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app/internal/window: [Android] replace RegisterFragment with Do

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Do is a function for accessing the underlying Android View in a safe
context, the main thread. Do is

- more general than RegisterFragment and may be expanded to other platforms
- simpler to implement (from the Gio side)

and as a bonus, the Do implementation avoids a race condition where
a call to RegisterFragment during an Activity re-create would be ignored.

Signed-off-by: Elias Naur <mail@eliasnaur.com>
This commit is contained in:
Elias Naur
2020-06-13 16:09:33 +02:00
parent f36674ddb3
commit 8688ed95c2
4 changed files with 60 additions and 57 deletions
Download Patch File Download Diff File Expand all files Collapse all files
app/internal/window/os_android.go
+23 -13
View File
@@ -80,7 +80,6 @@ type window struct {
mshowTextInput C.jmethodID
mhideTextInput C.jmethodID
mpostFrameCallback C.jmethodID
mRegisterFragment C.jmethodID
}
type jvalue uint64 // The largest JNI type fits in 64 bits.
@@ -193,7 +192,6 @@ func Java_org_gioui_GioView_onCreateView(env *C.JNIEnv, class C.jclass, view C.j
mshowTextInput: getMethodID(env, class, "showTextInput", "()V"),
mhideTextInput: getMethodID(env, class, "hideTextInput", "()V"),
mpostFrameCallback: getMethodID(env, class, "postFrameCallback", "()V"),
mRegisterFragment: getMethodID(env, class, "registerFragment", "(Ljava/lang/String;)V"),
}
wopts := <-mainWindow.out
w.callbacks = wopts.window
@@ -416,7 +414,6 @@ func runInJVM(jvm *C.JavaVM, f func(env *C.JNIEnv)) {
runtime.LockOSThread()
defer runtime.UnlockOSThread()
var env *C.JNIEnv
var detach bool
if res := C.gio_jni_GetEnv(jvm, &env, C.JNI_VERSION_1_6); res != C.JNI_OK {
if res != C.JNI_EDETACHED {
panic(fmt.Errorf("JNI GetEnv failed with error %d", res))
@@ -424,14 +421,9 @@ func runInJVM(jvm *C.JavaVM, f func(env *C.JNIEnv)) {
if C.gio_jni_AttachCurrentThread(jvm, &env, nil) != C.JNI_OK {
panic(errors.New("runInJVM: AttachCurrentThread failed"))
}
detach = true
defer C.gio_jni_DetachCurrentThread(jvm)
}
if detach {
defer func() {
C.gio_jni_DetachCurrentThread(jvm)
}()
}
f(env)
}
@@ -537,11 +529,21 @@ func javaString(env *C.JNIEnv, str string) C.jstring {
return C.gio_jni_NewString(env, (*C.jchar)(unsafe.Pointer(&utf16Chars[0])), C.int(len(utf16Chars)))
}
func (w *window) RegisterFragment(del string) {
w.runOnMain(func(env *C.JNIEnv) {
jstr := javaString(env, del)
callVoidMethod(env, w.view, w.mRegisterFragment, jvalue(jstr))
// Do invokes the function with a global JNI handle to the view. If
// the view is destroyed, Do returns false and does not invoke the
// function.
//
// NOTE: Do must be invoked on the Android main thread.
func (w *window) Do(f func(view uintptr)) bool {
if w.view == 0 {
return false
}
runInJVM(javaVM(), func(env *C.JNIEnv) {
view := C.gio_jni_NewGlobalRef(env, w.view)
defer C.gio_jni_DeleteGlobalRef(env, view)
f(uintptr(view))
})
return true
}
func varArgs(args []jvalue) *C.jvalue {
@@ -645,6 +647,14 @@ func (w *window) ReadClipboard() {
})
}
// RunOnMain is the exported version of runOnMain without a JNI
// environement.
func RunOnMain(f func()) {
runOnMain(func(_ *C.JNIEnv) {
f()
})
}
// runOnMain runs a function on the Java main thread.
func runOnMain(f func(env *C.JNIEnv)) {
go func() {