SF: Parse Physical display size in framework

More EDID fields are required as a part of migrating to EDID-based
display IDs. This CL parses the physical display size in CM from bytes
21-22 of block 0 in the EDID blob and serves it as a part of the Edid
struct.

Later, amongst others, this value will be used to fabricate a unique
display ID that is based on the display's EDID.

See:
1. EDID spec: https://glenwing.github.io/docs/VESA-EEDID-A2.pdf
2. https://en.wikipedia.org/wiki/Extended_Display_Identification_Data#Structure,_version_1.4

Flag: com.android.graphics.surfaceflinger.flags.stable_edid_ids
Bug: 378922658
Test: DisplayIdentification_test
Change-Id: I0bb27f267421941aa56f6147082a05ea3b13f33f

1 files changed, 10 insertions, 0 deletions

diff --git a/libs/ui/DisplayIdentification.cpp b/libs/ui/DisplayIdentification.cpp
index 8b13d78840..503f92ff32 100644
--- a/libs/ui/DisplayIdentification.cpp
+++ b/libs/ui/DisplayIdentification.cpp
@@ -212,6 +212,15 @@ std::optional<Edid> parseEdid(const DisplayIdentificationData& edid) {
     ALOGW_IF(manufactureOrModelYear <= 0xf,
              "Invalid EDID: model year or manufacture year cannot be in the range [0x0, 0xf].");
 
+    constexpr size_t kMaxHorizontalPhysicalSizeOffset = 21;
+    constexpr size_t kMaxVerticalPhysicalSizeOffset = 22;
+    if (edid.size() < kMaxVerticalPhysicalSizeOffset + sizeof(uint8_t)) {
+        ALOGE("Invalid EDID: display's physical size is truncated.");
+        return {};
+    }
+    ui::Size maxPhysicalSizeInCm(edid[kMaxHorizontalPhysicalSizeOffset],
+                                 edid[kMaxVerticalPhysicalSizeOffset]);
+
     constexpr size_t kDescriptorOffset = 54;
     if (edid.size() < kDescriptorOffset) {
         ALOGE("Invalid EDID: descriptors are missing.");
@@ -346,6 +355,7 @@ std::optional<Edid> parseEdid(const DisplayIdentificationData& edid) {
             .displayName = displayName,
             .manufactureOrModelYear = manufactureOrModelYear,
             .manufactureWeek = manufactureWeek,
+            .physicalSizeInCm = maxPhysicalSizeInCm,
             .cea861Block = cea861Block,
             .preferredDetailedTimingDescriptor = preferredDetailedTimingDescriptor,
     };