Added API for removing objects from annotations

Bug=pdfium:737

Change-Id: Ia485219b9288b9fe7e1ae226035b37dde2bc3abd
Reviewed-on: https://pdfium-review.googlesource.com/7213
Commit-Queue: Jane Liu <janeliulwq@google.com>
Commit-Queue: dsinclair <dsinclair@chromium.org>
Reviewed-by: dsinclair <dsinclair@chromium.org>
Reviewed-by: Lei Zhang <thestig@chromium.org>

4 files changed, 135 insertions, 55 deletions

diff --git a/fpdfsdk/fpdfannot.cpp b/fpdfsdk/fpdfannot.cpp
index b8043b0a66..faa4f4c8fb 100644
--- a/fpdfsdk/fpdfannot.cpp
+++ b/fpdfsdk/fpdfannot.cpp
@@ -176,6 +176,15 @@ CFX_ByteString CFXByteStringFromFPDFWideString(FPDF_WIDESTRING text) {
   return CFX_WideString::FromUTF16LE(text, CFX_WideString::WStringLength(text))
       .UTF8Encode();
 }
+void UpdateContentStream(CPDF_Form* pForm, CPDF_Stream* pStream) {
+  ASSERT(pForm);
+  ASSERT(pStream);
+
+  CPDF_PageContentGenerator generator(pForm);
+  std::ostringstream buf;
+  generator.ProcessPageObjects(&buf);
+  pStream->SetData(&buf);
+}
 
 }  // namespace
 
@@ -266,6 +275,12 @@ FPDFAnnot_GetSubtype(FPDF_ANNOTATION annot) {
       CPDF_Annot::StringToAnnotSubtype(pAnnotDict->GetStringFor("Subtype")));
 }
 
+DLLEXPORT FPDF_BOOL STDCALL
+FPDFAnnot_IsObjectSupportedSubtype(FPDF_ANNOTATION_SUBTYPE subtype) {
+  // The supported subtypes must also be communicated in the user doc.
+  return subtype == FPDF_ANNOT_INK || subtype == FPDF_ANNOT_STAMP;
+}
+
 DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_UpdateObject(FPDF_ANNOTATION annot,
                                                    FPDF_PAGEOBJECT obj) {
   CPDF_AnnotContext* pAnnot = CPDFAnnotContextFromFPDFAnnotation(annot);
@@ -274,8 +289,7 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_UpdateObject(FPDF_ANNOTATION annot,
     return false;
 
   // Check that the annotation type is supported by this method.
-  FPDF_ANNOTATION_SUBTYPE subtype = FPDFAnnot_GetSubtype(annot);
-  if (subtype != FPDF_ANNOT_INK && subtype != FPDF_ANNOT_STAMP)
+  if (!FPDFAnnot_IsObjectSupportedSubtype(FPDFAnnot_GetSubtype(annot)))
     return false;
 
   // Check that the annotation already has an appearance stream, since an
@@ -286,7 +300,8 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_UpdateObject(FPDF_ANNOTATION annot,
     return false;
 
   // Check that the object is already in this annotation's object list.
-  CPDF_PageObjectList* pObjList = pAnnot->GetForm()->GetPageObjectList();
+  CPDF_Form* pForm = pAnnot->GetForm();
+  CPDF_PageObjectList* pObjList = pForm->GetPageObjectList();
   auto it =
       std::find_if(pObjList->begin(), pObjList->end(),
                    [pObj](const std::unique_ptr<CPDF_PageObject>& candidate) {
@@ -296,11 +311,7 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_UpdateObject(FPDF_ANNOTATION annot,
     return false;
 
   // Update the content stream data in the annotation's AP stream.
-  CPDF_PageContentGenerator generator(pAnnot->GetForm());
-  std::ostringstream buf;
-  generator.ProcessPageObjects(&buf);
-  pStream->SetData(reinterpret_cast<const uint8_t*>(buf.str().c_str()),
-                   buf.tellp());
+  UpdateContentStream(pForm, pStream);
   return true;
 }
 
@@ -317,8 +328,7 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_AppendObject(FPDF_ANNOTATION annot,
     return false;
 
   // Check that the annotation type is supported by this method.
-  FPDF_ANNOTATION_SUBTYPE subtype = FPDFAnnot_GetSubtype(annot);
-  if (subtype != FPDF_ANNOT_INK && subtype != FPDF_ANNOT_STAMP)
+  if (!FPDFAnnot_IsObjectSupportedSubtype(FPDFAnnot_GetSubtype(annot)))
     return false;
 
