Make backends optional

7 files changed, 87 insertions, 10 deletions

diff --git a/Makefile b/Makefile
index ca41af0..9e16cfd 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,7 @@
 .PHONY: imv clean check install uninstall doc
 
+include config.mk
+
 PREFIX ?= /usr
 BINPREFIX ?= $(PREFIX)/bin
 MANPREFIX ?= $(PREFIX)/share/man
@@ -8,11 +10,8 @@ CONFIGPREFIX ?= /etc
 
 CFLAGS ?= -W -Wall -pedantic -Wmissing-prototypes
 CFLAGS += -std=c99
-CFLAGS += $(shell pkg-config --cflags librsvg-2.0)
 CPPFLAGS += $(shell sdl2-config --cflags) -D_XOPEN_SOURCE=700
 LIBS := $(shell sdl2-config --libs)
-LIBS += -lfreeimage -lpng
-LIBS += $(shell pkg-config --libs librsvg-2.0)
 LIBS += -lSDL2_ttf -lfontconfig -lpthread
 
 BUILDDIR ?= build
@@ -28,6 +27,22 @@ VERSION != git describe --dirty --always --tags 2> /dev/null || echo v3.0.0
 
 CFLAGS += -DIMV_VERSION=\""$(VERSION)"\"
 
+# Add backends to build as configured
+ifeq ($(BACKEND_FREEIMAGE),yes)
+	CFLAGS += -DIMV_BACKEND_FREEIMAGE
+	LIBS += -lfreeimage
+endif
+
+ifeq ($(BACKEND_LIBPNG),yes)
+	CFLAGS += -DIMV_BACKEND_LIBPNG
+	LIBS += -lpng
+endif
+
+ifeq ($(BACKEND_LIBRSVG),yes)
+	CFLAGS += -DIMV_BACKEND_LIBRSVG $(shell pkg-config --cflags librsvg-2.0)
+	LIBS += $(shell pkg-config --libs librsvg-2.0)
+endif
+
 imv: $(TARGET)
 
 $(TARGET): $(OBJECTS)
diff --git a/config.mk b/config.mk
new file mode 100644
index 0000000..e2fa1bf
--- /dev/null
+++ b/config.mk
@@ -0,0 +1,19 @@
+# Configure available backends:
+
+# FreeImage http://freeimage.sourceforge.net
+# provides: png, jpg, animated gif, raw, psd, bmp, tiff, webp, etc.
+# depends: libjpeg, openexr, openjpeg2, libwebp, libraw, jxrlib
+# license: FIPL v1.0
+BACKEND_FREEIMAGE=yes
+
+# libpng http://www.libpng.org/pub/png/libpng.html
+# provides: png
+# depends: zlib
+# license: libpng license
+BACKEND_LIBPNG=no
+
+# librsvg https://wiki.gnome.org/Projects/LibRsvg
+# provides: svg
+# depends: gdk-pixbuf2 pango libcroco
+# license: LGPL
+BACKEND_LIBRSVG=yes
diff --git a/src/backend_freeimage.c b/src/backend_freeimage.c
index 8849922..9443075 100644
--- a/src/backend_freeimage.c
+++ b/src/backend_freeimage.c
@@ -6,6 +6,8 @@
 #include <stdio.h>
 #include <string.h>
 
+#ifdef IMV_BACKEND_FREEIMAGE
+
 #include <FreeImage.h>
 
 struct private {
@@ -269,3 +271,12 @@ struct imv_backend *imv_backend_freeimage(void)
   backend->free = &backend_free;
   return backend;
 }
+
+#else
+
+struct imv_backend *imv_backend_freeimage(void)
+{
+  return NULL;
+}
+
+#endif
diff --git a/src/backend_libpng.c b/src/backend_libpng.c
index 20606b4..d5a2676 100644
--- a/src/backend_libpng.c
+++ b/src/backend_libpng.c
@@ -1,12 +1,13 @@
 #include "backend_libpng.h"
 #include "backend.h"
 #include "source.h"
-
 #include <alloca.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
 
+#ifdef IMV_BACKEND_LIBPNG
+
 #include <png.h>
 
 struct private {
@@ -191,3 +192,12 @@ struct imv_backend *imv_backend_libpng(void)
   backend->free = &backend_free;
   return backend;
 }
+
+#else
+
+struct imv_backend *imv_backend_libpng(void)
+{
+  return NULL;
+}
+
+#endif
diff --git a/src/backend_rsvg.c b/src/backend_librsvg.c
index f259e5c..416743a 100644
--- a/src/backend_rsvg.c
+++ b/src/backend_librsvg.c
@@ -1,7 +1,11 @@
-#include "backend_rsvg.h"
+#include "backend_librsvg.h"
 #include "backend.h"
 #include "source.h"
 
+#include <stddef.h>
+
+#ifdef IMV_BACKEND_LIBRSVG
+
 #include <librsvg/rsvg.h>
 
 /* Some systems like GNU/Hurd don't define PATH_MAX */
@@ -131,11 +135,20 @@ static void backend_free(struct imv_backend *backend)
   free(backend);
 }
 
-struct imv_backend *imv_backend_rsvg(void)
+struct imv_backend *imv_backend_librsvg(void)
 {
   struct imv_backend *backend = malloc(sizeof(struct imv_backend));
-  backend->name = "rsvg (LGPL license)";
+  backend->name = "librsvg (LGPL license)";
   backend->open_path = &open_path;
   backend->free = &backend_free;
   return backend;
 }
+
+#else
+
+struct imv_backend *imv_backend_librsvg(void)
+{
+  return NULL;
+}
+
+#endif
diff --git a/src/backend_rsvg.h b/src/backend_librsvg.h
index 126892a..16dd6c8 100644
--- a/src/backend_rsvg.h
+++ b/src/backend_librsvg.h
@@ -4,6 +4,6 @@
 struct imv_backend;
 
 /* Create an instance of the rsvg backend */
-struct imv_backend *imv_backend_rsvg(void);
+struct imv_backend *imv_backend_librsvg(void);
 
 #endif
diff --git a/src/main.c b/src/main.c
index 8b88340..06baced 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,9 +1,10 @@
 #include "imv.h"
 
 #include "backend.h"
+
 #include "backend_freeimage.h"
 #include "backend_libpng.h"
-#include "backend_rsvg.h"
+#include "backend_librsvg.h"
 
 int main(int argc, char** argv)
 {
@@ -13,9 +14,17 @@ int main(int argc, char** argv)
     return 1;
   }
 
-  imv_install_backend(imv, imv_backend_rsvg());
+#ifdef IMV_BACKEND_FREEIMAGE
   imv_install_backend(imv, imv_backend_freeimage());
+#endif
+
+#ifdef IMV_BACKEND_LIBPNG
   imv_install_backend(imv, imv_backend_libpng());
+#endif
+
+#ifdef IMV_BACKEND_LIBRSVG
+  imv_install_backend(imv, imv_backend_librsvg());
+#endif
 
   if(!imv_load_config(imv)) {
     imv_free(imv);