Do not save content stream if all page objects were removed from it.

Bug: pdfium:1051
Change-Id: Ia990a47eeceb47fd2b15fe4ea7226861507484db
Reviewed-on: https://pdfium-review.googlesource.com/35115
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>

1 files changed, 342 insertions, 2 deletions

diff --git a/fpdfsdk/fpdf_edit_embeddertest.cpp b/fpdfsdk/fpdf_edit_embeddertest.cpp
index c78700ea67..f2690499d1 100644
--- a/fpdfsdk/fpdf_edit_embeddertest.cpp
+++ b/fpdfsdk/fpdf_edit_embeddertest.cpp
@@ -748,8 +748,6 @@ TEST_F(FPDFEditEmbeddertest, RemoveExistingPageObjectSplitStreamsLonely) {
   CloseSavedDocument();
 }
 
-// TODO(pdfium:1051): Extend this test to remove some elements and verify
-// saving works.
 TEST_F(FPDFEditEmbeddertest, GetContentStream) {
   // Load document with some text split across streams.
   EXPECT_TRUE(OpenDocument("split_streams.pdf"));
@@ -776,6 +774,348 @@ TEST_F(FPDFEditEmbeddertest, GetContentStream) {
   UnloadPage(page);
 }
 
+TEST_F(FPDFEditEmbeddertest, RemoveAllFromStream) {
+  // Load document with some text split across streams.
+  EXPECT_TRUE(OpenDocument("split_streams.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Content stream 0: page objects 0-14.
+  // Content stream 1: page objects 15-17.
+  // Content stream 2: page object 18.
+  ASSERT_EQ(19, FPDFPage_CountObjects(page));
+
+  // Loop backwards because objects will being removed, which shifts the indexes
+  // after the removed position.
+  for (int i = 18; i >= 0; i--) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, i);
+    ASSERT_TRUE(page_object);
+    CPDF_PageObject* cpdf_page_object =
+        CPDFPageObjectFromFPDFPageObject(page_object);
+
+    // Empty content stream 1.
+    if (cpdf_page_object->GetContentStream() == 1) {
+      EXPECT_TRUE(FPDFPage_RemoveObject(page, page_object));
+      FPDFPageObj_Destroy(page_object);
+    }
+  }
+
+  // Content stream 0: page objects 0-14.
+  // Content stream 2: page object 15.
+  ASSERT_EQ(16, FPDFPage_CountObjects(page));
+  for (int i = 0; i < 16; i++) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, i);
+    ASSERT_TRUE(page_object);
+    CPDF_PageObject* cpdf_page_object =
+        CPDFPageObjectFromFPDFPageObject(page_object);
+    if (i < 15)
+      EXPECT_EQ(0, cpdf_page_object->GetContentStream()) << i;
+    else
+      EXPECT_EQ(2, cpdf_page_object->GetContentStream()) << i;
+  }
+
+  // Generate contents should remove the empty stream and update the page
+  // objects' contents stream indexes.
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+
+  // Content stream 0: page objects 0-14.
+  // Content stream 1: page object 15.
+  ASSERT_EQ(16, FPDFPage_CountObjects(page));
+  for (int i = 0; i < 16; i++) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, i);
+    ASSERT_TRUE(page_object);
+    CPDF_PageObject* cpdf_page_object =
+        CPDFPageObjectFromFPDFPageObject(page_object);
+    if (i < 15)
+      EXPECT_EQ(0, cpdf_page_object->GetContentStream()) << i;
+    else
+      EXPECT_EQ(1, cpdf_page_object->GetContentStream()) << i;
+  }
+
+#if _FX_PLATFORM_ == _FX_PLATFORM_APPLE_
+  const char kStream1RemovedMD5[] = "d2e21fbd5a6de563f619feeeb6163331";
+#elif _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
+  const char kStream1RemovedMD5[] = "b4140f203523e38793283a5943d8075b";
+#else
+  const char kStream1RemovedMD5[] = "e86a3efc160ede6cfcb1f59bcacf1105";
+#endif
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kStream1RemovedMD5);
+  }
+
+  // Save the file
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the page object count is still 16, and that
+  // content stream 1 was removed.
+  OpenSavedDocument();
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+
+  // Content stream 0: page objects 0-14.
