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Fix Screengrab DPI scaling on Windows 10 version 1607+ #4000

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Merged
radarhere merged 3 commits into from
Sep 30, 2019
Merged

Fix Screengrab DPI scaling on Windows 10 version 1607+ #4000

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cacbdc6
override Win10 dpi scaling in screengrab
nulano Jul 25, 2019
d46f81a
Windows Screengrab DPI fix improvements (#2)
radarhere Aug 3, 2019
ee5c134
Merge branch 'master' into dpi_fix
nulano Sep 27, 2019
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22 changes: 22 additions & 0 deletions src/display.c
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Original file line number Diff line number Diff line change
Expand Up @@ -319,6 +319,8 @@ PyImaging_DisplayModeWin32(PyObject* self, PyObject* args)
/* -------------------------------------------------------------------- */
/* Windows screen grabber */

typedef HANDLE(__stdcall* Func_SetThreadDpiAwarenessContext)(HANDLE);

PyObject*
PyImaging_GrabScreenWin32(PyObject* self, PyObject* args)
{
Expand All @@ -329,6 +331,9 @@ PyImaging_GrabScreenWin32(PyObject* self, PyObject* args)
HDC screen, screen_copy;
DWORD rop;
PyObject* buffer;
HANDLE dpiAwareness;
HMODULE user32;
Func_SetThreadDpiAwarenessContext SetThreadDpiAwarenessContext_function;

if (!PyArg_ParseTuple(args, "|ii", &includeLayeredWindows, &all_screens))
return NULL;
Expand All @@ -339,6 +344,17 @@ PyImaging_GrabScreenWin32(PyObject* self, PyObject* args)
screen = CreateDC("DISPLAY", NULL, NULL, NULL);
screen_copy = CreateCompatibleDC(screen);

// added in Windows 10 (1607)
// loaded dynamically to avoid link errors
user32 = LoadLibraryA("User32.dll");
SetThreadDpiAwarenessContext_function =
(Func_SetThreadDpiAwarenessContext)
GetProcAddress(user32, "SetThreadDpiAwarenessContext");
if (SetThreadDpiAwarenessContext_function != NULL) {
// DPI_AWARENESS_CONTEXT_PER_MONITOR_AWARE = ((DPI_CONTEXT_HANDLE)-3)
dpiAwareness = SetThreadDpiAwarenessContext_function((HANDLE) -3);
}

if (all_screens) {
x = GetSystemMetrics(SM_XVIRTUALSCREEN);
y = GetSystemMetrics(SM_YVIRTUALSCREEN);
Expand All @@ -349,6 +365,12 @@ PyImaging_GrabScreenWin32(PyObject* self, PyObject* args)
height = GetDeviceCaps(screen, VERTRES);
}

if (SetThreadDpiAwarenessContext_function != NULL) {
SetThreadDpiAwarenessContext_function(dpiAwareness);
}

FreeLibrary(user32);

bitmap = CreateCompatibleBitmap(screen, width, height);
if (!bitmap)
goto error;
Expand Down