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Android: deliver Back once, including the Android 13+ system gesture #32

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63 changes: 62 additions & 1 deletion tools/cargo_makepad/src/android/java/dev/makepad/android/MakepadActivity.java
View file
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Original file line number Diff line number Diff line change
Expand Up @@ -615,6 +615,13 @@ public void onGlobalLayout() {
@SuppressWarnings("deprecation")
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
// Back is not a surface key. Left unhandled it reaches the activity,
// which delivers it once through dispatchBackPressed: from onKeyUp ->
// onBackPressed below API 33, or from the OnBackInvokedCallback on
// API 33+ (which also carries the system edge gesture). Forwarding it
// here as well produced a second native BackPressed: one closed the
// current panel and the next left the app.
if (keyCode == KeyEvent.KEYCODE_BACK) return false;
if (event.getAction() == KeyEvent.ACTION_DOWN && keyCode != 0) {
int metaState = event.getMetaState();
boolean isRepeat = event.getRepeatCount() > 0;
Expand Down Expand Up @@ -1115,6 +1122,7 @@ public class MakepadActivity
private FrameLayout mRootLayout;
private FrameLayout mApplicationOverlay;
private ApplicationExtension mApplicationExtension;
private android.window.OnBackInvokedCallback mBackInvokedCallback;

/** Optional app Java client. Implementations enqueue blocking work on workers. */
public interface ApplicationExtension {
Expand All @@ -1124,7 +1132,16 @@ public interface ApplicationExtension {
void onIntent(Intent intent);
void onDestroy();
default boolean onActivityResult(int requestCode, int resultCode, Intent data) { return false; }
/** Return true to consume Back before it reaches the native widget tree. */
default boolean onBackPressed() { return false; }
/**
* True when the extension registers its own Android 13+
* OnBackInvokedCallback (calling {@link MakepadActivity#onBackPressed}).
* The activity then registers none and drops the compatibility Back
* key, so each Back is delivered once. Most extensions should leave
* this false and implement {@link #onBackPressed} instead.
*/
default boolean usesSystemBackCallback() { return false; }
}

private void createApplicationExtension() {
Expand Down Expand Up @@ -1532,6 +1549,7 @@ public void onCreate(Bundle savedInstanceState) {
}
MakepadNative.activityOnCreate(this);
createApplicationExtension();
registerBackInvokedCallback();
registerPhysicalKeyboardListener();

mVideoPlaybackThread = new HandlerThread("VideoPlayerThread");
Expand Down Expand Up @@ -1635,6 +1653,7 @@ protected void onStop() {

@Override
protected void onDestroy() {
unregisterBackInvokedCallback();
if (mApplicationExtension != null) {
mApplicationExtension.onDestroy();
mApplicationExtension = null;
Expand Down Expand Up @@ -1717,6 +1736,12 @@ public void onLowMemory() {
// key (BACK included) and forwards it to Rust, so onBackPressed never runs.
@Override
public boolean dispatchKeyEvent(KeyEvent event) {
// An extension that owns the system Back callback receives every Back
// through it; its compatibility key must not navigate a second time.
if (Build.VERSION.SDK_INT >= 33 && event.getKeyCode() == KeyEvent.KEYCODE_BACK
&& extensionOwnsSystemBack()) {
return true;
}
if (mQrScanning && event.getKeyCode() == KeyEvent.KEYCODE_BACK) {
if (event.getAction() == KeyEvent.ACTION_UP) closeQrScanner("cancelled");
return true;
Expand All @@ -1727,11 +1752,47 @@ public boolean dispatchKeyEvent(KeyEvent event) {
@Override
@SuppressWarnings("deprecation")
public void onBackPressed() {
dispatchBackPressed();
}

/** The single delivery point for Back: key, button and system gesture. */
private void dispatchBackPressed() {
if (mQrScanning) {
closeQrScanner("cancelled");
return;
}
if (mApplicationExtension != null && mApplicationExtension.onBackPressed()) return;
super.onBackPressed();
// No super.onBackPressed(): Activity's default finishes (or, on API
// 31+, backgrounds) the activity before the widget tree has seen the
// event. Navigation belongs to the native BackPressed handlers.
MakepadNative.onBackPressed();
}

private boolean extensionOwnsSystemBack() {
return mApplicationExtension != null && mApplicationExtension.usesSystemBackCallback();
}

