Add Gray8 pixel config

This is still just linear (non-sRGB), but adding sRGB will
be the next step. I've verified that this is really making
R8 textures when uploading Gray8 bitmaps. Tests pass, and
the all_bitmap_configs GM still renders correctly (unlike
when we just mapped Gray8 to Alpha8).

This adds another pixel config, which could grow our cache
footprint, but the benefits of not using 4bpp for 1bpp data
should outweigh that?

Re-land of https://skia-review.googlesource.com/c/6817/,
with fixes for Vulkan.

BUG=skia:6110

Change-Id: Ia763c276808be28027ed0005ee4b88637306583f
Reviewed-on: https://skia-review.googlesource.com/6839
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>

12 files changed, 104 insertions, 67 deletions

diff --git a/include/gpu/GrColor.h b/include/gpu/GrColor.h
index 7277f0b21c..2bd43487e6 100644
--- a/include/gpu/GrColor.h
+++ b/include/gpu/GrColor.h
@@ -288,6 +288,7 @@ static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
     static const uint32_t kFlags[] = {
         0,                              // kUnknown_GrPixelConfig
         kA_GrColorComponentFlag,        // kAlpha_8_GrPixelConfig
+        kRGB_GrColorComponentFlags,     // kGray_8_GrPixelConfig
         kRGBA_GrColorComponentFlags,    // kIndex_8_GrPixelConfig
         kRGB_GrColorComponentFlags,     // kRGB_565_GrPixelConfig
         kRGBA_GrColorComponentFlags,    // kRGBA_4444_GrPixelConfig
@@ -308,21 +309,22 @@ static inline uint32_t GrPixelConfigComponentMask(GrPixelConfig config) {
 
     GR_STATIC_ASSERT(0  == kUnknown_GrPixelConfig);
     GR_STATIC_ASSERT(1  == kAlpha_8_GrPixelConfig);
-    GR_STATIC_ASSERT(2  == kIndex_8_GrPixelConfig);
-    GR_STATIC_ASSERT(3  == kRGB_565_GrPixelConfig);
-    GR_STATIC_ASSERT(4  == kRGBA_4444_GrPixelConfig);
-    GR_STATIC_ASSERT(5  == kRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(6  == kBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(7  == kSRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(8  == kSBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(9  == kRGBA_8888_sint_GrPixelConfig);
-    GR_STATIC_ASSERT(10 == kETC1_GrPixelConfig);
-    GR_STATIC_ASSERT(11 == kLATC_GrPixelConfig);
-    GR_STATIC_ASSERT(12 == kR11_EAC_GrPixelConfig);
-    GR_STATIC_ASSERT(13 == kASTC_12x12_GrPixelConfig);
-    GR_STATIC_ASSERT(14 == kRGBA_float_GrPixelConfig);
-    GR_STATIC_ASSERT(15 == kAlpha_half_GrPixelConfig);
-    GR_STATIC_ASSERT(16 == kRGBA_half_GrPixelConfig);
+    GR_STATIC_ASSERT(2  == kGray_8_GrPixelConfig);
+    GR_STATIC_ASSERT(3  == kIndex_8_GrPixelConfig);
+    GR_STATIC_ASSERT(4  == kRGB_565_GrPixelConfig);
+    GR_STATIC_ASSERT(5  == kRGBA_4444_GrPixelConfig);
+    GR_STATIC_ASSERT(6  == kRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(7  == kBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(8  == kSRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(9  == kSBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(10 == kRGBA_8888_sint_GrPixelConfig);
+    GR_STATIC_ASSERT(11 == kETC1_GrPixelConfig);
+    GR_STATIC_ASSERT(12 == kLATC_GrPixelConfig);
+    GR_STATIC_ASSERT(13 == kR11_EAC_GrPixelConfig);
+    GR_STATIC_ASSERT(14 == kASTC_12x12_GrPixelConfig);
+    GR_STATIC_ASSERT(15 == kRGBA_float_GrPixelConfig);
+    GR_STATIC_ASSERT(16 == kAlpha_half_GrPixelConfig);
+    GR_STATIC_ASSERT(17 == kRGBA_half_GrPixelConfig);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFlags) == kGrPixelConfigCnt);
 }
 
