The document discusses different techniques for implementing activity transitions in Android apps. It covers the basics of shared element transitions introduced in Lollipop, as well as workarounds for older Android versions using custom animations. It also addresses questions about transitions after network requests and between recycler views.

1. ActivityTransition
Ted

3. more about
https://www.youtube.com/watch?v=RhiPJByIMr
M
2:45

4. step 1
<style name="AppTheme" parent="android:Theme.Material.Light">
<item name="android:windowSharedElementEnterTransition">
@transition/change_image_transform</item>
<item name="android:windowSharedElementExitTransition">
@transition/change_image_transform</item>
</style>

5. step 2
res/transition/ 加入change_image_transform
<?xml version="1.0" encoding="utf-8"?>
<transitionSet xmlns:android="http://schemas.android.com/apk/res/android">
<changeBounds />
<changeImageTransform/>
</transitionSet>

6. step3
Intent intent = new Intent(this,NextActivity.class);
ActivityOptions options = ActivityOptions
.makeSceneTransitionAnimation(this,
Pair.create(event.getView(),
NextActivity.VIEW_NAME));
startActivity(intent, options.toBundle());

7. final step
img.setTransitionName(VIEW_NAME);
sample code:
https://github.com/nightbear1009/LolipopActivityTransition

8. what about pre-L

10. step1
overridePendingTransition(0, 0);

11. step2
<style name="Transparent" parent="android:Theme.Holo.Light.DarkActionBar">>
<item name="android:windowIsTranslucent">true</item>
<item name="android:windowBackground">@android:color/transparent</item>
</style>

12. step3
int[] screenLocation = new int[2];
view.getLocationOnScreen(screenLocation);
intent.putExtra("left", screenLocation[0]).
putExtra("top", screenLocation[1]).
putExtra("width", view.getWidth()).
putExtra("height", view.getHeight());

13. step4
mView.setPivotX(0);
mView.setPivotY(0);
mView.setScaleX(mWidthScale);
mView.setScaleY(mHeightScale);
mView.setTranslationX(mLeftDelta);
mView.setTranslationY(mTopDelta);

14. step5
mView.animate().setDuration(duration).
scaleX(1).scaleY(1).
translationX(0).translationY(0).
setInterpolator(sDecelerator);

16. mView.animate().setDuration(duration).
scaleX(mWidthScale).scaleY(mHeightScale).
translationX(mLeftDelta).translationY(mTopDelta);
ObjectAnimator bgAnim = ObjectAnimator.ofFloat(mView, "alpha", 0);
bgAnim.setDuration(duration);
bgAnim.start();
sample code
https://github.com/nightbear1009/ActivityAnimations

17. the end...

18. no~ not yet!!

19. what about transition after http request?
nothing will happen….
what about transition from recyclerview to
recyclerview?
nothing will happen...

22. postponeEnterTransition();
&
holder.imageView.getViewTreeObserver().addOnPreDrawListener(new
ViewTreeObserver.OnPreDrawListener() {
@Override
public boolean onPreDraw() {
startPostponedEnterTransition();
return true;
}
});

23. reminder
postponeEnterTransition(); will block ui thread.
所以我們必須將這個activity要顯示的資料從上個activity先帶進來，等到http request 結束之後才換成新
的資料
sample code
https://github.com/nightbear1009/LolipopActivityTransition