From 569f29da862372ab8faeaf851966c2d620bb696c Mon Sep 17 00:00:00 2001
From: Mike Reed <reed@google.com>
Date: Wed, 30 Jun 2021 18:15:43 -0400
Subject: [PATCH] Only trigger serializing blender if it isn't a mode

Change-Id: I9f9cf7f92232c365538f3dd29df226933827771c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/423582
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Reed <reed@google.com>
---
 src/core/SkPaint.cpp | 20 +++++++++++++++-----
 tests/PaintTest.cpp  |  4 ++--
 2 files changed, 17 insertions(+), 7 deletions(-)

diff --git a/src/core/SkPaint.cpp b/src/core/SkPaint.cpp
index edb687b1c8..d428070c2b 100644
--- a/src/core/SkPaint.cpp
+++ b/src/core/SkPaint.cpp
@@ -248,6 +248,8 @@ template <typename T> uint32_t shift_bits(T value, unsigned shift, unsigned bits
     return v << shift;
 }
 
+constexpr uint8_t CUSTOM_BLEND_MODE_SENTINEL = 0xFF;
+
 /*  Packing the paint
  flags :  8  // 2...
  blend :  8  // 30+
@@ -260,9 +262,13 @@ template <typename T> uint32_t shift_bits(T value, unsigned shift, unsigned bits
  */
 static uint32_t pack_v68(const SkPaint& paint, unsigned flatFlags) {
     uint32_t packed = 0;
+    const auto bm = paint.asBlendMode();
+    const unsigned mode = bm ? static_cast<unsigned>(bm.value())
+                             : CUSTOM_BLEND_MODE_SENTINEL;
+
     packed |= shift_bits(((unsigned)paint.isDither() << 1) |
                           (unsigned)paint.isAntiAlias(), 0, 8);
-    packed |= shift_bits(paint.getBlendMode(),      8, 8);
+    packed |= shift_bits(mode,                      8, 8);
     packed |= shift_bits(paint.getStrokeCap(),     16, 2);
     packed |= shift_bits(paint.getStrokeJoin(),    18, 2);
     packed |= shift_bits(paint.getStyle(),         20, 2);
@@ -277,7 +283,13 @@ static uint32_t unpack_v68(SkPaint* paint, uint32_t packed, SkSafeRange& safe) {
     paint->setAntiAlias((packed & 1) != 0);
     paint->setDither((packed & 2) != 0);
     packed >>= 8;
-    paint->setBlendMode(safe.checkLE(packed & 0xFF, SkBlendMode::kLastMode));
+    {
+        unsigned mode = packed & 0xFF;
+        if (mode != CUSTOM_BLEND_MODE_SENTINEL) { // sentinel for custom blender
+            paint->setBlendMode(safe.checkLE(mode, SkBlendMode::kLastMode));
+        }
+        // else we will unflatten the custom blender
+    }
     packed >>= 8;
     paint->setStrokeCap(safe.checkLE(packed & 0x3, SkPaint::kLast_Cap));
     packed >>= 2;
@@ -303,7 +315,7 @@ void SkPaintPriv::Flatten(const SkPaint& paint, SkWriteBuffer& buffer) {
         paint.getMaskFilter() ||
         paint.getColorFilter() ||
         paint.getImageFilter() ||
-        paint.getBlender()) {
+        !paint.asBlendMode()) {
         flatFlags |= kHasEffects_FlatFlag;
     }
 
@@ -343,7 +355,6 @@ SkReadPaintResult SkPaintPriv::Unflatten(SkPaint* paint, SkReadBuffer& buffer, S
         paint->setMaskFilter(nullptr);
         paint->setColorFilter(nullptr);
         paint->setImageFilter(nullptr);
-        paint->experimental_setBlender(nullptr);
     } else if (buffer.isVersionLT(SkPicturePriv::kSkBlenderInSkPaint)) {
         // This paint predates the introduction of user blend functions (via SkBlender).
         paint->setPathEffect(buffer.readPathEffect());
@@ -352,7 +363,6 @@ SkReadPaintResult SkPaintPriv::Unflatten(SkPaint* paint, SkReadBuffer& buffer, S
         paint->setColorFilter(buffer.readColorFilter());
         (void)buffer.read32();  // was drawLooper (now deprecated)
         paint->setImageFilter(buffer.readImageFilter());
-        paint->experimental_setBlender(nullptr);
     } else {
         paint->setPathEffect(buffer.readPathEffect());
         paint->setShader(buffer.readShader());
diff --git a/tests/PaintTest.cpp b/tests/PaintTest.cpp
index 560f020a59..2db0ed6b80 100644
--- a/tests/PaintTest.cpp
+++ b/tests/PaintTest.cpp
@@ -158,8 +158,8 @@ DEF_TEST(Paint_MoreFlattening, r) {
     ASSERT(reader.offset() == writer.bytesWritten());
 
     // No matter the encoding, these must always hold.
-    ASSERT(other.getColor()      == paint.getColor());
-    ASSERT(other.getBlendMode()  == paint.getBlendMode());
+    ASSERT(other.getColor()    == paint.getColor());
+    ASSERT(other.asBlendMode() == paint.asBlendMode());
 }
 
 #include "include/effects/SkColorMatrixFilter.h"