Rewrite content stream regeneration.

Loop through the dirty page objects and streams and regenerate all
streams that are dirty.

Bug: pdfium:1051
Change-Id: I837b5a7cd9542b7777e7c7ae7ac9cc75f69f30b5
Reviewed-on: https://pdfium-review.googlesource.com/34330
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>

3 files changed, 82 insertions, 33 deletions

diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
index 19994fa57f..ba8d03d7f9 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator.cpp
@@ -6,6 +6,9 @@
 
 #include "core/fpdfapi/edit/cpdf_pagecontentgenerator.h"
 
+#include <map>
+#include <memory>
+#include <set>
 #include <tuple>
 #include <utility>
 
@@ -73,33 +76,67 @@ void CPDF_PageContentGenerator::GenerateContent() {
 
 std::map<int32_t, std::unique_ptr<std::ostringstream>>
 CPDF_PageContentGenerator::GenerateModifiedStreams() {
-  auto buf = pdfium::MakeUnique<std::ostringstream>();
+  // Make sure default graphics are created.
+  (void)GetOrCreateDefaultGraphics();
 
+  // Figure out which streams are dirty.
+  std::set<int32_t> all_dirty_streams;
+  for (auto& pPageObj : m_pageObjects) {
+    if (pPageObj->IsDirty())
+      all_dirty_streams.insert(pPageObj->GetContentStream());
+  }
+  const std::set<int32_t>* marked_dirty_streams =
+      m_pObjHolder->GetDirtyStreams();
+  all_dirty_streams.insert(marked_dirty_streams->begin(),
+                           marked_dirty_streams->end());
+
+  // Start regenerating dirty streams.
   std::map<int32_t, std::unique_ptr<std::ostringstream>> streams;
-  if (GenerateStreamWithNewObjects(buf.get()))
-    streams[CPDF_PageObject::kNoContentStream] = std::move(buf);
+  std::map<int32_t, bool> stream_is_empty;
 
-  // TODO(pdfium:1051): Generate other streams and add to |streams|.
+  for (int32_t dirty_stream : all_dirty_streams) {
+    std::unique_ptr<std::ostringstream> buf =
+        pdfium::MakeUnique<std::ostringstream>();
 
-  return streams;
-}
+    // Set the default graphic state values
+    *buf << "q\n";
+    if (!m_pObjHolder->GetLastCTM().IsIdentity())
+      *buf << m_pObjHolder->GetLastCTM().GetInverse() << " cm\n";
 
-bool CPDF_PageContentGenerator::GenerateStreamWithNewObjects(
-    std::ostringstream* buf) {
-  // Set the default graphic state values
-  *buf << "q\n";
-  if (!m_pObjHolder->GetLastCTM().IsIdentity())
-    *buf << m_pObjHolder->GetLastCTM().GetInverse() << " cm\n";
-  ProcessDefaultGraphics(buf);
-
-  // Process the page objects
-  if (!ProcessPageObjects(buf))
-    return false;
+    ProcessDefaultGraphics(buf.get());
 
-  // Return graphics to original state
-  *buf << "Q\n";
+    streams[dirty_stream] = std::move(buf);
+    stream_is_empty[dirty_stream] = true;
+  }
 
-  return true;
+  // Process the page objects, write into each dirty stream.
+  for (auto& pPageObj : m_pageObjects) {
+    int stream_index = pPageObj->GetContentStream();
+    auto it = streams.find(stream_index);
+    if (it == streams.end())
+      continue;
+
+    std::ostringstream* buf = it->second.get();
+    stream_is_empty[stream_index] = false;
+    ProcessPageObject(buf, pPageObj.Get());
+  }
+
+  // Finish dirty streams.
+  for (int32_t dirty_stream : all_dirty_streams) {
+    std::ostringstream* buf = streams[dirty_stream].get();
+    if (stream_is_empty[dirty_stream]) {
+      // Clear to show that this stream needs to be deleted.
+      buf->str("");
+    } else {
+      // Return graphics to original state
+      *buf << "Q\n";
+    }
+  }
+
+  // Clear dirty streams in m_pObjHolder
+  m_pObjHolder->ClearDirtyStreams();
+
+  return streams;
 }
 
 void CPDF_PageContentGenerator::UpdateContentStreams(
@@ -124,6 +161,9 @@ void CPDF_PageContentGenerator::UpdateContentStreams(
         page_content_manager.GetStreamByIndex(stream_index);
     ASSERT(old_stream);
 
