From e7541d9b0884e559b208f13a04ac1fb8a1a20c2f Mon Sep 17 00:00:00 2001
From: Mike Klein <mtklein@google.com>
Date: Wed, 13 Jan 2021 13:53:05 -0600
Subject: [PATCH] make SkShaderBase::onProgram pure virtual

This makes it easier to see which shaders do not have an SkVM
implementation (tricolor for drawVertices, perlin noise) and lets us
reserve the default onProgram() for other uses, like mutually recursive
F32/Half onProgram(), just as we've done previously for color filters.

I've marked both tricolor and perlin noise as "TODO?" rather than just a
simple "TODO", mostly because they're both intriguing to handle in other
ways, perhaps in externalizable SkSL.

Change-Id: I6ccd14a85dee1519b10d53ecbfc1074916954eca
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/353319
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Klein <mtklein@google.com>
---
 src/core/SkDraw_vertices.cpp        | 10 ++++++++++
 src/shaders/SkPerlinNoiseShader.cpp | 10 ++++++++++
 src/shaders/SkShader.cpp            |  9 ---------
 src/shaders/SkShaderBase.h          |  2 +-
 4 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/core/SkDraw_vertices.cpp b/src/core/SkDraw_vertices.cpp
index c0161cd530..1b21424bad 100644
--- a/src/core/SkDraw_vertices.cpp
+++ b/src/core/SkDraw_vertices.cpp
@@ -16,6 +16,7 @@
 #include "src/core/SkRasterClip.h"
 #include "src/core/SkRasterPipeline.h"
 #include "src/core/SkScan.h"
+#include "src/core/SkVM.h"
 #include "src/core/SkVertState.h"
 #include "src/core/SkVerticesPriv.h"
 #include "src/shaders/SkComposeShader.h"
@@ -147,6 +148,15 @@ protected:
         return true;
     }
 
+    skvm::Color onProgram(skvm::Builder*,
+                          skvm::Coord, skvm::Coord, skvm::Color,
+                          const SkMatrixProvider&, const SkMatrix*,
+                          SkFilterQuality, const SkColorInfo&,
+                          skvm::Uniforms*, SkArenaAlloc*) const override {
+        // TODO?
+        return {};
+    }
+
 private:
     bool isOpaque() const override { return fIsOpaque; }
     // For serialization.  This will never be called.
diff --git a/src/shaders/SkPerlinNoiseShader.cpp b/src/shaders/SkPerlinNoiseShader.cpp
index 5260ff32bf..73f6d0a88d 100644
--- a/src/shaders/SkPerlinNoiseShader.cpp
+++ b/src/shaders/SkPerlinNoiseShader.cpp
@@ -16,6 +16,7 @@
 #include "src/core/SkArenaAlloc.h"
 #include "src/core/SkMatrixProvider.h"
 #include "src/core/SkReadBuffer.h"
+#include "src/core/SkVM.h"
 #include "src/core/SkWriteBuffer.h"
 
 #if SK_SUPPORT_GPU
@@ -301,6 +302,15 @@ public:
     std::unique_ptr<GrFragmentProcessor> asFragmentProcessor(const GrFPArgs&) const override;
 #endif
 
+    skvm::Color onProgram(skvm::Builder*,
+                          skvm::Coord, skvm::Coord, skvm::Color,
+                          const SkMatrixProvider&, const SkMatrix*,
+                          SkFilterQuality, const SkColorInfo&,
+                          skvm::Uniforms*, SkArenaAlloc*) const override {
+        // TODO?
+        return {};
+    }
+
 protected:
     void flatten(SkWriteBuffer&) const override;
 #ifdef SK_ENABLE_LEGACY_SHADERCONTEXT
diff --git a/src/shaders/SkShader.cpp b/src/shaders/SkShader.cpp
index 4e8c79f178..0ee0913b4b 100644
--- a/src/shaders/SkShader.cpp
+++ b/src/shaders/SkShader.cpp
@@ -238,15 +238,6 @@ skvm::Color SkShaderBase::program(skvm::Builder* p,
     return {};
 }
 
-skvm::Color SkShaderBase::onProgram(skvm::Builder*,
-                                    skvm::Coord device, skvm::Coord local, skvm::Color paint,
-                                    const SkMatrixProvider&, const SkMatrix* localM,
-                                    SkFilterQuality quality, const SkColorInfo& dst,
-                                    skvm::Uniforms* uniforms, SkArenaAlloc* alloc) const {
-    // SkDebugf("cannot onProgram %s\n", this->getTypeName());
-    return {};
-}
-
 // need a cheap way to invert the alpha channel of a shader (i.e. 1 - a)
 sk_sp<SkShader> SkShaderBase::makeInvertAlpha() const {
     return this->makeWithColorFilter(SkColorFilters::Blend(0xFFFFFFFF, SkBlendMode::kSrcOut));
diff --git a/src/shaders/SkShaderBase.h b/src/shaders/SkShaderBase.h
index 1e74f833e9..35a5beb9a8 100644
--- a/src/shaders/SkShaderBase.h
+++ b/src/shaders/SkShaderBase.h
@@ -252,7 +252,7 @@ private:
                                   skvm::Coord device, skvm::Coord local, skvm::Color paint,
                                   const SkMatrixProvider&, const SkMatrix* localM,
                                   SkFilterQuality quality, const SkColorInfo& dst,
-                                  skvm::Uniforms* uniforms, SkArenaAlloc* alloc) const;
+                                  skvm::Uniforms* uniforms, SkArenaAlloc* alloc) const = 0;
 
     using INHERITED = SkShader;
 };