.137 + private int mRecentVelocityCount; /* Number of values put into mRecentVelocities (unbounded). */
1.138 + private boolean mScrollingDisabled; /* Whether movement on this axis is locked. */
1.139 + private boolean mDisableSnap; /* Whether overscroll snapping is disabled. */
1.140 + private float mDisplacement;
1.141 +
1.142 + private FlingStates mFlingState = FlingStates.STOPPED; /* The fling state we're in on this axis. */
1.143 +
1.144 + protected abstract float getOrigin();
1.145 + protected abstract float getViewportLength();
1.146 + protected abstract float getPageStart();
1.147 + protected abstract float getPageLength();
1.148 + protected abstract float getMarginStart();
1.149 + protected abstract float getMarginEnd();
1.150 + protected abstract boolean marginsHidden();
1.151 +
1.152 + Axis(SubdocumentScrollHelper subscroller) {
1.153 + mSubscroller = subscroller;
1.154 + mOverscrollMode = View.OVER_SCROLL_IF_CONTENT_SCROLLS;
1.155 + mRecentVelocities = new float[FLING_VELOCITY_POINTS];
1.156 + }
1.157 +
1.158 + // Implementors can override these to show effects when the axis overscrolls
1.159 + protected void overscrollFling(float velocity) { }
1.160 + protected void overscrollPan(float displacement) { }
1.161 +
1.162 + public void setOverScrollMode(int overscrollMode) {
1.163 + mOverscrollMode = overscrollMode;
1.164 + }
1.165 +
1.166 + public int getOverScrollMode() {
1.167 + return mOverscrollMode;
1.168 + }
1.169 +
1.170 + private float getViewportEnd() {
1.171 + return getOrigin() + getViewportLength();
1.172 + }
1.173 +
1.174 + private float getPageEnd() {
1.175 + return getPageStart() + getPageLength();
1.176 + }
1.177 +
1.178 + void startTouch(float pos) {
1.179 + mVelocity = 0.0f;
1.180 + mScrollingDisabled = false;
1.181 + mFirstTouchPos = mTouchPos = mLastTouchPos = pos;
1.182 + mRecentVelocityCount = 0;
1.183 + }
1.184 +
1.185 + float panDistance(float currentPos) {
1.186 + return currentPos - mFirstTouchPos;
1.187 + }
1.188 +
1.189 + void setScrollingDisabled(boolean disabled) {
1.190 + mScrollingDisabled = disabled;
1.191 + }
1.192 +
1.193 + void saveTouchPos() {
1.194 + mLastTouchPos = mTouchPos;
1.195 + }
1.196 +
1.197 + void updateWithTouchAt(float pos, float timeDelta) {
1.198 + float newVelocity = (mTouchPos - pos) / timeDelta * MS_PER_FRAME;
1.199 +
1.200 + mRecentVelocities[mRecentVelocityCount % FLING_VELOCITY_POINTS] = newVelocity;
1.201 + mRecentVelocityCount++;
1.202 +
1.203 + // If there's a direction change, or current velocity is very low,
1.204 + // allow setting of the velocity outright. Otherwise, use the current
1.205 + // velocity and a maximum change factor to set the new velocity.
1.206 + boolean curVelocityIsLow = Math.abs(mVelocity) < 1.0f / FRAMERATE_MULTIPLIER;
1.207 + boolean directionChange = (mVelocity > 0) != (newVelocity > 0);
1.208 + if (curVelocityIsLow || (directionChange && !FloatUtils.fuzzyEquals(newVelocity, 0.0f))) {
1.209 + mVelocity = newVelocity;
1.210 + } else {
1.211 + float maxChange = Math.abs(mVelocity * timeDelta * MAX_EVENT_ACCELERATION);
1.212 + mVelocity = Math.min(mVelocity + maxChange, Math.max(mVelocity - maxChange, newVelocity));
1.213 + }
1.214 +
1.215 + mTouchPos = pos;
1.216 + }
1.217 +
1.218 + boolean overscrolled() {
1.219 + return getOverscroll() != Overscroll.NONE;
1.220 + }
1.221 +
1.222 + private Overscroll getOverscroll() {
1.223 + boolean minus = (getOrigin() < getPageStart());
1.224 + boolean plus = (getViewportEnd() > getPageEnd());
1.225 + if (minus && plus) {
1.226 + return Overscroll.BOTH;
1.227 + } else if (minus) {
1.228 + return Overscroll.MINUS;
1.229 + } else if (plus) {
1.230 + return Overscroll.PLUS;
1.231 + } else {
1.232 + return Overscroll.NONE;
1.233 + }
1.234 + }
1.235 +
1.236 + // Returns the amount that the page has been overscrolled. If the page hasn't been
1.237 + // overscrolled on this axis, returns 0.
