Merge to XFA: Add new public APIs to find the z-order for links and widgets.

- Implement FPDFLink_GetLinkZOrderAtPoint().
- Implement FPDFPage_FormFieldZOrderAtPoint().
- Mark FPDPage_HasFormFieldAtPoint() as deprecated.
- Modify CPDF_LinkList and CPDF_InterForm to support new APIs.
- Clean up dead code in CPDF_LinkList and CPDF_InterForm.

BUG=chromium:515837
R=jun_fang@foxitsoftware.com, tsepez@chromium.org

Review URL: https://codereview.chromium.org/1278053004 .

(cherry picked from commit 24fbf134d43a7ec4226de3db601f0a617bbe428b)

Review URL: https://codereview.chromium.org/1295893005 .

2 files changed, 73 insertions, 21 deletions

diff --git a/public/fpdf_doc.h b/public/fpdf_doc.h
index 9e3f0af6d1..ca16d26627 100644
--- a/public/fpdf_doc.h
+++ b/public/fpdf_doc.h
@@ -177,27 +177,52 @@ DLLEXPORT unsigned long STDCALL FPDFDest_GetPageIndex(FPDF_DOCUMENT document,
                                                       FPDF_DEST dest);
 
 // Function: FPDFLink_GetLinkAtPoint
-//          Find a link at specified point on a document page.
+//     Find a link at specified point on a document page.
 // Parameters:
-//          page        -   Handle to the document page.
-//          x           -   The x coordinate of the point, specified in page
-//          coordinate system.
-//          y           -   The y coordinate of the point, specified in page
-//          coordinate system.
+//     page        -   Handle to the document page.
+//     x           -   The x coordinate of the point, specified in page
+//                     coordinate system.
+//     y           -   The y coordinate of the point, specified in page
+//                     coordinate system.
 // Return value:
-//          Handle to the link. NULL if no link found at that point.
+//     Handle to the link. NULL if no link found at that point.
 // Comments:
-//          The point coordinates are specified in page coordinate system. You
-//          can convert coordinates
-//          from screen system to page system using FPDF_DeviceToPage functions.
+//     The point coordinates are specified in page coordinate system. You can
+//     convert coordinates from screen system to page system using
+//     FPDF_DeviceToPage().
+//
 // Notes:
-//          The method can not support this feature for the document consists of
-//          dynamic XFA fields.
+//     The method can not support this feature for the document consists of
+//     dynamic XFA fields.
 //
 DLLEXPORT FPDF_LINK STDCALL FPDFLink_GetLinkAtPoint(FPDF_PAGE page,
                                                     double x,
                                                     double y);
 
+// Function: FPDFLink_GetLinkZOrderAtPoint
+//     Find the z-order of a link at specified point on a document page.
+// Parameters:
+//     page        -   Handle to the document page.
+//     x           -   The x coordinate of the point, specified in page
+//                     coordinate system.
+//     y           -   The y coordinate of the point, specified in page
+//                     coordinate system.
+// Return value:
+//     Z-order of the link, or -1 if no link found at that point.
+//     Higher numbers are closer to the front.
+// Comments:
+//     The point coordinates are specified in page coordinate system. You can
+//     convert coordinates from screen system to page system using
+//     FPDF_DeviceToPage().
+//
+// Notes:
+//     The method can not support this feature for the document consists of
+//     dynamic XFA fields.
+//
+//
+DLLEXPORT int STDCALL
+FPDFLink_GetLinkZOrderAtPoint(FPDF_PAGE page, double x, double y);
+
 // Function: FPDFLink_GetDest
 //          Get destination info of a link.
 // Parameters:
diff --git a/public/fpdf_formfill.h b/public/fpdf_formfill.h
index 73fe491435..7be678cd47 100644
--- a/public/fpdf_formfill.h
+++ b/public/fpdf_formfill.h
@@ -1311,17 +1311,26 @@ DLLEXPORT FPDF_BOOL STDCALL FORM_ForceToKillFocus(FPDF_FORMHANDLE hHandle);
 #define FPDF_FORMFIELD_XFA 7          // text field type.
 
 /**
- * Function: FPDPage_HasFormFieldAtPoint
- *          Check the form filed position by point.
+ * Function: FPDFPage_HasFormFieldAtPoint
+ *     Get the form field type by point.
  * Parameters:
- *          hHandle     -   Handle to the form fill module. Returned by
- *FPDFDOC_InitFormFillEnvironment.
- *          page        -   Handle to the page. Returned by FPDF_LoadPage
- *function.
- *          page_x      -   X position in PDF "user space".
- *          page_y      -   Y position in PDF "user space".
+ *     hHandle     -   Handle to the form fill module. Returned by
+ *                     FPDFDOC_InitFormFillEnvironment().
+ *     page        -   Handle to the page. Returned by FPDF_LoadPage().
+ *     page_x      -   X position in PDF "user space".
+ *     page_y      -   Y position in PDF "user space".
  * Return Value:
- *          Return the type of the formfiled; -1 indicates no fields.
+ *     Return the type of the form field; -1 indicates no field.
+ *     See field types above.
+ **/
+DLLEXPORT int STDCALL FPDFPage_HasFormFieldAtPoint(FPDF_FORMHANDLE hHandle,
+                                                   FPDF_PAGE page,
+                                                   double page_x,
+                                                   double page_y);
+
+/**
+ * Function: FPDPage_HasFormFieldAtPoint
+ *     DEPRECATED. Please use FPDFPage_HasFormFieldAtPoint.
  **/
 DLLEXPORT int STDCALL FPDPage_HasFormFieldAtPoint(FPDF_FORMHANDLE hHandle,
                                                   FPDF_PAGE page,
@@ -1329,6 +1338,24 @@ DLLEXPORT int STDCALL FPDPage_HasFormFieldAtPoint(FPDF_FORMHANDLE hHandle,
                                                   double page_y);
 
 /**
+ * Function: FPDFPage_FormFieldZOrderAtPoint
+ *     Get the form field z-order by point.
+ * Parameters:
+ *     hHandle     -   Handle to the form fill module. Returned by
+ *                     FPDFDOC_InitFormFillEnvironment().
+ *     page        -   Handle to the page. Returned by FPDF_LoadPage().
+ *     page_x      -   X position in PDF "user space".
+ *     page_y      -   Y position in PDF "user space".
+ * Return Value:
+ *     Return the z-order of the form field; -1 indicates no field.
+ *     Higher numbers are closer to the front.
+ **/
+DLLEXPORT int STDCALL FPDFPage_FormFieldZOrderAtPoint(FPDF_FORMHANDLE hHandle,
+                                                      FPDF_PAGE page,
+                                                      double page_x,
+                                                      double page_y);
+
+/**
  * Function: FPDF_SetFormFieldHighlightColor
  *          Set the highlight color of specified or all the form fields in the
  *document.