Encode images with DCTDecode (JPEG) in PDFs if it makes sense. Fallback to FlateDecode (zip) if it makes sense. Otherewise include uncompressed stream.

This change will reduce the size of PDFs to 50% (in the case of the existing SKPs, we reduce the total size of PDFs from 105MB to 50MB) 
Review URL: https://codereview.appspot.com/7068055

git-svn-id: http://skia.googlecode.com/svn/trunk@8835 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 120 insertions, 1 deletions

diff --git a/tests/PDFPrimitivesTest.cpp b/tests/PDFPrimitivesTest.cpp
index 3b54d1772d..cf929b4488 100644
--- a/tests/PDFPrimitivesTest.cpp
+++ b/tests/PDFPrimitivesTest.cpp
@@ -6,11 +6,13 @@
  * found in the LICENSE file.
  */
 
-
 #include "Test.h"
+#include "SkBitmap.h"
 #include "SkCanvas.h"
 #include "SkData.h"
 #include "SkFlate.h"
+#include "SkImageEncoder.h"
+#include "SkMatrix.h"
 #include "SkPDFCatalog.h"
 #include "SkPDFDevice.h"
 #include "SkPDFStream.h"
@@ -37,6 +39,11 @@ private:
     SkTDArray<SkPDFObject*> fResources;
 };
 
+static bool encode_to_dct_stream(SkWStream* stream, const SkBitmap& bitmap, const SkIRect& rect) {
+    stream->writeText("DCT compessed stream.");
+    return true;
+}
+
 static bool stream_equals(const SkDynamicMemoryWStream& stream, size_t offset,
                           const void* buffer, size_t len) {
     SkAutoDataUnref data(stream.copyToData());
@@ -46,6 +53,20 @@ static bool stream_equals(const SkDynamicMemoryWStream& stream, size_t offset,
     return memcmp(data->bytes() + offset, buffer, len) == 0;
 }
 
+static bool stream_contains(const SkDynamicMemoryWStream& stream,
+                            const char* buffer) {
+    SkAutoDataUnref data(stream.copyToData());
+    int len = strlen(buffer);  // our buffer does not have EOSs.
+
+    for (int offset = 0 ; offset < (int)data->size() - len; offset++) {
+        if (memcmp(data->bytes() + offset, buffer, len) == 0) {
+            return true;
+        }
+    }
+
+    return false;
+}
+
 static void CheckObjectOutput(skiatest::Reporter* reporter, SkPDFObject* obj,
                               const char* expectedData, size_t expectedSize,
                               bool indirect, bool compression) {
@@ -219,6 +240,102 @@ static void TestSubstitute(skiatest::Reporter* reporter) {
                                             buffer.getOffset()));
 }
 
+// Create a bitmap that would be easier to be compressed in a JPEG than ZIP.
+static void setup_jpegBitmap(SkBitmap* bitmap, int width, int height) {
+    bitmap->setConfig(SkBitmap::kARGB_8888_Config, width, height);
+    bitmap->allocPixels();
+    for (int y = 0;  y < bitmap->height(); y++) {
+        for (int x = 0; x < bitmap->width(); x++) {
+            *bitmap->getAddr32(x, y) =
+                SkColorSetRGB(0 + y % 20 + 128 + 100 * cos(x * 0.01F),
+                              1 + y % 20 + 128 + 100 * cos(x * 0.1F),
+                              2 + y % 20 + 128 + 100 * cos(x * 1.0F));
+        }
+    }
+}
+
+// Create a bitmap that would be very eficiently compressed in a ZIP.
+static void setup_solidBitmap(SkBitmap* bitmap, int width, int height) {
+    bitmap->setConfig(SkBitmap::kARGB_8888_Config, width, height);
+    bitmap->allocPixels();
+    bitmap->eraseColor(SK_ColorWHITE);
+}
+
+static void TestImage(skiatest::Reporter* reporter, const SkBitmap& bitmap,
+                      const char* expected, bool useDCTEncoder) {
+    SkISize pageSize = SkISize::Make(bitmap.width(), bitmap.height());
+    SkPDFDevice* dev = new SkPDFDevice(pageSize, pageSize, SkMatrix::I());
+
+    if (useDCTEncoder) {
+        dev->setDCTEncoder(encode_to_dct_stream);
+    }
+
+    SkCanvas c(dev);
+    c.drawBitmap(bitmap, 0, 0, NULL);
+
+    SkPDFDocument doc;
+    doc.appendPage(dev);
+
+    SkDynamicMemoryWStream stream;
+    doc.emitPDF(&stream);
+
+    REPORTER_ASSERT(reporter, stream_contains(stream, expected));
+}
+
+static void TestUncompressed(skiatest::Reporter* reporter) {
+    SkBitmap bitmap;
+    setup_solidBitmap(&bitmap, 1, 1);
+    TestImage(reporter, bitmap,
+              "/Subtype /Image\n"
+              "/Width 1\n"
+              "/Height 1\n"
+              "/ColorSpace /DeviceRGB\n"
+              "/BitsPerComponent 8\n"
+              "/Length 3\n"
+              ">> stream",
+              true);
+}
+
+static void TestFlateDecode(skiatest::Reporter* reporter) {
+    if (!SkFlate::HaveFlate()) {
+        return;
+    }
+    SkBitmap bitmap;   
+    setup_solidBitmap(&bitmap, 10, 10);
+    TestImage(reporter, bitmap,
+              "/Subtype /Image\n"
+              "/Width 10\n"
+              "/Height 10\n"
+              "/ColorSpace /DeviceRGB\n"
+              "/BitsPerComponent 8\n"
+              "/Filter /FlateDecode\n"
+              "/Length 13\n"
+              ">> stream",
+              false);
+}
+
+static void TestDCTDecode(skiatest::Reporter* reporter) {
+    SkBitmap bitmap;
+    setup_jpegBitmap(&bitmap, 32, 32);
+    TestImage(reporter, bitmap,
+              "/Subtype /Image\n"
+              "/Width 32\n"
+              "/Height 32\n"
+              "/ColorSpace /DeviceRGB\n"
+              "/BitsPerComponent 8\n"
+              "/Filter /DCTDecode\n"
+              "/ColorTransform 0\n"
+              "/Length 21\n"
+              ">> stream",
+              true);
+}
+
+static void TestImages(skiatest::Reporter* reporter) {
+    TestUncompressed(reporter);
+    TestFlateDecode(reporter);
+    TestDCTDecode(reporter);
+}
+
 // This test used to assert without the fix submitted for
 // http://code.google.com/p/skia/issues/detail?id=1083.
 // SKP files might have invalid glyph ids. This test ensures they are ignored,
@@ -324,6 +441,8 @@ static void TestPDFPrimitives(skiatest::Reporter* reporter) {
     TestSubstitute(reporter);
 
     test_issue1083();
+
+    TestImages(reporter);    
 }
 
 #include "TestClassDef.h"