SkDocument::setDCTEncoder() for old versions of webkit

tests/PDFDocumentTest.cpp

Index: tests/PDFDocumentTest.cpp
diff --git a/tests/PDFDocumentTest.cpp b/tests/PDFDocumentTest.cpp
index 04c3ede6aa4c595ae7ea6799c23e9d26b1f5d90a..0a693e7bd45ed3b231f0b42689a7314ef1652d5e 100644
--- a/tests/PDFDocumentTest.cpp
+++ b/tests/PDFDocumentTest.cpp
@@ -6,6 +6,7 @@
  */
 #include "Test.h"
 
+#include "Resources.h"
 #include "SkCanvas.h"
 #include "SkDocument.h"
 #include "SkOSFile.h"
@@ -110,3 +111,36 @@ DEF_TEST(document_tests, reporter) {
     test_file(reporter);
     test_close(reporter);
 }
+
+static SkData* encode_dct(const SkPixmap& pixmap) {
+    SkBitmap bm;
+    return bm.installPixels(pixmap.info(),
+                            const_cast<void*>(pixmap.addr()),
+                            pixmap.rowBytes(),
+                            pixmap.ctable(),
+                            nullptr, nullptr)
+            ? SkImageEncoder::EncodeData(bm, SkImageEncoder::kJPEG_Type, 85)

[dogben, 2015/12/07 20:34:17]

nit: Why not use the other override of EncodeData?

+            : nullptr;
+}
+
+size_t count_bytes(const SkBitmap& bm, bool useDCT) {
+    SkDynamicMemoryWStream stream;
+    SkAutoTUnref<SkDocument> doc(SkDocument::CreatePDF(&stream));
+    if (useDCT) {
+        doc->setDCTEncoder(&encode_dct);
+    }
+    SkCanvas* canvas = doc->beginPage(64, 64);
+    canvas->drawBitmap(bm, 0, 0);
+    doc->endPage();
+    doc->close();
+    return stream.bytesWritten();
+}
+
+DEF_TEST(document_dct_encoder, r) {
+    REQUIRE_PDF_DOCUMENT(document_dct_encoder, r);
+    SkBitmap bm;
+    if (GetResourceAsBitmap("mandrill_64.png", &bm)) {
+        // Lossy encoding works better on photographs.
+        REPORTER_ASSERT(r, count_bytes(bm, true) < count_bytes(bm, false));
+    }
+}