autotools: correctly build canvas-related code

spice client and spice server shares code from
common/{gdi,gl,sw}_canvas.[ch]. However, while most of the code is
shared, the server code wants a canvas compiled with
SW_CANVAS_IMAGE_CACHE defined while the client code wants a canvas
compiled with SW_CANVAS_CACHE.

The initial autotools refactoring didn't take that into account,
this is now fixed by this commit. After this commit, the canvas
files from common/ are no longer compiled as part of the
libspice-common.la convenience library. Instead, there are "proxy"
canvas source files in client/ and server/ which #include the
appropriate C files after defining the relevant #define for the
binary that is being built.

To prevent misuse of the canvas c files and headers in common/,
SPICE_CANVAS_INTERNAL must be set when including the canvas headers
from common/ or when building the c files from common/ otherwise
the build will error out.

Makefile.am

@@ -6,7 +6,6 @@ NULL =
 
 noinst_LTLIBRARIES = libspice-common.la
 libspice_common_la_SOURCES =		\
-	canvas_base.h			\
 	canvas_utils.c			\
 	canvas_utils.h			\
 	draw.h				\
@@ -34,21 +33,10 @@ libspice_common_la_SOURCES =		\
 	rop3.c				\
 	rop3.h				\
 	spice_common.h			\
-	sw_canvas.c			\
-	sw_canvas.h			\
 	$(NULL)
 
-if OS_WIN32
-libspice_common_la_SOURCES +=		\
-	gdi_canvas.h			\
-	gdi_canvas.c			\
-	$(NULL)
-endif
-
 if SUPPORT_GL
 libspice_common_la_SOURCES +=		\
-	gl_canvas.h			\
-	gl_canvas.c			\
 	gl_utils.h			\
 	glc.h				\
 	glc.c				\
@@ -58,7 +46,6 @@ libspice_common_la_SOURCES +=		\
 endif
 
 INCLUDES = \
-	-DSW_CANVAS_IMAGE_CACHE		\
 	$(GL_CFLAGS)			\
 	$(PIXMAN_CFLAGS)		\
 	$(PROTOCOL_CFLAGS)		\
@@ -69,6 +56,13 @@ INCLUDES = \
 
 EXTRA_DIST =				\
 	canvas_base.c			\
+	canvas_base.h			\
+	gdi_canvas.c			\
+	gdi_canvas.h			\
+	gl_canvas.c			\
+	gl_canvas.h			\
+	sw_canvas.c			\
+	sw_canvas.h			\
 	lz_compress_tmpl.c		\
 	lz_decompress_tmpl.c		\
 	quic_family_tmpl.c		\

canvas_base.c

@@ -16,6 +16,10 @@
    License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This file shouldn't be compiled directly"
+#endif
+
 #include <stdarg.h>
 #include <stdlib.h>
 #include <setjmp.h>

canvas_base.h

@@ -19,6 +19,9 @@
 #ifndef _H_CANVAS_BASE
 #define _H_CANVAS_BASE
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This header shouldn't be included directly"
+#endif
 
 #include "pixman_utils.h"
 #include "lz.h"

gdi_canvas.c

@@ -16,6 +16,11 @@
    License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
 
+
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This file shouldn't be compiled directly"
+#endif
+
 #include <windows.h>
 #include <wingdi.h>
 #include "gdi_canvas.h"

gdi_canvas.h

@@ -19,6 +19,10 @@
 #ifndef _H__GDI_CANVAS
 #define _H__GDI_CANVAS
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This header shouldn't be included directly"
+#endif
+
 #include <stdint.h>
 
 #ifdef __cplusplus

gl_canvas.c

@@ -16,11 +16,14 @@
    License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This file shouldn't be compiled directly"
+#endif
+
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include "gl_canvas.h"
 #include "quic.h"
 #include "rop3.h"
 #include "region.h"

gl_canvas.h

@@ -20,6 +20,10 @@
 #include "canvas_base.h"
 #include "region.h"
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This header shouldn't be included directly"
+#endif
+
 #ifndef _H__GL_CANVAS
 #define _H__GL_CANVAS
 

sw_canvas.c

@@ -16,6 +16,10 @@
    License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This file shouldn't be compiled directly"
+#endif
+
 #include <math.h>
 #include "sw_canvas.h"
 #define CANVAS_USE_PIXMAN

sw_canvas.h

@@ -19,6 +19,10 @@
 #ifndef _H__CANVAS
 #define _H__CANVAS
 
+#ifndef SPICE_CANVAS_INTERNAL
+#error "This header shouldn't be included directly"
+#endif
+
 #include <stdint.h>
 
 #include "draw.h"