This change will break Darwin. I have only built and tested this on
desktop linux and Android linux. A follow-up CL will fix Darwin.
Currently, OpenGL gets its own thread, and UI C code (e.g. the Android
event loop, or the X11 event loop) gets its own thread. This relies on
multiple system-provided UI-related C libraries working nicely together,
even when running on different threads. Keeping all the C code on the
one thread seems more sound.
As side-effects:
- In package app/debug, DrawFPS now takes an explicit Config.
- In package app, some callbacks now take an explicit Config.
- In package exp/sprite, Render now takes an explicit Config.
- In package event, there are new events (Config, Draw, Lifecycle),
and an event filter mechanism to replace multiple app Callbacks.
- In package geom, the deprecated Width, Height and PixelsPerPt global
variables were removed in favor of an event.Config that is
explicitly passed around (and does not require mutex-locking).
Converting a geom.Pt to pixels now requires passing a pixelsPerPt.
- In package gl, the Do, Start and Stop functions are removed, as well
as the need to call Start in its own goroutine. There is no longer a
separate GL thread. Instead, package app explicitly performs any GL
work (gl.DoWork) when some is available (gl.WorkAvailable).
- In package gl/glutil, Image.Draw now takes an explicit Config.
Callbacks are no longer executed on 'the UI thread'.
Changing the app programming model from callbacks to events (since a
channel of events works with select) will be a follow-up change.
Change-Id: Id9865cd9ee1c45a98c613e9021a63c17226a64b1
Reviewed-on: https://go-review.googlesource.com/11351
Reviewed-by: David Crawshaw <crawshaw@golang.org>
An example of how to handle multiple concurrent touches using this design:
var touched = map[event.TouchSequenceID]*Widget{}
func touch(t event.Touch) {
if t.Type == event.TouchStart {
if w := widgetAt(t.Loc); w != nil {
touched[t.ID] = w
}
}
if w, ok := touched[t.ID]; ok {
// move/scroll widget, etc
}
if t.Type == event.TouchEnd {
delete(touched, t.ID)
}
}
Change-Id: I79910ef30abe9a41bc0720783022b1af081fbd43
Reviewed-on: https://go-review.googlesource.com/1895
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Burcu Dogan <jbd@google.com>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Nigel Tao
Gordon Klaus
David Symonds
Andrew Gerrand
David Crawshaw