skia WIPjarred/canvas

1 files changed, 110 insertions, 0 deletions

diff --git a/src/deps/skia/include/private/SkPaintParamsKey.h b/src/deps/skia/include/private/SkPaintParamsKey.h
new file mode 100644
index 000000000..44a88f59f
--- /dev/null
+++ b/src/deps/skia/include/private/SkPaintParamsKey.h
@@ -0,0 +1,110 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPaintParamsKey_DEFINED
+#define SkPaintParamsKey_DEFINED
+
+#include <array>
+#include <limits>
+#include "include/core/SkTypes.h"
+
+enum class SkBackend : uint8_t {
+    kGanesh,
+    kGraphite,
+    kSkVM
+};
+
+// TODO: this needs to be expanded into a more flexible dictionary (esp. for user-supplied SkSL)
+// TODO: should this enum actually be in ShaderCodeDictionary.h?
+enum class CodeSnippetID : uint8_t {
+    // TODO: It seems like this requires some refinement. Fundamentally this doesn't seem like a
+    // draw that originated from a PaintParams.
+    kDepthStencilOnlyDraw,
+
+    // SkShader code snippets
+    kSolidColorShader,
+    kLinearGradientShader,
+    kRadialGradientShader,
+    kSweepGradientShader,
+    kConicalGradientShader,
+
+    // BlendMode code snippets
+    kSimpleBlendMode,
+
+    kLast = kSimpleBlendMode
+};
+static constexpr int kCodeSnippetIDCount = static_cast<int>(CodeSnippetID::kLast) + 1;
+
+// This class is a compact representation of the shader needed to implement a given
+// PaintParams. Its structure is a series of blocks where each block has a
+// header that consists of 2-bytes - a 1-byte code-snippet ID and a 1-byte number-of-bytes-in-the-
+// block field. The rest of the data in the block is dependent on the individual code snippet.
+class SkPaintParamsKey {
+public:
+    static const int kBlockHeaderSizeInBytes = 2;
+    static const int kBlockSizeOffsetInBytes = 1; // offset to the block size w/in the header
+
+    // Block headers have the following structure:
+    //  1st byte: codeSnippetID
+    //  2nd byte: total blockSize in bytes
+    // Returns the header's offset in the key - to be passed back into endBlock
+    int beginBlock(CodeSnippetID codeSnippetID) {
+        SkASSERT(fNumBytes < kMaxKeySize);
+
+        this->addByte((uint8_t) codeSnippetID);
+        this->addByte(0); // this needs to be patched up with a call to endBlock
+        return fNumBytes - kBlockHeaderSizeInBytes;
+    }
+
+    // Update the size byte of a block header
+    void endBlock(int headerOffset, CodeSnippetID codeSnippetID) {
+        SkASSERT(fData[headerOffset] == (uint32_t) codeSnippetID);
+        int blockSize = fNumBytes - headerOffset;
+        SkASSERT(blockSize <= kMaxBlockSize);
+        fData[headerOffset+1] = blockSize;
+    }
+
+    std::pair<CodeSnippetID, uint8_t> readCodeSnippetID(int headerOffset) const {
+        SkASSERT(headerOffset < kMaxKeySize - kBlockHeaderSizeInBytes);
+
+        CodeSnippetID id = static_cast<CodeSnippetID>(fData[headerOffset]);
+        uint8_t blockSize = fData[headerOffset+1];
+        SkASSERT(headerOffset + blockSize <= this->sizeInBytes());
+
+        return { id, blockSize };
+    }
+
+    void addByte(uint8_t byte) {
+        SkASSERT(fNumBytes < kMaxKeySize);
+
+        fData[fNumBytes++] = byte;
+    }
+
+#ifdef SK_DEBUG
+    static int DumpBlock(const SkPaintParamsKey&, int headerOffset);
+    void dump() const;
+#endif
+
+    uint8_t byte(int offset) const { SkASSERT(offset < fNumBytes); return fData[offset]; }
+    const void* data() const { return fData.data(); }
+    int sizeInBytes() const { return fNumBytes; }
+
+    bool operator==(const SkPaintParamsKey& that) const;
+    bool operator!=(const SkPaintParamsKey& that) const { return !(*this == that); }
+
+private:
+    // TODO: need to make it so the key can can dynamically grow
+    static const int kMaxKeySize = 32;
+    static const int kMaxBlockSize = std::numeric_limits<uint8_t>::max();
+
+    // TODO: It is probably overkill but we could encode the SkBackend in the first byte of
+    // the key.
+    int fNumBytes = 0;
+    std::array<uint8_t, kMaxKeySize> fData;
+};
+
+#endif // SkPaintParamsKey_DEFINED