vo_gpu: move d3d11_screenshot to shared code

This can be used by the ANGLE backend and ra_d3d11.

2 files changed, 85 insertions, 0 deletions

diff --git a/video/out/gpu/d3d11_helpers.c b/video/out/gpu/d3d11_helpers.c
index 7912a8c23a..6391ed92cd 100644
--- a/video/out/gpu/d3d11_helpers.c
+++ b/video/out/gpu/d3d11_helpers.c
@@ -399,3 +399,84 @@ done:
     SAFE_RELEASE(dxgi_dev);
     return success;
 }
+
+struct mp_image *mp_d3d11_screenshot(IDXGISwapChain *swapchain)
+{
+    ID3D11Device *dev = NULL;
+    ID3D11DeviceContext *ctx = NULL;
+    ID3D11Texture2D *frontbuffer = NULL;
+    ID3D11Texture2D *staging = NULL;
+    struct mp_image *img = NULL;
+    HRESULT hr;
+
+    // Validate the swap chain. This screenshot method will only work on DXGI
+    // 1.2+ flip/sequential swap chains. It's probably not possible at all with
+    // discard swap chains, since by definition, the backbuffer contents is
+    // discarded on Present().
+    DXGI_SWAP_CHAIN_DESC scd;
+    hr = IDXGISwapChain_GetDesc(swapchain, &scd);
+    if (FAILED(hr))
+        goto done;
+    if (scd.SwapEffect != DXGI_SWAP_EFFECT_FLIP_SEQUENTIAL)
+        goto done;
+
+    // Get the last buffer that was presented with Present(). This should be
+    // the n-1th buffer for a swap chain of length n.
+    hr = IDXGISwapChain_GetBuffer(swapchain, scd.BufferCount - 1,
+        &IID_ID3D11Texture2D, (void**)&frontbuffer);
+    if (FAILED(hr))
+        goto done;
+
+    ID3D11Texture2D_GetDevice(frontbuffer, &dev);
+    ID3D11Device_GetImmediateContext(dev, &ctx);
+
+    D3D11_TEXTURE2D_DESC td;
+    ID3D11Texture2D_GetDesc(frontbuffer, &td);
+    if (td.SampleDesc.Count > 1)
+        goto done;
+
+    // Validate the backbuffer format and convert to an mpv IMGFMT
+    enum mp_imgfmt fmt;
+    switch (td.Format) {
+    case DXGI_FORMAT_B8G8R8A8_UNORM: fmt = IMGFMT_BGR0; break;
+    case DXGI_FORMAT_R8G8B8A8_UNORM: fmt = IMGFMT_RGB0; break;
+    default:
+        goto done;
+    }
+
+    // Create a staging texture based on the frontbuffer with CPU access
+    td.BindFlags = 0;
+    td.MiscFlags = 0;
+    td.CPUAccessFlags = D3D11_CPU_ACCESS_READ;
+    td.Usage = D3D11_USAGE_STAGING;
+    hr = ID3D11Device_CreateTexture2D(dev, &td, 0, &staging);
+    if (FAILED(hr))
+        goto done;
+
+    ID3D11DeviceContext_CopyResource(ctx, (ID3D11Resource*)staging,
+        (ID3D11Resource*)frontbuffer);
+
+    // Attempt to map the staging texture to CPU-accessible memory
+    D3D11_MAPPED_SUBRESOURCE lock;
+    hr = ID3D11DeviceContext_Map(ctx, (ID3D11Resource*)staging, 0,
+                                 D3D11_MAP_READ, 0, &lock);
+    if (FAILED(hr))
+        goto done;
+
+    img = mp_image_alloc(fmt, td.Width, td.Height);
+    if (!img)
+        return NULL;
+    for (int i = 0; i < td.Height; i++) {
+        memcpy(img->planes[0] + img->stride[0] * i,
+               (char*)lock.pData + lock.RowPitch * i, td.Width * 4);
+    }
+
+    ID3D11DeviceContext_Unmap(ctx, (ID3D11Resource*)staging, 0);
+
+done:
+    SAFE_RELEASE(frontbuffer);
+    SAFE_RELEASE(staging);
+    SAFE_RELEASE(ctx);
+    SAFE_RELEASE(dev);
+    return img;
+}
diff --git a/video/out/gpu/d3d11_helpers.h b/video/out/gpu/d3d11_helpers.h
index 6d99c62a51..481c183b4d 100644
--- a/video/out/gpu/d3d11_helpers.h
+++ b/video/out/gpu/d3d11_helpers.h
@@ -23,6 +23,8 @@
 #include <d3d11.h>
 #include <dxgi1_2.h>
 
+#include "video/mp_image.h"
+
 #define D3D_FEATURE_LEVEL_12_0 (0xc000)
 #define D3D_FEATURE_LEVEL_12_1 (0xc100)
 
@@ -76,4 +78,6 @@ bool mp_d3d11_create_swapchain(ID3D11Device *dev, struct mp_log *log,
                                struct d3d11_swapchain_opts *opts,
                                IDXGISwapChain **swapchain_out);
 
+struct mp_image *mp_d3d11_screenshot(IDXGISwapChain *swapchain);
+
 #endif