app: add RegisterFragment method on *Window for Android

RegisterFragment creates an instance of a Java class and registers
it as a Fragment in the window's Context.

Signed-off-by: Greg Pomerantz <gmp.gio@wow.st>

app/app.go

@@ -9,13 +9,6 @@ import (
 	"gioui.org/app/internal/window"
 )
 
-type Handle window.Handle
-
-// PlatformHandle returns the platform specific Handle.
-func PlatformHandle() *Handle {
-	return (*Handle)(window.PlatformHandle)
-}
-
 // extraArgs contains extra arguments to append to
 // os.Args. The arguments are separated with |.
 // Useful for running programs on mobiles where the

app/app_android.go

@@ -0,0 +1,30 @@
+package app
+
+import (
+	"gioui.org/app/internal/window"
+)
+
+type Handle window.Handle
+
+// PlatformHandle returns the Android platform-specific Handle.
+func PlatformHandle() *Handle {
+	return (*Handle)(window.PlatformHandle)
+}
+
+// androidDriver is an interface that allows the Window's run method
+// to call the RegisterFragment method of the Android window driver.
+type androidDriver interface {
+	RegisterFragment(string)
+}
+
+// RegisterFragment constructs a Java instance of the specified class
+// and registers it as a Fragment in the Context in which the View was
+// created.
+func (w *Window) RegisterFragment(del string) {
+	go func() {
+		w.driverFuncs <- func() {
+			d := w.driver.(androidDriver)
+			d.RegisterFragment(del)
+		}
+	}()
+}

app/internal/window/GioView.java

@@ -2,12 +2,21 @@
 
 package org.gioui;
 
+import java.lang.Class;
+import java.lang.IllegalAccessException;
+import java.lang.InstantiationException;
+import java.lang.ExceptionInInitializerError;
+import java.lang.SecurityException;
+import android.app.Activity;
+import android.app.Fragment;
+import android.app.FragmentManager;
+import android.app.FragmentTransaction;
 import android.content.Context;
 import android.graphics.Rect;
 import android.os.Build;
 import android.os.Handler;
-import android.util.AttributeSet;
 import android.text.Editable;
+import android.util.AttributeSet;
 import android.view.Choreographer;
 import android.view.KeyCharacterMap;
 import android.view.KeyEvent;
@@ -57,11 +66,12 @@ public class GioView extends SurfaceView implements Choreographer.FrameCallback
 
 	public GioView(Context context, AttributeSet attrs) {
 		super(context, attrs);
+
+		handler = new Handler();
 		// Late initialization of the Go runtime to wait for a valid context.
 		initialize(context.getApplicationContext());
 
 		nhandle = onCreateView(this);
-		handler = new Handler();
 		imm = (InputMethodManager)context.getSystemService(Context.INPUT_METHOD_SERVICE);
 		setFocusable(true);
 		setFocusableInTouchMode(true);
@@ -207,6 +217,35 @@ public class GioView extends SurfaceView implements Choreographer.FrameCallback
 		return onBack(nhandle);
 	}
 
+	public void registerFragment(String del) {
+		final Class cls;
+		try {
+			cls = getContext().getClassLoader().loadClass(del);
+		} catch (ClassNotFoundException e) {
+			throw new RuntimeException("RegisterFragment: fragment class not found: " + e.getMessage());
+		}
+
+		handler.post(new Runnable() {
+			public void run() {
+				final Fragment frag;
+				try {
+					frag = (Fragment)cls.newInstance();
+				} catch (IllegalAccessException | InstantiationException | ExceptionInInitializerError | SecurityException | ClassCastException e) {
+					throw new RuntimeException("RegisterFragment: error instantiating fragment: " + e.getMessage());
+				}
+				final FragmentManager fm;
+				try {
+					fm = ((Activity)getContext()).getFragmentManager();
+				} catch (ClassCastException e) {
+					throw new RuntimeException("RegisterFragment: cannot get fragment manager from View Context: " + e.getMessage());
+				}
+				FragmentTransaction ft = fm.beginTransaction();
+				ft.add(frag, del);
+				ft.commitNow();
+			}
+		});
+	}
+
 	static private native long onCreateView(GioView view);
 	static private native void onDestroyView(long handle);
 	static private native void onStartView(long handle);

app/internal/window/handle.go

@@ -1,7 +0,0 @@
-// +build !android
-
-package window
-
-var PlatformHandle *Handle
-
-type Handle struct{}

