SkPDF: Refactor PDFShader to use ShTHashMap<>

my tests run ~14% faster.

  - Split out gradient shaders from image shaders.  new compilation
    unit: SkPDFGradientShader
  - Common functions InverseTransformBBox and PopulateTilingPatternDict
    moved to SkPDFUtils
  - Split SkPDFShader::State into image and gradient structures.
  - SkPDFCanon is now a simpler structure, with no logic of its own.
    I am considering just moving all of its fields into SkPDFDocument
  - SkPDFShader::State (the image/fallback shader) now is POD, making
    the use of a hashmap for canonicalization straightforward.
    Formerly, we used a linear search.
  - Do not bother trying to canonicalize the falback image shader.
  - SkPDFGradientShader::Key is not POD; comparison of two objects
    requires looking at the contents of two variable-sized arrays.
    We now pre-calculate the hash of the arrays using SkOpts::hash and
    store a hash for the object in the fHash field.
    Using that hash, we can now canonicalize using a hashmap instead
    of a linar search!
  - several static functions renamed to follow style guidelines
  - stop using codeFunction function pointer; I find that less
    clear than it could be.
  - operator==() for SkPDFShader::State and SkPDFGradientShader::Key is
    now much simpler and can now be inlined.
  - SkArrayEqual template in SkPDFUtils.h

No change to PDF output.

BUG=skia:3585
Change-Id: I354ad1b600be6d6749abccb58d13db257370bc0b
Reviewed-on: https://skia-review.googlesource.com/21376
Reviewed-by: Ben Wagner <bungeman@google.com>
Commit-Queue: Hal Canary <halcanary@google.com>

1 files changed, 30 insertions, 0 deletions

diff --git a/src/pdf/SkPDFUtils.cpp b/src/pdf/SkPDFUtils.cpp
index 3cbf038369..510be6c27a 100644
--- a/src/pdf/SkPDFUtils.cpp
+++ b/src/pdf/SkPDFUtils.cpp
@@ -486,3 +486,33 @@ void SkPDFUtils::WriteString(SkWStream* wStream, const char* cin, size_t len) {
         wStream->writeText(">");
     }
 }
+
+bool SkPDFUtils::InverseTransformBBox(const SkMatrix& matrix, SkRect* bbox) {
+    SkMatrix inverse;
+    if (!matrix.invert(&inverse)) {
+        return false;
+    }
+    inverse.mapRect(bbox);
+    return true;
+}
+
+void SkPDFUtils::PopulateTilingPatternDict(SkPDFDict* pattern,
+                                           SkRect& bbox,
+                                           sk_sp<SkPDFDict> resources,
+                                           const SkMatrix& matrix) {
+    const int kTiling_PatternType = 1;
+    const int kColoredTilingPattern_PaintType = 1;
+    const int kConstantSpacing_TilingType = 1;
+
+    pattern->insertName("Type", "Pattern");
+    pattern->insertInt("PatternType", kTiling_PatternType);
+    pattern->insertInt("PaintType", kColoredTilingPattern_PaintType);
+    pattern->insertInt("TilingType", kConstantSpacing_TilingType);
+    pattern->insertObject("BBox", SkPDFUtils::RectToArray(bbox));
+    pattern->insertScalar("XStep", bbox.width());
+    pattern->insertScalar("YStep", bbox.height());
+    pattern->insertObject("Resources", std::move(resources));
+    if (!matrix.isIdentity()) {
+        pattern->insertObject("Matrix", SkPDFUtils::MatrixToArray(matrix));
+    }
+}