Open FPDFDest_GetView API.

FPDFDest_GetView returns the view fit type and the parameters of the
view for a given destination.

This is useful to have more precise internal links and bookmarks that
are able to manipulate the viewport position and zoom level to focus
on the part of the PDF that it links to.

Bug: 55776, 535978, 748852
Change-Id: Ibf7df40a852030d75ec78cec7662380319569850
Reviewed-on: https://pdfium-review.googlesource.com/21790
Commit-Queue: Henrique Nakashima <hnakashima@chromium.org>
Reviewed-by: Ryan Harrison <rharrison@chromium.org>

2 files changed, 26 insertions, 4 deletions

diff --git a/core/fpdfdoc/cpdf_dest.cpp b/core/fpdfdoc/cpdf_dest.cpp
index ebe3834e91..cb15bf1c33 100644
--- a/core/fpdfdoc/cpdf_dest.cpp
+++ b/core/fpdfdoc/cpdf_dest.cpp
@@ -6,6 +6,8 @@
 
 #include "core/fpdfdoc/cpdf_dest.h"
 
+#include <algorithm>
+
 #include "core/fpdfapi/parser/cpdf_array.h"
 #include "core/fpdfapi/parser/cpdf_document.h"
 #include "core/fpdfapi/parser/cpdf_name.h"
@@ -13,8 +15,14 @@
 
 namespace {
 
-const char* const g_sZoomModes[] = {"XYZ",  "Fit",   "FitH",  "FitV", "FitR",
-                                    "FitB", "FitBH", "FitBV", nullptr};
+// These arrays are indexed by the PDFDEST_VIEW_* constants.
+
+// Last element is a sentinel.
+const char* const g_sZoomModes[] = {"Unknown", "XYZ",  "Fit",  "FitH",
+                                    "FitV",    "FitR", "FitB", "FitBH",
+                                    "FitBV",   nullptr};
+
+const int g_sZoomModeMaxParamCount[] = {0, 3, 0, 1, 1, 4, 0, 1, 1, 0};
 
 }  // namespace
 
@@ -66,9 +74,9 @@ int CPDF_Dest::GetZoomMode() {
     return 0;
 
   ByteString mode = pObj->GetString();
-  for (int i = 0; g_sZoomModes[i]; ++i) {
+  for (int i = 1; g_sZoomModes[i]; ++i) {
     if (mode == g_sZoomModes[i])
-      return i + 1;
+      return i;
   }
 
   return 0;
@@ -121,6 +129,16 @@ bool CPDF_Dest::GetXYZ(bool* pHasX,
   return true;
 }
 
+unsigned int CPDF_Dest::GetNumParams() {
+  CPDF_Array* pArray = ToArray(m_pObj.Get());
+  if (!pArray || pArray->GetCount() < 2)
+    return 0;
+
+  size_t maxParamsForFitType = g_sZoomModeMaxParamCount[GetZoomMode()];
+  size_t numParamsInArray = pArray->GetCount() - 2;
+  return std::min(maxParamsForFitType, numParamsInArray);
+}
+
 float CPDF_Dest::GetParam(int index) {
   CPDF_Array* pArray = ToArray(m_pObj.Get());
   return pArray ? pArray->GetNumberAt(2 + index) : 0;
diff --git a/core/fpdfdoc/cpdf_dest.h b/core/fpdfdoc/cpdf_dest.h
index 2836ebb471..4959901972 100644
--- a/core/fpdfdoc/cpdf_dest.h
+++ b/core/fpdfdoc/cpdf_dest.h
@@ -25,7 +25,11 @@ class CPDF_Dest {
   ByteString GetRemoteName();
   int GetPageIndex(CPDF_Document* pDoc);
   uint32_t GetPageObjNum();
+
+  // Returns the zoom mode, as one of the PDFDEST_VIEW_* values in fpdf_doc.h.
   int GetZoomMode();
+
+  unsigned int GetNumParams();
   float GetParam(int index);
 
   bool GetXYZ(bool* pHasX,