commit eed9d5db739e2342c4219a2ef23f77097b3581f7
author Alec Mouri <alecmouri@google.com> Wed Dec 14 00:47:13 2022 +0000
committer Alec Mouri <alecmouri@google.com> Wed Dec 14 01:12:07 2022 +0000
tree e27a1bbdb0fb60cb2bcc73f0dca14aada7e7f42e
parent fc55603abca981af151a6cea915be6ca8a542545

Treat extended range sRGB dataspaces as HDR

Linear and non-linear extended sRGB support luminance values beyond
the historic nominal white point of 80 nits defined for sRGB. To detect
extended sRGB, we just check for the EXTENDED_RANGE bit.

This also allows for custom extended range formats to be used to support
HDR at the display level. This is useful for achieving HDR on devices that
do not advertise fp16 support, which would otherwise be desired for
non-video HDR formats as (a) having enough bits for "good enough" fidelity
and (b) being a floating point format that allows for describing colors
beyond the SDR max of 1.0. For instance, an application could use a
10-bit sRGB-encoded fixed point buffer to represent HDR as long as the
rendered content is referred by a reasonable SDR luminance.

Bug: 241001465
Test: Custom apk sending buffers directly to a SurfaceControl.
Change-Id: I03ffa7f0a45633c9bb19e3ae7c17b189277ca06a

libs/ui/include_types/ui/DataspaceUtils.h

diff --git a/libs/ui/include_types/ui/DataspaceUtils.h b/libs/ui/include_types/ui/DataspaceUtils.h
index a461cb4..cd31167 100644
--- a/libs/ui/include_types/ui/DataspaceUtils.h
+++ b/libs/ui/include_types/ui/DataspaceUtils.h
@@ -22,8 +22,10 @@
 
 inline bool isHdrDataspace(ui::Dataspace dataspace) {
     const auto transfer = dataspace & HAL_DATASPACE_TRANSFER_MASK;
+    const auto range = dataspace & HAL_DATASPACE_RANGE_MASK;
 
-    return transfer == HAL_DATASPACE_TRANSFER_ST2084 || transfer == HAL_DATASPACE_TRANSFER_HLG;
+    return transfer == HAL_DATASPACE_TRANSFER_ST2084 || transfer == HAL_DATASPACE_TRANSFER_HLG ||
+            range == HAL_DATASPACE_RANGE_EXTENDED;
 }
 
-} // namespace android
\ No newline at end of file
+} // namespace android

libs/ui/tests/DataspaceUtils_test.cpp

diff --git a/libs/ui/tests/DataspaceUtils_test.cpp b/libs/ui/tests/DataspaceUtils_test.cpp
index 3e09671..ffe6438 100644
--- a/libs/ui/tests/DataspaceUtils_test.cpp
+++ b/libs/ui/tests/DataspaceUtils_test.cpp
@@ -29,12 +29,13 @@
     EXPECT_TRUE(isHdrDataspace(ui::Dataspace::BT2020_ITU_PQ));
     EXPECT_TRUE(isHdrDataspace(ui::Dataspace::BT2020_PQ));
     EXPECT_TRUE(isHdrDataspace(ui::Dataspace::BT2020_HLG));
+    // The original formulation of scRGB indicates the same white points as that
+    // of sRGB, however scRGB may be used to implement HDR.
+    EXPECT_TRUE(isHdrDataspace(ui::Dataspace::V0_SCRGB_LINEAR));
+    EXPECT_TRUE(isHdrDataspace(ui::Dataspace::V0_SCRGB));
 
     EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_SRGB_LINEAR));
-    // scRGB defines a very wide gamut but not an expanded luminance range
-    EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_SCRGB_LINEAR));
     EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_SRGB));
-    EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_SCRGB));
     EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_JFIF));
     EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_BT601_625));
     EXPECT_FALSE(isHdrDataspace(ui::Dataspace::V0_BT601_525));