SkPDF: clean up skpdfdocument, add static functions

Add SkPDFDocument::EmitPDF and SkPDFDocument::GetCountOfFontTypes

Also, make SkPDFDocument::appendPage return void, not bool.

Motivation: These static functions can be used to print subsets of a
pdf document (functionality to be added in a later CL).

BUG=skia:3585

Review URL: https://codereview.chromium.org/1036853002

2 files changed, 47 insertions, 27 deletions

diff --git a/src/pdf/SkPDFDocument.cpp b/src/pdf/SkPDFDocument.cpp
index 4009cef9b6..57eab950ed 100644
--- a/src/pdf/SkPDFDocument.cpp
+++ b/src/pdf/SkPDFDocument.cpp
@@ -39,10 +39,6 @@ static void perform_font_subsetting(SkPDFCatalog* catalog,
     }
 }
 
-SkPDFDocument::SkPDFDocument() {}
-
-SkPDFDocument::~SkPDFDocument() { fPageDevices.unrefAll(); }
-
 static void emit_pdf_header(SkWStream* stream) {
     stream->writeText("%PDF-1.4\n%");
     // The PDF spec recommends including a comment with four bytes, all
@@ -69,15 +65,16 @@ static void emit_pdf_footer(SkWStream* stream,
     stream->writeText("\n%%EOF");
 }
 
-bool SkPDFDocument::emitPDF(SkWStream* stream) {
-    // SkTDArray<SkPDFDevice*> fPageDevices;
-    if (fPageDevices.isEmpty()) {
+bool SkPDFDocument::EmitPDF(const SkTDArray<SkPDFDevice*>& pageDevices,
+                            SkWStream* stream) {
+    if (pageDevices.isEmpty()) {
         return false;
     }
     SkTDArray<SkPDFPage*> pages;
-    for (int i = 0; i < fPageDevices.count(); i++) {
+    for (int i = 0; i < pageDevices.count(); i++) {
+        SkASSERT(pageDevices[i]);
         // Reference from new passed to pages.
-        pages.push(SkNEW_ARGS(SkPDFPage, (fPageDevices[i])));
+        pages.push(SkNEW_ARGS(SkPDFPage, (pageDevices[i])));
     }
     SkPDFCatalog catalog;
 
@@ -194,19 +191,20 @@ bool SkPDFDocument::emitPDF(SkWStream* stream) {
 }
 
 // TODO(halcanary): expose notEmbeddableCount in SkDocument
-void SkPDFDocument::getCountOfFontTypes(
+void SkPDFDocument::GetCountOfFontTypes(
+        const SkTDArray<SkPDFDevice*>& pageDevices,
         int counts[SkAdvancedTypefaceMetrics::kOther_Font + 1],
         int* notSubsettableCount,
-        int* notEmbeddableCount) const {
+        int* notEmbeddableCount) {
     sk_bzero(counts, sizeof(int) *
                      (SkAdvancedTypefaceMetrics::kOther_Font + 1));
     SkTDArray<SkFontID> seenFonts;
     int notSubsettable = 0;
     int notEmbeddable = 0;
 
-    for (int pageNumber = 0; pageNumber < fPageDevices.count(); pageNumber++) {
+    for (int pageNumber = 0; pageNumber < pageDevices.count(); pageNumber++) {
         const SkTDArray<SkPDFFont*>& fontResources =
-                fPageDevices[pageNumber]->getFontResources();
+                pageDevices[pageNumber]->getFontResources();
         for (int font = 0; font < fontResources.count(); font++) {
             SkFontID fontID = fontResources[font]->typeface()->uniqueID();
             if (seenFonts.find(fontID) == -1) {
diff --git a/src/pdf/SkPDFDocument.h b/src/pdf/SkPDFDocument.h
index e4c0521cbe..fce9f9df83 100644
--- a/src/pdf/SkPDFDocument.h
+++ b/src/pdf/SkPDFDocument.h
@@ -29,34 +29,56 @@ template <typename T> class SkTSet;
 */
 class SkPDFDocument {
 public:
-    SkPDFDocument();
-    ~SkPDFDocument();
+    SkPDFDocument() {}
+    ~SkPDFDocument() { fPageDevices.unrefAll(); }
 
     /** Output the PDF to the passed stream.  It is an error to call this (it
-     *  will return false and not modify stream) if no pages have been added
-     *  or there are pages missing (i.e. page 1 and 3 have been added, but not
-     *  page 2).
+     *  will return false and not modify stream) if pageDevices is empty.
+     *  No device pointer can be NULL.
+     *
+     *  @param pageDevices An array of pages, in order.  All pages
+     *                     should be created using the same SkPDFCanon.
+     *                     TODO(halcanary): ASSERT this condition.
+     *  @param SkWStream   The writable output stream to send the PDF to.
+     */
+    static bool EmitPDF(const SkTDArray<SkPDFDevice*>& pageDevices, SkWStream*);
+
+    /** Output the PDF to the passed stream.  It is an error to call this (it
+     *  will return false and not modify stream) if no pages have been added.
      *
      *  @param stream    The writable output stream to send the PDF to.
      */
-    bool emitPDF(SkWStream* stream);
+    bool emitPDF(SkWStream* stream) const {
+        return SkPDFDocument::EmitPDF(fPageDevices, stream);
+    }
 
-    /** Append the passed pdf device to the document as a new page.  Returns
-     *  true if successful.  Will fail if the document has already been emitted.
+    /** Append the passed pdf device to the document as a new page.
      *
-     *  @param pdfDevice The page to add to this document.
+     *  @param pdfDevice The page to add to this document. All pages
+     *                   added to this document should be created
+     *                   using the same SkPDFCanon.
      */
-    bool appendPage(SkPDFDevice* pdfDevice) {
+    void appendPage(SkPDFDevice* pdfDevice) {
         fPageDevices.push(SkRef(pdfDevice));
-        return true;
     }
 
+    /** Get the count of unique font types used in the given pages.
+     */
+    static void GetCountOfFontTypes(
+            const SkTDArray<SkPDFDevice*>& pageDevices,
+            int counts[SkAdvancedTypefaceMetrics::kOther_Font + 1],
+            int* notSubsettableCount,
+            int* notEmbedddableCount);
+
     /** Get the count of unique font types used in the document.
      */
     void getCountOfFontTypes(
-        int counts[SkAdvancedTypefaceMetrics::kOther_Font + 1],
-        int* notSubsettableCount,
-        int* notEmbedddableCount) const;
+            int counts[SkAdvancedTypefaceMetrics::kOther_Font + 1],
+            int* notSubsettableCount,
+            int* notEmbedddableCount) const {
+        return SkPDFDocument::GetCountOfFontTypes(
+                fPageDevices, counts, notSubsettableCount, notEmbedddableCount);
+    }
 
 private:
     SkTDArray<SkPDFDevice*> fPageDevices;