+    // TODO(pdfium:1051): Remove streams that are now empty. If buf is empty,
+    // remove this instead of setting the data.
+
     old_stream->SetData(buf);
   }
 }
@@ -162,21 +202,28 @@ bool CPDF_PageContentGenerator::ProcessPageObjects(std::ostringstream* buf) {
       continue;
 
     bDirty = true;
-    if (CPDF_ImageObject* pImageObject = pPageObj->AsImage())
-      ProcessImage(buf, pImageObject);
-    else if (CPDF_PathObject* pPathObj = pPageObj->AsPath())
-      ProcessPath(buf, pPathObj);
-    else if (CPDF_TextObject* pTextObj = pPageObj->AsText())
-      ProcessText(buf, pTextObj);
-    pPageObj->SetDirty(false);
+    ProcessPageObject(buf, pPageObj.Get());
   }
   return bDirty;
 }
 
 void CPDF_PageContentGenerator::UpdateStreamlessPageObjects(
     int new_content_stream_index) {
-  // TODO(pdfium:1051): Mark page objects that did not have a content stream
-  // with the new content stream index.
+  for (auto& pPageObj : m_pageObjects) {
+    if (pPageObj->GetContentStream() == CPDF_PageObject::kNoContentStream)
+      pPageObj->SetContentStream(new_content_stream_index);
+  }
+}
+
+void CPDF_PageContentGenerator::ProcessPageObject(std::ostringstream* buf,
+                                                  CPDF_PageObject* pPageObj) {
+  if (CPDF_ImageObject* pImageObject = pPageObj->AsImage())
+    ProcessImage(buf, pImageObject);
+  else if (CPDF_PathObject* pPathObj = pPageObj->AsPath())
+    ProcessPath(buf, pPathObj);
+  else if (CPDF_TextObject* pTextObj = pPageObj->AsText())
+    ProcessText(buf, pTextObj);
+  pPageObj->SetDirty(false);
 }
 
 void CPDF_PageContentGenerator::ProcessImage(std::ostringstream* buf,
diff --git a/core/fpdfapi/edit/cpdf_pagecontentgenerator.h b/core/fpdfapi/edit/cpdf_pagecontentgenerator.h
index 04adf1c1d2..13b8431f18 100644
--- a/core/fpdfapi/edit/cpdf_pagecontentgenerator.h
+++ b/core/fpdfapi/edit/cpdf_pagecontentgenerator.h
@@ -35,6 +35,7 @@ class CPDF_PageContentGenerator {
  private:
   friend class CPDF_PageContentGeneratorTest;
 
+  void ProcessPageObject(std::ostringstream* buf, CPDF_PageObject* pPageObj);
   void ProcessPath(std::ostringstream* buf, CPDF_PathObject* pPathObj);
   void ProcessImage(std::ostringstream* buf, CPDF_ImageObject* pImageObj);
   void ProcessGraphics(std::ostringstream* buf, CPDF_PageObject* pPageObj);
@@ -49,9 +50,6 @@ class CPDF_PageContentGenerator {
   std::map<int32_t, std::unique_ptr<std::ostringstream>>
   GenerateModifiedStreams();
 
-  // Generate new stream data with all dirty page objects.
-  bool GenerateStreamWithNewObjects(std::ostringstream* buf);
-
   // Add buffer as a stream in page's 'Contents'
   void UpdateContentStreams(
       std::map<int32_t, std::unique_ptr<std::ostringstream>>* buf);
diff --git a/core/fpdfapi/page/cpdf_pageobject.h b/core/fpdfapi/page/cpdf_pageobject.h
index 39e7629541..3fc35aa063 100644
--- a/core/fpdfapi/page/cpdf_pageobject.h
+++ b/core/fpdfapi/page/cpdf_pageobject.h
@@ -65,10 +65,14 @@ class CPDF_PageObject : public CPDF_GraphicStates {
   // Get what content stream the object was parsed from in its page. This number
   // is the index of the content stream in the "Contents" array, or 0 if there
   // is a single content stream. If the object is newly created,
-  // kNoContentStream is returned.
+  // |kNoContentStream| is returned.
+  //
   // If the object is spread among more than one content stream, this is the
   // index of the last stream.
   int32_t GetContentStream() const { return m_ContentStream; }
+  void SetContentStream(int32_t new_content_stream) {
+    m_ContentStream = new_content_stream;
+  }
 
   float m_Left;
   float m_Right;