add per-monitor dpi support

4 files changed, 128 insertions, 15 deletions

diff --git a/alf/alf.cpp b/alf/alf.cpp
index 2ec33ca..9b2f60f 100644
--- a/alf/alf.cpp
+++ b/alf/alf.cpp
@@ -1,5 +1,9 @@
 #include "alfpriv.h"
 
+#ifndef WM_DPICHANGED
+#define WM_DPICHANGED       0x02E0
+#endif
+
 /* ALF App and Window */
 
 static void
@@ -39,31 +43,25 @@ ALF_UpdateFontForWidget(ALFWindowPriv *priv, ALFWidgetPriv *widget)
 {
     if (widget->hwnd && (widget->flags & ALF_MESSAGEFONT) == ALF_MESSAGEFONT) {
         SendMessage(widget->hwnd, WM_SETFONT, (WPARAM)priv->fonts.hMessageFont, (LPARAM)NULL);
+
+        // XXX: Invalidating should IMHO be the decision of the control, but at
+        // least the commctl32 V5 static control doesn't do it.
+        InvalidateRect(widget->hwnd, NULL, TRUE);
     }
 }
 
 void
 ALF_UpdateFonts(HWND win)
 {
-    // TODO per-monitor DPI aware: GetDpiForWindow, SystemParametersInfoForDpi etc.
     ALFWindowPriv *priv = (ALFWindowPriv*)GetWindowLongPtr(win, 0);
 
-    priv->fonts.dpi = 0;
-    HDC hdcScreen = GetDC(NULL);
-    if (hdcScreen) {
-        priv->fonts.dpi = GetDeviceCaps(hdcScreen, LOGPIXELSY);
-        ReleaseDC(NULL, hdcScreen);
-    }
-
-    if (!priv->fonts.dpi) {
-        priv->fonts.dpi = 96; // FIXME! fallback to default DPI
-    }
+    priv->fonts.dpi = priv->app->compatFn->GetDpiForWindow(win);
 
     NONCLIENTMETRICS ncm;
     ZeroMemory(&ncm, sizeof(ncm));
     ncm.cbSize = sizeof(ncm);
 
-    if (SystemParametersInfoW(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0)) {
+    if (priv->app->compatFn->SystemParametersInfoForDpi(SPI_GETNONCLIENTMETRICS, ncm.cbSize, &ncm, 0, priv->fonts.dpi)) {
         priv->fonts.lfMessageFont = ncm.lfMessageFont;
     } else {
         // FIXME! fallback to default font, 8pt MS Shell Dlg
@@ -375,11 +373,12 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
         tmp.right = priv->layout.totalMinWidth;
         tmp.bottom = priv->layout.totalMinHeight;
 
-        // TODO ..ForDpi
-        if (AdjustWindowRectEx(&tmp,
+        if (priv->app->compatFn->AdjustWindowRectExForDpi(
+                               &tmp,
                                GetWindowLong(hwnd, GWL_STYLE),
                                GetMenu(hwnd) != NULL,
-                               GetWindowLong(hwnd, GWL_EXSTYLE))) {
+                               GetWindowLong(hwnd, GWL_EXSTYLE),
+                               priv->fonts.dpi)) {
             MINMAXINFO *i = (MINMAXINFO *)lparam;
             i->ptMinTrackSize.x = tmp.right - tmp.left;
             i->ptMinTrackSize.y = tmp.bottom - tmp.top;
@@ -417,6 +416,13 @@ ALF_DefWindowProc(HWND hwnd, UINT msg, WPARAM wparam, LPARAM lparam)
         ALF_DestroyWindowPriv(priv);
     }
 
+    if (msg == WM_DPICHANGED) {
+        ALF_UpdateFonts(hwnd);
+        ALF_RecalculateLayout(hwnd);
+        RECT *r = (RECT*)lparam;
+        SetWindowPos(hwnd, NULL, r->left, r->top, r->right-r->left, r->bottom-r->top, SWP_NOACTIVATE|SWP_NOZORDER);
+    }
+
     if (msg == DM_GETDEFID) {
         if (priv->defid == (WORD)-1) {
             return 0;
diff --git a/alf/alf.h b/alf/alf.h
index d21a295..16767a7 100644
--- a/alf/alf.h
+++ b/alf/alf.h
@@ -76,10 +76,22 @@ typedef struct {
     BOOL (WINAPI *RemoveWindowSubclass)(HWND, ALF_COMPAT_SUBCLASSPROC, UINT_PTR);
     int (WINAPI *GetSystemMetricsForDpi)(int,  UINT);
     BOOL (WINAPI *IsAppThemed)(void);
+    UINT (WINAPI *GetDpiForWindow)(HWND);
+    BOOL (WINAPI *SystemParametersInfoForDpi)(UINT,UINT,PVOID,UINT,UINT);
+    BOOL (WINAPI *AdjustWindowRectExForDpi)(LPRECT,DWORD,BOOL,DWORD,UINT);
 } ALFCompatFunctions;
 
 typedef struct ALFAppPriv *ALFAPP;
 
