dxgi: real composition swapchains (CreateSwapChainForComposition) on top of 02. LGPL-2.1-or-later.

diff --git a/dlls/dxgi/dxgi_private.h b/dlls/dxgi/dxgi_private.h
index ed82d36..9ac7e20 100644
--- a/dlls/dxgi/dxgi_private.h
+++ b/dlls/dxgi/dxgi_private.h
@@ -185,8 +185,16 @@ struct d3d11_swapchain
     IDXGIOutput *target;
     LONG present_count;
     LONG in_set_fullscreen_state;
+
+    /* Hidden window backing a CreateSwapChainForComposition() swapchain. */
+    HWND composition_window;
+    DXGI_ALPHA_MODE alpha_mode;
+    DXGI_SWAP_EFFECT swap_effect;
 };
 
+BOOL d3d11_swapchain_set_composition_window(IDXGISwapChain1 *iface, HWND window,
+        DXGI_ALPHA_MODE alpha_mode, DXGI_SWAP_EFFECT swap_effect);
+
 HRESULT d3d11_swapchain_init(struct d3d11_swapchain *swapchain, struct dxgi_device *device,
         struct wined3d_swapchain_desc *desc, const DXGI_SWAP_CHAIN_FULLSCREEN_DESC *fullscreen_desc);
 
diff --git a/dlls/dxgi/factory.c b/dlls/dxgi/factory.c
index d1015dd..bc717c6 100644
--- a/dlls/dxgi/factory.c
+++ b/dlls/dxgi/factory.c
@@ -390,13 +390,66 @@ static void STDMETHODCALLTYPE dxgi_factory_UnregisterOcclusionStatus(IWineDXGIFa
 static HRESULT STDMETHODCALLTYPE dxgi_factory_CreateSwapChainForComposition(IWineDXGIFactory *iface,
         IUnknown *device, const DXGI_SWAP_CHAIN_DESC1 *desc, IDXGIOutput *output, IDXGISwapChain1 **swapchain)
 {
-    HWND hwnd;
+    IWineDXGISwapChainFactory *swapchain_factory;
+    DXGI_SWAP_CHAIN_DESC1 composition_desc;
+    IDXGISwapChain1 *object;
+    HWND window;
+    HRESULT hr;
 
-    FIXME("iface %p, device %p, desc %p, output %p, swapchain %p stub!\n",
+    TRACE("iface %p, device %p, desc %p, output %p, swapchain %p.\n",
             iface, device, desc, output, swapchain);
 
-    hwnd = CreateWindowA("static", NULL, WS_POPUP, 0, 0, desc->Width, desc->Height, 0, 0, 0, NULL);
-    return dxgi_factory_CreateSwapChainForHwnd(iface, device, hwnd, desc, NULL, output, swapchain);
+    if (!device || !desc || !swapchain)
+        return DXGI_ERROR_INVALID_CALL;
+    *swapchain = NULL;
+
+    if (desc->SwapEffect != DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL && desc->SwapEffect != DXGI_SWAP_EFFECT_FLIP_DISCARD)
+    {
+        WARN("Invalid swap effect %#x for a composition swapchain.\n", desc->SwapEffect);
+        return DXGI_ERROR_INVALID_CALL;
+    }
+    if (!desc->Width || !desc->Height)
+    {
+        WARN("Invalid size %ux%u for a composition swapchain.\n", desc->Width, desc->Height);
+        return DXGI_ERROR_INVALID_CALL;
+    }
+
+    /* Only D3D10/11 devices; dcomp reads composition content back through D3D11. */
+    if (FAILED(IUnknown_QueryInterface(device, &IID_IWineDXGISwapChainFactory, (void **)&swapchain_factory)))
+    {
+        FIXME("Composition swapchains are only implemented for D3D10/11 devices.\n");
+        return E_NOTIMPL;
+    }
+    IWineDXGISwapChainFactory_Release(swapchain_factory);
+
+    /* There is no compositor to hand the buffers to. Present into a hidden
+     * window instead and let dcomp.dll read the presented buffers back. */
+    /* A message-only window: it is never shown, and broadcasts do not wait on
+     * the thread that created the swapchain. */
+    if (!(window = CreateWindowExW(0, L"static", NULL, WS_DISABLED, 0, 0,
+            desc->Width, desc->Height, HWND_MESSAGE, NULL, NULL, NULL)))
+        return HRESULT_FROM_WIN32(GetLastError());
+
+    /* wined3d discards a FLIP_DISCARD buffer once it has been presented, but
+     * that is the buffer dcomp.dll reads the frame from. */
+    composition_desc = *desc;
+    composition_desc.SwapEffect = DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL;
+    if (FAILED(hr = dxgi_factory_CreateSwapChainForHwnd(iface, device, window, &composition_desc, NULL, output, &object)))
+    {
+        DestroyWindow(window);
+        return hr;
+    }
+
+    if (!d3d11_swapchain_set_composition_window(object, window, desc->AlphaMode, desc->SwapEffect))
+    {
+        ERR("Unexpected swapchain implementation.\n");
+        IDXGISwapChain1_Release(object);
+        DestroyWindow(window);
+        return E_FAIL;
+    }
+
+    *swapchain = object;
+    return S_OK;
 }
 