diff --git a/include/gpu/GrTypes.h b/include/gpu/GrTypes.h
index 86e83f93e8..d780c32600 100644
--- a/include/gpu/GrTypes.h
+++ b/include/gpu/GrTypes.h
@@ -219,6 +219,7 @@ static inline int GrMaskFormatBytesPerPixel(GrMaskFormat format) {
 enum GrPixelConfig {
     kUnknown_GrPixelConfig,
     kAlpha_8_GrPixelConfig,
+    kGray_8_GrPixelConfig,
     kIndex_8_GrPixelConfig,
     kRGB_565_GrPixelConfig,
     /**
@@ -379,6 +380,7 @@ static inline size_t GrBytesPerPixel(GrPixelConfig config) {
     SkASSERT(!GrPixelConfigIsCompressed(config));
     switch (config) {
         case kAlpha_8_GrPixelConfig:
+        case kGray_8_GrPixelConfig:
             return 1;
         case kRGB_565_GrPixelConfig:
         case kRGBA_4444_GrPixelConfig:
@@ -403,6 +405,7 @@ static inline bool GrPixelConfigIsOpaque(GrPixelConfig config) {
     switch (config) {
         case kETC1_GrPixelConfig:
         case kRGB_565_GrPixelConfig:
+        case kGray_8_GrPixelConfig:
             return true;
         default:
             return false;
diff --git a/include/private/GrSwizzle.h b/include/private/GrSwizzle.h
index 5fa39dd987..4acf7e44c7 100644
--- a/include/private/GrSwizzle.h
+++ b/include/private/GrSwizzle.h
@@ -93,6 +93,7 @@ public:
     static GrSwizzle RGBA() { return GrSwizzle("rgba"); }
     static GrSwizzle AAAA() { return GrSwizzle("aaaa"); }
     static GrSwizzle RRRR() { return GrSwizzle("rrrr"); }
+    static GrSwizzle RRRA() { return GrSwizzle("rrra"); }
     static GrSwizzle BGRA() { return GrSwizzle("bgra"); }
 
     static GrSwizzle CreateRandom(SkRandom* random) {
diff --git a/src/gpu/GrCaps.cpp b/src/gpu/GrCaps.cpp
index 0cc33462eb..2b18fac767 100644
--- a/src/gpu/GrCaps.cpp
+++ b/src/gpu/GrCaps.cpp
@@ -170,6 +170,7 @@ SkString GrCaps::dump() const {
     static const char* kConfigNames[] = {
         "Unknown",       // kUnknown_GrPixelConfig
         "Alpha8",        // kAlpha_8_GrPixelConfig,
+        "Gray8",         // kGray_8_GrPixelConfig,
         "Index8",        // kIndex_8_GrPixelConfig,
         "RGB565",        // kRGB_565_GrPixelConfig,
         "RGBA444",       // kRGBA_4444_GrPixelConfig,
@@ -188,21 +189,22 @@ SkString GrCaps::dump() const {
     };
     GR_STATIC_ASSERT(0  == kUnknown_GrPixelConfig);
     GR_STATIC_ASSERT(1  == kAlpha_8_GrPixelConfig);
-    GR_STATIC_ASSERT(2  == kIndex_8_GrPixelConfig);
-    GR_STATIC_ASSERT(3  == kRGB_565_GrPixelConfig);
-    GR_STATIC_ASSERT(4  == kRGBA_4444_GrPixelConfig);
-    GR_STATIC_ASSERT(5  == kRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(6  == kBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(7  == kSRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(8  == kSBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(9  == kRGBA_8888_sint_GrPixelConfig);
-    GR_STATIC_ASSERT(10 == kETC1_GrPixelConfig);
-    GR_STATIC_ASSERT(11 == kLATC_GrPixelConfig);
-    GR_STATIC_ASSERT(12 == kR11_EAC_GrPixelConfig);
-    GR_STATIC_ASSERT(13 == kASTC_12x12_GrPixelConfig);
-    GR_STATIC_ASSERT(14 == kRGBA_float_GrPixelConfig);
-    GR_STATIC_ASSERT(15 == kAlpha_half_GrPixelConfig);
-    GR_STATIC_ASSERT(16 == kRGBA_half_GrPixelConfig);
+    GR_STATIC_ASSERT(2  == kGray_8_GrPixelConfig);
+    GR_STATIC_ASSERT(3  == kIndex_8_GrPixelConfig);
+    GR_STATIC_ASSERT(4  == kRGB_565_GrPixelConfig);
+    GR_STATIC_ASSERT(5  == kRGBA_4444_GrPixelConfig);
+    GR_STATIC_ASSERT(6  == kRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(7  == kBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(8  == kSRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(9  == kSBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(10 == kRGBA_8888_sint_GrPixelConfig);
+    GR_STATIC_ASSERT(11 == kETC1_GrPixelConfig);
+    GR_STATIC_ASSERT(12 == kLATC_GrPixelConfig);
+    GR_STATIC_ASSERT(13 == kR11_EAC_GrPixelConfig);
+    GR_STATIC_ASSERT(14 == kASTC_12x12_GrPixelConfig);
+    GR_STATIC_ASSERT(15 == kRGBA_float_GrPixelConfig);
+    GR_STATIC_ASSERT(16 == kAlpha_half_GrPixelConfig);
+    GR_STATIC_ASSERT(17 == kRGBA_half_GrPixelConfig);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kConfigNames) == kGrPixelConfigCnt);
 
