api-impl-jni: add workarounds for Gtk's non-graceful handling of layout changes during the snapshot phase

src/api-impl-jni/app/android_app_AlertDialog.c

@@ -65,7 +65,7 @@ static void bind_listitem_cb(GtkListItemFactory *factory, GtkListItem *list_item
 	GtkWidget *label = gtk_list_item_get_child(list_item);
 	ListEntry *entry = gtk_list_item_get_item(list_item);
 
-	gtk_label_set_text(GTK_LABEL(label), entry->text);
+	atl_safe_gtk_label_set_text(GTK_LABEL(label), entry->text);
 }
 
 static void activate_cb(GtkListView *list, guint position, struct click_callback_data *d)

src/api-impl-jni/util.c

@@ -2,6 +2,8 @@
 #include <dlfcn.h>
 #include <pthread.h>
 
+#include <gtk/gtk.h>
+
 #include "util.h"
 #include "src/api-impl-jni/defines.h"
 
@@ -279,3 +281,92 @@ int get_nio_buffer_size(JNIEnv *env, jobject buffer)
 
 	return limit - position;
 }
+
+
+/* Calling these functions while snapshotting will cause Gtk to not snapshot the affected widgets.
+ * Below are "safe" wrappers which will postpone the calls if inside a snapshot.
+ * Specifically, gtk_widget_add_tick_callback will make sure the calls are made in the next
+ * Update phase. */
+
+/* callbacks */
+static gboolean queue_set_text(GtkWidget *label, GdkFrameClock *frame_clock, gpointer str)
+{
+	gtk_label_set_text(GTK_LABEL(label), str);
+	/* we always call strdup so we always want to free */
+	free(str);
+	return G_SOURCE_REMOVE;
+}
+
+static gboolean queue_queue_allocate(GtkWidget *widget, GdkFrameClock *frame_clock, gpointer user_data)
+{
+	gtk_widget_queue_allocate(widget);
+	return G_SOURCE_REMOVE;
+}
+
+static gboolean queue_queue_resize(GtkWidget *widget, GdkFrameClock *frame_clock, gpointer user_data)
+{
+	gtk_widget_queue_resize(widget);
+	return G_SOURCE_REMOVE;
+}
+
+/* Some functions call gtk_widget_queue_allocate or similar internally.
+ * To prevent that from breaking the snapshotting process, when called at the wrong time,
+ * we have to follow those functions with this pile of hacks that will unset the problematic flags. */
+extern int snapshot_in_progress;
+void atl_ensure_widget_snapshotability(GtkWidget *widget)
+{
+	if(snapshot_in_progress) {
+		GtkAllocation allocation;
+		G_GNUC_BEGIN_IGNORE_DEPRECATIONS
+		/* we probably don't need to use this deprecated function but it sure is convenient */
+		gtk_widget_get_allocation(widget, &allocation);
+		G_GNUC_END_IGNORE_DEPRECATIONS
+		/* this clears resize request, which seems to be necessary in some cases */
+		gtk_widget_get_request_mode(widget);
+		gtk_widget_size_allocate(widget, &allocation, gtk_widget_get_baseline(widget));
+		gtk_widget_add_tick_callback(widget, queue_queue_allocate, NULL, NULL);
+
+		/* the problematic flags get set all the way up the hierarchy */
+		GtkWidget *parent = gtk_widget_get_parent(widget);
+		if (parent) {
+			atl_ensure_widget_snapshotability(parent);
+		}
+	}
+}
+
+void atl_safe_gtk_label_set_text(GtkLabel* label, const char* str)
+{
+	if(!snapshot_in_progress) {
+		gtk_label_set_text(label, str);
+	} else {
+		/* strdup since the string may not exist by the time the callback runs */
+		gtk_widget_add_tick_callback(GTK_WIDGET(label), queue_set_text, (gpointer)strdup(str), NULL);
+	}
+}
+
+void atl_safe_gtk_widget_set_visible(GtkWidget *widget, gboolean visible)
+{
+	gtk_widget_set_visible(widget, visible);
+	GtkWidget *parent = gtk_widget_get_parent(widget);
+	if (parent) {
+		atl_ensure_widget_snapshotability(parent);
+	}
+}
+
+void atl_safe_gtk_widget_queue_allocate(GtkWidget *widget)
+{
+	if(!snapshot_in_progress) {
+		gtk_widget_queue_allocate(widget);
+	} else {
+		gtk_widget_add_tick_callback(widget, queue_queue_allocate, NULL, NULL);
+	}
+}
+
+void atl_safe_gtk_widget_queue_resize(GtkWidget *widget)
+{
+	if(!snapshot_in_progress) {
+		gtk_widget_queue_resize(widget);
+	} else {
+		gtk_widget_add_tick_callback(widget, queue_queue_resize, NULL, NULL);
+	}
+}

