Remove SkPaint::getHash

This was a particularly bad hash (A == B didn't imply
hash(A) == hash(B)). It was also entirely unused.

Change-Id: Id923bf1035effce04e12b1cc01d1c6aa4d11fdb6
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/419336
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Mike Reed <reed@google.com>

RELEASE_NOTES.txt

@@ -6,7 +6,8 @@ This file includes a list of high level updates for each milestone release.
 
 Milestone 93
 ------------
-  *
+  * Removed SkPaint::getHash
+    https://review.skia.org/419336
 
 * * *
 

docs/examples/Paint_getHash.cpp

@@ -1,14 +0,0 @@
-// Copyright 2019 Google LLC.
-// Use of this source code is governed by a BSD-style license that can be found in the LICENSE file.
-#include "tools/fiddle/examples.h"
-// HASH=7f7e1b701361912b344f90ae6b530393
-REG_FIDDLE(Paint_getHash, 256, 256, true, 0) {
-void draw(SkCanvas* canvas) {
-    SkPaint paint1, paint2;
-    paint1.setColor(SK_ColorRED);
-    paint2.setColor(0xFFFF0000);
-    SkDebugf("paint1 %c= paint2\n", paint1 == paint2 ? '=' : '!');
-    SkDebugf("paint1.getHash() %c= paint2.getHash()\n",
-             paint1.getHash() == paint2.getHash() ? '=' : '!');
-}
-}  // END FIDDLE

include/core/SkPaint.h

@@ -144,22 +144,6 @@ public:
         return !(a == b);
     }
 
-    /** Returns a hash generated from SkPaint values and pointers.
-        Identical hashes guarantee that the paints are
-        equivalent, but differing hashes do not guarantee that the paints have differing
-        contents.
-
-        If operator==(const SkPaint& a, const SkPaint& b) returns true for two paints,
-        their hashes are also equal.
-
-        The hash returned is platform and implementation specific.
-
-        @return  a shallow hash
-
-        example: https://fiddle.skia.org/c/@Paint_getHash
-    */
-    uint32_t getHash() const;
-
     /** Sets all SkPaint contents to their initial values. This is equivalent to replacing
         SkPaint with the result of SkPaint().
 

src/core/SkPaint.cpp

@@ -439,12 +439,3 @@ bool SkPaint::nothingToDraw() const {
     }
     return false;
 }
-
-uint32_t SkPaint::getHash() const {
-    // We're going to hash 5 pointers and 6 floats, finishing up with fBitfields,
-    // so fBitfields should be 5 pointers and 6 floats from the start.
-    static_assert(offsetof(SkPaint, fBitfieldsUInt) == 5 * sizeof(void*) + 6 * sizeof(float),
-                  "SkPaint_notPackedTightly");
-    return SkOpts::hash(reinterpret_cast<const uint32_t*>(this),
-                        offsetof(SkPaint, fBitfieldsUInt) + sizeof(fBitfieldsUInt));
-}

tests/PaintTest.cpp

@@ -31,7 +31,6 @@ DEF_TEST(Paint_copy, reporter) {
 
     // copy the paint using the copy constructor and check they are the same
     SkPaint copiedPaint = paint;
-    REPORTER_ASSERT(reporter, paint.getHash() == copiedPaint.getHash());
     REPORTER_ASSERT(reporter, paint == copiedPaint);
 
     // copy the paint using the equal operator and check they are the same
@@ -163,26 +162,6 @@ DEF_TEST(Paint_MoreFlattening, r) {
     ASSERT(other.getBlendMode()  == paint.getBlendMode());
 }
 
-DEF_TEST(Paint_getHash, r) {
-    // Try not to inspect the actual hash values in here.
-    // We might want to change the hash function.
-
-    SkPaint paint;
-    const uint32_t defaultHash = paint.getHash();
-
-    // Check that some arbitrary field affects the hash.
-    paint.setColor(0xFF00FF00);
-    REPORTER_ASSERT(r, paint.getHash() != defaultHash);
-    paint.setColor(SK_ColorBLACK);  // Reset to default value.
-    REPORTER_ASSERT(r, paint.getHash() == defaultHash);
-
-    // This is part of fBitfields, the last field we hash.
-    paint.setBlendMode(SkBlendMode::kSrc);
-    REPORTER_ASSERT(r, paint.getHash() != defaultHash);
-    paint.setBlendMode(SkBlendMode::kSrcOver);
-    REPORTER_ASSERT(r, paint.getHash() == defaultHash);
-}
-
 #include "include/effects/SkColorMatrixFilter.h"
 
 DEF_TEST(Paint_nothingToDraw, r) {

tools/fiddle/all_examples.cpp

@@ -530,7 +530,6 @@
 #include "../../docs/examples/Paint_getFlags.cpp"
 #include "../../docs/examples/Paint_getFontMetrics.cpp"
 #include "../../docs/examples/Paint_getFontSpacing.cpp"
-#include "../../docs/examples/Paint_getHash.cpp"
 #include "../../docs/examples/Paint_getHinting.cpp"
 #include "../../docs/examples/Paint_getImageFilter.cpp"
 #include "../../docs/examples/Paint_getMaskFilter.cpp"

tools/fiddle/documumentation_examples_map.txt

@@ -2044,10 +2044,6 @@ SkScalar getFontMetrics(SkFontMetrics* metrics) const;
 SkPaint
 SkScalar getFontSpacing() const;
 
-[Paint_getHash]
-SkPaint
-uint32_t getHash() const;
-
 [Paint_getHinting]
 SkPaint
 SkFontHinting getHinting() const;