     SkASSERT(!this->isConfigRenderable(kUnknown_GrPixelConfig, false));
diff --git a/src/gpu/GrContext.cpp b/src/gpu/GrContext.cpp
index 30f596fe10..fd8aba0ae7 100644
--- a/src/gpu/GrContext.cpp
+++ b/src/gpu/GrContext.cpp
@@ -680,6 +680,7 @@ static inline GrPixelConfig GrPixelConfigFallback(GrPixelConfig config) {
     static const GrPixelConfig kFallback[] = {
         kUnknown_GrPixelConfig,        // kUnknown_GrPixelConfig
         kRGBA_8888_GrPixelConfig,      // kAlpha_8_GrPixelConfig
+        kUnknown_GrPixelConfig,        // kGray_8_GrPixelConfig
         kUnknown_GrPixelConfig,        // kIndex_8_GrPixelConfig
         kRGBA_8888_GrPixelConfig,      // kRGB_565_GrPixelConfig
         kRGBA_8888_GrPixelConfig,      // kRGBA_4444_GrPixelConfig
@@ -700,21 +701,22 @@ static inline GrPixelConfig GrPixelConfigFallback(GrPixelConfig config) {
 
     GR_STATIC_ASSERT(0  == kUnknown_GrPixelConfig);
     GR_STATIC_ASSERT(1  == kAlpha_8_GrPixelConfig);
-    GR_STATIC_ASSERT(2  == kIndex_8_GrPixelConfig);
-    GR_STATIC_ASSERT(3  == kRGB_565_GrPixelConfig);
-    GR_STATIC_ASSERT(4  == kRGBA_4444_GrPixelConfig);
-    GR_STATIC_ASSERT(5  == kRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(6  == kBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(7  == kSRGBA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(8  == kSBGRA_8888_GrPixelConfig);
-    GR_STATIC_ASSERT(9  == kRGBA_8888_sint_GrPixelConfig);
-    GR_STATIC_ASSERT(10 == kETC1_GrPixelConfig);
-    GR_STATIC_ASSERT(11 == kLATC_GrPixelConfig);
-    GR_STATIC_ASSERT(12 == kR11_EAC_GrPixelConfig);
-    GR_STATIC_ASSERT(13 == kASTC_12x12_GrPixelConfig);
-    GR_STATIC_ASSERT(14 == kRGBA_float_GrPixelConfig);
-    GR_STATIC_ASSERT(15 == kAlpha_half_GrPixelConfig);
-    GR_STATIC_ASSERT(16 == kRGBA_half_GrPixelConfig);
+    GR_STATIC_ASSERT(2  == kGray_8_GrPixelConfig);
+    GR_STATIC_ASSERT(3  == kIndex_8_GrPixelConfig);
+    GR_STATIC_ASSERT(4  == kRGB_565_GrPixelConfig);
+    GR_STATIC_ASSERT(5  == kRGBA_4444_GrPixelConfig);
+    GR_STATIC_ASSERT(6  == kRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(7  == kBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(8  == kSRGBA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(9  == kSBGRA_8888_GrPixelConfig);
+    GR_STATIC_ASSERT(10 == kRGBA_8888_sint_GrPixelConfig);
+    GR_STATIC_ASSERT(11 == kETC1_GrPixelConfig);
+    GR_STATIC_ASSERT(12 == kLATC_GrPixelConfig);
+    GR_STATIC_ASSERT(13 == kR11_EAC_GrPixelConfig);
+    GR_STATIC_ASSERT(14 == kASTC_12x12_GrPixelConfig);
+    GR_STATIC_ASSERT(15 == kRGBA_float_GrPixelConfig);
+    GR_STATIC_ASSERT(16 == kAlpha_half_GrPixelConfig);
+    GR_STATIC_ASSERT(17 == kRGBA_half_GrPixelConfig);
     GR_STATIC_ASSERT(SK_ARRAY_COUNT(kFallback) == kGrPixelConfigCnt);
 }
 
diff --git a/src/gpu/GrShaderCaps.cpp b/src/gpu/GrShaderCaps.cpp
index 3e6323f255..90df176051 100644
--- a/src/gpu/GrShaderCaps.cpp
+++ b/src/gpu/GrShaderCaps.cpp
@@ -202,6 +202,7 @@ void GrShaderCaps::initSamplerPrecisionTable() {
         uint8_t* table = fSamplerPrecisions[visibility];
         table[kUnknown_GrPixelConfig]        = kDefault_GrSLPrecision;
         table[kAlpha_8_GrPixelConfig]        = lowp;
+        table[kGray_8_GrPixelConfig]         = lowp;
         table[kIndex_8_GrPixelConfig]        = lowp;
         table[kRGB_565_GrPixelConfig]        = lowp;
         table[kRGBA_4444_GrPixelConfig]      = lowp;
@@ -218,7 +219,7 @@ void GrShaderCaps::initSamplerPrecisionTable() {
         table[kAlpha_half_GrPixelConfig]     = mediump;
         table[kRGBA_half_GrPixelConfig]      = mediump;
 
-        GR_STATIC_ASSERT(17 == kGrPixelConfigCnt);
+        GR_STATIC_ASSERT(18 == kGrPixelConfigCnt);
     }
 }
 
