High level pdf classes and pdf specific interface.

The guts of the implementation will be in SkPDFDevice and below.  This is a first implementation of everything above that point.

Review URL: http://codereview.appspot.com/2342043

git-svn-id: http://skia.googlecode.com/svn/trunk@602 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/include/pdf/SkPDFPage.h b/include/pdf/SkPDFPage.h
new file mode 100644
index 0000000..7e96212
--- /dev/null
+++ b/include/pdf/SkPDFPage.h
@@ -0,0 +1,98 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef SkPDFPage_DEFINED
+#define SkPDFPage_DEFINED
+
+#include "SkPDFTypes.h"
+#include "SkPDFStream.h"
+#include "SkRefCnt.h"
+#include "SkTDArray.h"
+
+class SkPDFCatalog;
+class SkPDFDevice;
+class SkWStream;
+
+/** \class SkPDFPage
+
+    A SkPDFPage contains meta information about a page, is used in the page
+    tree and points to the content of the page.
+*/
+class SkPDFPage : public SkPDFDict {
+public:
+    /** Create a PDF page with the passed PDF device.  The device need not
+     *  have content on it yet.
+     *  @param content    The page content.
+     */
+    explicit SkPDFPage(const SkRefPtr<SkPDFDevice>& content);
+    ~SkPDFPage();
+
+    /** Before a page and its contents can be sized and emitted, it must
+     *  be finalized.  No changes to the PDFDevice will be honored after
+     *  finalizePage has been called.  This function adds the page content
+     *  to the passed catalog, so it must be called for each document
+     *  that the page is part of.
+     *  @param catalog        The catalog to add page content objects to.
+     *  @param firstPage      Indicate if this is the first page of a document.
+     *  @param resouceObjects The resource objects used on the page are added
+     *                        to this array.  This gives the caller a chance
+     *                        to deduplicate resources across pages.
+     */
+    void finalizePage(SkPDFCatalog* catalog, bool firstPage,
+                      SkTDArray<SkPDFObject*>* resourceObjects);
+
+    /** Determine the size of the page content and store to the catalog
+     *  the offsets of all nonresource-indirect objects that make up the page
+     *  content.  This must be called before emitPage(), but after finalizePage.
+     *  @param catalog    The catalog to add the object offsets to.
+     *  @param fileOffset The file offset where the page content will be
+     *                    emitted.
+     */
+    off_t getPageSize(SkPDFCatalog* catalog, off_t fileOffset);
+
+    /** Output the page content to the passed stream.
+     *  @param stream     The writable output stream to send the content to.
+     *  @param catalog    The active object catalog.
+     */
+    void emitPage(SkWStream* stream, SkPDFCatalog* catalog);
+
+    /** Generate a page tree for the passed vector of pages.  New objects are
+     *  added to the catalog.  The pageTree vector is populated with all of
+     *  the 'Pages' dictionaries as well as the 'Page' objects.  Page trees
+     *  have both parent and children links, creating reference cycles, so
+     *  it must be torn down explicitly.  The first page is not added to
+     *  the pageTree dictionary array so the caller can handle it specially.
+     *  @param pages      The ordered vector of page objects.
+     *  @param catalog    The catalog to add new objects into.
+     *  @param pageTree   An output vector with all of the internal and leaf
+     *                    nodes of the pageTree.
+     *  @param rootNode   An output parameter set to the root node.
+     */
+    static void generatePageTree(const SkTDArray<SkPDFPage*>& pages,
+                                 SkPDFCatalog* catalog,
+                                 SkTDArray<SkPDFDict*>* pageTree,
+                                 SkPDFDict** rootNode);
+
+private:
+    // Multiple pages may reference the content.
+    SkRefPtr<SkPDFDevice> fDevice;
+
+    SkString fContent;
+    // Once the content is finalized, put it into a stream for output.
+    SkRefPtr<SkPDFStream> fContentStream;
+};
+
+#endif