 static UINT STDMETHODCALLTYPE dxgi_factory_GetCreationFlags(IWineDXGIFactory *iface)
diff --git a/dlls/dxgi/swapchain.c b/dlls/dxgi/swapchain.c
index 1186527..ad4335b 100644
--- a/dlls/dxgi/swapchain.c
+++ b/dlls/dxgi/swapchain.c
@@ -256,6 +256,8 @@ static ULONG STDMETHODCALLTYPE d3d11_swapchain_Release(IDXGISwapChain4 *iface)
     if (!refcount)
     {
         IWineDXGIDevice *device = swapchain->device;
+        HWND composition_window = swapchain->composition_window;
+
         if (swapchain->target)
         {
             WARN("Releasing fullscreen swapchain.\n");
@@ -264,6 +266,16 @@ static ULONG STDMETHODCALLTYPE d3d11_swapchain_Release(IDXGISwapChain4 *iface)
         IWineDXGIFactory_Release(swapchain->factory);
         wined3d_swapchain_decref(swapchain->wined3d_swapchain);
         IWineDXGIDevice_Release(device);
+        /* The wined3d swapchain owned the memory of "swapchain". */
+        if (composition_window)
+        {
+            /* Only the creating thread may destroy the window; elsewhere let
+             * the static control destroy itself when it handles WM_CLOSE. */
+            if (GetWindowThreadProcessId(composition_window, NULL) == GetCurrentThreadId())
+                DestroyWindow(composition_window);
+            else
+                PostMessageW(composition_window, WM_CLOSE, 0, 0);
+        }
     }
 
     return refcount;
@@ -537,7 +549,8 @@ static HRESULT STDMETHODCALLTYPE d3d11_swapchain_GetDesc(IDXGISwapChain4 *iface,
     desc->BufferCount = wined3d_desc.backbuffer_count;
     desc->OutputWindow = wined3d_desc.device_window;
     desc->Windowed = wined3d_desc.windowed;
-    desc->SwapEffect = dxgi_swap_effect_from_wined3d(wined3d_desc.swap_effect);
+    desc->SwapEffect = swapchain->composition_window ? swapchain->swap_effect
+            : dxgi_swap_effect_from_wined3d(wined3d_desc.swap_effect);
     desc->Flags = dxgi_swapchain_flags_from_wined3d(wined3d_desc.flags);
 
     return S_OK;
@@ -681,8 +694,9 @@ static HRESULT STDMETHODCALLTYPE d3d11_swapchain_GetDesc1(IDXGISwapChain4 *iface
     desc->BufferUsage = dxgi_usage_from_wined3d_bind_flags(wined3d_desc.backbuffer_bind_flags);
     desc->BufferCount = wined3d_desc.backbuffer_count;
     desc->Scaling = DXGI_SCALING_STRETCH;
-    desc->SwapEffect = dxgi_swap_effect_from_wined3d(wined3d_desc.swap_effect);
-    desc->AlphaMode = DXGI_ALPHA_MODE_IGNORE;
+    desc->SwapEffect = swapchain->composition_window ? swapchain->swap_effect
+            : dxgi_swap_effect_from_wined3d(wined3d_desc.swap_effect);
+    desc->AlphaMode = swapchain->composition_window ? swapchain->alpha_mode : DXGI_ALPHA_MODE_IGNORE;
     desc->Flags = dxgi_swapchain_flags_from_wined3d(wined3d_desc.flags);
 
     return S_OK;
@@ -741,6 +755,56 @@ static HRESULT STDMETHODCALLTYPE d3d11_swapchain_GetCoreWindow(IDXGISwapChain4 *
     return DXGI_ERROR_INVALID_CALL;
 }
 
