fix: Tutorial 2-5

Author: SmartToolFactory

External-Tutorial-GridToPager/src/main/java/com/google/samples/gridtopager/fragment/GridFragment.java

@@ -125,7 +125,8 @@ public void onMapSharedElements(List<String> names, Map<String, View> sharedElem
 
                         System.out.println("🎃  setExitSharedElementCallback() " +
                                 " thisFragment: " + thisFragment.getClass().getSimpleName() +
-                                " viewBefore: " + (viewBefore != null ? viewBefore.hashCode() : -1) +
+                                "\nMainActivity.currentPosition: " +  MainActivity.currentPosition+
+                                "\nviewBefore: " + (viewBefore != null ? viewBefore.hashCode() : -1) +
                                 "\nviewAfter: " + (viewAfter != null ? viewAfter.hashCode() : -1));
                     }
                 });

External-Tutorial-GridToPager/src/main/java/com/google/samples/gridtopager/fragment/ImagePagerFragment.java

@@ -17,22 +17,21 @@
 package com.google.samples.gridtopager.fragment;
 
 import android.os.Bundle;
-
-import androidx.annotation.Nullable;
-import androidx.fragment.app.Fragment;
-import androidx.core.app.SharedElementCallback;
-import androidx.viewpager.widget.ViewPager;
-
 import android.transition.Transition;
 import android.transition.TransitionInflater;
 import android.view.LayoutInflater;
 import android.view.View;
 import android.view.ViewGroup;
 import android.widget.Toast;
 
+import androidx.annotation.Nullable;
+import androidx.core.app.SharedElementCallback;
+import androidx.fragment.app.Fragment;
+import androidx.viewpager.widget.ViewPager;
+
 import com.google.samples.gridtopager.MainActivity;
-import com.google.samples.gridtopager.adapter.ImagePagerAdapter;
 import com.google.samples.gridtopager.R;
+import com.google.samples.gridtopager.adapter.ImagePagerAdapter;
 
 import java.util.List;
 import java.util.Map;
@@ -113,7 +112,8 @@ public void onMapSharedElements(List<String> names, Map<String, View> sharedElem
 
                         System.out.println("👻  setEnterSharedElementCallback() " +
                                 " thisFragment: " + thisFragment.getClass().getSimpleName() +
-                                " viewBefore: " + (viewBefore != null ? viewBefore.hashCode() : -1) +
+                                "\nMainActivity.currentPosition: " +  MainActivity.currentPosition+
+                                "\nviewBefore: " + (viewBefore != null ? viewBefore.hashCode() : -1) +
                                 "\nviewAfter: " + (viewAfter != null ? viewAfter.hashCode() : -1));
                     }
                 });