diff --git a/src/gpu/SkGr.cpp b/src/gpu/SkGr.cpp
index 4147855e13..9d6072c551 100644
--- a/src/gpu/SkGr.cpp
+++ b/src/gpu/SkGr.cpp
@@ -253,25 +253,6 @@ GrTexture* GrUploadPixmapToTexture(GrContext* ctx, const SkPixmap& pixmap, SkBud
         pmap = &tmpPixmap;
         // must rebuild desc, since we've forced the info to be N32
         desc = GrImageInfoToSurfaceDesc(pmap->info(), *caps);
-    } else if (kGray_8_SkColorType == pixmap.colorType()) {
-        // We don't have Gray8 support as a pixel config, so expand to 8888
-
-        // We should have converted sRGB Gray8 above (if we have sRGB support):
-        SkASSERT(!caps->srgbSupport() || !pixmap.info().colorSpace() ||
-                 !pixmap.info().colorSpace()->gammaCloseToSRGB());
-
-        SkImageInfo info = SkImageInfo::MakeN32(pixmap.width(), pixmap.height(),
-                                                kOpaque_SkAlphaType);
-        tmpBitmap.allocPixels(info);
-        if (!pixmap.readPixels(info, tmpBitmap.getPixels(), tmpBitmap.rowBytes())) {
-            return nullptr;
-        }
-        if (!tmpBitmap.peekPixels(&tmpPixmap)) {
-            return nullptr;
-        }
-        pmap = &tmpPixmap;
-        // must rebuild desc, since we've forced the info to be N32
-        desc = GrImageInfoToSurfaceDesc(pmap->info(), *caps);
     } else if (kIndex_8_SkColorType == pixmap.colorType()) {
         if (caps->isConfigTexturable(kIndex_8_GrPixelConfig)) {
             size_t imageSize = GrCompressedFormatDataSize(kIndex_8_GrPixelConfig,
@@ -482,7 +463,7 @@ GrPixelConfig SkImageInfo2GrPixelConfig(SkColorType ct, SkAlphaType, const SkCol
         case kIndex_8_SkColorType:
             return kIndex_8_GrPixelConfig;
         case kGray_8_SkColorType:
-            return kAlpha_8_GrPixelConfig; // TODO: gray8 support on gpu
+            return kGray_8_GrPixelConfig;
         case kRGBA_F16_SkColorType:
             return kRGBA_half_GrPixelConfig;
     }
@@ -496,6 +477,9 @@ bool GrPixelConfigToColorType(GrPixelConfig config, SkColorType* ctOut) {
         case kAlpha_8_GrPixelConfig:
             ct = kAlpha_8_SkColorType;
             break;
+        case kGray_8_GrPixelConfig:
+            ct = kGray_8_SkColorType;
+            break;
         case kIndex_8_GrPixelConfig:
             ct = kIndex_8_SkColorType;
             break;
diff --git a/src/gpu/gl/GrGLCaps.cpp b/src/gpu/gl/GrGLCaps.cpp
index d3adc28d4c..bd9380cd20 100644
--- a/src/gpu/gl/GrGLCaps.cpp
+++ b/src/gpu/gl/GrGLCaps.cpp
@@ -1756,6 +1756,39 @@ void GrGLCaps::initConfigTable(const GrContextOptions& contextOptions,
