[gtk/wip/chergert/GTK_DEBUG_TEXT_DIR: 13/13] gtkmain: add support for GTK_DEBUG=invert-text-dir

[Christian Hergert <chergert src gnome org>]

commit 8f1db27b6be1a0154a0bfce7d9882db298f7dc5e
Author: Christian Hergert <chergert redhat com>
Date:   Wed Jun 1 11:26:44 2022 -0700

    gtkmain: add support for GTK_DEBUG=invert-text-dir
    
    This allows inverting the default text-direction in an application for
    debugging, testing, and QA purposes. IDEs such as Builder may automate this
    to encourage more application developers to test with a text-direction
    different than their own.

 gtk/gtkdebug.h |  1 +
 gtk/gtkmain.c  | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtkdebug.h b/gtk/gtkdebug.h
index f1cad3ea59..a5b8eff2d1 100644
--- a/gtk/gtkdebug.h
+++ b/gtk/gtkdebug.h
@@ -82,6 +82,7 @@ typedef enum {
   GTK_DEBUG_BUILDER_OBJECTS = 1 << 16,
   GTK_DEBUG_A11Y            = 1 << 17,
   GTK_DEBUG_ICONFALLBACK    = 1 << 18,
+  GTK_DEBUG_INVERT_TEXT_DIR = 1 << 19,
 } GtkDebugFlags;
 
 #ifdef G_ENABLE_DEBUG
diff --git a/gtk/gtkmain.c b/gtk/gtkmain.c
index 7cc39c35f8..80c7542b03 100644
--- a/gtk/gtkmain.c
+++ b/gtk/gtkmain.c
@@ -203,6 +203,7 @@ static const GdkDebugKey gtk_debug_keys[] = {
   { "snapshot", GTK_DEBUG_SNAPSHOT, "Generate debug render nodes" },
   { "accessibility", GTK_DEBUG_A11Y, "Information about accessibility state changes" },
   { "iconfallback", GTK_DEBUG_ICONFALLBACK, "Information about icon fallback" },
+  { "invert-text-dir", GTK_DEBUG_INVERT_TEXT_DIR, "Invert the default text direction" },
 };
 
 /* This checks to see if the process is running suid or sgid
@@ -523,6 +524,7 @@ static void
 do_post_parse_initialization (void)
 {
   GdkDisplayManager *display_manager;
+  GtkTextDirection text_dir;
   gint64 before G_GNUC_UNUSED;
 
   if (gtk_initialized)
@@ -536,7 +538,16 @@ do_post_parse_initialization (void)
   signal (SIGPIPE, SIG_IGN);
 #endif
 
-  gtk_widget_set_default_direction (gtk_get_locale_direction ());
+  text_dir = gtk_get_locale_direction ();
+
+  /* We always allow inverting the text direction, even in
+   * production builds, as SDK/IDE tooling may provide the
+   * ability for developers to test rtl/ltr inverted.
+   */
+  if (gtk_get_debug_flags () & GTK_DEBUG_INVERT_TEXT_DIR)
+    text_dir = (text_dir == GTK_TEXT_DIR_LTR) ? GTK_TEXT_DIR_RTL : GTK_TEXT_DIR_LTR;
+
+  gtk_widget_set_default_direction (text_dir);
 
   gdk_event_init_types ();