Qt+prefs: Add a dark theme check and default colors.

Add prefs_set_gui_theme_is_dark and call it in the WiresharkApplication
constructor. Add a set of dark syntax color defaults.

We could alternatively add a preference for the syntax foreground color,
but that would imply adding a preference for the background color as
well.

Bug: 11131
Bug: 13738
Change-Id: Iefe135ed04e63372ed434c5b9759647c9f4046e3
Reviewed-on: https://code.wireshark.org/review/21827
Reviewed-by: Gerald Combs <gerald@wireshark.org>
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Anders Broman <a.broman58@gmail.com>

3 files changed, 40 insertions, 11 deletions

diff --git a/epan/prefs.c b/epan/prefs.c
index 35ff3fa2a2..0c53992d4a 100644
--- a/epan/prefs.c
+++ b/epan/prefs.c
@@ -78,6 +78,7 @@ static void try_convert_to_custom_column(gpointer *el_data);
 static gboolean prefs_initialized = FALSE;
 static gchar *gpf_path = NULL;
 static gchar *cols_hidden_list = NULL;
+static gboolean gui_theme_is_dark = FALSE;
 
 /*
  * XXX - variables to allow us to attempt to interpret the first
@@ -413,6 +414,11 @@ prefs_cleanup(void)
     gpf_path = NULL;
 }
 
+void prefs_set_gui_theme_is_dark(gboolean is_dark)
+{
+    gui_theme_is_dark = is_dark;
+}
+
 /*
  * Register a module that will have preferences.
  * Specify the module under which to register it or NULL to register it
@@ -3959,15 +3965,31 @@ pre_init_prefs(void)
     prefs.st_server_bg.red           = 60909;
     prefs.st_server_bg.green         = 60909;
     prefs.st_server_bg.blue          = 64507;
-    prefs.gui_text_valid.red         = 0xAFFF; /* light green */
-    prefs.gui_text_valid.green       = 0xFFFF;
-    prefs.gui_text_valid.blue        = 0xAFFF;
-    prefs.gui_text_invalid.red       = 0xFFFF; /* light red */
-    prefs.gui_text_invalid.green     = 0xAFFF;
-    prefs.gui_text_invalid.blue      = 0xAFFF;
-    prefs.gui_text_deprecated.red    = 0xFFFF; /* light yellow */
-    prefs.gui_text_deprecated.green  = 0xFFFF;
-    prefs.gui_text_deprecated.blue   = 0xAFFF;
+
+    if (gui_theme_is_dark) {
+        // Green, red and yellow with HSV V = 84
+        prefs.gui_text_valid.red         = 0x0000; /* dark green */
+        prefs.gui_text_valid.green       = 0x66ff;
+        prefs.gui_text_valid.blue        = 0x0000;
+        prefs.gui_text_invalid.red       = 0x66FF; /* dark red */
+        prefs.gui_text_invalid.green     = 0x0000;
+        prefs.gui_text_invalid.blue      = 0x0000;
+        prefs.gui_text_deprecated.red    = 0x66FF; /* dark yellow / olive */
+        prefs.gui_text_deprecated.green  = 0x66FF;
+        prefs.gui_text_deprecated.blue   = 0x0000;
+    } else {
+        // Green, red and yellow with HSV V = 20
+        prefs.gui_text_valid.red         = 0xAFFF; /* light green */
+        prefs.gui_text_valid.green       = 0xFFFF;
+        prefs.gui_text_valid.blue        = 0xAFFF;
+        prefs.gui_text_invalid.red       = 0xFFFF; /* light red */
+        prefs.gui_text_invalid.green     = 0xAFFF;
+        prefs.gui_text_invalid.blue      = 0xAFFF;
+        prefs.gui_text_deprecated.red    = 0xFFFF; /* light yellow */
+        prefs.gui_text_deprecated.green  = 0xFFFF;
+        prefs.gui_text_deprecated.blue   = 0xAFFF;
+    }
+
     prefs.gui_geometry_save_position = TRUE;
     prefs.gui_geometry_save_size     = TRUE;
     prefs.gui_geometry_save_maximized= TRUE;
diff --git a/epan/prefs.h b/epan/prefs.h
index e757a25533..e68b187d11 100644
--- a/epan/prefs.h
+++ b/epan/prefs.h
@@ -151,7 +151,7 @@ typedef struct _e_prefs {
   gint         num_cols;
   color_t      st_client_fg, st_client_bg, st_server_fg, st_server_bg;
   color_t      gui_text_valid, gui_text_invalid, gui_text_deprecated;
-  gboolean     gui_altern_colors;
+  gboolean     gui_altern_colors; /* GTK only */
   gboolean     gui_expert_composite_eyecandy;
   gboolean     filter_toolbar_show_in_statusbar;
   gint         gui_ptree_line_style;
@@ -170,7 +170,7 @@ typedef struct _e_prefs {
   gboolean     gui_geometry_save_position;
   gboolean     gui_geometry_save_size;
   gboolean     gui_geometry_save_maximized;
-  gboolean     gui_macosx_style;
+  gboolean     gui_macosx_style; /* GTK only */
   console_open_e gui_console_open;
   guint        gui_recent_df_entries_max;
   guint        gui_recent_files_count_max;
@@ -269,6 +269,9 @@ WS_DLL_PUBLIC void prefs_reset(void);
 /** Frees memory used by proto routines. Called at program shutdown */
 void prefs_cleanup(void);
 
+/** Provide a hint about the darkness of the current UI theme so that we can adjust colors when needed */
+WS_DLL_PUBLIC void prefs_set_gui_theme_is_dark(gboolean is_dark);
+
 /*
  * Register that a protocol has preferences.
  */
diff --git a/ui/qt/wireshark_application.cpp b/ui/qt/wireshark_application.cpp
index 93fb1ec675..8414cb4502 100644
--- a/ui/qt/wireshark_application.cpp
+++ b/ui/qt/wireshark_application.cpp
@@ -833,6 +833,10 @@ WiresharkApplication::WiresharkApplication(int &argc,  char **argv) :
 #endif
     qApp->setStyleSheet(app_style_sheet);
 
+    // If our window text is lighter than the window background, assume the theme is dark.
+    QPalette gui_pal = QGuiApplication::palette();
+    prefs_set_gui_theme_is_dark(gui_pal.windowText().color().value() > gui_pal.window().color().value());
+
 #ifdef HAVE_SOFTWARE_UPDATE
     connect(this, SIGNAL(softwareUpdateQuit()), this, SLOT(quit()), Qt::QueuedConnection);
 #endif