w32: use DisplayConfig API to retrieve correct monitor refresh rate

This is based on an older patch by James Ross-Gowan. It was rebased and
cleaned up. Also, the DWM API usage present in the older patch was
removed, because DWM reports nonsense rates at least on Windows 8.1
(they are rounded to integers, just like with the old GDI API - except
the GDI API had a good excuse, as it could report only integers).

Signed-off-by: wm4 <wm4@nowhere>

2 files changed, 263 insertions, 0 deletions

diff --git a/video/out/win32/displayconfig.c b/video/out/win32/displayconfig.c
new file mode 100644
index 0000000000..635e8b6b36
--- /dev/null
+++ b/video/out/win32/displayconfig.c
@@ -0,0 +1,236 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <windows.h>
+#include <stdbool.h>
+#include <string.h>
+#include <pthread.h>
+
+#include "displayconfig.h"
+
+#include "talloc.h"
+
+// Some DisplayConfig definitions are broken in mingw-w64 (as of 2015-3-13.) To
+// get the correct struct alignment, it's necessary to define them properly.
+#include <pshpack1.h>
+
+typedef enum {
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_OTHER                 = -1,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_HD15                  = 0,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_SVIDEO                = 1,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_COMPOSITE_VIDEO       = 2,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_COMPONENT_VIDEO       = 3,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_DVI                   = 4,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_HDMI                  = 5,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_LVDS                  = 6,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_D_JPN                 = 8,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_SDI                   = 9,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_DISPLAYPORT_EXTERNAL  = 10,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_DISPLAYPORT_EMBEDDED  = 11,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_UDI_EXTERNAL          = 12,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_UDI_EMBEDDED          = 13,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_SDTVDONGLE            = 14,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_MIRACAST              = 15,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_INTERNAL              = -2147483647 - 1,
+    MP_DISPLAYCONFIG_OUTPUT_TECHNOLOGY_FORCE_UINT32          = 0x7FFFFFFF
+} MP_DISPLAYCONFIG_VIDEO_OUTPUT_TECHNOLOGY;
+
+typedef struct MP_DISPLAYCONFIG_PATH_TARGET_INFO {
+    LUID adapterId;
+    UINT32 id;
+    UINT32 modeInfoIdx;
+    MP_DISPLAYCONFIG_VIDEO_OUTPUT_TECHNOLOGY outputTechnology;
+    DISPLAYCONFIG_ROTATION rotation;
+    DISPLAYCONFIG_SCALING scaling;
+    DISPLAYCONFIG_RATIONAL refreshRate;
+    DISPLAYCONFIG_SCANLINE_ORDERING scanLineOrdering;
+    WINBOOL targetAvailable;
+    UINT32 statusFlags;
+} MP_DISPLAYCONFIG_PATH_TARGET_INFO;
+#define DISPLAYCONFIG_PATH_TARGET_INFO MP_DISPLAYCONFIG_PATH_TARGET_INFO
+
+typedef struct MP_DISPLAYCONFIG_PATH_INFO {
+    DISPLAYCONFIG_PATH_SOURCE_INFO sourceInfo;
+    MP_DISPLAYCONFIG_PATH_TARGET_INFO targetInfo;
+    UINT32 flags;
+} MP_DISPLAYCONFIG_PATH_INFO;
+#define DISPLAYCONFIG_PATH_INFO MP_DISPLAYCONFIG_PATH_INFO
+
+typedef struct MP_DISPLAYCONFIG_TARGET_DEVICE_NAME {
+    DISPLAYCONFIG_DEVICE_INFO_HEADER header;
+    DISPLAYCONFIG_TARGET_DEVICE_NAME_FLAGS flags;
+    MP_DISPLAYCONFIG_VIDEO_OUTPUT_TECHNOLOGY outputTechnology;
+    UINT16 edidManufactureId;
+    UINT16 edidProductCodeId;
+    UINT32 connectorInstance;
+    WCHAR monitorFriendlyDeviceName[64];
+    WCHAR monitorDevicePath[128];
+} MP_DISPLAYCONFIG_TARGET_DEVICE_NAME;
+#define DISPLAYCONFIG_TARGET_DEVICE_NAME MP_DISPLAYCONFIG_TARGET_DEVICE_NAME
+
+#include <poppack.h>
+
+static pthread_once_t displayconfig_load_ran = PTHREAD_ONCE_INIT;
+static bool displayconfig_loaded = false;
+
+static LONG (WINAPI *pDisplayConfigGetDeviceInfo)(
+        DISPLAYCONFIG_DEVICE_INFO_HEADER*);
+static LONG (WINAPI *pGetDisplayConfigBufferSizes)(UINT32, UINT32*, UINT32*);
+static LONG (WINAPI *pQueryDisplayConfig)(UINT32, UINT32*,
+        DISPLAYCONFIG_PATH_INFO*, UINT32*, DISPLAYCONFIG_MODE_INFO*,
+        DISPLAYCONFIG_TOPOLOGY_ID*);
+
+static void displayconfig_load(void)
+{
+    HMODULE user32 = GetModuleHandleW(L"user32.dll");
+    if (!user32)
+        return;
+
+    pDisplayConfigGetDeviceInfo =
+        (LONG (WINAPI*)(DISPLAYCONFIG_DEVICE_INFO_HEADER*))
+        GetProcAddress(user32, "DisplayConfigGetDeviceInfo");
+    if (!pDisplayConfigGetDeviceInfo)
+        return;
+    pGetDisplayConfigBufferSizes =
+        (LONG (WINAPI*)(UINT32, UINT32*, UINT32*))
+        GetProcAddress(user32, "GetDisplayConfigBufferSizes");
+    if (!pGetDisplayConfigBufferSizes)
