add runtime option to provide data->imagegenerator factory

tests/ImageGeneratorTest.cpp

Index: tests/ImageGeneratorTest.cpp
diff --git a/tests/ImageGeneratorTest.cpp b/tests/ImageGeneratorTest.cpp
index 94867bc945f446be34abfdd1fdd2641b633bcdfd..c856d8be604d020dc54243693fb86443692a5777 100644
--- a/tests/ImageGeneratorTest.cpp
+++ b/tests/ImageGeneratorTest.cpp
@@ -5,9 +5,39 @@
  * found in the LICENSE file.
  */
 
+#include "SkData.h"
+#include "SkGraphics.h"
 #include "SkImageGenerator.h"
 #include "Test.h"
 
+static SkImageGenerator* my_factory(SkData* data) {
+    int* ptr = *(int**)data->data();
+    *ptr = 1;   // signal that we were called
+    return NULL;
+}
+
+static void test_imagegenerator_factory(skiatest::Reporter* reporter) {

[scroggo, 2015/07/09 19:01:15]

Why not make this its own test, with DEF_TEST?

[reed1, 2015/07/09 19:05:45]

Just style difference. When I see the output from running the tool, I'm ok with
fewer lines, so just "ImageGenerator" instead of N lines for N different ideas,
seems ok.

+    int factoryHasBeenCalled = 0;
+    int* sentinelPtr = &factoryHasBeenCalled;
+    SkData* data = SkData::NewWithCopy(&sentinelPtr, sizeof(sentinelPtr));
+
+    SkImageGenerator* gen;
+    REPORTER_ASSERT(reporter, 0 == *sentinelPtr);
+
+    gen = SkImageGenerator::NewFromEncoded(data);
+    REPORTER_ASSERT(reporter, NULL == gen);
+    REPORTER_ASSERT(reporter, 0 == *sentinelPtr);
+
+    // Test is racy, in that it hopes no other thread is changing this global...
+    SkGraphics::ImageGeneratorFromEncodedFactory prev =
+                                                SkGraphics::GetImageGeneratorFromEncodedFactory();
+    SkGraphics::SetImageGeneratorFromEncodedFactory(my_factory);
+    gen = SkImageGenerator::NewFromEncoded(data);
+    REPORTER_ASSERT(reporter, NULL == gen);
+    REPORTER_ASSERT(reporter, 1 == *sentinelPtr);
+    SkGraphics::SetImageGeneratorFromEncodedFactory(prev);
+}
+
 class MyImageGenerator : public SkImageGenerator {
 public:
     MyImageGenerator() : SkImageGenerator(SkImageInfo::MakeN32Premul(0, 0)) {}
@@ -36,4 +66,6 @@ DEF_TEST(ImageGenerator, reporter) {
     rowBytes[0] = rowBytes[1] = rowBytes[2] = 250;
 
     ig.getYUV8Planes(sizes, planes, rowBytes, &colorSpace);
+
+    test_imagegenerator_factory(reporter);
 }