src/api-impl-jni/util.h

@@ -1,6 +1,8 @@
 #ifndef _UTILS_H_
 #define _UTILS_H_
 
+#include <gtk/gtk.h>
+
 #include <jni.h>
 
 #include "defines.h"
@@ -186,4 +188,10 @@ void *get_nio_buffer(JNIEnv *env, jobject buffer, jarray *array_ref, jbyte **arr
 void release_nio_buffer(JNIEnv *env, jarray array_ref, jbyte *array);
 int get_nio_buffer_size(JNIEnv *env, jobject buffer);
 
+void atl_ensure_widget_snapshotability(GtkWidget *widget);
+void atl_safe_gtk_label_set_text(GtkLabel* label, const char* str);
+void atl_safe_gtk_widget_set_visible(GtkWidget *widget, gboolean visible);
+void atl_safe_gtk_widget_queue_allocate(GtkWidget *widget);
+void atl_safe_gtk_widget_queue_resize(GtkWidget *widget);
+
 #endif

src/api-impl-jni/views/android_view_View.c

@@ -446,6 +446,8 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1setLayoutParams(JNIEnv *en
 		android_layout_set_params(ATL_ANDROID_LAYOUT(layout_manager), width, height);
 
 	wrapper_widget_set_layout_params(WRAPPER_WIDGET(widget), width, height);
+
+	atl_ensure_widget_snapshotability(widget);
 }
 
 #pragma GCC diagnostic push
@@ -473,7 +475,7 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1setPadding(JNIEnv *env, jo
 JNIEXPORT void JNICALL Java_android_view_View_native_1setVisibility(JNIEnv *env, jobject this, jlong widget_ptr, jint visibility, jfloat alpha) {
 	GtkWidget *widget = gtk_widget_get_parent(GTK_WIDGET(_PTR(widget_ptr)));
 
-	gtk_widget_set_visible(widget, visibility != android_view_View_GONE);
+	atl_safe_gtk_widget_set_visible(widget, visibility != android_view_View_GONE);
 	gtk_widget_set_opacity(widget, (visibility != android_view_View_INVISIBLE) * alpha);
 	gtk_widget_set_sensitive(widget, visibility != android_view_View_INVISIBLE && alpha != 0.0f);
 }
@@ -481,7 +483,7 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1setVisibility(JNIEnv *env,
 /** JavaWidget:
  * Minimal gtk widget class which does nothing.
  * Drawing will be overwritten by WrapperWidget.
- * If it holds children, they will be layouted by AndroidLayout
+ * If it holds children, they will be laid out by AndroidLayout
  */
 struct _JavaWidget {GtkWidget parent_instance;};
 G_DECLARE_FINAL_TYPE(JavaWidget, java_widget, JAVA, WIDGET, GtkWidget)
@@ -595,7 +597,7 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1layout(JNIEnv *env, jobjec
 		wrapper->real_width = width;
 		wrapper->real_height = height;
 		if (!wrapper->needs_allocation)
-			gtk_widget_queue_allocate(widget);
+			atl_safe_gtk_widget_queue_allocate(widget);
 	}
 	if (wrapper->needs_allocation) {
 		allocation.width = width;
@@ -607,7 +609,7 @@ JNIEXPORT void JNICALL Java_android_view_View_native_1layout(JNIEnv *env, jobjec
 JNIEXPORT void JNICALL Java_android_view_View_native_1requestLayout(JNIEnv *env, jobject this, jlong widget_ptr) {
 	GtkWidget *widget = GTK_WIDGET(_PTR(widget_ptr));
 
-	gtk_widget_queue_resize(widget);
+	atl_safe_gtk_widget_queue_resize(widget);
 }
 
 /* we kinda need per-widget css */
@@ -711,7 +713,7 @@ JNIEXPORT jboolean JNICALL Java_android_view_View_native_1getMatrix(JNIEnv *env,
 