         fConfigTable[kAlpha_8_GrPixelConfig].fFlags |= ConfigInfo::kCanUseTexStorage_Flag;
     }
 
+    if (this->textureRedSupport()) {
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fBaseInternalFormat = GR_GL_RED;
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fSizedInternalFormat = GR_GL_R8;
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fExternalFormat[kOther_ExternalFormatUsage] =
+            GR_GL_RED;
+        fConfigTable[kGray_8_GrPixelConfig].fSwizzle = GrSwizzle::RRRA();
+        if (texelBufferSupport) {
+            fConfigTable[kGray_8_GrPixelConfig].fFlags |= ConfigInfo::kCanUseWithTexelBuffer_Flag;
+        }
+    } else {
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fBaseInternalFormat = GR_GL_LUMINANCE;
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fSizedInternalFormat = GR_GL_LUMINANCE8;
+        fConfigTable[kGray_8_GrPixelConfig].fFormats.fExternalFormat[kOther_ExternalFormatUsage] =
+            GR_GL_LUMINANCE;
+        fConfigTable[kGray_8_GrPixelConfig].fSwizzle = GrSwizzle::RGBA();
+    }
+    fConfigTable[kGray_8_GrPixelConfig].fFormats.fExternalType = GR_GL_UNSIGNED_BYTE;
+    fConfigTable[kGray_8_GrPixelConfig].fFormatType = kNormalizedFixedPoint_FormatType;
+    fConfigTable[kGray_8_GrPixelConfig].fFlags = ConfigInfo::kTextureable_Flag;
+#if 0 // Leaving Gray8 as non-renderable, to keep things simple and match raster
+    if (this->textureRedSupport() ||
+        (kDesktop_ARB_MSFBOType == this->msFBOType() &&
+         ctxInfo.renderer() != kOSMesa_GrGLRenderer)) {
+        // desktop ARB extension/3.0+ supports LUMINANCE8 as renderable.
+        // However, osmesa fails if it used even when GL_ARB_framebuffer_object is present.
+        // Core profile removes LUMINANCE8 support, but we should have chosen R8 in that case.
+        fConfigTable[kGray_8_GrPixelConfig].fFlags |= allRenderFlags;
+    }
+#endif
+    if (texStorageSupported) {
+        fConfigTable[kGray_8_GrPixelConfig].fFlags |= ConfigInfo::kCanUseTexStorage_Flag;
+    }
+
     // Check for [half] floating point texture support
     // NOTE: We disallow floating point textures on ES devices if linear filtering modes are not
     // supported. This is for simplicity, but a more granular approach is possible. Coincidentally,
diff --git a/src/gpu/gl/GrGLDefines.h b/src/gpu/gl/GrGLDefines.h
index 18dee280f0..05a594e0e6 100644
--- a/src/gpu/gl/GrGLDefines.h
+++ b/src/gpu/gl/GrGLDefines.h
@@ -461,6 +461,9 @@
 #define GR_GL_R32I                           0x8235
 #define GR_GL_R32UI                          0x8236
 