   // If the annotation does not have an AP stream yet, generate and set it.
@@ -343,13 +353,12 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_AppendObject(FPDF_ANNOTATION annot,
   if (!pAnnot->HasForm())
     pAnnot->SetForm(pStream);
 
-  CPDF_Form* pForm = pAnnot->GetForm();
-
   // Check that the object did not come from the same annotation. If this check
   // succeeds, then it is assumed that the object came from
   // FPDFPageObj_CreateNew{Path|Rect}() or FPDFPageObj_New{Text|Image}Obj().
   // Note that an object that came from a different annotation must not be
   // passed here, since an object cannot belong to more than one annotation.
+  CPDF_Form* pForm = pAnnot->GetForm();
   CPDF_PageObjectList* pObjList = pForm->GetPageObjectList();
   auto it =
       std::find_if(pObjList->begin(), pObjList->end(),
@@ -364,11 +373,7 @@ DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_AppendObject(FPDF_ANNOTATION annot,
   pObjList->push_back(std::move(pPageObjHolder));
 
   // Set the content stream data in the annotation's AP stream.
-  CPDF_PageContentGenerator generator(pForm);
-  std::ostringstream buf;
-  generator.ProcessPageObjects(&buf);
-  pStream->SetData(reinterpret_cast<const uint8_t*>(buf.str().c_str()),
-                   buf.tellp());
+  UpdateContentStream(pForm, pStream);
   return true;
 }
 
@@ -406,6 +411,32 @@ DLLEXPORT FPDF_PAGEOBJECT STDCALL FPDFAnnot_GetObject(FPDF_ANNOTATION annot,
   return pAnnot->GetForm()->GetPageObjectList()->GetPageObjectByIndex(index);
 }
 
+DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_RemoveObject(FPDF_ANNOTATION annot,
+                                                   int index) {
+  CPDF_AnnotContext* pAnnot = CPDFAnnotContextFromFPDFAnnotation(annot);
+  if (!pAnnot || !pAnnot->GetAnnotDict() || !pAnnot->HasForm() || index < 0)
+    return false;
+
+  // Check that the annotation type is supported by this method.
+  if (!FPDFAnnot_IsObjectSupportedSubtype(FPDFAnnot_GetSubtype(annot)))
+    return false;
+
+  // Check that the annotation already has an appearance stream, since an
+  // existing object is to be deleted.
+  CPDF_Stream* pStream = FPDFDOC_GetAnnotAP(pAnnot->GetAnnotDict(),
+                                            CPDF_Annot::AppearanceMode::Normal);
+  if (!pStream)
+    return false;
+
+  CPDF_PageObjectList* pObjList = pAnnot->GetForm()->GetPageObjectList();
+  if (static_cast<size_t>(index) >= pObjList->size())
+    return false;
+
+  pObjList->erase(pObjList->begin() + index);
+  UpdateContentStream(pAnnot->GetForm(), pStream);
+  return true;
+}
+
 DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_SetColor(FPDF_ANNOTATION annot,
                                                FPDFANNOT_COLORTYPE type,
                                                unsigned int R,
diff --git a/fpdfsdk/fpdfannot_embeddertest.cpp b/fpdfsdk/fpdfannot_embeddertest.cpp
index c2bd82ae72..c042b764a2 100644
--- a/fpdfsdk/fpdfannot_embeddertest.cpp
+++ b/fpdfsdk/fpdfannot_embeddertest.cpp
@@ -468,17 +468,20 @@ TEST_F(FPDFAnnotEmbeddertest, RemoveAnnotation) {
 