+  // Content stream 1: page object 15.
+  EXPECT_EQ(16, FPDFPage_CountObjects(saved_page));
+  for (int i = 0; i < 16; i++) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(saved_page, i);
+    ASSERT_TRUE(page_object);
+    CPDF_PageObject* cpdf_page_object =
+        CPDFPageObjectFromFPDFPageObject(page_object);
+    if (i < 15)
+      EXPECT_EQ(0, cpdf_page_object->GetContentStream()) << i;
+    else
+      EXPECT_EQ(1, cpdf_page_object->GetContentStream()) << i;
+  }
+
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kStream1RemovedMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
+TEST_F(FPDFEditEmbeddertest, RemoveAllFromSingleStream) {
+  // Load document with a single stream.
+  EXPECT_TRUE(OpenDocument("hello_world.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Content stream 0: page objects 0-1.
+  ASSERT_EQ(2, FPDFPage_CountObjects(page));
+
+  // Loop backwards because objects will being removed, which shifts the indexes
+  // after the removed position.
+  for (int i = 1; i >= 0; i--) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, i);
+    ASSERT_TRUE(page_object);
+    CPDF_PageObject* cpdf_page_object =
+        CPDFPageObjectFromFPDFPageObject(page_object);
+    ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+    ASSERT_TRUE(FPDFPage_RemoveObject(page, page_object));
+    FPDFPageObj_Destroy(page_object);
+  }
+
+  // No more objects in the stream
+  ASSERT_EQ(0, FPDFPage_CountObjects(page));
+
+  // Generate contents should remove the empty stream and update the page
+  // objects' contents stream indexes.
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+
+  ASSERT_EQ(0, FPDFPage_CountObjects(page));
+
+  const char kAllRemovedMD5[] = "eee4600ac08b458ac7ac2320e225674c";
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kAllRemovedMD5);
+  }
+
+  // Save the file
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the page object count is still 0.
+  OpenSavedDocument();
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+
+  EXPECT_EQ(0, FPDFPage_CountObjects(saved_page));
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kAllRemovedMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
+TEST_F(FPDFEditEmbeddertest, RemoveFirstFromSingleStream) {
+  // Load document with a single stream.
+  EXPECT_TRUE(OpenDocument("hello_world.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Content stream 0: page objects 0-1.
+  ASSERT_EQ(2, FPDFPage_CountObjects(page));
+
+  // Remove first object.
+  FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, 0);
+  ASSERT_TRUE(page_object);
+  CPDF_PageObject* cpdf_page_object =
+      CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+  ASSERT_TRUE(FPDFPage_RemoveObject(page, page_object));
+  FPDFPageObj_Destroy(page_object);
+
+  // One object left in the stream.
+  ASSERT_EQ(1, FPDFPage_CountObjects(page));
+  page_object = FPDFPage_GetObject(page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+
+  // Still one object left in the stream.
+  ASSERT_EQ(1, FPDFPage_CountObjects(page));
+  page_object = FPDFPage_GetObject(page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+
+#if _FX_PLATFORM_ == _FX_PLATFORM_APPLE_
+  const char kFirstRemovedMD5[] = "af760c4702467cb1492a57fb8215efaa";
+#elif _FX_PLATFORM_ == _FX_PLATFORM_WINDOWS_
+  const char kFirstRemovedMD5[] = "72be917349bf7004a5c39661fe1fc433";
+#else
+  const char kFirstRemovedMD5[] = "b76df015fe88009c3c342395df96abf1";
+#endif
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kFirstRemovedMD5);
+  }
+
+  // Save the file
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the page object count is still 0.
+  OpenSavedDocument();
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+
+  ASSERT_EQ(1, FPDFPage_CountObjects(saved_page));