app/internal/window/os_android.c

@@ -166,3 +166,8 @@ void gio_jni_ReleaseByteArrayElements(JNIEnv *env, jbyteArray arr, jbyte *bytes)
 jsize gio_jni_GetArrayLength(JNIEnv *env, jbyteArray arr) {
 	return (*env)->GetArrayLength(env, arr);
 }
+
+void gio_jni_RegisterFragment(JNIEnv *env, jobject view, jmethodID mid, char* del) {
+	jstring jdel = (*env)->NewStringUTF(env, del);
+	(*env)->CallObjectMethod(env, view, mid, jdel);
+}

app/internal/window/os_android.go

@@ -54,6 +54,7 @@ type window struct {
 	mhideTextInput                 C.jmethodID
 	mpostFrameCallback             C.jmethodID
 	mpostFrameCallbackOnMainThread C.jmethodID
+	mRegisterFragment              C.jmethodID
 }
 
 var dataDirChan = make(chan string, 1)
@@ -119,6 +120,7 @@ func onCreateView(env *C.JNIEnv, class C.jclass, view C.jobject) C.jlong {
 		mhideTextInput:                 jniGetMethodID(env, class, "hideTextInput", "()V"),
 		mpostFrameCallback:             jniGetMethodID(env, class, "postFrameCallback", "()V"),
 		mpostFrameCallbackOnMainThread: jniGetMethodID(env, class, "postFrameCallbackOnMainThread", "()V"),
+		mRegisterFragment:              jniGetMethodID(env, class, "registerFragment", "(Ljava/lang/String;)V"),
 	}
 	wopts := <-mainWindow.out
 	w.callbacks = wopts.window
@@ -443,6 +445,14 @@ func (w *window) ShowTextInput(show bool) {
 	})
 }
 
+func (w *window) RegisterFragment(del string) {
+	runInJVM(func(env *C.JNIEnv) {
+		cdel := C.CString(del)
+		defer C.free(unsafe.Pointer(cdel))
+		C.gio_jni_RegisterFragment(env, w.view, w.mRegisterFragment, cdel)
+	})
+}
+
 func Main() {
 }
 

app/internal/window/os_android.h

@@ -17,3 +17,4 @@ __attribute__ ((visibility ("hidden"))) void gio_jni_CallVoidMethod_J(JNIEnv *en
 __attribute__ ((visibility ("hidden"))) jbyte *gio_jni_GetByteArrayElements(JNIEnv *env, jbyteArray arr);
 __attribute__ ((visibility ("hidden"))) void gio_jni_ReleaseByteArrayElements(JNIEnv *env, jbyteArray arr, jbyte *bytes);
 __attribute__ ((visibility ("hidden"))) jsize gio_jni_GetArrayLength(JNIEnv *env, jbyteArray arr);
+__attribute__ ((visibility ("hidden"))) void gio_jni_RegisterFragment(JNIEnv *env, jobject view, jmethodID mid, char* del);

app/window.go

@@ -29,6 +29,10 @@ type Window struct {
 	driver window.Driver
 	gpu    *gpu.GPU
 
+	// driverFuncs is a channel of functions to run when
+	// the Window has a valid driver.
+	driverFuncs chan func()
+
 	out         chan event.Event
 	in          chan event.Event
 	ack         chan struct{}
@@ -95,6 +99,7 @@ func NewWindow(options ...Option) *Window {
 		invalidates: make(chan struct{}, 1),
 		frames:      make(chan *op.Ops),
 		frameAck:    make(chan struct{}),
+		driverFuncs: make(chan func()),
 	}
 	w.callbacks.w = w
 	go w.run(opts)
@@ -227,6 +232,10 @@ func (w *Window) run(opts *window.Options) {
 		return
 	}
 	for {
+		var driverFuncs chan func() = nil
+		if w.driver != nil {
+			driverFuncs = w.driverFuncs
+		}
 		var timer <-chan time.Time
 		if w.delayedDraw != nil {
 			timer = w.delayedDraw.C
@@ -238,6 +247,8 @@ func (w *Window) run(opts *window.Options) {
 		case <-w.invalidates:
 			w.setNextFrame(time.Time{})
 			w.updateAnimation()
+		case f := <-driverFuncs:
+			f()
 		case e := <-w.in:
 			switch e2 := e.(type) {
 			case system.StageEvent: