From a3a139e3efe294c40371a70d46bedfe0836f0cbf Mon Sep 17 00:00:00 2001
From: driver1998 <driver1998@foxmail.com>
Date: Wed, 2 Sep 2020 11:03:14 +0800
Subject: [PATCH] Add PMv2 related APIs

---
 src/include/86box/win.h | 15 ++++++++++++++
 src/win/win_ui.c        | 44 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+)

diff --git a/src/include/86box/win.h b/src/include/86box/win.h
index 5537f4f30..9d3e8724b 100644
--- a/src/include/86box/win.h
+++ b/src/include/86box/win.h
@@ -33,6 +33,19 @@
 # include "resource.h"
 # undef BITMAP
 
+/* DPI Awareness Context, copied from MinGW-w64 windef.h */
+#ifndef _DPI_AWARENESS_CONTEXTS_
+DECLARE_HANDLE(DPI_AWARENESS_CONTEXT);
+#define DPI_AWARENESS_CONTEXT_UNAWARE              ((DPI_AWARENESS_CONTEXT)-1)
+#define DPI_AWARENESS_CONTEXT_SYSTEM_AWARE         ((DPI_AWARENESS_CONTEXT)-2)
+#define DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE    ((DPI_AWARENESS_CONTEXT)-3)
+#define DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 ((DPI_AWARENESS_CONTEXT)-4)
+#define DPI_AWARENESS_CONTEXT_UNAWARE_GDISCALED    ((DPI_AWARENESS_CONTEXT)-5)
+#endif
+
+#ifndef WM_DPICHANGED_AFTERPARENT
+#define WM_DPICHANGED_AFTERPARENT 0x02E3
+#endif
 
 /* Class names and such. */
 #define CLASS_NAME		L"86BoxMainWnd"
@@ -119,6 +132,8 @@ extern void     win_joystick_handle(PRAWINPUT raw);
 
 extern void     win_notify_dlg_open(void);
 extern void     win_notify_dlg_closed(void);
+extern int      win_get_dpi(HWND hwnd);
+extern int      win_get_system_metrics(int i, int dpi);
 
 extern LPARAM	win_get_string(int id);
 
diff --git a/src/win/win_ui.c b/src/win/win_ui.c
index edcf91385..ef7d6cd89 100644
--- a/src/win/win_ui.c
+++ b/src/win/win_ui.c
@@ -37,6 +37,7 @@
 #include <86box/vid_ega.h>		// for update_overscan
 #include <86box/plat.h>
 #include <86box/plat_midi.h>
+#include <86box/plat_dynld.h>
 #include <86box/ui.h>
 #include <86box/win.h>
 #include <86box/version.h>
@@ -73,6 +74,43 @@ static int	save_window_pos = 0, pause_state = 0;
 
 static int vis = -1;
 
+/* Per Monitor DPI Aware v2 APIs, Windows 10 v1703+ */
+void* user32_handle = NULL;
+static UINT  (WINAPI *pGetDpiForWindow)(HWND);
+static UINT (WINAPI *pGetSystemMetricsForDpi)(int i, UINT dpi);
+static DPI_AWARENESS_CONTEXT (WINAPI *pGetWindowDpiAwarenessContext)(HWND);
+static BOOL (WINAPI *pAreDpiAwarenessContextsEqual)(DPI_AWARENESS_CONTEXT A, DPI_AWARENESS_CONTEXT B);
+static dllimp_t user32_imports[] = {
+{ "GetDpiForWindow",	&pGetDpiForWindow },
+{ "GetSystemMetricsForDpi", &pGetSystemMetricsForDpi },
+{ "GetWindowDpiAwarenessContext", &pGetWindowDpiAwarenessContext },
+{ "AreDpiAwarenessContextsEqual", &pAreDpiAwarenessContextsEqual },
+{ NULL,		NULL		}
+};
+
+int
+win_get_dpi(HWND hwnd) {
+    if (user32_handle != NULL) {
+        return pGetDpiForWindow(hwnd);
+    } else {
+        HDC dc = GetDC(hwnd);
+        UINT dpi = GetDeviceCaps(dc, LOGPIXELSX);
+        ReleaseDC(hwnd, dc);
+        return dpi;
+    }
+}
+
+int win_get_system_metrics(int index, int dpi) {
+    if (user32_handle != NULL) {
+        /* Only call GetSystemMetricsForDpi when we are using PMv2 */
+        DPI_AWARENESS_CONTEXT c = pGetWindowDpiAwarenessContext(hwndMain);
+        if (pAreDpiAwarenessContextsEqual(c, DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2))
+            return pGetSystemMetricsForDpi(index, dpi);
+    }
+    
+    return GetSystemMetrics(index);
+}
+
 /* Set host cursor visible or not. */
 void
 show_cursor(int val)
@@ -894,6 +932,9 @@ ui_init(int nCmdShow)
     TASKDIALOGCONFIG tdconfig = {0};
     TASKDIALOG_BUTTON tdbuttons[] = {{IDCANCEL, MAKEINTRESOURCE(IDS_2119)}};
 
+    /* Load DPI related Windows 10 APIs */
+    user32_handle = dynld_module("user32.dll", user32_imports);
+
     /* Set up TaskDialog configuration. */
     tdconfig.cbSize = sizeof(tdconfig);
     tdconfig.dwFlags = TDF_ENABLE_HYPERLINKS;
@@ -1137,6 +1178,9 @@ ui_init(int nCmdShow)
     discord_close();
 #endif
 
+	if (user32_handle != NULL)
+    	dynld_close(user32_handle);
+
     return(messages.wParam);
 }