Add a build target and a proper export header for shared library builds.

This CL adds support for Chromium's component build feature to pdfium.

The export header stub in fpdfview.h is expanded to match Chromium's
export mechanisms and patterns (fixes pdfium:825).

A component/shared library build can be triggered by adding

is_component_build = true

as a gn argument. Please note that setting this will also affect some
of pdfiums dependencies like v8, which will be build as components
too.

Additionally, this CL provides a "pdf_source_set" template which
dynamically enables the use of "source_set" when building a complete
static library or a shared library to reduce build time.

When testing this it is recommended to only build the pdfium target as
most of pdfiums test rely on non-public functions which aren't exported
by the shared library.

Bug: pdfium:825,pdfium:826
Change-Id: Icedc538ec535e11d1e53c4d5fabc8c064b275752
Reviewed-on: https://pdfium-review.googlesource.com/8970
Reviewed-by: dsinclair <dsinclair@chromium.org>
Commit-Queue: dsinclair <dsinclair@chromium.org>

1 files changed, 11 insertions, 9 deletions

diff --git a/public/fpdf_structtree.h b/public/fpdf_structtree.h
index 9cf46cc306..688471f28d 100644
--- a/public/fpdf_structtree.h
+++ b/public/fpdf_structtree.h
@@ -21,7 +21,8 @@ extern "C" {
 //          function.
 // Return value:
 //          A handle to the structure tree or NULL on error.
-DLLEXPORT FPDF_STRUCTTREE STDCALL FPDF_StructTree_GetForPage(FPDF_PAGE page);
+FPDF_EXPORT FPDF_STRUCTTREE FPDF_CALLCONV
+FPDF_StructTree_GetForPage(FPDF_PAGE page);
 
 // Function: FPDF_StructTree_Close
 //          Release the resource allocate by FPDF_StructTree_GetForPage.
@@ -30,7 +31,8 @@ DLLEXPORT FPDF_STRUCTTREE STDCALL FPDF_StructTree_GetForPage(FPDF_PAGE page);
 //          FPDF_StructTree_LoadPage function.
 // Return value:
 //          NULL
-DLLEXPORT void STDCALL FPDF_StructTree_Close(FPDF_STRUCTTREE struct_tree);
+FPDF_EXPORT void FPDF_CALLCONV
+FPDF_StructTree_Close(FPDF_STRUCTTREE struct_tree);
 
 // Function: FPDF_StructTree_CountChildren
 //          Count the number of children for the structure tree.
@@ -39,7 +41,7 @@ DLLEXPORT void STDCALL FPDF_StructTree_Close(FPDF_STRUCTTREE struct_tree);
 //          FPDF_StructTree_LoadPage function.
 // Return value:
 //          The number of children, or -1 on error.
-DLLEXPORT int STDCALL
+FPDF_EXPORT int FPDF_CALLCONV
 FPDF_StructTree_CountChildren(FPDF_STRUCTTREE struct_tree);
 
 // Function: FPDF_StructTree_GetChildAtIndex
@@ -50,7 +52,7 @@ FPDF_StructTree_CountChildren(FPDF_STRUCTTREE struct_tree);
 //          index       -   The index for the child, 0-based.
 // Return value:
 //          The child at the n-th index or NULL on error.
-DLLEXPORT FPDF_STRUCTELEMENT STDCALL
+FPDF_EXPORT FPDF_STRUCTELEMENT FPDF_CALLCONV
 FPDF_StructTree_GetChildAtIndex(FPDF_STRUCTTREE struct_tree, int index);
 
 // Function: FPDF_StructElement_GetAltText
@@ -68,7 +70,7 @@ FPDF_StructTree_GetChildAtIndex(FPDF_STRUCTTREE struct_tree, int index);
 //          encoding. The string is terminated by a UTF16 NUL character. If
 //          |buflen| is less than the required length, or |buffer| is NULL,
 //          |buffer| will not be modified.
-DLLEXPORT unsigned long STDCALL
+FPDF_EXPORT unsigned long FPDF_CALLCONV
 FPDF_StructElement_GetAltText(FPDF_STRUCTELEMENT struct_element,
                               void* buffer,
                               unsigned long buflen);
@@ -88,7 +90,7 @@ FPDF_StructElement_GetAltText(FPDF_STRUCTELEMENT struct_element,
 //           encoding. The string is terminated by a UTF16 NUL character. If
 //           |buflen| is less than the required length, or |buffer| is NULL,
 //           |buffer| will not be modified.
-DLLEXPORT unsigned long STDCALL
+FPDF_EXPORT unsigned long FPDF_CALLCONV
 FPDF_StructElement_GetType(FPDF_STRUCTELEMENT struct_element,
                            void* buffer,
                            unsigned long buflen);
@@ -108,7 +110,7 @@ FPDF_StructElement_GetType(FPDF_STRUCTELEMENT struct_element,
 //           encoding. The string is terminated by a UTF16 NUL character. If
 //           |buflen| is less than the required length, or |buffer| is NULL,
 //           |buffer| will not be modified.
-DLLEXPORT unsigned long STDCALL
+FPDF_EXPORT unsigned long FPDF_CALLCONV
 FPDF_StructElement_GetTitle(FPDF_STRUCTELEMENT struct_element,
                             void* buffer,
                             unsigned long buflen);
@@ -119,7 +121,7 @@ FPDF_StructElement_GetTitle(FPDF_STRUCTELEMENT struct_element,
 //          struct_element -   Handle to the struct element.
 // Return value:
 //          The number of children, or -1 on error.
-DLLEXPORT int STDCALL
+FPDF_EXPORT int FPDF_CALLCONV
 FPDF_StructElement_CountChildren(FPDF_STRUCTELEMENT struct_element);
 
 // Function: FPDF_StructElement_GetChildAtIndex
@@ -132,7 +134,7 @@ FPDF_StructElement_CountChildren(FPDF_STRUCTELEMENT struct_element);
 // Comments:
 //          If the child exists but is not an element, then this function will
 //          return NULL. This will also return NULL for out of bounds indices.
-DLLEXPORT FPDF_STRUCTELEMENT STDCALL
+FPDF_EXPORT FPDF_STRUCTELEMENT FPDF_CALLCONV
 FPDF_StructElement_GetChildAtIndex(FPDF_STRUCTELEMENT struct_element,
                                    int index);