Avoid annotation popups to be clipped at page edges

Currently, annotation popups are placed at a fixed location relative to
the annotation. If an annotation is too much on the right or the bottom
of the page, then its popup will be clipped at the edge of the page.

This CL translates the popups appropriately to avoid getting clipped at
page edges. Also, if an annotation is at the bottom-right corner of the
page, then the popup is placed above and to the left of the annotation,
instead of below and to the right of it.

See a set of comparison screenshots here:
https://drive.google.com/drive/folders/0B7Fvv7JszRyGZXZXR05yVEFWSlE?usp=sharing

Bug=chromium:645367,pdfium:750

Change-Id: Ie048281e965523c292dcc704b51188d794f8877b
Reviewed-on: https://pdfium-review.googlesource.com/11470
Commit-Queue: Jane Liu <janeliulwq@google.com>
Reviewed-by: dsinclair <dsinclair@chromium.org>

1 files changed, 18 insertions, 3 deletions

diff --git a/core/fpdfdoc/cpdf_annotlist.cpp b/core/fpdfdoc/cpdf_annotlist.cpp
index 1f94779c15..e4ecf466f5 100644
--- a/core/fpdfdoc/cpdf_annotlist.cpp
+++ b/core/fpdfdoc/cpdf_annotlist.cpp
@@ -6,6 +6,7 @@
 
 #include "core/fpdfdoc/cpdf_annotlist.h"
 
+#include <algorithm>
 #include <memory>
 #include <utility>
 
@@ -26,7 +27,8 @@
 namespace {
 
 std::unique_ptr<CPDF_Annot> CreatePopupAnnot(CPDF_Annot* pAnnot,
-                                             CPDF_Document* pDocument) {
+                                             CPDF_Document* pDocument,
+                                             CPDF_Page* pPage) {
   CPDF_Dictionary* pParentDict = pAnnot->GetAnnotDict();
   if (!pParentDict)
     return nullptr;
@@ -48,7 +50,20 @@ std::unique_ptr<CPDF_Annot> CreatePopupAnnot(CPDF_Annot* pAnnot,
   CFX_FloatRect rect = pParentDict->GetRectFor("Rect");
   rect.Normalize();
   CFX_FloatRect popupRect(0, 0, 200, 200);
-  popupRect.Translate(rect.left, rect.bottom - popupRect.Height());
+  // Note that if the popup can set its own dimensions, then we will need to
+  // make sure that it isn't larger than the page size.
+  if (rect.left + popupRect.Width() > pPage->GetPageWidth() &&
+      rect.bottom - popupRect.Height() < 0) {
+    // If the annotation is on the bottom-right corner of the page, then place
+    // the popup above and to the left of the annotation.
+    popupRect.Translate(rect.right - popupRect.Width(), rect.top);
+  } else {
+    // Place the popup below and to the right of the annotation without getting
+    // clipped by page edges.
+    popupRect.Translate(
+        std::min(rect.left, pPage->GetPageWidth() - popupRect.Width()),
+        std::max(rect.bottom - popupRect.Height(), 0.f));
+  }
 
   pAnnotDict->SetRectFor("Rect", popupRect);
   pAnnotDict->SetNewFor<CPDF_Number>("F", 0);
@@ -94,7 +109,7 @@ CPDF_AnnotList::CPDF_AnnotList(CPDF_Page* pPage)
   size_t nAnnotListSize = m_AnnotList.size();
   for (size_t i = 0; i < nAnnotListSize; ++i) {
     std::unique_ptr<CPDF_Annot> pPopupAnnot(
-        CreatePopupAnnot(m_AnnotList[i].get(), m_pDocument));
+        CreatePopupAnnot(m_AnnotList[i].get(), m_pDocument, pPage));
     if (pPopupAnnot)
       m_AnnotList.push_back(std::move(pPopupAnnot));
   }