1.238 + private float getExcess() {
1.239 + switch (getOverscroll()) {
1.240 + case MINUS: return getPageStart() - getOrigin();
1.241 + case PLUS: return getViewportEnd() - getPageEnd();
1.242 + case BOTH: return (getViewportEnd() - getPageEnd()) + (getPageStart() - getOrigin());
1.243 + default: return 0.0f;
1.244 + }
1.245 + }
1.246 +
1.247 + /*
1.248 + * Returns true if the page is zoomed in to some degree along this axis such that scrolling is
1.249 + * possible and this axis has not been scroll locked while panning. Otherwise, returns false.
1.250 + */
1.251 + boolean scrollable() {
1.252 + // If we're scrolling a subdocument, ignore the viewport length restrictions (since those
1.253 + // apply to the top-level document) and only take into account axis locking.
1.254 + if (mSubscroller.scrolling()) {
1.255 + return !mScrollingDisabled;
1.256 + }
1.257 +
1.258 + // if we are axis locked, return false
1.259 + if (mScrollingDisabled) {
1.260 + return false;
1.261 + }
1.262 +
1.263 + // if there are margins on this axis but they are currently hidden,
1.264 + // we must be able to scroll in order to make them visible, so allow
1.265 + // scrolling in that case
1.266 + if (marginsHidden()) {
1.267 + return true;
1.268 + }
1.269 +
1.270 + // there is scrollable space, and we're not disabled, or the document fits the viewport
1.271 + // but we always allow overscroll anyway
1.272 + return getViewportLength() <= getPageLength() - MIN_SCROLLABLE_DISTANCE ||
1.273 + getOverScrollMode() == View.OVER_SCROLL_ALWAYS;
1.274 + }
1.275 +
1.276 + /*
1.277 + * Returns the resistance, as a multiplier, that should be taken into account when
1.278 + * tracking or pinching.
1.279 + */
1.280 + float getEdgeResistance(boolean forPinching) {
1.281 + float excess = getExcess();
1.282 + if (excess > 0.0f && (getOverscroll() == Overscroll.BOTH || !forPinching)) {
1.283 + // excess can be greater than viewport length, but the resistance
1.284 + // must never drop below 0.0
1.285 + return Math.max(0.0f, SNAP_LIMIT - excess / getViewportLength());
1.286 + }
1.287 + return 1.0f;
1.288 + }
1.289 +
1.290 + /* Returns the velocity. If the axis is locked, returns 0. */
1.291 + float getRealVelocity() {
1.292 + return scrollable() ? mVelocity : 0f;
1.293 + }
1.294 +
1.295 + void startPan() {
1.296 + mFlingState = FlingStates.PANNING;
1.297 + }
1.298 +
1.299 + private float calculateFlingVelocity() {
1.300 + int usablePoints = Math.min(mRecentVelocityCount, FLING_VELOCITY_POINTS);
1.301 + if (usablePoints <= 1) {
1.302 + return mVelocity;
1.303 + }
1.304 + float average = 0;
1.305 + for (int i = 0; i < usablePoints; i++) {
1.306 + average += mRecentVelocities[i];
1.307 + }
1.308 + return average / usablePoints;
1.309 + }
1.310 +
1.311 + void startFling(boolean stopped) {
1.312 + mDisableSnap = mSubscroller.scrolling();
1.313 +
1.314 + if (stopped) {
1.315 + mFlingState = FlingStates.STOPPED;
1.316 + } else {
1.317 + mVelocity = calculateFlingVelocity();
1.318 + mFlingState = FlingStates.FLINGING;
1.319 + }
1.320 + }
1.321 +
1.322 + /* Advances a fling animation by one step. */
1.323 + boolean advanceFling(long realNsPerFrame) {
1.324 + if (mFlingState != FlingStates.FLINGING) {
1.325 + return false;
1.326 + }
1.327 + if (mSubscroller.scrolling() && !mSubscroller.lastScrollSucceeded()) {
1.328 + // if the subdocument stopped scrolling, it's because it reached the end
1.329 + // of the subdocument. we don't do overscroll on subdocuments, so there's
1.330 + // no point in continuing this fling.