+typedef enum {
+    ALF_DPI_AWARENESS_UNAWARE,
+    ALF_DPI_AWARENESS_SYSTEM_AWARE,
+    ALF_DPI_AWARENESS_PER_MONITOR_AWARE_V2
+} ALFDpiAwareness;
+
+void
+ALF_SetDpiAwareness(ALFDpiAwareness awareness);
+
 ALFAPP
 ALF_CreateApplication(HINSTANCE hInstance);
 
diff --git a/alf/alfcompat.cpp b/alf/alfcompat.cpp
index 3ffc9f9..e6a9851 100644
--- a/alf/alfcompat.cpp
+++ b/alf/alfcompat.cpp
@@ -41,6 +41,42 @@ fallbackIsAppThemed(void)
     return FALSE;
 }
 
+static UINT WINAPI
+fallbackGetDpiForWindow(HWND win)
+{
+    (void)win;
+
+    UINT dpi = 0;
+
+    HDC hdcScreen = GetDC(NULL);
+    if (hdcScreen) {
+        dpi = GetDeviceCaps(hdcScreen, LOGPIXELSY);
+        ReleaseDC(NULL, hdcScreen);
+    }
+
+    if (!dpi) {
+        dpi = 96; // FIXME! fallback to default DPI
+    }
+
+    return dpi;
+}
+
+static BOOL WINAPI
+fallbackSystemParametersInfoForDpi(UINT uiAction, UINT uiParam, PVOID pvParam, UINT fWinIni, UINT dpi)
+{
+    (void)dpi;
+
+    return SystemParametersInfo(uiAction, uiParam, pvParam, fWinIni);
+}
+
+static BOOL WINAPI
+fallbackAdjustWindowRectExForDpi(LPRECT lpRect, DWORD dwStyle, BOOL bMenu, DWORD dwExStyle, UINT dpi)
+{
+    (void)dpi;
+
+    return AdjustWindowRectEx(lpRect, dwStyle, bMenu, dwExStyle);
+}
+
 ALFCompatFunctions *
 ALF_CreateCompatFuncTable(void)
 {
@@ -61,6 +97,19 @@ ALF_CreateCompatFuncTable(void)
     COMPAT(comctl32.dll, DefSubclassProc, 413, NULL);
     COMPAT(comctl32.dll, RemoveWindowSubclass, 412, NULL);
     COMPAT(user32.dll, GetSystemMetricsForDpi, 0, fallbackGetSystemMetricsForDpi);
+    COMPAT(user32.dll, GetDpiForWindow, 0, fallbackGetDpiForWindow);
+
+    // FIXME: SystemParametersInfoForDpi is Unicode-Only.
+    // Writing a wrapper function would have been The Right Way, but such a function
+    // is yet to be written. So the current practical recommendation is to make
+    // ANSI builds System DPI aware only.
+#ifdef UNICODE
+    COMPAT(user32.dll, SystemParametersInfoForDpi, 0, fallbackSystemParametersInfoForDpi);
+#else
+    compatfn->SystemParametersInfoForDpi = fallbackSystemParametersInfoForDpi;
+#endif
+
+    COMPAT(user32.dll, AdjustWindowRectExForDpi, 0, fallbackAdjustWindowRectExForDpi);
 
     // IsAppThemed would return TRUE even when we're linked against comctl32 v5
     if (ALF_DllGetVersion("comctl32.dll") >= 0x60000) {
diff --git a/alf/alfdpiaware.cpp b/alf/alfdpiaware.cpp
new file mode 100644
index 0000000..8f998f7
--- /dev/null
+++ b/alf/alfdpiaware.cpp
@@ -0,0 +1,46 @@
+#include "alfpriv.h"
+
+typedef BOOL (WINAPI *PSetProcessDpiAwarenessContext)(HANDLE);
+typedef BOOL (WINAPI *PSetProcessDPIAware)(void);
+
+static void
+ALF_SetSystemDpiAwareness(void)
+{
+    HMODULE user32 = GetModuleHandleA("user32.dll");
+
+    PSetProcessDPIAware p = (PSetProcessDPIAware)
+        (void*)GetProcAddress(user32, "SetProcessDPIAware");
+    if (p) {
+        p();
+    }
+}
+
+static void
+ALF_SetPerMonitorAwareness(void)
+{
+    HMODULE user32 = GetModuleHandleA("user32.dll");
+
+    PSetProcessDpiAwarenessContext p = (PSetProcessDpiAwarenessContext)
+        (void*)GetProcAddress(user32, "SetProcessDpiAwarenessContext");
+
+    if (p && p((HANDLE)-4)) /* DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE_V2 */
+            return;
+
+    ALF_SetSystemDpiAwareness();
+}
+
+void
+ALF_SetDpiAwareness(ALFDpiAwareness awareness)
+{
+    switch (awareness) {
+        case ALF_DPI_AWARENESS_PER_MONITOR_AWARE_V2:
+            ALF_SetPerMonitorAwareness();
+            return;
+        case ALF_DPI_AWARENESS_SYSTEM_AWARE:
+            ALF_SetSystemDpiAwareness();
+            return;
+        default:
+            // unaware, or could not set awareness
+            return;
+    }
+}