SkMultiPictureDocument & SkMultiPictureDocumentReader

src/utils/SkMultiPictureDocumentReader.cpp

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkMultiPictureDocumentPriv.h"
+#include "SkMultiPictureDocumentReader.h"
+#include "SkPicture.h"
+#include "SkStream.h"
+
+bool SkMultiPictureDocumentReader::init(SkStreamSeekable* stream) {
+    if (!stream) {
+        return false;
+    }
+    stream->seek(0);
+    const size_t size = sizeof(SkMultiPictureDocumentProtocol::kMagic) - 1;
+    char buffer[size];
+    if (size != stream->read(buffer, size) ||
+        0 != memcmp(SkMultiPictureDocumentProtocol::kMagic, buffer, size)) {
+        stream = nullptr;
+        return false;
+    }
+    bool good = true;
+    uint32_t versionNumber = stream->readU32();
+    if (versionNumber != 1) {
+        return false;
+    }
+    uint32_t pageCount = stream->readU32();
+    fSizes.reset(pageCount);
+    fOffsets.reset(pageCount);
+    for (uint32_t i = 0; i < pageCount; ++i) {
+        SkMultiPictureDocumentProtocol::Entry entry;
+        good &= sizeof(entry) == stream->read(&entry, sizeof(entry));
+        fSizes[i] = SkSize::Make(entry.sizeX, entry.sizeY);
+        good &= SkTFitsIn<size_t>(entry.offset);
+        fOffsets[i] = static_cast<size_t>(entry.offset);
+    }
+    return good;
+}
+
+sk_sp<SkPicture> SkMultiPictureDocumentReader::readPage(SkStreamSeekable* stream,
+                                                        int pageNumber) const {
+    SkASSERT(pageNumber >= 0);
+    SkASSERT(pageNumber < fOffsets.count());
+    SkAssertResult(stream->seek(fOffsets[pageNumber]));
+    return SkPicture::MakeFromStream(stream);
+}