mobileledger/ui/FabManager.java

   1 /*
   2  * Copyright © 2021 Damyan Ivanov.
   3  * This file is part of MoLe.
   4  * MoLe is free software: you can distribute it and/or modify it
   5  * under the term of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your opinion), any later version.
   8  *
   9  * MoLe is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  12  * GNU General Public License terms for details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with MoLe. If not, see <https://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.ktnx.mobileledger.ui;
  19
  20 import android.animation.Animator;
  21 import android.animation.AnimatorListenerAdapter;
  22 import android.animation.TimeInterpolator;
  23 import android.annotation.SuppressLint;
  24 import android.content.Context;
  25 import android.os.Handler;
  26 import android.view.MotionEvent;
  27 import android.view.ViewGroup;
  28 import android.view.ViewPropertyAnimator;
  29
  30 import androidx.annotation.NonNull;
  31 import androidx.recyclerview.widget.RecyclerView;
  32
  33 import com.google.android.material.floatingactionbutton.FloatingActionButton;
  34
  35 import net.ktnx.mobileledger.utils.DimensionUtils;
  36 import net.ktnx.mobileledger.utils.Logger;
  37
  38 public class FabManager {
  39     private static final boolean FAB_SHOWN = true;
  40     private static final boolean FAB_HIDDEN = false;
  41     private static final int AUTO_SHOW_DELAY_MILLS = 4000;
  42     private final FloatingActionButton fab;
  43     private boolean wantedFabState = FAB_SHOWN;
  44     private ViewPropertyAnimator fabSlideAnimator;
  45     private int fabVerticalOffset;
  46     public FabManager(FloatingActionButton fab) {
  47         this.fab = fab;
  48     }
  49     public static void handle(FabHandler fabHandler, RecyclerView recyclerView) {
  50         new ScrollFabHandler(fabHandler, recyclerView);
  51     }
  52     private void slideFabTo(int target, long duration, TimeInterpolator interpolator) {
  53         fabSlideAnimator = fab.animate()
  54                               .translationY((float) target)
  55                               .setInterpolator(interpolator)
  56                               .setDuration(duration)
  57                               .setListener(new AnimatorListenerAdapter() {
  58                                   public void onAnimationEnd(Animator animation) {
  59                                       fabSlideAnimator = null;
  60                                   }
  61                               });
  62     }
  63     public void showFab() {
  64         if (wantedFabState == FAB_SHOWN) {
  65 //            Logger.debug("fab", "Ignoring request to show already visible FAB");
  66             return;
  67         }
  68
  69 //        b.btnAddTransaction.show();
  70         if (this.fabSlideAnimator != null) {
  71             this.fabSlideAnimator.cancel();
  72             fab.clearAnimation();
  73         }
  74
  75         Logger.debug("fab", "Showing FAB");
  76         wantedFabState = FAB_SHOWN;
  77         slideFabTo(0, 200L,
  78                 com.google.android.material.animation.AnimationUtils.LINEAR_OUT_SLOW_IN_INTERPOLATOR);
  79     }
  80     public void hideFab() {
  81         if (wantedFabState == FAB_HIDDEN) {
  82 //            Logger.debug("fab", "Ignoring request to hide FAB -- already hidden");
  83             return;
  84         }
  85
  86         calcVerticalFabOffset();
  87
  88 //        b.btnAddTransaction.hide();
  89         if (this.fabSlideAnimator != null) {
  90             this.fabSlideAnimator.cancel();
  91             fab.clearAnimation();
  92         }
  93
  94         Logger.debug("fab", "Hiding FAB");
  95         wantedFabState = FAB_HIDDEN;
  96         slideFabTo(fabVerticalOffset, 150L,
  97                 com.google.android.material.animation.AnimationUtils.FAST_OUT_LINEAR_IN_INTERPOLATOR);
  98     }
  99     private void calcVerticalFabOffset() {
 100         if (fabVerticalOffset > 0)
 101             return;// already calculated
 102         fab.measure(0, 0);
 103
 104         int height = fab.getMeasuredHeight();
 105
 106         int bottomMargin;
 107
 108         ViewGroup.LayoutParams layoutParams = fab.getLayoutParams();
