rhi: Expose HDR output info in a saner way

Don't bother with exposing the IDXGIOutput6. Instead, report the values,
just the ones that matter for tonemapping or transfer functions in a
cross-platform way that's also prepared for Metal's different way of doing
things.

Change-Id: I28c7b6144f8267a9d3d44eff1e40697fb543385f
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

src/gui/rhi/qrhi.cpp

@@ -4465,18 +4465,37 @@ QRhiResource::Type QRhiSwapChain::resourceType() const
     Regardless of the return value, calling destroy() is always safe.
  */
 
-/*!
-    \return a pointer to a backend-specific QRhiNativeHandles subclass, such as
-    QRhiD3D11SwapChainNativeHandles. The returned value is \nullptr when
-    exposing the underlying native resources is not supported by the backend.
-
-    \sa QRhiD3D11SwapChainNativeHandles
- */
-const QRhiNativeHandles *QRhiSwapChain::nativeHandles()
+QRhiSwapChainHdrInfo QRhiSwapChain::hdrInfo()
 {
-    return nullptr;
+    QRhiSwapChainHdrInfo info;
+    info.isHardCodedDefaults = true;
+    info.limitsType = QRhiSwapChainHdrInfo::LuminanceInNits;
+    info.limits.luminanceInNits.minLuminance = 0.0f;
+    info.limits.luminanceInNits.maxLuminance = 1000.0f;
+    return info;
 }
 
+#ifndef QT_NO_DEBUG_STREAM
+QDebug operator<<(QDebug dbg, const QRhiSwapChainHdrInfo &info)
+{
+    QDebugStateSaver saver(dbg);
+    dbg.nospace() << "QRhiSwapChainHdrInfo(" << (info.isHardCodedDefaults ? "with hard-coded defaults" : "queried from system");
+    switch (info.limitsType) {
+    case QRhiSwapChainHdrInfo::LuminanceInNits:
+        dbg.nospace() << " minLuminance=" << info.limits.luminanceInNits.minLuminance
+                      << " maxLuminance=" << info.limits.luminanceInNits.maxLuminance;
+        break;
+    case QRhiSwapChainHdrInfo::ColorComponentValue:
+        dbg.nospace() << " maxColorComponentValue=" << info.limits.colorComponentValue.maxColorComponentValue;
+        break;
+    default:
+        break;
+    }
+    dbg.nospace() << ')';
+    return dbg;
+}
+#endif
+
 /*!
     \class QRhiComputePipeline
     \internal

src/gui/rhi/qrhi_p.h

@@ -1313,6 +1313,31 @@ Q_DECLARE_OPERATORS_FOR_FLAGS(QRhiGraphicsPipeline::Flags)
 Q_DECLARE_OPERATORS_FOR_FLAGS(QRhiGraphicsPipeline::ColorMask)
 Q_DECLARE_TYPEINFO(QRhiGraphicsPipeline::TargetBlend, Q_RELOCATABLE_TYPE);
 
+struct QRhiSwapChainHdrInfo
+{
+    bool isHardCodedDefaults;
+    enum LimitsType {
+        LuminanceInNits,
+        ColorComponentValue
+    };
+    LimitsType limitsType;
+    union {
+        struct {
+            float minLuminance;
+            float maxLuminance;
+        } luminanceInNits;
+        struct {
+            float maxColorComponentValue;
+        } colorComponentValue;
+    } limits;
+};
+
+Q_DECLARE_TYPEINFO(QRhiSwapChainHdrInfo, Q_RELOCATABLE_TYPE);
+
+#ifndef QT_NO_DEBUG_STREAM
+Q_GUI_EXPORT QDebug operator<<(QDebug, const QRhiSwapChainHdrInfo &);
+#endif
+
 class Q_GUI_EXPORT QRhiSwapChain : public QRhiResource
 {
 public:
@@ -1360,8 +1385,7 @@ public:
     virtual bool isFormatSupported(Format f) = 0;
     virtual QRhiRenderPassDescriptor *newCompatibleRenderPassDescriptor() = 0;
     virtual bool createOrResize() = 0;
-
-    virtual const QRhiNativeHandles *nativeHandles();
+    virtual QRhiSwapChainHdrInfo hdrInfo();
 
 protected:
     QRhiSwapChain(QRhiImplementation *rhi);

src/gui/rhi/qrhid3d11.cpp

@@ -115,18 +115,6 @@ QT_BEGIN_NAMESPACE
     \c{ID3D11Device *} and \c{ID3D11DeviceContext *}.
  */
 
-/*!
-    \class QRhiD3D11SwapChainNativeHandles
-    \internal
-    \inmodule QtGui
-    \brief Exposes D3D/DXGI specific data for a swapchain
-
-    dxgiOutput6 is the IDXGIOutput6* for the swapchain's current output, if
-    supported, null otherwise. The current output is determined based on the
-    position of the swapchain's associated window at the time of calling
-    QRhiSwapChain::createOrResize().
- */
-
 // help mingw with its ancient sdk headers
 #ifndef DXGI_ADAPTER_FLAG_SOFTWARE
 #define DXGI_ADAPTER_FLAG_SOFTWARE 2
@@ -4376,11 +4364,6 @@ void QD3D11SwapChain::destroy()
     swapChain->Release();
     swapChain = nullptr;
 
