1 files changed, 65 insertions, 0 deletions
diff --git a/gfx/skia/skia/src/shaders/SkEmptyShader.cpp b/gfx/skia/skia/src/shaders/SkEmptyShader.cpp
new file mode 100644
index 0000000000..94040338a8
--- /dev/null
+++ b/gfx/skia/skia/src/shaders/SkEmptyShader.cpp
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "src/shaders/SkShaderBase.h"
+
+#include "include/core/SkFlattenable.h"
+#include "src/core/SkVM.h"
+
+/**
+ *  \class SkEmptyShader
+ *  A Shader that always draws nothing. Its createContext always returns nullptr.
+ */
+class SkEmptyShader : public SkShaderBase {
+public:
+    SkEmptyShader() {}
+
+protected:
+    void flatten(SkWriteBuffer& buffer) const override {
+        // Do nothing.
+        // We just don't want to fall through to SkShader::flatten(),
+        // which will write data we don't care to serialize or decode.
+    }
+
+    bool appendStages(const SkStageRec&, const MatrixRec&) const override { return false; }
+
+    skvm::Color program(skvm::Builder*,
+                        skvm::Coord,
+                        skvm::Coord,
+                        skvm::Color,
+                        const MatrixRec&,
+                        const SkColorInfo&,
+                        skvm::Uniforms*,
+                        SkArenaAlloc*) const override;
+
+private:
+    friend void ::SkRegisterEmptyShaderFlattenable();
+    SK_FLATTENABLE_HOOKS(SkEmptyShader)
+
+    using INHERITED = SkShaderBase;
+};
+
+skvm::Color SkEmptyShader::program(skvm::Builder*,
+                                   skvm::Coord,
+                                   skvm::Coord,
+                                   skvm::Color,
+                                   const MatrixRec&,
+                                   const SkColorInfo&,
+                                   skvm::Uniforms*,
+                                   SkArenaAlloc*) const {
+    return {};  // signal failure
+}
+
+sk_sp<SkFlattenable> SkEmptyShader::CreateProc(SkReadBuffer&) {
+    return SkShaders::Empty();
+}
+
+sk_sp<SkShader> SkShaders::Empty() { return sk_make_sp<SkEmptyShader>(); }
+
+void SkRegisterEmptyShaderFlattenable() {
+    SK_REGISTER_FLATTENABLE(SkEmptyShader);
+}