Build libsharpyuv as a full installable library.

Headers are installed in a "sharpyuv" subdirectory of the webp
dir, e.g. /usr/local/include/webp/sharpyuv/
Remove unnecessary dependency from sharpyuv to webp/types.h

Add SHARPYUV_EXTERN so that only symbols meant to be public
are exported.

Sharpyuv users can use the library with:

find_package(WebP)
if(TARGET WebP::sharpyuv)
  # ... use WebP::sharpyuv
endif()

Change-Id: I602a25521a135a2edc39d6587610484fe6447ec5

sharpyuv/Makefile.am

@@ -1,12 +1,16 @@
 AM_CPPFLAGS += -I$(top_builddir) -I$(top_srcdir)
 AM_CPPFLAGS += -I$(top_builddir)/src -I$(top_srcdir)/src
+
+lib_LTLIBRARIES = libsharpyuv.la
+
 noinst_LTLIBRARIES =
-noinst_LTLIBRARIES += libsharpyuv.la
 noinst_LTLIBRARIES += libsharpyuv_sse2.la
 noinst_LTLIBRARIES += libsharpyuv_neon.la
 
+libsharpyuvinclude_HEADERS =
+libsharpyuvinclude_HEADERS += sharpyuv.h
+libsharpyuvinclude_HEADERS += sharpyuv_csp.h
 noinst_HEADERS =
-noinst_HEADERS += ../src/webp/types.h
 noinst_HEADERS += ../src/dsp/cpu.h
 
 libsharpyuv_sse2_la_SOURCES =
@@ -26,9 +30,8 @@ libsharpyuv_la_SOURCES += sharpyuv_gamma.c sharpyuv_gamma.h
 libsharpyuv_la_SOURCES += sharpyuv.c sharpyuv.h
 
 libsharpyuv_la_CPPFLAGS = $(AM_CPPFLAGS)
-libsharpyuv_la_LDFLAGS =
+libsharpyuv_la_LDFLAGS = -no-undefined -version-info 0:0:0
 libsharpyuv_la_LIBADD =
 libsharpyuv_la_LIBADD += libsharpyuv_sse2.la
 libsharpyuv_la_LIBADD += libsharpyuv_neon.la
-
-noinst_PROGRAMS =
+libsharpyuvincludedir = $(includedir)/webp/sharpyuv

sharpyuv/sharpyuv.c

@@ -417,7 +417,7 @@ static int DoSharpArgbToYuv(const uint8_t* r_ptr, const uint8_t* g_ptr,
 // Hidden exported init function.
 // By default SharpYuvConvert calls it with NULL. If needed, users can declare
 // it as extern and call it with a VP8CPUInfo function.
-extern void SharpYuvInit(VP8CPUInfo cpu_info_func);
+SHARPYUV_EXTERN void SharpYuvInit(VP8CPUInfo cpu_info_func);
 void SharpYuvInit(VP8CPUInfo cpu_info_func) {
   static volatile VP8CPUInfo sharpyuv_last_cpuinfo_used =
       (VP8CPUInfo)&sharpyuv_last_cpuinfo_used;

sharpyuv/sharpyuv.h

@@ -18,6 +18,20 @@
 extern "C" {
 #endif
 
+#ifndef SHARPYUV_EXTERN
+#ifdef WEBP_EXTERN
+#define SHARPYUV_EXTERN WEBP_EXTERN
+#else
+// This explicitly marks library functions and allows for changing the
+// signature for e.g., Windows DLL builds.
+#if defined(__GNUC__) && __GNUC__ >= 4
+#define SHARPYUV_EXTERN extern __attribute__((visibility("default")))
+#else
+#define SHARPYUV_EXTERN extern
+#endif /* __GNUC__ >= 4 */
+#endif /* WEBP_EXTERN */
+#endif /* SHARPYUV_EXTERN */
+
 // SharpYUV API version following the convention from semver.org
 #define SHARPYUV_VERSION_MAJOR 0
 #define SHARPYUV_VERSION_MINOR 1
@@ -65,11 +79,13 @@ typedef struct {
 //     adjacent pixels on the y, u and v channels. If yuv_bit_depth > 8, they
 //     should be multiples of 2.
 // width, height: width and height of the image in pixels
-int SharpYuvConvert(const void* r_ptr, const void* g_ptr, const void* b_ptr,
-                    int rgb_step, int rgb_stride, int rgb_bit_depth,
-                    void* y_ptr, int y_stride, void* u_ptr, int u_stride,
-                    void* v_ptr, int v_stride, int yuv_bit_depth, int width,
-                    int height, const SharpYuvConversionMatrix* yuv_matrix);
+SHARPYUV_EXTERN int SharpYuvConvert(const void* r_ptr, const void* g_ptr,
+                                    const void* b_ptr, int rgb_step,
+                                    int rgb_stride, int rgb_bit_depth,
+                                    void* y_ptr, int y_stride, void* u_ptr,
+                                    int u_stride, void* v_ptr, int v_stride,
+                                    int yuv_bit_depth, int width, int height,
+                                    const SharpYuvConversionMatrix* yuv_matrix);
 
 // TODO(b/194336375): Add YUV444 to YUV420 conversion. Maybe also add 422
 // support (it's rarely used in practice, especially for images).

sharpyuv/sharpyuv_csp.h

@@ -35,8 +35,9 @@ typedef struct {
 } SharpYuvColorSpace;
 
 // Fills in 'matrix' for the given YUVColorSpace.
-void SharpYuvComputeConversionMatrix(const SharpYuvColorSpace* yuv_color_space,
-                                     SharpYuvConversionMatrix* matrix);
+SHARPYUV_EXTERN void SharpYuvComputeConversionMatrix(
+    const SharpYuvColorSpace* yuv_color_space,
+    SharpYuvConversionMatrix* matrix);
 
 // Enums for precomputed conversion matrices.
 typedef enum {
@@ -49,7 +50,7 @@ typedef enum {
 } SharpYuvMatrixType;
 
 // Returns a pointer to a matrix for one of the predefined colorspaces.
-const SharpYuvConversionMatrix* SharpYuvGetConversionMatrix(
+SHARPYUV_EXTERN const SharpYuvConversionMatrix* SharpYuvGetConversionMatrix(
     SharpYuvMatrixType matrix_type);
 
 #ifdef __cplusplus