-    if (output6) {
-        output6->Release();
-        output6 = nullptr;
-    }
-
     QRHI_RES_RHI(QRhiD3D11);
     if (rhiD)
         rhiD->unregisterResource(this);
@@ -4458,6 +4441,22 @@ bool QD3D11SwapChain::isFormatSupported(Format f)
     return false;
 }
 
+QRhiSwapChainHdrInfo QD3D11SwapChain::hdrInfo()
+{
+    QRhiSwapChainHdrInfo info = QRhiSwapChain::hdrInfo();
+    if (m_format != QRhiSwapChain::SDR && m_window) {
+        QRHI_RES_RHI(QRhiD3D11);
+        DXGI_OUTPUT_DESC1 hdrOutputDesc;
+        if (outputDesc1ForWindow(m_window, rhiD->activeAdapter, &hdrOutputDesc)) {
+            info.isHardCodedDefaults = false;
+            info.limitsType = QRhiSwapChainHdrInfo::LuminanceInNits;
+            info.limits.luminanceInNits.minLuminance = hdrOutputDesc.MinLuminance;
+            info.limits.luminanceInNits.maxLuminance = hdrOutputDesc.MaxLuminance;
+        }
+    }
+    return info;
+}
+
 QRhiRenderPassDescriptor *QD3D11SwapChain::newCompatibleRenderPassDescriptor()
 {
     return new QD3D11RenderPassDescriptor(m_rhi);
@@ -4546,13 +4545,9 @@ bool QD3D11SwapChain::createOrResize()
         HRESULT hr;
         if (useFlipDiscard) {
             DXGI_COLOR_SPACE_TYPE hdrColorSpace = DXGI_COLOR_SPACE_RGB_FULL_G22_NONE_P709; // SDR
-            if (output6) {
-                output6->Release();
-                output6 = nullptr;
-            }
-            if (output6ForWindow(m_window, rhiD->activeAdapter, &output6) && m_format != SDR) {
+            DXGI_OUTPUT_DESC1 hdrOutputDesc;
+            if (outputDesc1ForWindow(m_window, rhiD->activeAdapter, &hdrOutputDesc) && m_format != SDR) {
                 // https://docs.microsoft.com/en-us/windows/win32/direct3darticles/high-dynamic-range
-                output6->GetDesc1(&hdrOutputDesc);
                 if (hdrOutputDesc.ColorSpace == DXGI_COLOR_SPACE_RGB_FULL_G2084_NONE_P2020) {
                     switch (m_format) {
                     case HDRExtendedSrgbLinear:
@@ -4767,12 +4762,6 @@ bool QD3D11SwapChain::createOrResize()
     return true;
 }
 
-const QRhiNativeHandles *QD3D11SwapChain::nativeHandles()
-{
-    nativeHandlesStruct.dxgiOutput6 = output6;
-    return &nativeHandlesStruct;
-}
-
 void QRhiD3D11::DeviceCurse::initResources()
 {
     framesLeft = framesToActivate;

src/gui/rhi/qrhid3d11_p.h

@@ -76,11 +76,6 @@ struct Q_GUI_EXPORT QRhiD3D11NativeHandles : public QRhiNativeHandles
     qint32 adapterLuidHigh = 0;
 };
 
-struct Q_GUI_EXPORT QRhiD3D11SwapChainNativeHandles : public QRhiNativeHandles
-{
-    void *dxgiOutput6 = nullptr;
-};
-
 QT_END_NAMESPACE
 
 #endif

src/gui/rhi/qrhid3d11_p_p.h

@@ -560,10 +560,10 @@ struct QD3D11SwapChain : public QRhiSwapChain
 
     QSize surfacePixelSize() override;
     bool isFormatSupported(Format f) override;
+    QRhiSwapChainHdrInfo hdrInfo() override;
 
     QRhiRenderPassDescriptor *newCompatibleRenderPassDescriptor() override;
     bool createOrResize() override;
-    const QRhiNativeHandles *nativeHandles() override;
 
     void releaseBuffers();
     bool newColorBuffer(const QSize &size, DXGI_FORMAT format, DXGI_SAMPLE_DESC sampleDesc,
@@ -589,9 +589,6 @@ struct QD3D11SwapChain : public QRhiSwapChain
     ID3D11Query *timestampDisjointQuery[BUFFER_COUNT];
     ID3D11Query *timestampQuery[BUFFER_COUNT * 2];
     UINT swapInterval = 1;
-    IDXGIOutput6 *output6 = nullptr;
-    DXGI_OUTPUT_DESC1 hdrOutputDesc;
-    QRhiD3D11SwapChainNativeHandles nativeHandlesStruct;
 };
 
 class QRhiD3D11 : public QRhiImplementation