Add AHB and Pixel- Formats for R8

Add AHARDWAREBUFFER_FORMAT_R8_UNORM and PIXEL_FORMAT_R_8. These will be
used for an alpha 8 buffer representing the screen decorations.

Enum value matches AIDL R_8 in
I6f6b7f22e76609151a413ca6a6dbf55bd91911dd.

Bug: 193170859
Test: make
Change-Id: I4846327b29736ee811672801a683deb287342a8e
diff --git a/libs/ui/DebugUtils.cpp b/libs/ui/DebugUtils.cpp
index 1f006ce..073da89 100644
--- a/libs/ui/DebugUtils.cpp
+++ b/libs/ui/DebugUtils.cpp
@@ -302,6 +302,8 @@
             return std::string("RGB_565");
         case android::PIXEL_FORMAT_BGRA_8888:
             return std::string("BGRA_8888");
+        case android::PIXEL_FORMAT_R_8:
+            return std::string("R_8");
         default:
             return StringPrintf("Unknown %#08x", format);
     }
diff --git a/libs/ui/PixelFormat.cpp b/libs/ui/PixelFormat.cpp
index d1925cb..799fbc9 100644
--- a/libs/ui/PixelFormat.cpp
+++ b/libs/ui/PixelFormat.cpp
@@ -35,6 +35,8 @@
         case PIXEL_FORMAT_RGBA_5551:
         case PIXEL_FORMAT_RGBA_4444:
             return 2;
+        case PIXEL_FORMAT_R_8:
+            return 1;
     }
     return 0;
 }
diff --git a/libs/ui/include/ui/PixelFormat.h b/libs/ui/include/ui/PixelFormat.h
index 91ff39e..f422ce4 100644
--- a/libs/ui/include/ui/PixelFormat.h
+++ b/libs/ui/include/ui/PixelFormat.h
@@ -62,6 +62,7 @@
     PIXEL_FORMAT_RGBA_4444    = 7,                             // 16-bit ARGB
     PIXEL_FORMAT_RGBA_FP16    = HAL_PIXEL_FORMAT_RGBA_FP16,    // 64-bit RGBA
     PIXEL_FORMAT_RGBA_1010102 = HAL_PIXEL_FORMAT_RGBA_1010102, // 32-bit RGBA
+    PIXEL_FORMAT_R_8          = 0x38,
 };
 
 typedef int32_t PixelFormat;