// Android 13+ delivers Back, including the system edge gesture, to
// OnBackInvokedCallbacks when the manifest opts in
// (android:enableOnBackInvokedCallback, which cargo-makepad writes);
// onBackPressed is then no longer called. PRIORITY_DEFAULT leaves the
// IME's own Back (dismissing the keyboard) ahead of app navigation.
private void registerBackInvokedCallback() {
if (Build.VERSION.SDK_INT < 33 || mBackInvokedCallback != null || extensionOwnsSystemBack()) {
return;
}
mBackInvokedCallback = this::dispatchBackPressed;
getOnBackInvokedDispatcher().registerOnBackInvokedCallback(
android.window.OnBackInvokedDispatcher.PRIORITY_DEFAULT, mBackInvokedCallback);
}

private void unregisterBackInvokedCallback() {
if (Build.VERSION.SDK_INT >= 33 && mBackInvokedCallback != null) {
getOnBackInvokedDispatcher().unregisterOnBackInvokedCallback(mBackInvokedCallback);
mBackInvokedCallback = null;
}
}

@Override
public void onWindowFocusChanged(boolean hasFocus) {
super.onWindowFocusChanged(hasFocus);
Expand Down
21 changes: 21 additions & 0 deletions tools/cargo_makepad/src/android/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -99,6 +99,7 @@ impl AndroidVariant {
android:configChanges="orientation|screenSize|keyboardHidden"
android:exported="true"
android:launchMode="singleTask"
android:enableOnBackInvokedCallback="true"
android:windowSoftInputMode="adjustNothing|stateUnchanged"
android:theme="@style/MakepadLaunchTheme">
<intent-filter>
Expand Down Expand Up @@ -193,6 +194,7 @@ impl AndroidVariant {
android:excludeFromRecents="false"
android:exported="true"
android:launchMode="singleTask"
android:enableOnBackInvokedCallback="true"
android:screenOrientation="landscape"
android:windowSoftInputMode="adjustNothing|stateUnchanged"
android:theme="@style/MakepadLaunchTheme"
Expand All @@ -209,6 +211,7 @@ impl AndroidVariant {
android:excludeFromRecents="false"
android:exported="true"
android:launchMode="singleTask"
android:enableOnBackInvokedCallback="true"
android:screenOrientation="landscape"
android:windowSoftInputMode="adjustNothing|stateUnchanged"
android:theme="@style/MakepadLaunchTheme"
Expand Down Expand Up @@ -283,6 +286,7 @@ Self::Quest=>format!(r#"<?xml version="1.0" encoding="utf-8"?>
android:name="{class_name}"
android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
android:launchMode="singleTask"
android:enableOnBackInvokedCallback="true"
android:screenOrientation="landscape"
android:excludeFromRecents="false"
android:configChanges="screenSize|screenLayout|orientation|keyboardHidden|keyboard|navigation|uiMode"
Expand All @@ -301,6 +305,7 @@ Self::Quest=>format!(r#"<?xml version="1.0" encoding="utf-8"?>
android:excludeFromRecents="false"
android:exported="true"
android:launchMode="singleTask"
android:enableOnBackInvokedCallback="true"
android:screenOrientation="landscape"
android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"
>
Expand Down Expand Up @@ -927,6 +932,22 @@ mod tests {
assert!(xml.contains("android:launchMode=\"singleTask\""));
}

#[test]
fn every_activity_opts_into_back_invoked_callbacks() {
// MakepadActivity registers one OnBackInvokedCallback on API 33+;
// without the opt-in Android ignores it and finishes the activity
// on a system Back gesture instead.
for variant in [AndroidVariant::Default, AndroidVariant::Quest] {
let xml = variant.manifest_xml(&test_args("App", "dev.makepad.app"));
assert_eq!(
xml.matches("android:launchMode=\"singleTask\"").count(),
xml.matches("android:enableOnBackInvokedCallback=\"true\"").count(),
"every activity needs the Back opt-in: {xml}"
);
assert!(xml.contains("android:enableOnBackInvokedCallback=\"true\""));
}
}

#[test]
fn quest_manifest_uses_splash_and_app_themes() {
let xml = AndroidVariant::Quest.manifest_xml(&test_args("App", "dev.makepad.app"));
Expand Down