Add tools/flatten to flatten nested pictures in .skps.

tools/flatten.cpp

+/*
+ * Copyright 2015 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkData.h"
+#include "SkForceLinking.h"
+#include "SkImageGenerator.h"
+#include "SkPicture.h"
+#include "SkPictureRecorder.h"
+#include "SkStream.h"
+#include <stdio.h>
+
+__SK_FORCE_IMAGE_DECODER_LINKING;
+
+#define ASSERTF(cond, fmt, ...) if (!(cond)) { fprintf(stderr, fmt"\n", __VA_ARGS__); exit(1); }
+
+static bool lazy_decode_bitmap(const void* src, size_t size, SkBitmap* dst) {
+    SkAutoTUnref<SkData> encoded(SkData::NewWithCopy(src, size));
+    return encoded && SkInstallDiscardablePixelRef(encoded, dst);
+}
+
+int main(int argc, char** argv) {
+    ASSERTF(argc == 3, "usage: %s nested.skp flat.skp", argv[0]);
+    const char *nestedPath = argv[1],
+               *flatPath   = argv[2];
+
+    // Read nested.skp.
+    SkFILEStream stream(nestedPath);
+    ASSERTF(stream.isValid(), "Couldn't read %s.", nestedPath);
+    SkAutoTUnref<const SkPicture> nested(SkPicture::CreateFromStream(&stream, &lazy_decode_bitmap));
+    ASSERTF(nested, "Couldn't parse %s as a picture.", nestedPath);
+
+    // Play it back into a new picture using kPlaybackDrawPicture_RecordFlag.
+    SkPictureRecorder recorder;
+    uint32_t flags = SkPictureRecorder::kPlaybackDrawPicture_RecordFlag;
+    nested->playback(recorder.beginRecording(nested->cullRect(), nullptr, flags));
+    SkAutoTUnref<const SkPicture> flat(recorder.endRecordingAsPicture());
+
+    // Write out that flat.skp
+    SkFILEWStream wstream(flatPath);
+    ASSERTF(wstream.isValid(), "Could not open %s.", flatPath);
+    flat->serialize(&wstream);
+    wstream.flush();
+
+    return 0;
+}