Re-re-land "added GrSkSLFP and converted DitherEffect to use it"

This reverts commit 6c48e4d11ce80fa5cfef56e13b2d5847fe94a7cc.

Bug: skia:
Change-Id: I7ee78990fc30eec545d1856e59eb6e0573089426
Reviewed-on: https://skia-review.googlesource.com/144348
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>

1 files changed, 37 insertions, 0 deletions

diff --git a/include/private/GrSkSLFPFactoryCache.h b/include/private/GrSkSLFPFactoryCache.h
new file mode 100644
index 0000000000..40e001a672
--- /dev/null
+++ b/include/private/GrSkSLFPFactoryCache.h
@@ -0,0 +1,37 @@
+/*
+ * Copyright 2018 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef GrSkSLFPFactoryCache_DEFINED
+#define GrSkSLFPFactoryCache_DEFINED
+
+#include "SkRefCnt.h"
+
+#include <vector>
+
+class GrSkSLFPFactory;
+
+// This is a cache used by GrSkSLFP to retain GrSkSLFPFactory instances, so we don't have to
+// re-process the SkSL source code every time we create a GrSkSLFP instance.
+// For thread safety, it is important that GrSkSLFP only interact with the cache from methods that
+// are only called from within the rendering thread, like onCreateGLSLInstance and
+// onGetGLSLProcessorKey.
+class GrSkSLFPFactoryCache : public SkNVRefCnt<GrSkSLFPFactoryCache> {
+public:
+    // Returns a factory by its numeric index, or null if no such factory exists. Indices are
+    // allocated by GrSkSLFP::NewIndex().
+    sk_sp<GrSkSLFPFactory> get(int index);
+
+    // Stores a new factory with the given index.
+    void set(int index, sk_sp<GrSkSLFPFactory> factory);
+
+    ~GrSkSLFPFactoryCache();
+
+private:
+    std::vector<GrSkSLFPFactory*> fFactories;
+};
+
+#endif