Android View-to-image Conversion for Message Capturing

Yu Hsien Che
LINE Taiwan Engineering 6 - Android Dev Android Dev
https://linedevday.linecorp.com/2020/ja/sessions/6276
https://linedevday.linecorp.com/2020/en/sessions/6276

Transcript

2. Agenda › What’s Message Capturing? › How Does it Work?
3. What’s Message Capturing? Demo
4. What’s Message Capturing? Demo
5. How Does it Work? Behind The Scenes Step 1 Prepare views Step 3 Repeat step 1 & 2 Step 2 Convert views to bitmaps
6. Step 1 - Prepare Views Step 1 Prepare views Step 3 Repeat step 1 & 2 Step 2 Convert views to bitmaps › Go through view drawing process › Don’t display views › Call View.measure() and View.layout() ourselves › Display views › Let system do the work Behind The Scenes
7. Step 1 - Prepare Views Don’t Display Views private fun prepareView(parentView: View, adapterPosition: Int) { // Create view val view = listView.adapter.getView(adapterPosition, null, null) // Measure and layout view val specWidth = View.MeasureSpec.makeMeasureSpec(parentView.width, View.MeasureSpec.EXACTLY) val specHeight = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED) view.measure(specWidth, specHeight) view.layout(0, 0, view.measuredWidth, view.measuredHeight) }
8. Step 1 - Prepare Views Don’t Display Views private fun prepareView(parentView: View, adapterPosition: Int) { // Create view val view = listView.adapter.getView(adapterPosition, null, null) // Measure and layout view val specWidth = View.MeasureSpec.makeMeasureSpec(parentView.width, View.MeasureSpec.EXACTLY) val specHeight = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED) view.measure(specWidth, specHeight) view.layout(0, 0, view.measuredWidth, view.measuredHeight) }
9. Step 1 - Prepare Views Display Views private fun displayView(adapterPosition: Int) { listView.setSelection(adapterPosition) }
10. Step 2 - Convert Views to Bitmaps Step 2 Convert views to bitmaps Step 3 Repeat step 1 & 2 Step 2 Convert views to bitmaps › Memory usage › Saving and recycling Behind The Scenes
11. Step 2 - Convert Views to Bitmaps Memory Usage height * width * 4 bytes (ARGB_8888: 4 bytes/ pixel) bitmap memory storage Android 3.0 ~ 7.1: in Java heap Android 8: in native heap
12. Step 2 - Convert Views to Bitmaps Saving and Recycling
13. Step 2 - Convert Views to Bitmaps Saving and Recycling 1st message view
14. Step 2 - Convert Views to Bitmaps Saving and Recycling 1st bitmap
15. Step 2 - Convert Views to Bitmaps Saving and Recycling 1st bitmap 2nd bitmap
16. Step 2 - Convert Views to Bitmaps Saving and Recycling 1st bitmap 3rd bitmap 2nd bitmap
17. Step 2 - Convert Views to Bitmaps Saving and Recycling 1st bitmap page height limit 3rd bitmap 2nd bitmap
18. Step 2 - Convert Views to Bitmaps Saving and Recycling long bitmap
19. Step 2 - Convert Views to Bitmaps Saving and Recycling long bitmap stored on disk and recycled 1st bitmap
20. Step 3 - Repeat Step 1 & 2 Step 3 Repeat step 1 & 2 Step 3 Repeat step 1 & 2 Step 2 Convert views to bitmaps › Message Pagination › Save memory › Avoid exception or crashing Behind The Scenes
21. › One page at a time › Pages have overlapping messages › Auto preloading before end of page
22. › One page at a time › Pages have overlapping messages › Auto preloading before end of page Page 1 Of Messages
23. › One page has 15 messages › Pages have overlapping messages › Auto preloading before end of page Page 1 Of Messages
24. › One page has 15 messages › Pages have overlapping messages › Auto preloading before end of page Page 1 Of Messages Page 2 Of Messages
25. › One page has 15 messages › Pages have 8 overlapping messages › Auto preloading before end of page Page 1 Of Messages Page 2 Of Messages
26. › One page has 15 messages › Pages have 8 overlapping messages › Auto preloading before end of page Page 1 Of Messages Page 2 Of Messages › Auto pre-load next page › Auto pre-load next page
27. › One page has 15 messages › Pages have 8 overlapping messages › Auto preloading is 3rd-to-last message Page 1 Of Messages Page 2 Of Messages › Auto pre-load next page › Auto pre-load next page
28. listView.setSelection(adapterPos) › Auto pre-load next page › Auto pre-load next page
29. listView.setSelection(adapterPos) › Auto pre-load next page › Auto pre-load next page
30. listView.setSelection(adapterPos) › Load next page preemptively › Re-calculate adapter position › Auto pre-load next page › Auto pre-load next page
31. Step 1 Prepare views Convert views to bitmaps Step 3 Step 2 Repeat step 1 & 2 › View drawing process › Memory usage › Saving and recycling › Message pagination
32. Thank you