Added WIC_FLAGS_FORCE_SRGB / LINEAR flags for WIC writer (#127)

DirectXTex/DirectXTex.h

@@ -194,6 +194,12 @@ namespace DirectX
         WIC_FLAGS_IGNORE_SRGB           = 0x20,
             // Ignores sRGB metadata if present in the file
 
+        WIC_FLAGS_FORCE_SRGB            = 0x40,
+            // Writes sRGB metadata into the file reguardless of format
+
+        WIC_FLAGS_FORCE_LINEAR          = 0x80,
+            // Writes linear gamma metadata into the file reguardless of format
+
         WIC_FLAGS_DITHER                = 0x10000,
             // Use ordered 4x4 dithering for any required conversions
 

DirectXTex/DirectXTexWIC.cpp

@@ -570,6 +570,7 @@ namespace
     // Encodes image metadata
     //-------------------------------------------------------------------------------------
     HRESULT EncodeMetadata(
+        DWORD flags,
         _In_ IWICBitmapFrameEncode* frame,
         const GUID& containerFormat,
         DXGI_FORMAT format)
@@ -584,7 +585,7 @@ namespace
             PROPVARIANT value;
             PropVariantInit(&value);
 
-            bool sRGB = IsSRGB(format);
+            bool sRGB = ((flags & WIC_FLAGS_FORCE_LINEAR) == 0) && ((flags & WIC_FLAGS_FORCE_SRGB) != 0 || IsSRGB(format));
 
             value.vt = VT_LPSTR;
             value.pszVal = const_cast<char*>("DirectXTex");
@@ -715,7 +716,7 @@ namespace
             return E_FAIL;
         }
 
-        hr = EncodeMetadata(frame, containerFormat, image.format);
+        hr = EncodeMetadata(flags, frame, containerFormat, image.format);
         if (FAILED(hr))
             return hr;