 TEST_F(FPDFAnnotEmbeddertest, AddAndModifyPath) {
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
-  const char md5[] = "c35408717759562d1f8bf33d317483d2";
-  const char md5_2[] = "cf3cea74bd46497520ff6c4d1ea228c8";
-  const char md5_3[] = "ee5372b31fede117fc83b9384598aa25";
+  const char md5_original[] = "c35408717759562d1f8bf33d317483d2";
+  const char md5_modified_path[] = "cf3cea74bd46497520ff6c4d1ea228c8";
+  const char md5_two_paths[] = "e8994452fc4385337bae5522354e10ff";
+  const char md5_new_annot[] = "ee5372b31fede117fc83b9384598aa25";
 #elif _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
-  const char md5[] = "4f64add0190ede63f7bb9eb1e2e83edb";
-  const char md5_2[] = "681f0d0738dded0722e146f6c219bfac";
-  const char md5_3[] = "262187984451bae2fe826067d68623ff";
+  const char md5_original[] = "4f64add0190ede63f7bb9eb1e2e83edb";
+  const char md5_modified_path[] = "681f0d0738dded0722e146f6c219bfac";
+  const char md5_two_paths[] = "67c7e90fc3b64e20f6b69a1744f7f4f0";
+  const char md5_new_annot[] = "262187984451bae2fe826067d68623ff";
 #else
-  const char md5[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
-  const char md5_2[] = "87a78cbacd8509b961a67be56b5665a2";
-  const char md5_3[] = "c95de7a9a1f61faca03d953961a319b9";
+  const char md5_original[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
+  const char md5_modified_path[] = "87a78cbacd8509b961a67be56b5665a2";
+  const char md5_two_paths[] = "76e985c18b73ceacf409f77f978176d4";
+  const char md5_new_annot[] = "c95de7a9a1f61faca03d953961a319b9";
 #endif
 
   // Open a file with two annotations and load its first page.
@@ -489,7 +492,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyPath) {
 
   // Check that the page renders correctly.
   FPDF_BITMAP bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5);
+  CompareBitmap(bitmap, 595, 842, md5_original);
   FPDFBitmap_Destroy(bitmap);
 
   // Retrieve the stamp annotation which has its AP stream already defined.
@@ -507,11 +510,34 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyPath) {
   // Modify the color of the path object.
   EXPECT_TRUE(FPDFPath_SetStrokeColor(path, 0, 0, 0, 255));
   EXPECT_TRUE(FPDFAnnot_UpdateObject(annot, path));
-  FPDFPage_CloseAnnot(annot);
 
   // Check that the page with the modified annotation renders correctly.
   bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5_2);
+  CompareBitmap(bitmap, 595, 842, md5_modified_path);
+  FPDFBitmap_Destroy(bitmap);
+
+  // Add a second path object to the same annotation.
+  FPDF_PAGEOBJECT dot = FPDFPageObj_CreateNewPath(7, 84);
+  EXPECT_TRUE(FPDFPath_BezierTo(dot, 9, 86, 10, 87, 11, 88));
+  EXPECT_TRUE(FPDFPath_SetStrokeColor(dot, 255, 0, 0, 100));
+  EXPECT_TRUE(FPDFPath_SetStrokeWidth(dot, 14));
+  EXPECT_TRUE(FPDFPath_SetDrawMode(dot, 0, 1));
+  EXPECT_TRUE(FPDFAnnot_AppendObject(annot, dot));
+  EXPECT_EQ(2, FPDFAnnot_GetObjectCount(annot));
+
+  // Check that the page with an annotation with two paths renders correctly.
+  bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
+  CompareBitmap(bitmap, 595, 842, md5_two_paths);
+  FPDFBitmap_Destroy(bitmap);
+
+  // Delete the newly added path object.
+  EXPECT_TRUE(FPDFAnnot_RemoveObject(annot, 1));
+  EXPECT_EQ(1, FPDFAnnot_GetObjectCount(annot));
+  FPDFPage_CloseAnnot(annot);
+
+  // Check that the page renders the same as before.
+  bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
+  CompareBitmap(bitmap, 595, 842, md5_modified_path);
   FPDFBitmap_Destroy(bitmap);
 
   // Create another stamp annotation and set its annotation rectangle.
@@ -549,7 +575,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyPath) {
   FPDF_ClosePage(page);
 
   // Open the saved document.
-  TestSaved(595, 842, md5_3);
+  TestSaved(595, 842, md5_new_annot);
 
   // Check that the document has a correct count of annotations and objects.
   EXPECT_EQ(3, FPDFPage_GetAnnotCount(m_SavedPage));
@@ -620,17 +646,17 @@ TEST_F(FPDFAnnotEmbeddertest, ModifyAnnotationFlags) {
 