+  page_object = FPDFPage_GetObject(saved_page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kFirstRemovedMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
+TEST_F(FPDFEditEmbeddertest, RemoveLastFromSingleStream) {
+  // Load document with a single stream.
+  EXPECT_TRUE(OpenDocument("hello_world.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Content stream 0: page objects 0-1.
+  ASSERT_EQ(2, FPDFPage_CountObjects(page));
+
+  // Remove last object
+  FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, 1);
+  ASSERT_TRUE(page_object);
+  CPDF_PageObject* cpdf_page_object =
+      CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+  ASSERT_TRUE(FPDFPage_RemoveObject(page, page_object));
+  FPDFPageObj_Destroy(page_object);
+
+  // One object left in the stream.
+  ASSERT_EQ(1, FPDFPage_CountObjects(page));
+  page_object = FPDFPage_GetObject(page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+
+  // Still one object left in the stream.
+  ASSERT_EQ(1, FPDFPage_CountObjects(page));
+  page_object = FPDFPage_GetObject(page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+
+#if _FX_PLATFORM_ == _FX_PLATFORM_APPLE_
+  const char kLastRemovedMD5[] = "f8fbd14a048b9e2ea8e5f059f22a910e";
+#else
+  const char kLastRemovedMD5[] = "93dcc09055f87a2792c8e3065af99a1b";
+#endif
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kLastRemovedMD5);
+  }
+
+  // Save the file
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the page object count is still 0.
+  OpenSavedDocument();
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+
+  ASSERT_EQ(1, FPDFPage_CountObjects(saved_page));
+  page_object = FPDFPage_GetObject(saved_page, 0);
+  ASSERT_TRUE(page_object);
+  cpdf_page_object = CPDFPageObjectFromFPDFPageObject(page_object);
+  ASSERT_EQ(0, cpdf_page_object->GetContentStream());
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kLastRemovedMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
+TEST_F(FPDFEditEmbeddertest, RemoveAllFromMultipleStreams) {
+  // Load document with some text.
+  EXPECT_TRUE(OpenDocument("hello_world_split_streams.pdf"));
+  FPDF_PAGE page = LoadPage(0);
+  ASSERT_TRUE(page);
+
+  // Content stream 0: page objects 0-1.
+  // Content stream 1: page object 2.
+  ASSERT_EQ(3, FPDFPage_CountObjects(page));
+
+  // Loop backwards because objects will being removed, which shifts the indexes
+  // after the removed position.
+  for (int i = 2; i >= 0; i--) {
+    FPDF_PAGEOBJECT page_object = FPDFPage_GetObject(page, i);
+    ASSERT_TRUE(page_object);
+    ASSERT_TRUE(FPDFPage_RemoveObject(page, page_object));
+    FPDFPageObj_Destroy(page_object);
+  }
+
+  // No more objects in the page.
+  ASSERT_EQ(0, FPDFPage_CountObjects(page));
+
+  // Generate contents should remove the empty streams and update the page
+  // objects' contents stream indexes.
+  EXPECT_TRUE(FPDFPage_GenerateContent(page));
+
+  ASSERT_EQ(0, FPDFPage_CountObjects(page));
+
+  const char kAllRemovedMD5[] = "eee4600ac08b458ac7ac2320e225674c";
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kAllRemovedMD5);
+  }
+
+  // Save the file
+  EXPECT_TRUE(FPDF_SaveAsCopy(document(), this, 0));
+  UnloadPage(page);
+
+  // Re-open the file and check the page object count is still 0.
+  OpenSavedDocument();
+  FPDF_PAGE saved_page = LoadSavedPage(0);
+
+  EXPECT_EQ(0, FPDFPage_CountObjects(saved_page));
+  {
+    ScopedFPDFBitmap page_bitmap = RenderPageWithFlags(saved_page, nullptr, 0);
+    CompareBitmap(page_bitmap.get(), 200, 200, kAllRemovedMD5);
+  }
+
+  CloseSavedPage(saved_page);
+  CloseSavedDocument();
+}
+
 TEST_F(FPDFEditEmbeddertest, InsertPageObjectAndSave) {
   // Load document with some text.
   EXPECT_TRUE(OpenDocument("hello_world.pdf"));