[PATCH weston] configure: Make libjpeg an optional dependency

[Emmanuel Gil Peyrot]

libjpeg is only used in shared/image-loader.c in weston, like libwebp
it doesn’t make sense to fail the entire build if it isn’t present, for
any reason.

I kept libpng a hard dependency in the image-loader because so many
other parts of weston depend on PNG, it is already mandatory from
everywhere else.

Signed-off-by: Emmanuel Gil Peyrot <linkmauve at linkmauve.fr>
---
 configure.ac          |  8 ++++----
 shared/image-loader.c | 23 ++++++++++++++++-------
 2 files changed, 20 insertions(+), 11 deletions(-)

diff --git a/configure.ac b/configure.ac
index bff6380..c42e32b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -311,13 +311,12 @@ fi
 AM_CONDITIONAL(ENABLE_VAAPI_RECORDER, test "x$have_libva" = xyes)
 
 
-AC_CHECK_LIB([jpeg], [jpeg_CreateDecompress], have_jpeglib=yes)
+AC_CHECK_LIB([jpeg], [jpeg_CreateDecompress], [have_jpeglib=yes], [have_jpeglib=no])
 if test x$have_jpeglib = xyes; then
   JPEG_LIBS="-ljpeg"
-else
-  AC_ERROR([libjpeg not found])
+  AC_SUBST(JPEG_LIBS)
+  AC_DEFINE([HAVE_JPEG], [1], [Have jpeg])
 fi
-AC_SUBST(JPEG_LIBS)
 
 PKG_CHECK_MODULES(CAIRO, [cairo])
 
@@ -676,6 +675,7 @@ AC_MSG_RESULT([
 
 	Colord Support			${have_colord}
 	LCMS2 Support			${have_lcms}
+	libjpeg Support			${have_jpeglib}
 	libwebp Support			${have_webp}
 	libunwind Support		${have_libunwind}
 	VA H.264 encoding Support	${have_libva}
diff --git a/shared/image-loader.c b/shared/image-loader.c
index ec75bd4..e6c0c7d 100644
--- a/shared/image-loader.c
+++ b/shared/image-loader.c
@@ -30,13 +30,16 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
-#include <jpeglib.h>
 #include <png.h>
 #include <pixman.h>
 
 #include "shared/helpers.h"
 #include "image-loader.h"
 
+#ifdef HAVE_JPEG
+#include <jpeglib.h>
+#endif
+
 #ifdef HAVE_WEBP
 #include <webp/decode.h>
 #endif
@@ -48,6 +51,14 @@ stride_for_width(int width)
 }
 
 static void
+pixman_image_destroy_func(pixman_image_t *image, void *data)
+{
+	free(data);
+}
+
+#ifdef HAVE_JPEG
+
+static void
 swizzle_row(JSAMPLE *row, JDIMENSION width)
 {
 	JSAMPLE *s;
@@ -68,12 +79,6 @@ error_exit(j_common_ptr cinfo)
 	longjmp(cinfo->client_data, 1);
 }
 
-static void
-pixman_image_destroy_func(pixman_image_t *image, void *data)
-{
-	free(data);
-}
-
 static pixman_image_t *
 load_jpeg(FILE *fp)
 {
@@ -132,6 +137,8 @@ load_jpeg(FILE *fp)
 	return pixman_image;
 }
 
+#endif
+
 static inline int
 multiply_alpha(int alpha, int color)
 {
@@ -363,7 +370,9 @@ struct image_loader {
 
 static const struct image_loader loaders[] = {
 	{ { 0x89, 'P', 'N', 'G' }, 4, load_png },
+#ifdef HAVE_JPEG
 	{ { 0xff, 0xd8 }, 2, load_jpeg },
+#endif
 #ifdef HAVE_WEBP
 	{ { 'R', 'I', 'F', 'F' }, 4, load_webp }
 #endif
-- 
2.7.0