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Commit 6a3088cb authored by Sally Qi's avatar Sally Qi
Browse files

Add HLG transfer function to proper dataspace 

- fix the issue of color washout in the textureview
- scale down hlg to [0, 1] in skia
- app side should enable wideColorGamut for it

Bug: 224841108
Test: test HLG video on Instagram
Change-Id: If9da8495139a0579667c64dcd8a61e9554b7da58
parent 2f58e1c3

libs/hwui/utils/Color.cpp

+25 −1
Original line number Diff line number Diff line
@@ -165,6 +165,14 @@ android_dataspace ColorSpaceToADataSpace(SkColorSpace* colorSpace, SkColorType c 
        if (SkColorSpace::Equals(colorSpace, rec2020PQ.get())) {

            return HAL_DATASPACE_BT2020_PQ;

        }

        // HLG

        const auto hlgFn = GetHLGScaleTransferFunction();

        if (hlgFn.has_value()) {

            auto rec2020HLG = SkColorSpace::MakeRGB(hlgFn.value(), SkNamedGamut::kRec2020);

            if (SkColorSpace::Equals(colorSpace, rec2020HLG.get())) {

                return static_cast<android_dataspace>(HAL_DATASPACE_BT2020_HLG);

            }

        }

        LOG_ALWAYS_FATAL("Only select non-numerical transfer functions are supported");

    }
@@ -247,6 +255,14 @@ sk_sp<SkColorSpace> DataSpaceToColorSpace(android_dataspace dataspace) { 
            return nullptr;

    }



    // HLG

    if ((dataspace & HAL_DATASPACE_TRANSFER_MASK) == HAL_DATASPACE_TRANSFER_HLG) {

        const auto hlgFn = GetHLGScaleTransferFunction();

        if (hlgFn.has_value()) {

            return SkColorSpace::MakeRGB(hlgFn.value(), gamut);

        }

    }



    switch (dataspace & HAL_DATASPACE_TRANSFER_MASK) {

        case HAL_DATASPACE_TRANSFER_LINEAR:

            return SkColorSpace::MakeRGB(SkNamedTransferFn::kLinear, gamut);
@@ -264,7 +280,6 @@ sk_sp<SkColorSpace> DataSpaceToColorSpace(android_dataspace dataspace) { 
            return SkColorSpace::MakeRGB(SkNamedTransferFn::kRec2020, gamut);

        case HAL_DATASPACE_TRANSFER_UNSPECIFIED:

            return nullptr;

        case HAL_DATASPACE_TRANSFER_HLG:

        default:

            ALOGV("Unsupported Gamma: %d", dataspace);

            return nullptr;
@@ -381,5 +396,14 @@ skcms_TransferFunction GetPQSkTransferFunction(float sdr_white_level) { 
    return fn;

}



// Skia skcms' default HLG maps encoded [0, 1] to linear [1, 12] in order to follow ARIB

// but LinearEffect expects a decoded [0, 1] range instead to follow Rec 2100.

std::optional<skcms_TransferFunction> GetHLGScaleTransferFunction() {

    std::optional<skcms_TransferFunction> hlgFn = {};

    skcms_TransferFunction_makeScaledHLGish(&hlgFn.value(), 1.f / 12.f, 2.f, 2.f, 1.f / 0.17883277f,

                                            0.28466892f, 0.55991073f);

    return hlgFn;

}



}  // namespace uirenderer

}  // namespace android

libs/hwui/utils/Color.h

+3 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ 
#include <math.h>

#include <system/graphics.h>



#include <optional>



struct ANativeWindow_Buffer;

struct AHardwareBuffer_Desc;
@@ -127,6 +129,7 @@ struct Lab { 
Lab sRGBToLab(SkColor color);

SkColor LabToSRGB(const Lab& lab, SkAlpha alpha);

skcms_TransferFunction GetPQSkTransferFunction(float sdr_white_level = 0.f);

std::optional<skcms_TransferFunction> GetHLGScaleTransferFunction();



} /* namespace uirenderer */

} /* namespace android */