+/* A flip-model Present1() with dirty rectangles shows the previously presented
+ * frame with only the dirty rectangles replaced, and applications such as
+ * JUCE 8 only redraw those rectangles. wined3d rotates its back buffers on
+ * present, so back buffer 0 holds an older frame by then. Rebuild the frame
+ * here: patch the dirty rectangles into the last presented buffer and copy the
+ * result into back buffer 0 before presenting it.
+ *
+ * This is limited to composition swapchains for now, where dcomp.dll shows
+ * the last presented buffer; HWND swapchains have the same problem. */
+static void d3d11_swapchain_merge_dirty_rects(struct d3d11_swapchain *swapchain,
+        const DXGI_PRESENT_PARAMETERS *parameters)
+{
+    struct wined3d_resource *back_buffer, *previous;
+    struct wined3d_device_context *context;
+    struct wined3d_swapchain_desc desc;
+    struct wined3d_box box;
+    unsigned int i;
+    RECT r;
+
+    wined3d_mutex_lock();
+    wined3d_swapchain_get_desc(swapchain->wined3d_swapchain, &desc);
+    if (!swapchain->composition_window || desc.swap_effect != WINED3D_SWAP_EFFECT_FLIP_SEQUENTIAL
+            || desc.backbuffer_count < 2 || !swapchain->present_count || !parameters->pDirtyRects)
+    {
+        wined3d_mutex_unlock();
+        return;
+    }
+
+    back_buffer = wined3d_texture_get_resource(wined3d_swapchain_get_back_buffer(swapchain->wined3d_swapchain, 0));
+    previous = wined3d_texture_get_resource(wined3d_swapchain_get_back_buffer(swapchain->wined3d_swapchain,
+            desc.backbuffer_count - 1));
+    context = wined3d_device_get_immediate_context(wined3d_swapchain_get_device(swapchain->wined3d_swapchain));
+
+    for (i = 0; i < parameters->DirtyRectsCount; ++i)
+    {
+        r = parameters->pDirtyRects[i];
+        r.left = max(r.left, 0);
+        r.top = max(r.top, 0);
+        r.right = min(r.right, (LONG)desc.backbuffer_width);
+        r.bottom = min(r.bottom, (LONG)desc.backbuffer_height);
+        if (r.left >= r.right || r.top >= r.bottom)
+            continue;
+        wined3d_box_set(&box, r.left, r.top, r.right, r.bottom, 0, 1);
+        wined3d_device_context_copy_sub_resource_region(context, previous, 0,
+                r.left, r.top, 0, back_buffer, 0, &box, 0);
+    }
+    wined3d_device_context_copy_resource(context, back_buffer, previous);
+    wined3d_mutex_unlock();
+}
+
 static HRESULT STDMETHODCALLTYPE d3d11_swapchain_Present1(IDXGISwapChain4 *iface,
         UINT sync_interval, UINT flags, const DXGI_PRESENT_PARAMETERS *present_parameters)
 {
@@ -750,7 +814,13 @@ static HRESULT STDMETHODCALLTYPE d3d11_swapchain_Present1(IDXGISwapChain4 *iface
             iface, sync_interval, flags, present_parameters);
 
     if (present_parameters)
-        FIXME("Ignored present parameters %p.\n", present_parameters);
+    {
+        if (present_parameters->pScrollRect || present_parameters->pScrollOffset)
+            FIXME("Ignoring scroll rectangle %p, offset %p.\n",
+                    present_parameters->pScrollRect, present_parameters->pScrollOffset);
+        if (present_parameters->DirtyRectsCount && !(flags & DXGI_PRESENT_TEST))
+            d3d11_swapchain_merge_dirty_rects(swapchain, present_parameters);
+    }
 
     return d3d11_swapchain_present(swapchain, sync_interval, flags);
 }
@@ -1043,6 +1113,21 @@ static HRESULT d3d11_swapchain_create_d3d11_textures(struct d3d11_swapchain *swa
     return hr;
 }
 
+BOOL d3d11_swapchain_set_composition_window(IDXGISwapChain1 *iface, HWND window,
+        DXGI_ALPHA_MODE alpha_mode, DXGI_SWAP_EFFECT swap_effect)
+{
+    struct d3d11_swapchain *swapchain;
+
+    if (iface->lpVtbl != (const IDXGISwapChain1Vtbl *)&d3d11_swapchain_vtbl)
+        return FALSE;
+
+    swapchain = d3d11_swapchain_from_IDXGISwapChain4((IDXGISwapChain4 *)iface);
+    swapchain->composition_window = window;
+    swapchain->alpha_mode = alpha_mode;
+    swapchain->swap_effect = swap_effect;
+    return TRUE;
+}
+
 HRESULT d3d11_swapchain_init(struct d3d11_swapchain *swapchain, struct dxgi_device *device,
         struct wined3d_swapchain_desc *desc, const DXGI_SWAP_CHAIN_FULLSCREEN_DESC *fullscreen_desc)
 {