add per-monitor dpi support

1 files changed, 46 insertions, 0 deletions

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;
+    }
+}