 TEST_F(FPDFAnnotEmbeddertest, AddAndModifyImage) {
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
-  const char md5[] = "c35408717759562d1f8bf33d317483d2";
-  const char md5_2[] = "ff012f5697436dfcaec25b32d1333596";
-  const char md5_3[] = "86cf8cb2755a7a2046a543e66d9c1e61";
+  const char md5_original[] = "c35408717759562d1f8bf33d317483d2";
+  const char md5_new_image[] = "ff012f5697436dfcaec25b32d1333596";
+  const char md5_modified_image[] = "86cf8cb2755a7a2046a543e66d9c1e61";
 #elif _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
-  const char md5[] = "4f64add0190ede63f7bb9eb1e2e83edb";
-  const char md5_2[] = "6fb176c20996cc554d0210d8c8b6138f";
-  const char md5_3[] = "546959714dfb0dcd7e7b00259e8d178c";
+  const char md5_original[] = "4f64add0190ede63f7bb9eb1e2e83edb";
+  const char md5_new_image[] = "6fb176c20996cc554d0210d8c8b6138f";
+  const char md5_modified_image[] = "546959714dfb0dcd7e7b00259e8d178c";
 #else
-  const char md5[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
-  const char md5_2[] = "e7658232abd8977cdc3367dd02aee04a";
-  const char md5_3[] = "f393432b9a9b452ea69022f46c8b3f75";
+  const char md5_original[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
+  const char md5_new_image[] = "e7658232abd8977cdc3367dd02aee04a";
+  const char md5_modified_image[] = "f393432b9a9b452ea69022f46c8b3f75";
 #endif
 
   // Open a file with two annotations and load its first page.
@@ -641,7 +667,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyImage) {
 
   // Check that the page renders correctly.
   FPDF_BITMAP bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5);
+  CompareBitmap(bitmap, 595, 842, md5_original);
   FPDFBitmap_Destroy(bitmap);
 
   // Create a stamp annotation and set its annotation rectangle.
@@ -670,7 +696,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyImage) {
 
   // Check that the page renders correctly with the new image object.
   bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5_2);
+  CompareBitmap(bitmap, 595, 842, md5_new_image);
   FPDFBitmap_Destroy(bitmap);
 
   // Retrieve the newly added stamp annotation and its image object.
@@ -691,7 +717,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyImage) {
   FPDF_ClosePage(page);
 
   // Test that the saved document renders the modified image object correctly.
-  TestSaved(595, 842, md5_3);
+  TestSaved(595, 842, md5_modified_image);
 
   FPDFBitmap_Destroy(image_bitmap);
   CloseSaved();
@@ -699,17 +725,17 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyImage) {
 
 TEST_F(FPDFAnnotEmbeddertest, AddAndModifyText) {
 #if _FXM_PLATFORM_ == _FXM_PLATFORM_APPLE_
-  const char md5[] = "c35408717759562d1f8bf33d317483d2";
-  const char md5_2[] = "e5680ed048c2cfd9a1d27212cdf41286";
-  const char md5_3[] = "79f5cfb0b07caaf936f65f6a7a57ce77";
+  const char md5_original[] = "c35408717759562d1f8bf33d317483d2";
+  const char md5_new_text[] = "e5680ed048c2cfd9a1d27212cdf41286";
+  const char md5_modified_text[] = "79f5cfb0b07caaf936f65f6a7a57ce77";
 #elif _FXM_PLATFORM_ == _FXM_PLATFORM_WINDOWS_
-  const char md5[] = "4f64add0190ede63f7bb9eb1e2e83edb";
-  const char md5_2[] = "998abae4962f8f41e094e7612d8339fc";
-  const char md5_3[] = "e89b82ca4589b8f0b45fff42ca3a96a4";
+  const char md5_original[] = "4f64add0190ede63f7bb9eb1e2e83edb";
+  const char md5_new_text[] = "998abae4962f8f41e094e7612d8339fc";
+  const char md5_modified_text[] = "e89b82ca4589b8f0b45fff42ca3a96a4";
 #else
-  const char md5[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
-  const char md5_2[] = "3fbbaec4d846ccf2be89e09daae0273d";
-  const char md5_3[] = "2ad0acaf2d8990bcdf48e1d12e6c44ad";
+  const char md5_original[] = "02e1c6adff8fee4aeabd91c2c2e4be43";
+  const char md5_new_text[] = "3fbbaec4d846ccf2be89e09daae0273d";
+  const char md5_modified_text[] = "2ad0acaf2d8990bcdf48e1d12e6c44ad";
 #endif
 
