[PATCH 0/1] MR10246: dxgi: Implement IDXGIOutput::WaitForVBlank()

[Mike Kozelkov (＠augenzi)]

In QT 6.9 QWindow update request are driven by a vblank watcher thread that calls IDXGIOutput::WaitForVBlank in loop (https://doc.qt.io/qt-6/whatsnew69.html#qt-gui-module).

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10246

[PATCH 1/1] dxgi: Implement IDXGIOutput::WaitForVBlank()

[Mike Kozelkov]

From: Mike Kozelkov <[e-mail]>

---
 dlls/dxgi/output.c | 30 ++++++++++++++++++++++++------
 1 file changed, 24 insertions(+), 6 deletions(-)

diff --git a/dlls/dxgi/output.c b/dlls/dxgi/output.c
index e828ed0d9d8..91ea25dd740 100644
--- a/dlls/dxgi/output.c
+++ b/dlls/dxgi/output.c
@@ -363,14 +363,32 @@ static HRESULT STDMETHODCALLTYPE dxgi_output_FindClosestMatchingMode(IDXGIOutput
 
 static HRESULT STDMETHODCALLTYPE dxgi_output_WaitForVBlank(IDXGIOutput6 *iface)
 {
-    static BOOL once = FALSE;
+    struct dxgi_output *output = impl_from_IDXGIOutput6(iface);
+    struct wined3d_raster_status raster_status;
+    int prev_scanline = 0;
+    HRESULT hr;
 
-    if (!once++)
-        FIXME("iface %p stub!\n", iface);
-    else
-        TRACE("iface %p stub!\n", iface);
+    TRACE("iface %p\n", iface);
 
-    return E_NOTIMPL;
+    for (;;)
+    {
+        wined3d_mutex_lock();
+        hr = wined3d_output_get_raster_status(output->wined3d_output, &raster_status);
+        wined3d_mutex_unlock();
+        if (FAILED(hr))
+        {
+            WARN("Failed to get raster status, hr %#lx.\n", hr);
+            return hr;
+        }
+        if (raster_status.in_vblank && prev_scanline > raster_status.scan_line)
+            break;
+
+        prev_scanline = raster_status.scan_line;
+
+        Sleep(0);
+    }
+
+    return S_OK;
 }
 
 static HRESULT STDMETHODCALLTYPE dxgi_output_TakeOwnership(IDXGIOutput6 *iface, IUnknown *device, BOOL exclusive)
-- 
GitLab

https://gitlab.winehq.org/wine/wine/-/merge_requests/10246

[Elizabeth Figura (＠zfigura)]

Ergh, I don't think busy-waiting is a good idea.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10246#note_131323

[Leo Fruijtier (＠Meleody)]

I'd like to bump this because I use Linux for Music Production and merging this would be a great Step towards compatibility with JUCE 8 Audio Plugins in my opinion: https://bugs.winehq.org/show_bug.cgi?id=56799

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10246#note_144597

[Henri Verbeet (＠hverbeet)]

The core of the implementation probably needs to be in something like winex11 or win32u. In principle that would use drmCrtcQueueSequence() on Linux, but perhaps we could use VK_DISPLAY_EVENT_TYPE_FIRST_PIXEL_OUT_EXT from VK_EXT_display_control for a slightly more general implementation.

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https://gitlab.winehq.org/wine/wine/-/merge_requests/10246#note_144650