windows icon sizing and WNDCLASSEX for small icon

windows/runner/Runner.rc

@@ -52,7 +52,16 @@ END
 
 // Icon with lowest ID value placed first to ensure application icon
 // remains consistent on all systems.
-IDI_APP_ICON            ICON                    "resources\\app_icon.ico"
+IDI_APP_ICON_LG          ICON                    "resources\\knot_256.ico"
+IDI_APP_ICON_SM          ICON                    "resources\\knot_64.ico"
+
+IDI_APP_ICON_256          ICON                    "resources\\knot_256.ico"
+IDI_APP_ICON_128          ICON                    "resources\\knot_128.ico"
+IDI_APP_ICON_64           ICON                    "resources\\knot_64.ico"
+IDI_APP_ICON_48           ICON                    "resources\\knot_48.ico"
+IDI_APP_ICON_32           ICON                    "resources\\knot_32.ico"
+IDI_APP_ICON_16           ICON                    "resources\\knot_16.ico"
+
 
 
 /////////////////////////////////////////////////////////////////////////////

windows/runner/resource.h

@@ -2,7 +2,16 @@
 // Microsoft Visual C++ generated include file.
 // Used by Runner.rc
 //
-#define IDI_APP_ICON                    101
+#define IDI_APP_ICON_LG                    101
+#define IDI_APP_ICON_SM                    102
+
+#define IDI_APP_ICON_256                   103
+#define IDI_APP_ICON_128                   104
+#define IDI_APP_ICON_64                    105
+#define IDI_APP_ICON_48                    106
+#define IDI_APP_ICON_32                    107
+#define IDI_APP_ICON_16                    108
+
 
 // Next default values for new objects
 //

windows/runner/win32_window.cpp

@@ -1,4 +1,5 @@
 #include "win32_window.h"
+#include "winuser.h"
 
 #include <flutter_windows.h>
 
@@ -70,19 +71,49 @@ WindowClassRegistrar* WindowClassRegistrar::instance_ = nullptr;
 
 const wchar_t* WindowClassRegistrar::GetWindowClass() {
   if (!class_registered_) {
-    WNDCLASS window_class{};
+    WNDCLASSEX window_class{};
+    window_class.cbSize = sizeof(WNDCLASSEX);
     window_class.hCursor = LoadCursor(nullptr, IDC_ARROW);
     window_class.lpszClassName = kWindowClassName;
     window_class.style = CS_HREDRAW | CS_VREDRAW;
     window_class.cbClsExtra = 0;
     window_class.cbWndExtra = 0;
     window_class.hInstance = GetModuleHandle(nullptr);
+    int icon_sz = GetSystemMetrics(SM_CXICON);
+    int iconh_id = IDI_APP_ICON_32;
+    if (icon_sz > 128) {
+        iconh_id = IDI_APP_ICON_256;
+    } else if (icon_sz > 64) {
+        iconh_id = IDI_APP_ICON_128;
+    } else if (icon_sz > 48) {
+        iconh_id = IDI_APP_ICON_64;
+    } else if (icon_sz > 32) {
+          iconh_id = IDI_APP_ICON_48;
+    }
     window_class.hIcon =
-        LoadIcon(window_class.hInstance, MAKEINTRESOURCE(IDI_APP_ICON));
+                LoadIcon(window_class.hInstance, MAKEINTRESOURCE(iconh_id));
+
+
+    int icon_sm_sz = GetSystemMetrics(SM_CXSMICON);
+    int iconsmh_id = IDI_APP_ICON_16;
+    if (icon_sm_sz > 128) {
+        iconsmh_id = IDI_APP_ICON_256;
+    } else if (icon_sm_sz > 64) {
+        iconsmh_id = IDI_APP_ICON_128;
+    } else if (icon_sm_sz > 48) {
+        iconsmh_id = IDI_APP_ICON_64;
+    } else if (icon_sm_sz > 32) {
+        iconsmh_id = IDI_APP_ICON_48;
+    } else if (icon_sm_sz > 16) {
+        iconsmh_id = IDI_APP_ICON_32;
+    }
+    window_class.hIconSm =
+        LoadIcon(window_class.hInstance, MAKEINTRESOURCE(iconsmh_id));
+
     window_class.hbrBackground = 0;
     window_class.lpszMenuName = nullptr;
     window_class.lpfnWndProc = Win32Window::WndProc;
-    RegisterClass(&window_class);
+    RegisterClassEx(&window_class);
     class_registered_ = true;
   }
   return kWindowClassName;