Qt: Add display information to the About dialog.

Add ColorUtils::themeIsDark and use it to report our dark / light mode
in the "About" dialog. Summarize the HiDPI capability of our displays as
well.

Change-Id: I242af1eb48017d49b90e71099bb753e67a8dd32b
Reviewed-on: https://code.wireshark.org/review/32115
Petri-Dish: Gerald Combs <gerald@wireshark.org>
Tested-by: Petri Dish Buildbot
Reviewed-by: Gerald Combs <gerald@wireshark.org>

ui/qt/main.cpp

@@ -94,6 +94,7 @@
 #include "caputils/capture-pcap-util.h"
 
 #include <QMessageBox>
+#include <QScreen>
 
 #ifdef _WIN32
 #  include "caputils/capture-wpcap.h"
@@ -239,6 +240,26 @@ get_gui_compiled_info(GString *str)
 void
 get_wireshark_runtime_info(GString *str)
 {
+    if (wsApp) {
+        // Display information
+        const char *display_mode = ColorUtils::themeIsDark() ? "dark" : "light";
+        g_string_append_printf(str, ", with %s display mode", display_mode);
+
+        int hidpi_count = 0;
+        foreach (QScreen *screen, wsApp->screens()) {
+            if (screen->devicePixelRatio() > 1.0) {
+                hidpi_count++;
+            }
+        }
+        if (hidpi_count == wsApp->screens().count()) {
+            g_string_append(str, ", with HiDPI");
+        } else if (hidpi_count) {
+            g_string_append(str, ", with mixed DPI");
+        } else {
+            g_string_append(str, ", without HiDPI");
+        }
+    }
+
 #ifdef HAVE_LIBPCAP
     /* Capture libraries */
     g_string_append(str, ", ");

ui/qt/utils/color_utils.cpp

@@ -9,6 +9,9 @@
 
 #include <ui/qt/utils/color_utils.h>
 #include <ui/qt/utils/tango_colors.h>
+#include <ui/qt/wireshark_application.h>
+
+#include <QPalette>
 
 // Colors we use in various parts of the UI.
 //
@@ -138,6 +141,11 @@ QRgb ColorUtils::sequenceColor(int item)
     return sequence_colors_[item % sequence_colors_.size()];
 }
 
+bool ColorUtils::themeIsDark()
+{
+    return wsApp->palette().windowText().color().lightness() < wsApp->palette().text().color().lightness();
+}
+
 /*
  * Editor modelines
  *

ui/qt/utils/color_utils.h

@@ -45,6 +45,8 @@ public:
     static QRgb graphColor(int item);
     static QRgb sequenceColor(int item);
 
+    static bool themeIsDark();
+
 signals:
 
 public slots: