Add compile checks for my navigation key change in libobs. Improve handling of 32-bit build.

Author: nleseul

CMakeLists.txt

@@ -1,6 +1,8 @@
 cmake_minimum_required (VERSION 2.8.12)
 project (obs-ghostscript)
 
+include(CheckCSourceCompiles)
+
 if (OBSSourcePath OR DEFINED ENV{OBSSourcePath})
     # Set already
 else()
@@ -17,10 +19,10 @@ endif()
 find_path(OBS_LIB_DIR
     NAMES obs.dll obs.lib
     HINTS
-        ${OBSSourcePath}/../build/libobs/Release/
         ${OBSSourcePath}/../build${_lib_suffix}/libobs/Release/
-        ${OBSSourcePath}/../build/libobs/Debug/
+        ${OBSSourcePath}/../build/libobs/Release/
         ${OBSSourcePath}/../build${_lib_suffix}/libobs/Debug/
+        ${OBSSourcePath}/../build/libobs/Debug/
     PATHS
 		/usr/lib /usr/local/lib /opt/local/lib /sw/lib)
 
@@ -40,12 +42,21 @@ find_path(GHOSTSCRIPT_LIB_DIR
 if (NOT GHOSTSCRIPT_INCLUDE_DIR OR NOT GHOSTSCRIPT_LIB_DIR)
     message("Ghostscript headers or libraries could not be found! Please ensure that Ghostscript is installed somewhere, and set the GSSourcePath and GSLibraryPath variables if necessary.")
 endif()
+
+# Check if the libobs being referenced has support for arrow key navigation when interacting with a source.
+
+set(CMAKE_REQUIRED_INCLUDES ${OBSSourcePath})
+
+check_c_source_compiles("#include <obs-interaction.h>
+    int main() { struct obs_key_event e; return e.navigation_keys; }" OBS_HAS_NAVKEY_SUPPORT)
+
+configure_file(${CMAKE_SOURCE_DIR}/src/config.h.in ${CMAKE_BINARY_DIR}/config/config.h)
 
 # Source
 file (GLOB SOURCES ${CMAKE_SOURCE_DIR}/src/*.c)
-file (GLOB HEADER_FILES ${CMAKE_SOURCE_DIR}/include/*.h)
+file (GLOB HEADER_FILES ${CMAKE_SOURCE_DIR}/include/*.h ${CMAKE_BINARY_DIR}/config/*.h)
 
-include_directories (include)
+include_directories (include ${CMAKE_BINARY_DIR}/config)
 add_library (${PROJECT_NAME} SHARED
 	${SOURCES}
 	${HEADER_FILES}
@@ -61,6 +72,6 @@ target_link_libraries (${PROJECT_NAME} libobs)
 # Ghostscript
 include_directories(${GHOSTSCRIPT_INCLUDE_DIR})
 add_library (gsdll SHARED IMPORTED)
-set_property (TARGET gsdll PROPERTY IMPORTED_LOCATION ${OBS_LIB_DIR}/gsdll${_lib_suffix}.dll)
+set_property (TARGET gsdll PROPERTY IMPORTED_LOCATION ${GHOSTSCRIPT_LIB_DIR}/gsdll${_lib_suffix}.dll)
 set_property (TARGET gsdll PROPERTY IMPORTED_IMPLIB ${GHOSTSCRIPT_LIB_DIR}/gsdll${_lib_suffix}.lib)
 target_link_libraries (${PROJECT_NAME} gsdll)

src/config.h.in

@@ -0,0 +1,3 @@
+#pragma once
+
+#cmakedefine OBS_HAS_NAVKEY_SUPPORT 1

src/obs-pdf.c

@@ -4,9 +4,18 @@
 #include <stdio.h>
 #include <inttypes.h>
 
+// Ghostscript expects a non-standard #define for indicating a Windows environment, apparently.
+// This ensures the Ghostscript API functions are referenced by the linker with the correct
+// calling convention (on x86). 
+#ifdef _WIN32
+#define _WINDOWS_
+#endif
+
 #include <psi/iapi.h>
 #include <devices/gdevdsp.h>
 
+#include <config.h>
+
 static void *shared_ghostscript_instance = NULL;
 
 struct pdf_source {
@@ -110,29 +119,6 @@ display_callback display =
 	NULL
 };
 
-static int ghostscript_stdin(void *instance, char *buf, int len)
-{
-	return 0;
-}
-
-static int ghostscript_stdout(void *instance, const char *str, int len)
-{
-	char buffer[256];
-	snprintf(buffer, 256, "gs-out: %.*s", len, str);
-	blog(LOG_INFO, buffer);
-
-	return len;
-}
-
-static int ghostscript_stderr(void *instance, const char *str, int len)
-{
-	char buffer[256];
-	snprintf(buffer, 256, "gs-err: %.*s", len, str);
-	blog(LOG_ERROR, buffer);
-
-	return len;
-}
-
 
 static void pdf_source_load(struct pdf_source *context)
 {
@@ -162,13 +148,19 @@ static void pdf_source_load(struct pdf_source *context)
 
 		int gs_argc = sizeof(gs_argv) / sizeof(gs_argv[0]);
 
-		int code = gsapi_init_with_args(shared_ghostscript_instance, gs_argc, gs_argv);
-		
+		// Here, we execute the Ghostscript command to parse the file and render the document. The display device
+		// callbacks indicated above will handle copying the Ghostscript buffer into an OBS texture if any page is
+		// rendered. 
+		gsapi_init_with_args(shared_ghostscript_instance, gs_argc, gs_argv);
 		gsapi_exit(shared_ghostscript_instance);
 	}
 
 	if (!context->cached_anypagesrendered)
 	{
+		// If the ghostscript_display_page() callback above was never called, that means the commands issued
+		// to Ghostscript did not result in a page in the document being rendered. That is most likely to happen
+		// if the document does not contain the requested page number. We simply destroy the texture and render
+		// nothing in that case. 
 		obs_enter_graphics();
 		gs_texture_destroy(context->texture);
 		context->texture = NULL;
@@ -367,7 +359,6 @@ OBS_MODULE_USE_DEFAULT_LOCALE("obs-pdf", "en-US")
 bool obs_module_load(void)
 {
 	gsapi_new_instance(&shared_ghostscript_instance, NULL);
-	gsapi_set_stdio(shared_ghostscript_instance, ghostscript_stdin, ghostscript_stdout, ghostscript_stderr);
 	gsapi_set_display_callback(shared_ghostscript_instance, &display);
 
 	obs_register_source(&pdf_source_info);