Merge tomhudson and mtklein SkPaint shrinking approaches.

tests/PaintTest.cpp

Index: tests/PaintTest.cpp
diff --git a/tests/PaintTest.cpp b/tests/PaintTest.cpp
index 3210e77f19b74e060b8d949aa1f6dbbef0875c1d..f1ad78caa3683275861e41bee4efaafbced74656 100644
--- a/tests/PaintTest.cpp
+++ b/tests/PaintTest.cpp
@@ -11,8 +11,11 @@
 #include "SkPaint.h"
 #include "SkPath.h"
 #include "SkRandom.h"
+#include "SkReadBuffer.h"
 #include "SkTypeface.h"
 #include "SkUtils.h"
+#include "SkWriteBuffer.h"
+#include "SkXfermode.h"
 #include "Test.h"
 
 static size_t uni_to_utf8(const SkUnichar src[], void* dst, int count) {
@@ -251,3 +254,39 @@ DEF_TEST(Paint, reporter) {
        test_cmap(reporter);
     }
 }
+
+#define ASSERT(expr) REPORTER_ASSERT(r, expr)
+
+DEF_TEST(Paint_FlatteningTraits, r) {
+    SkPaint paint;
+    paint.setColor(0x00AABBCC);
+    paint.setTextScaleX(1.0f);  // Encoded despite being the default value.

[tomhudson, 2014/02/17 16:25:01]

Nit: I take your comment to mean "Even though this is the the default value,
since we're explicitly setting it, it's going to get marked as dirty and we're
going to explicitly serialize it." Do we really want it to be invariant that the
class behaves this way? Or is this just an irrelevant implementation detail? Why
does it matter for correctness?

[mtklein_C, 2014/02/18 15:49:33]

Implementation detail.  Just a white-box test.

+    paint.setTextSize(19);
+    paint.setXfermode(SkXfermode::Create(SkXfermode::kModulate_Mode));
+    paint.setLooper(NULL);  // Ignored.
+
+    SkWriteBuffer writer;
+    SkPaint::FlatteningTraits::flatten(writer, paint);
+    ASSERT(writer.bytesWritten() == 48);

[tomhudson, 2014/02/17 16:25:01]

Hmm, == or <=?

[mtklein_C, 2014/02/18 15:49:33]

Let's leave it ==.  We can change the value as the implementation changes.

+
+    const uint32_t* written = writer.getWriter32()->contiguousArray();
+    SkASSERT(written != NULL);
+    ASSERT(*written == ((1<<0) | (1<<2) | (1<<3) | (1<<9)));  // Dirty bits for our 4.
+
+    SkReadBuffer reader(written, writer.bytesWritten());
+    SkPaint other;
+    SkPaint::FlatteningTraits::unflatten(reader, &other);
+    ASSERT(reader.offset() == writer.bytesWritten());
+
+    // No matter the encoding, these must always hold.
+    ASSERT(other.getColor()      == paint.getColor());
+    ASSERT(other.getTextScaleX() == paint.getTextScaleX());
+    ASSERT(other.getTextSize()   == paint.getTextSize());
+    ASSERT(other.getLooper()     == paint.getLooper());
+
+    // We have to be a little looser and compare just the modes.  Pointers might not be the same.
+    SkXfermode::Mode otherMode, paintMode;
+    ASSERT(other.getXfermode()->asMode(&otherMode));
+    ASSERT(paint.getXfermode()->asMode(&paintMode));
+    ASSERT(otherMode == paintMode);
+}