README.md

@@ -287,6 +287,7 @@ ExitSharedElementCallback is triggered in first Activity, in second Activity Ent
 * 🔥🔥🔥 Make sure that you are importing  ```androidx.transition```, do NOT import *android.transition* components,
 mixing different import packages causes ***Wrong Transition Exception***
 * exitTransition, enterTransition, returnTransition and reEnterTransitions are null for fragments by default.
+
 *  🔥🔥 Setting allowReturnTransitionOverlap to false lets this fragment's reenterTransition to wait previous fragment's returnTransition to finish
 * add sharedElement to fragments with ```addSharedElement(ivPhoto, ivPhoto.transitionName)```
 and use ```setReorderingAllowed(true)``` to optimize for shared element transition
@@ -304,6 +305,17 @@ val extras = FragmentNavigatorExtras(
 findNavController().navigate(direction, extras)
 ```
 
+* 🔥🔥🔥 With transitions, it's required for start and end values to be different from each other to call
+```createAnimator``` method. 
+
+To make sure that it gets called, either set **captureStartValues**
+and **captureEndValues** manually, or in fragment transitioned to, create ** setEnterSharedElementCallback**
+and override **onSharedElementStart** and **onSharedElementEnd** methods and set properties of
+objects that are not shared in both fragments.
+ 
+ Without doing this enter or exit might not work because
+of ***Transition*** start and end point to same value.
+
 ### Resources and References
 Wonderful and very helpful resources, check them out 🤩😍
 

Tutorial3-1Transitions/src/main/java/com/smarttoolfactory/tutorial3_1transitions/adapter/model/MagazineModel.kt

@@ -8,5 +8,8 @@ import kotlinx.android.parcel.Parcelize
 data class MagazineModel(
     @DrawableRes val drawableRes: Int,
     val title: String,
-    val body: String
-) : Parcelable
+    val body: String,
+    val transitionId: Int = 0
+) : Parcelable {
+    var transitionName = "tr$drawableRes$transitionId"
+}

Tutorial3-1Transitions/src/main/java/com/smarttoolfactory/tutorial3_1transitions/adapter/viewholder/MagazineListViewBinder.kt

@@ -70,7 +70,7 @@ class MagazineListViewHolder(
                     false,
                     3,
                     0f,
-                    ratio = 2f
+                    ratio = 1.8f
                 )
         }
 

Tutorial3-1Transitions/src/main/java/com/smarttoolfactory/tutorial3_1transitions/adapter/viewholder/MagazineViewBinder.kt

@@ -51,7 +51,7 @@ class MagazineViewHolder(
     fun bind(model: MagazineModel) {
 
         // 🔥 Set transition name to resource to drawable
-        binding.ivMagazineCover.transitionName = "${model.drawableRes}"
+        binding.ivMagazineCover.transitionName = model.transitionName
         setImageUrl(binding.ivMagazineCover, model.drawableRes)
 
         binding.tvMagazineTitle.transitionName = model.title

Tutorial3-1Transitions/src/main/java/com/smarttoolfactory/tutorial3_1transitions/chapter2_fragment_transitions/Fragment2_4MagazineDetail.kt

@@ -9,6 +9,7 @@ import android.view.animation.AccelerateDecelerateInterpolator
 import android.view.animation.AnimationUtils
 import android.widget.ImageView
 import android.widget.TextView
+import androidx.core.app.SharedElementCallback
 import androidx.fragment.app.Fragment
 import androidx.transition.Slide
 import androidx.transition.Transition
@@ -74,6 +75,9 @@ class Fragment2_4MagazineDetail : Fragment() {
         // This is shared transition for imageView and title
         val moveTransition =
             TransitionInflater.from(context).inflateTransition(android.R.transition.move)
+                .apply {
+                    duration = 500
+                }
 
         sharedElementEnterTransition = moveTransition
 
@@ -106,6 +110,55 @@ class Fragment2_4MagazineDetail : Fragment() {
 //                circularReveal.start()
 //            }
 //        })
+
+        setEnterSharedElementCallback(object : SharedElementCallback() {
+
+            var startTime = 0L
+
+            override fun onMapSharedElements(
+                names: MutableList<String>?,
+                sharedElements: MutableMap<String, View>?
+            ) {
+                super.onMapSharedElements(names, sharedElements)
+                println("🔥 DetailFragment setEnterSharedElementCallback() onMapSharedElements() names: $names, sharedElements: $sharedElements")
+            }
+
+            override fun onRejectSharedElements(rejectedSharedElements: MutableList<View>?) {
+                super.onRejectSharedElements(rejectedSharedElements)
+                println("👻 DetailFragment setEnterSharedElementCallback() onRejectSharedElements() $rejectedSharedElements")
+            }
+
+            override fun onSharedElementStart(
+                sharedElementNames: MutableList<String>?,
+                sharedElements: MutableList<View>?,
+                sharedElementSnapshots: MutableList<View>?
+            ) {
+                super.onSharedElementStart(
+                    sharedElementNames,
+                    sharedElements,
+                    sharedElementSnapshots
+                )
+
+                println("🚙 DetailFragment setEnterSharedElementCallback() onSharedElementStart sharedElementNames: $sharedElementNames")
+                startTime = System.currentTimeMillis()
+            }
+
+            override fun onSharedElementEnd(
+                sharedElementNames: MutableList<String>?,
+                sharedElements: MutableList<View>?,
+                sharedElementSnapshots: MutableList<View>?
+            ) {
+                super.onSharedElementEnd(sharedElementNames, sharedElements, sharedElementSnapshots)
+
+                println(
+                    "🚙 DetailFragment onSharedElementStart " +
+                            "sharedElementNames: $sharedElementNames, " +
+                            "duration: ${System.currentTimeMillis() - startTime}"
+                )
+
+            }
+
+        })
     }
 
     private fun createEnterTransition(view: View): Transition {
@@ -184,7 +237,7 @@ class Fragment2_4MagazineDetail : Fragment() {
         val ivMagazineCover = view.findViewById<ImageView>(R.id.ivMagazineCover)
         val tvMagazineTitle = view.findViewById<TextView>(R.id.tvMagazineTitle)
 
-        ivMagazineCover.transitionName = "${magazineModel.drawableRes}"
+        ivMagazineCover.transitionName = magazineModel.transitionName
         ivMagazineCover.setImageResource(magazineModel.drawableRes)
         tvMagazineTitle.text = magazineModel.title
         tvMagazineTitle.transitionName = magazineModel.title