 109         if (layoutParams instanceof ViewGroup.MarginLayoutParams)
 110             bottomMargin = ((ViewGroup.MarginLayoutParams) layoutParams).bottomMargin;
 111         else
 112             throw new RuntimeException("Unsupported layout params " + layoutParams.getClass()
 113                                                                                   .getCanonicalName());
 114
 115         fabVerticalOffset = height + bottomMargin;
 116     }
 117     public interface FabHandler {
 118         Context getContext();
 119
 120         void showManagedFab();
 121
 122         void hideManagedFab();
 123     }
 124
 125     public static class ScrollFabHandler {
 126         final private FabHandler fabHandler;
 127         private int generation = 0;
 128         @SuppressLint("ClickableViewAccessibility")
 129         ScrollFabHandler(FabHandler fabHandler, RecyclerView recyclerView) {
 130             this.fabHandler = fabHandler;
 131             final float triggerAbsolutePixels = DimensionUtils.dp2px(fabHandler.getContext(), 20f);
 132             final float triggerRelativePixels = triggerAbsolutePixels / 4f;
 133             recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
 134                 @Override
 135                 public void onScrolled(@NonNull RecyclerView recyclerView, int dx, int dy) {
 136 //                    Logger.debug("touch", "Scrolled " + dy);
 137                     if (dy <= 0) {
 138                         showFab();
 139                     }
 140                     else
 141                         hideFab();
 142
 143                     super.onScrolled(recyclerView, dx, dy);
 144                 }
 145             });
 146             recyclerView.addOnItemTouchListener(new RecyclerView.SimpleOnItemTouchListener() {
 147                 private float absoluteAnchor = -1;
 148                 @Override
 149                 public boolean onInterceptTouchEvent(@NonNull RecyclerView rv,
 150                                                      @NonNull MotionEvent e) {
 151                     switch (e.getActionMasked()) {
 152                         case MotionEvent.ACTION_DOWN:
 153                             absoluteAnchor = e.getRawY();
 154 //                        Logger.debug("touch",
 155 //                                String.format(Locale.US, "Touch down at %4.2f", absoluteAnchor));
 156                             break;
 157                         case MotionEvent.ACTION_MOVE:
 158                             if (absoluteAnchor < 0)
 159                                 break;
 160
 161                             final float absoluteY = e.getRawY();
 162 //                        Logger.debug("touch", String.format(Locale.US, "Move to %4.2f",
 163 //                        absoluteY));
 164
 165                             if (absoluteY > absoluteAnchor + triggerAbsolutePixels) {
 166                                 // swipe down
 167 //                            Logger.debug("touch", "SHOW");
 168                                 showFab();
 169                                 absoluteAnchor = absoluteY;
 170                             }
 171                             else if (absoluteY < absoluteAnchor - triggerAbsolutePixels) {
 172                                 // swipe up
 173 //                            Logger.debug("touch", "HIDE");
 174                                 hideFab();
 175                                 absoluteAnchor = absoluteY;
 176                             }
 177
 178                             break;
 179                     }
 180                     return false;
 181                 }
 182             });
 183         }
 184         private void hideFab() {
 185             generation++;
 186             int thisGeneration = generation;
 187             fabHandler.hideManagedFab();
 188             new Handler().postDelayed(() -> {
 189                 if (generation != thisGeneration)
 190                     return;
 191
 192                 showFab();
 193             }, AUTO_SHOW_DELAY_MILLS);
 194         }
 195         private void showFab() {
 196             generation++;
 197             fabHandler.showManagedFab();
 198         }
 199     }
 200 }