   // Open a file with two annotations and load its first page.
@@ -720,7 +746,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyText) {
 
   // Check that the page renders correctly.
   FPDF_BITMAP bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5);
+  CompareBitmap(bitmap, 595, 842, md5_original);
   FPDFBitmap_Destroy(bitmap);
 
   // Create a stamp annotation and set its annotation rectangle.
@@ -747,7 +773,7 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyText) {
 
   // Check that the page renders correctly with the new text object.
   bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5_2);
+  CompareBitmap(bitmap, 595, 842, md5_new_text);
   FPDFBitmap_Destroy(bitmap);
 
   // Retrieve the newly added stamp annotation and its text object.
@@ -766,13 +792,13 @@ TEST_F(FPDFAnnotEmbeddertest, AddAndModifyText) {
 
   // Check that the page renders correctly with the modified text object.
   bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5_3);
+  CompareBitmap(bitmap, 595, 842, md5_modified_text);
   FPDFBitmap_Destroy(bitmap);
 
   // Remove the new annotation, and check that the page renders as before.
   EXPECT_TRUE(FPDFPage_RemoveAnnot(page, 2));
   bitmap = RenderPageWithFlags(page, form_handle_, FPDF_ANNOT);
-  CompareBitmap(bitmap, 595, 842, md5);
+  CompareBitmap(bitmap, 595, 842, md5_original);
   FPDFBitmap_Destroy(bitmap);
 
   UnloadPage(page);
diff --git a/fpdfsdk/fpdfview_c_api_test.c b/fpdfsdk/fpdfview_c_api_test.c
index e6a58734d2..1c066dd295 100644
--- a/fpdfsdk/fpdfview_c_api_test.c
+++ b/fpdfsdk/fpdfview_c_api_test.c
@@ -42,10 +42,12 @@ int CheckPDFiumCApi() {
     CHK(FPDFPage_CloseAnnot);
     CHK(FPDFPage_RemoveAnnot);
     CHK(FPDFAnnot_GetSubtype);
+    CHK(FPDFAnnot_IsObjectSupportedSubtype);
     CHK(FPDFAnnot_UpdateObject);
     CHK(FPDFAnnot_AppendObject);
     CHK(FPDFAnnot_GetObjectCount);
     CHK(FPDFAnnot_GetObject);
+    CHK(FPDFAnnot_RemoveObject);
     CHK(FPDFAnnot_SetColor);
     CHK(FPDFAnnot_GetColor);
     CHK(FPDFAnnot_HasAttachmentPoints);
diff --git a/public/fpdf_annot.h b/public/fpdf_annot.h
index 31779a5cd8..c42b7059dc 100644
--- a/public/fpdf_annot.h
+++ b/public/fpdf_annot.h
@@ -142,6 +142,17 @@ DLLEXPORT FPDF_ANNOTATION_SUBTYPE STDCALL
 FPDFAnnot_GetSubtype(FPDF_ANNOTATION annot);
 
 // Experimental API.
+// Check if an annotation subtype is currently supported for object extraction,
+// update, and removal.
+// Currently supported subtypes: ink and stamp.
+//
+//   subtype   - the subtype to be checked.
+//
+// Returns true if this subtype supported.
+DLLEXPORT FPDF_BOOL STDCALL
+FPDFAnnot_IsObjectSupportedSubtype(FPDF_ANNOTATION_SUBTYPE subtype);
+
+// Experimental API.
 // Update |obj| in |annot|. |obj| must be in |annot| already and must have
 // been retrieved by FPDFAnnot_GetObject(). Currently, only ink and stamp
 // annotations are supported by this API. Also note that only path, image, and
@@ -189,6 +200,16 @@ DLLEXPORT FPDF_PAGEOBJECT STDCALL FPDFAnnot_GetObject(FPDF_ANNOTATION annot,
                                                       int index);
 
 // Experimental API.
+// Remove the object in |annot| at |index|.
+//
+//   annot  - handle to an annotation.
+//   index  - the index of the object to be removed.
+//
+// Return true if successful.
+DLLEXPORT FPDF_BOOL STDCALL FPDFAnnot_RemoveObject(FPDF_ANNOTATION annot,
+                                                   int index);
+
+// Experimental API.
 // Set the color of an annotation. Fails when called on annotations with
 // appearance streams already defined; instead use
 // FPDFPath_Set{Stroke|Fill}Color().