By Kevin Read

1. Javascript code in a
native app
Graphically intensive and interactive
Kevin Read
kread@boerse-go.de
@unverbraucht

2. Javascript rocks
● It's great
○ fast
○ cross-platform
○ runs (nearly) everywhere
● So we built a Canvas-based chart analysis
tool in JS with a gazillion features:
○ Quick demo

3. ● On mobile, canvas not there yet for us
○ 2-3 fps performance
○ Differences in touch handling over browsers
● Porting not an option
○ 30k LOC of JS times two platforms
● Idea: Reuse JS version
○ Embed JS VM into app, here v8
○ Custom code for canvas, AJAX, websocket, ...
JS isn't for everything

4. Android embedding architecture
Dalvik VM
(Java) App (Views, Activities)

5. Android embedding architecture
Dalvik VM
(Java)
v8Engine singleton
JNI
(C/C++) BGJSContext
v8
(JS)
JS Chart
App (Views, Activities)
initializes
load and
execute
requires
Other JS files

6. Android embedding architecture
Dalvik VM
(Java)
v8Engine singleton
JNI
(C/C++) BGJSContext
v8
(JS)
JS Chart
BGJSModules
App (Views, Activities)
initializes
Ejecta + BG
(Canvas in
OpenGL)
register as
JS functions
load and
execute
Other JS files
requires

7. Android embedding architecture
Dalvik VM
(Java)
v8Engine singleton
JNI
(C/C++) BGJSContext
v8
(JS)
JS Chart
BGJSModules
App (Views, Activities)
initializes
v8TextureView
(GL init, pageflip,
touch, ..)
adds
Ejecta + BG
(Canvas in
OpenGL)
register as
JS functions
load and
execute
Other JS files
requires

8. Android embedding architecture
Dalvik VM
(Java)
v8Engine singleton
JNI
(C/C++) BGJSContext
v8
(JS)
JS Chart
Ajax Helper
(threading, IO, ...)
BGJSModules
App (Views, Activities)
initializes
v8TextureView
(GL init, pageflip,
touch, ..)
adds
AjaxModule
Ejecta + BG
(Canvas in
OpenGL)
register as
JS functions
load and
execute
AuthModule
...
Other JS files
requires

9. Demo
Finger crossing plz.

10. Lessons learned and end
● Embedding a JS VM is a big to epic win
○ Performance gain x20 (!)
○ Oh, and works on x86 too of course :D
● But plan to take some time:
○ v8 is great, but steep learning curve.
○ Debugging JNI/NDK can be very painful.
Thanks for your time.
@unverbraucht
+Kevin Read: http://gplus.to/unverbraucht
EjectaJS for iOS: http://impactjs.com/ejecta
Martins stuff: https://github.com/Tharit
gplus.to/unverbraucht