 JNIEXPORT void JNICALL Java_android_view_View_native_1queueAllocate(JNIEnv *env, jobject this, jlong widget_ptr)
 {
-	gtk_widget_queue_allocate(GTK_WIDGET(_PTR(widget_ptr)));
+	atl_safe_gtk_widget_queue_allocate(GTK_WIDGET(_PTR(widget_ptr)));
 }
 
 JNIEXPORT void JNICALL Java_android_view_View_native_1drawBackground(JNIEnv *env, jobject this, jlong widget_ptr, jlong snapshot_ptr)

src/api-impl-jni/widgets/WrapperWidget.c

@@ -168,7 +168,7 @@ void wrapper_widget_allocate(GtkWidget *widget, int width, int height, int basel
 			layout->real_width = width;
 			layout->real_height = height;
 			if (!layout->needs_allocation)
-				gtk_widget_queue_allocate(wrapper->child);
+				atl_safe_gtk_widget_queue_allocate(wrapper->child);
 		}
 		if (layout->needs_allocation)
 			gtk_widget_size_allocate(wrapper->child, &allocation, baseline);
@@ -181,8 +181,12 @@ void wrapper_widget_allocate(GtkWidget *widget, int width, int height, int basel
 		gtk_widget_size_allocate(wrapper->background, &allocation, baseline);
 }
 
+/* this is used to avoid queing layout changes in the middle of snapshotting */
+int snapshot_in_progress = 0;
 static void wrapper_widget_snapshot(GtkWidget *widget, GdkSnapshot *snapshot)
 {
+	snapshot_in_progress++;
+
 	WrapperWidget *wrapper = WRAPPER_WIDGET(widget);
 	if (wrapper->real_height > 0 && wrapper->real_width > 0) {
 		gtk_snapshot_push_clip(snapshot, &GRAPHENE_RECT_INIT(0, 0, wrapper->real_width, wrapper->real_height));
@@ -204,6 +208,8 @@ static void wrapper_widget_snapshot(GtkWidget *widget, GdkSnapshot *snapshot)
 	if (wrapper->real_height > 0 && wrapper->real_width > 0) {
 		gtk_snapshot_pop(snapshot);
 	}
+
+	snapshot_in_progress--;
 }
 
 static void wrapper_widget_class_init(WrapperWidgetClass *class)
@@ -257,8 +263,9 @@ void wrapper_widget_queue_draw(WrapperWidget *wrapper)
 
 	if(wrapper->child)
 		gtk_widget_queue_draw(wrapper->child);
-	if (wrapper->computeScroll_method)
-		gtk_widget_queue_allocate(GTK_WIDGET(wrapper));
+	if (wrapper->computeScroll_method) {
+		atl_safe_gtk_widget_queue_allocate(GTK_WIDGET(wrapper));
+	}
 }
 
 static bool on_click(GtkGestureClick *gesture, int n_press, double x, double y, jobject this)

src/api-impl-jni/widgets/android_widget_Button.c

@@ -36,7 +36,7 @@ JNIEXPORT void JNICALL Java_android_widget_Button_native_1setText(JNIEnv *env, j
 	GtkButton *button = GTK_BUTTON(_PTR(widget_ptr));
 
 	const char *nativeText = ((*env)->GetStringUTFChars(env, text, NULL));
-	gtk_label_set_text(box_get_label(env, gtk_button_get_child(button)), nativeText);
+	atl_safe_gtk_label_set_text(box_get_label(env, gtk_button_get_child(button)), nativeText);
 	((*env)->ReleaseStringUTFChars(env, text, nativeText));
 }
 

src/api-impl-jni/widgets/android_widget_TextView.c

@@ -43,7 +43,7 @@ JNIEXPORT jlong JNICALL Java_android_widget_TextView_native_1constructor(JNIEnv
 JNIEXPORT void JNICALL Java_android_widget_TextView_native_1setText(JNIEnv *env, jobject this, jobject charseq)
 {
 	const char *text = charseq ? (*env)->GetStringUTFChars(env, charseq, NULL) : NULL;
-	gtk_label_set_text(box_get_label(env, _PTR(_GET_LONG_FIELD(this, "widget"))), text ?: "");
+	atl_safe_gtk_label_set_text(box_get_label(env, _PTR(_GET_LONG_FIELD(this, "widget"))), text ?: "");
 	if(text)
 		(*env)->ReleaseStringUTFChars(env, charseq, text);
 }