Support LIBSDL2_TTF_SHLIB

The environment variable avoids the runtime search for the SDL2_ttf shared library and also the Unix-specific fallback to pkg-config. It allows a debug library (ex. SDL2_ttfd.dll) to be used.
sanette · Mar 7, 2024 · 8013965 · 8013965
1 parent edb9b92
commit 8013965
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -1,3 +1,9 @@
+# Pending
+
+* Allow exact location of `libSDL2_ttf-2.0.so.0` to be set in
+  `LIBSDL2_TTF_SHLIB` for situations where you have a debug shared
+  library or you don't want `pkg-config` invoked.
+
 # 0.6 2023/08/05 hide startup log
 
 * Use system category to log "Loading Sdl_ttf" message. (We now

diff --git a/src/tsdl_ttf.ml b/src/tsdl_ttf.ml
@@ -65,7 +65,7 @@ module Ttf = struct
      #require "tsdl-ttf"
      in the toplevel, see
      https://github.com/ocamllabs/ocaml-ctypes/issues/70 *)
-  let from : Dl.library option =
+  let from_with_search : Dl.library option =
     (if debug then
        Sdl.(
          log_info Log.category_system "Loading Sdl_ttf, Target = %s"
@@ -116,6 +116,11 @@ module Ttf = struct
               ("Cannot find " ^ filename ^ ", please set LIBSDL2_PATH");
             None)
 
+  let from : Dl.library option =
+    let shlib = try Sys.getenv "LIBSDL2_TTF_SHLIB" with Not_found -> "" in
+    if shlib = "" then from_with_search
+    else Some Dl.(dlopen ~filename:shlib ~flags:[ RTLD_NOW ])
+
   let foreign = foreign ?from
   let init = foreign "TTF_Init" (void @-> returning zero_to_ok)