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[WIP] Fix background flicker when toBack is true #336

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[WIP] Fix background flicker when toBack is true #336

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b571e47
Initial plan
Codex Apr 10, 2026
6e95932
Fix Android system bar flicker in toBack mode
Codex Apr 10, 2026
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71 changes: 71 additions & 0 deletions android/src/main/java/app/capgo/capacitor/camera/preview/CameraPreview.java
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Original file line number Diff line number Diff line change
Expand Up @@ -108,6 +108,7 @@ protected void handleOnDestroy() {
cameraXView = null;
}
lastSessionConfig = null;
restoreSystemUiForToBackMode(getBridge().getActivity());
}

private CameraSessionConfiguration lastSessionConfig;
Expand Down Expand Up @@ -136,6 +137,9 @@ protected void handleOnDestroy() {
private Drawable originalWindowBackground;
private Float originalWebViewAlpha;
private Drawable originalWebViewParentBackground;
private Integer originalStatusBarColor;
private Integer originalNavigationBarColor;
private Boolean originalNavigationBarContrastEnforced;
private boolean isCameraPermissionDialogShowing = false;

@PluginMethod
Expand Down Expand Up @@ -433,6 +437,7 @@ public void stop(final PluginCall call) {
originalWindowBackground = null;
}
restoreWebViewVisualState();
restoreSystemUiForToBackMode(getBridge().getActivity());
call.resolve();
});
}
Expand Down Expand Up @@ -947,6 +952,7 @@ private void startCamera(final PluginCall call) {
getBridge()
.getActivity()
.runOnUiThread(() -> {
lockSystemUiForToBackMode(getBridge().getActivity(), toBack);
// Ensure transparent background when preview is behind the WebView (Android 10 fix)
if (toBack) {
try {
Expand Down Expand Up @@ -1531,6 +1537,70 @@ private boolean isMiuiDevice() {
return manufacturer.contains("xiaomi") || brand.contains("xiaomi") || brand.contains("redmi") || brand.contains("poco");
}

private int toOpaqueColor(int color) {
return Color.argb(255, Color.red(color), Color.green(color), Color.blue(color));
}

private void lockSystemUiForToBackMode(Activity activity, boolean toBack) {
if (activity == null) {
return;
}
if (!toBack) {
return;
}
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@chatgpt-codex-connector chatgpt-codex-connector Bot Apr 23, 2026

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P1 Badge Restore system UI before returning on non-toBack start

This early return skips cleanup when a previous session already locked system bars for toBack=true. In a valid flow like start({ force: true, toBack: false }), the old session is stopped without calling stop(), so originalStatusBarColor/originalNavigationBarColor remain cached and the status/navigation bars stay forced to opaque colors (and contrast disabled on Android Q+) even though the new session is not toBack; this leaves the app UI in an incorrect state until a later explicit restore path runs.

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try {
if (originalStatusBarColor == null) {
originalStatusBarColor = activity.getWindow().getStatusBarColor();
}
if (originalNavigationBarColor == null) {
originalNavigationBarColor = activity.getWindow().getNavigationBarColor();
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q && originalNavigationBarContrastEnforced == null) {
originalNavigationBarContrastEnforced = activity.getWindow().isNavigationBarContrastEnforced();
}

int statusBarColor = toOpaqueColor(originalStatusBarColor != null ? originalStatusBarColor : Color.BLACK);
int navigationBarColor = toOpaqueColor(originalNavigationBarColor != null ? originalNavigationBarColor : Color.BLACK);

activity.getWindow().setStatusBarColor(statusBarColor);
activity.getWindow().setNavigationBarColor(navigationBarColor);

if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
activity.getWindow().setNavigationBarContrastEnforced(false);
}
} catch (Exception e) {
Log.w(TAG, "Failed to lock system UI colors for toBack mode", e);
}
}

private void restoreSystemUiForToBackMode(Activity activity) {
final Integer statusBarColor = originalStatusBarColor;
final Integer navigationBarColor = originalNavigationBarColor;
final Boolean navigationBarContrastEnforced = originalNavigationBarContrastEnforced;
originalStatusBarColor = null;
originalNavigationBarColor = null;
originalNavigationBarContrastEnforced = null;

if (activity == null) {
return;
}

activity.runOnUiThread(() -> {
try {
if (statusBarColor != null) {
activity.getWindow().setStatusBarColor(statusBarColor);
}
if (navigationBarColor != null) {
activity.getWindow().setNavigationBarColor(navigationBarColor);
}
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q && navigationBarContrastEnforced != null) {
activity.getWindow().setNavigationBarContrastEnforced(navigationBarContrastEnforced);
}
} catch (Exception ignored) {}
});
}

private void applyTransparentBackgroundsForToBack() {
if (!isToBackMode()) {
return;
Expand Down Expand Up @@ -1801,6 +1871,7 @@ public void onCameraStartError(String message) {
}
}
restoreWebViewVisualState();
restoreSystemUiForToBackMode(getBridge().getActivity());
}

@PluginMethod
Expand Down