+/* Luminance sized formats */
+#define GR_GL_LUMINANCE8                     0x8040
+
 /* Alpha sized formats */
 #define GR_GL_ALPHA8                         0x803C
 #define GR_GL_ALPHA16                        0x803E
diff --git a/src/gpu/gl/GrGLGpu.cpp b/src/gpu/gl/GrGLGpu.cpp
index 577aca844f..74e52583dd 100644
--- a/src/gpu/gl/GrGLGpu.cpp
+++ b/src/gpu/gl/GrGLGpu.cpp
@@ -927,6 +927,7 @@ static inline GrGLint config_alignment(GrPixelConfig config) {
     SkASSERT(!GrPixelConfigIsCompressed(config));
     switch (config) {
         case kAlpha_8_GrPixelConfig:
+        case kGray_8_GrPixelConfig:
             return 1;
         case kRGB_565_GrPixelConfig:
         case kRGBA_4444_GrPixelConfig:
diff --git a/src/gpu/vk/GrVkCaps.cpp b/src/gpu/vk/GrVkCaps.cpp
index 0c52643ee8..f614ae39c6 100644
--- a/src/gpu/vk/GrVkCaps.cpp
+++ b/src/gpu/vk/GrVkCaps.cpp
@@ -148,7 +148,9 @@ void GrVkCaps::initShaderCaps(const VkPhysicalDeviceProperties& properties, uint
             shaderCaps->fConfigTextureSwizzle[i] = GrSwizzle::RRRR();
             shaderCaps->fConfigOutputSwizzle[i] = GrSwizzle::AAAA();
         } else {
-            if (kRGBA_4444_GrPixelConfig == config) {
+            if (kGray_8_GrPixelConfig == config) {
+                shaderCaps->fConfigTextureSwizzle[i] = GrSwizzle::RRRA();
+            } else if (kRGBA_4444_GrPixelConfig == config) {
                 // The vulkan spec does not require R4G4B4A4 to be supported for texturing so we
                 // store the data in a B4G4R4A4 texture and then swizzle it when doing texture reads
                 // or writing to outputs. Since we're not actually changing the data at all, the
diff --git a/src/gpu/vk/GrVkUtil.cpp b/src/gpu/vk/GrVkUtil.cpp
index 3071fc8d83..b92f03e7d8 100644
--- a/src/gpu/vk/GrVkUtil.cpp
+++ b/src/gpu/vk/GrVkUtil.cpp
@@ -48,6 +48,9 @@ bool GrPixelConfigToVkFormat(GrPixelConfig config, VkFormat* format) {
         case kAlpha_8_GrPixelConfig:
             *format = VK_FORMAT_R8_UNORM;
             return true;
+        case kGray_8_GrPixelConfig:
+            *format = VK_FORMAT_R8_UNORM;
+            return true;
         case kETC1_GrPixelConfig:
             // converting to ETC2 which is a superset of ETC1
             *format = VK_FORMAT_ETC2_R8G8B8_UNORM_BLOCK;