+        return;
+    pQueryDisplayConfig =
+        (LONG (WINAPI*)(UINT32, UINT32*, DISPLAYCONFIG_PATH_INFO*, UINT32*,
+                        DISPLAYCONFIG_MODE_INFO*, DISPLAYCONFIG_TOPOLOGY_ID*))
+        GetProcAddress(user32, "QueryDisplayConfig");
+    if (!pQueryDisplayConfig)
+        return;
+
+    displayconfig_loaded = true;
+}
+
+static int get_config(void *ctx,
+                      UINT32 *num_paths, DISPLAYCONFIG_PATH_INFO** paths,
+                      UINT32 *num_modes, DISPLAYCONFIG_MODE_INFO** modes)
+{
+    LONG res;
+    *paths = NULL;
+    *modes = NULL;
+
+    // The display configuration could change between the call to
+    // GetDisplayConfigBufferSizes and the call to QueryDisplayConfig, so call
+    // them in a loop until the correct buffer size is chosen
+    do {
+        res = pGetDisplayConfigBufferSizes(QDC_ONLY_ACTIVE_PATHS, num_paths,
+                                           num_modes);
+        if (res != ERROR_SUCCESS)
+            goto fail;
+
+        // Free old buffers if they exist and allocate new ones
+        talloc_free(*paths);
+        talloc_free(*modes);
+        *paths = talloc_array(ctx, DISPLAYCONFIG_PATH_INFO, *num_paths);
+        *modes = talloc_array(ctx, DISPLAYCONFIG_MODE_INFO, *num_modes);
+
+        res = pQueryDisplayConfig(QDC_ONLY_ACTIVE_PATHS, num_paths, *paths,
+                                  num_modes, *modes, NULL);
+    } while (res == ERROR_INSUFFICIENT_BUFFER);
+    if (res != ERROR_SUCCESS)
+        goto fail;
+
+    return 0;
+fail:
+    talloc_free(*paths);
+    talloc_free(*modes);
+    return -1;
+}
+
+static DISPLAYCONFIG_PATH_INFO *get_path(UINT32 num_paths,
+                                         DISPLAYCONFIG_PATH_INFO* paths,
+                                         const wchar_t *device)
+{
+    // Search for a path with a matching device name
+    for (UINT32 i = 0; i < num_paths; i++) {
+        // Send a GET_SOURCE_NAME request
+        DISPLAYCONFIG_SOURCE_DEVICE_NAME source = {
+            .header = {
+                .size = sizeof source,
+                .type = DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME,
+                .adapterId = paths[i].sourceInfo.adapterId,
+                .id = paths[i].sourceInfo.id,
+            }
+        };
+        if (pDisplayConfigGetDeviceInfo(&source.header) != ERROR_SUCCESS)
+            return NULL;
+
+        // Check if the device name matches
+        if (!wcscmp(device, source.viewGdiDeviceName))
+            return &paths[i];
+    }
+
+    return NULL;
+}
+
+static double get_refresh_rate_from_mode(DISPLAYCONFIG_MODE_INFO *mode)
+{
+    if (mode->infoType != DISPLAYCONFIG_MODE_INFO_TYPE_TARGET)
+        return 0.0;
+
+    DISPLAYCONFIG_VIDEO_SIGNAL_INFO *info =
+        &mode->targetMode.targetVideoSignalInfo;
+    if (info->vSyncFreq.Denominator == 0)
+        return 0.0;
+
+    return ((double)info->vSyncFreq.Numerator) /
+           ((double)info->vSyncFreq.Denominator);
+}
+
+double mp_w32_displayconfig_get_refresh_rate(const wchar_t *device)
+{
+    // Load Windows 7 DisplayConfig API
+    pthread_once(&displayconfig_load_ran, displayconfig_load);
+    if (!displayconfig_loaded)
+        return 0.0;
+
+    void *ctx = talloc_new(NULL);
+    double freq = 0.0;
+
+    // Get the current display configuration
+    UINT32 num_paths;
+    DISPLAYCONFIG_PATH_INFO* paths;
+    UINT32 num_modes;
+    DISPLAYCONFIG_MODE_INFO* modes;
+    if (get_config(ctx, &num_paths, &paths, &num_modes, &modes))
+        goto end;
+
+    // Get the path for the specified monitor
+    DISPLAYCONFIG_PATH_INFO* path;
+    if (!(path = get_path(num_paths, paths, device)))
+        goto end;
+
+    // Try getting the refresh rate from the mode first. The value in the mode
+    // overrides the value in the path.
+    if (path->targetInfo.modeInfoIdx != DISPLAYCONFIG_PATH_MODE_IDX_INVALID)
+        freq = get_refresh_rate_from_mode(&modes[path->targetInfo.modeInfoIdx]);
+
+    // If the mode didn't contain a valid refresh rate, try the path
+    if (freq == 0.0 && path->targetInfo.refreshRate.Denominator != 0) {
+        freq = ((double)path->targetInfo.refreshRate.Numerator) /
+               ((double)path->targetInfo.refreshRate.Denominator);
+    }
+
+end:
+    talloc_free(ctx);
+    return freq;
+}
diff --git a/video/out/win32/displayconfig.h b/video/out/win32/displayconfig.h
new file mode 100644
index 0000000000..ee6cd037f0
--- /dev/null
+++ b/video/out/win32/displayconfig.h
@@ -0,0 +1,27 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef MP_WIN32_DISPLAYCONFIG_H_
+#define MP_WIN32_DISPLAYCONFIG_H_
+
+#include <wchar.h>
+
+// Given a GDI monitor device name, get the precise refresh rate using the
+// Windows 7 DisplayConfig API. Returns 0.0 on failure.
+double mp_w32_displayconfig_get_refresh_rate(const wchar_t *device);
+
+#endif