1.331 + return false;
1.332 + }
1.333 +
1.334 + float excess = getExcess();
1.335 + Overscroll overscroll = getOverscroll();
1.336 + boolean decreasingOverscroll = false;
1.337 + if ((overscroll == Overscroll.MINUS && mVelocity > 0) ||
1.338 + (overscroll == Overscroll.PLUS && mVelocity < 0))
1.339 + {
1.340 + decreasingOverscroll = true;
1.341 + }
1.342 +
1.343 + if (mDisableSnap || FloatUtils.fuzzyEquals(excess, 0.0f) || decreasingOverscroll) {
1.344 + // If we aren't overscrolled, just apply friction.
1.345 + if (Math.abs(mVelocity) >= VELOCITY_THRESHOLD) {
1.346 + mVelocity *= getFrameAdjustedFriction(FRICTION_FAST, realNsPerFrame);
1.347 + } else {
1.348 + float t = mVelocity / VELOCITY_THRESHOLD;
1.349 + mVelocity *= FloatUtils.interpolate(getFrameAdjustedFriction(FRICTION_SLOW, realNsPerFrame),
1.350 + getFrameAdjustedFriction(FRICTION_FAST, realNsPerFrame), t);
1.351 + }
1.352 + } else {
1.353 + // Otherwise, decrease the velocity linearly.
1.354 + float elasticity = 1.0f - excess / (getViewportLength() * SNAP_LIMIT);
1.355 + float overscrollDecelRate = getFrameAdjustedFriction(OVERSCROLL_DECEL_RATE, realNsPerFrame);
1.356 + if (overscroll == Overscroll.MINUS) {
1.357 + mVelocity = Math.min((mVelocity + overscrollDecelRate) * elasticity, 0.0f);
1.358 + } else { // must be Overscroll.PLUS
1.359 + mVelocity = Math.max((mVelocity - overscrollDecelRate) * elasticity, 0.0f);
1.360 + }
1.361 + }
1.362 +
1.363 + return true;
1.364 + }
1.365 +
1.366 + void stopFling() {
1.367 + mVelocity = 0.0f;
1.368 + mFlingState = FlingStates.STOPPED;
1.369 + }
1.370 +
1.371 + // Performs displacement of the viewport position according to the current velocity.
1.372 + void displace() {
1.373 + // if this isn't scrollable just return
1.374 + if (!scrollable())
1.375 + return;
1.376 +
1.377 + if (mFlingState == FlingStates.PANNING)
1.378 + mDisplacement += (mLastTouchPos - mTouchPos) * getEdgeResistance(false);
1.379 + else
1.380 + mDisplacement += mVelocity * getEdgeResistance(false);
1.381 +
1.382 + // if overscroll is disabled and we're trying to overscroll, reset the displacement
1.383 + // to remove any excess. Using getExcess alone isn't enough here since it relies on
1.384 + // getOverscroll which doesn't take into account any new displacment being applied.
1.385 + // If we using a subscroller, we don't want to alter the scrolling being done
1.386 + if (getOverScrollMode() == View.OVER_SCROLL_NEVER && !mSubscroller.scrolling()) {
1.387 + float originalDisplacement = mDisplacement;
1.388 +
1.389 + if (mDisplacement + getOrigin() < getPageStart() - getMarginStart()) {
1.390 + mDisplacement = getPageStart() - getMarginStart() - getOrigin();
1.391 + } else if (mDisplacement + getViewportEnd() > getPageEnd() + getMarginEnd()) {
1.392 + mDisplacement = getPageEnd() - getMarginEnd() - getViewportEnd();
1.393 + }
1.394 +
1.395 + // Return the amount of overscroll so that the overscroll controller can draw it for us
1.396 + if (originalDisplacement != mDisplacement) {
1.397 + if (mFlingState == FlingStates.FLINGING) {
1.398 + overscrollFling(mVelocity / MS_PER_FRAME * 1000);
1.399 + stopFling();
1.400 + } else if (mFlingState == FlingStates.PANNING) {
1.401 + overscrollPan(originalDisplacement - mDisplacement);
1.402 + }
1.403 + }
1.404 + }
1.405 + }
1.406 +
1.407 + float resetDisplacement() {
1.408 + float d = mDisplacement;
1.409 + mDisplacement = 0.0f;
1.410 + return d;
1.411 + }
1.412 +
1.413 + void setAutoscrollVelocity(float velocity) {
1.414 + if (mFlingState != FlingStates.STOPPED) {
1.415 + Log.e(LOGTAG, "Setting autoscroll velocity while in a fling is not allowed!");
1.416 + return;
1.417 + }
1.418 + mVelocity = velocity;
1.419 + }
1.420 +}
