boilerplate: Add a describe vfunc

This function is supposed to describe the backend in use. The describe
function is optional - and therefore initialized as NULL everywhere.
Note:
It is well known that the xlib backend uses X. What is not known is what
version the server supports or what graphics card it is running on. That
is the information the describe vfunc is supposed to provide.

20 files changed, 71 insertions, 34 deletions

diff --git a/boilerplate/Makefile.win32.features b/boilerplate/Makefile.win32.features
index fd0e9c73..d79fe2f2 100644
--- a/boilerplate/Makefile.win32.features
+++ b/boilerplate/Makefile.win32.features
@@ -209,6 +209,14 @@ enabled_cairo_boilerplate_private += $(cairo_boilerplate_png_private)
 enabled_cairo_boilerplate_sources += $(cairo_boilerplate_png_sources)
 endif
 
+supported_cairo_boilerplate_headers += $(cairo_boilerplate_glew_headers)
+all_cairo_boilerplate_headers += $(cairo_boilerplate_glew_headers)
+all_cairo_boilerplate_private += $(cairo_boilerplate_glew_private)
+all_cairo_boilerplate_sources += $(cairo_boilerplate_glew_sources)
+enabled_cairo_boilerplate_headers += $(cairo_boilerplate_glew_headers)
+enabled_cairo_boilerplate_private += $(cairo_boilerplate_glew_private)
+enabled_cairo_boilerplate_sources += $(cairo_boilerplate_glew_sources)
+
 unsupported_cairo_boilerplate_headers += $(cairo_boilerplate_gl_headers)
 all_cairo_boilerplate_headers += $(cairo_boilerplate_gl_headers)
 all_cairo_boilerplate_private += $(cairo_boilerplate_gl_private)
diff --git a/boilerplate/cairo-boilerplate-directfb.c b/boilerplate/cairo-boilerplate-directfb.c
index 39252aca..6b657f1d 100644
--- a/boilerplate/cairo-boilerplate-directfb.c
+++ b/boilerplate/cairo-boilerplate-directfb.c
@@ -217,7 +217,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_directfb_cleanup,
-	NULL, TRUE, FALSE, FALSE
+	NULL, NULL, TRUE, FALSE, FALSE
     },
     {
 	"directfb-bitmap", "directfb", NULL, NULL,
@@ -228,7 +228,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_directfb_cleanup,
-	NULL, FALSE, FALSE, FALSE
+	NULL, NULL, FALSE, FALSE, FALSE
     },
 };
 CAIRO_BOILERPLATE (directfb, targets);
diff --git a/boilerplate/cairo-boilerplate-drm.c b/boilerplate/cairo-boilerplate-drm.c
index 5d5d17f7..40c7049d 100644
--- a/boilerplate/cairo-boilerplate-drm.c
+++ b/boilerplate/cairo-boilerplate-drm.c
@@ -85,6 +85,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	NULL,
 	_cairo_boilerplate_drm_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -97,6 +98,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	NULL,
 	_cairo_boilerplate_drm_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 };
diff --git a/boilerplate/cairo-boilerplate-egl.c b/boilerplate/cairo-boilerplate-egl.c
index 0bf28559..75439a9b 100644
--- a/boilerplate/cairo-boilerplate-egl.c
+++ b/boilerplate/cairo-boilerplate-egl.c
@@ -139,6 +139,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_egl_cleanup,
 	_cairo_boilerplate_egl_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     }
 };
diff --git a/boilerplate/cairo-boilerplate-glx.c b/boilerplate/cairo-boilerplate-glx.c
index a3e0338d..3fe7149e 100644
--- a/boilerplate/cairo-boilerplate-glx.c
+++ b/boilerplate/cairo-boilerplate-glx.c
@@ -357,6 +357,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_gl_cleanup,
 	_cairo_boilerplate_gl_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -369,6 +370,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_gl_cleanup,
 	_cairo_boilerplate_gl_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -382,6 +384,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_gl_cleanup,
 	_cairo_boilerplate_gl_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -395,6 +398,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_gl_cleanup,
 	_cairo_boilerplate_gl_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 };
diff --git a/boilerplate/cairo-boilerplate-pdf.c b/boilerplate/cairo-boilerplate-pdf.c
index 9d83b937..6f4afe97 100644
--- a/boilerplate/cairo-boilerplate-pdf.c
+++ b/boilerplate/cairo-boilerplate-pdf.c
@@ -249,7 +249,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_pdf_get_image_surface,
 	_cairo_boilerplate_pdf_surface_write_to_png,
 	_cairo_boilerplate_pdf_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"pdf", "pdf", ".pdf", NULL,
@@ -261,7 +261,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_pdf_get_image_surface,
 	_cairo_boilerplate_pdf_surface_write_to_png,
 	_cairo_boilerplate_pdf_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
 #endif
 };
diff --git a/boilerplate/cairo-boilerplate-ps.c b/boilerplate/cairo-boilerplate-ps.c
index de5a6eab..09dce6e1 100644
--- a/boilerplate/cairo-boilerplate-ps.c
+++ b/boilerplate/cairo-boilerplate-ps.c
@@ -310,7 +310,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_ps_get_image_surface,
 	_cairo_boilerplate_ps_surface_write_to_png,
 	_cairo_boilerplate_ps_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"ps2", "ps", ".ps", NULL,
@@ -322,7 +322,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_ps_get_image_surface,
 	_cairo_boilerplate_ps_surface_write_to_png,
 	_cairo_boilerplate_ps_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"ps3", "ps", ".ps", NULL,
@@ -335,7 +335,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_ps_get_image_surface,
 	_cairo_boilerplate_ps_surface_write_to_png,
 	_cairo_boilerplate_ps_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"ps3", "ps", ".ps", NULL,
@@ -347,7 +347,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_ps_get_image_surface,
 	_cairo_boilerplate_ps_surface_write_to_png,
 	_cairo_boilerplate_ps_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
 #endif
 };
diff --git a/boilerplate/cairo-boilerplate-quartz.c b/boilerplate/cairo-boilerplate-quartz.c
index 19d5928d..67bd5bbb 100644
--- a/boilerplate/cairo-boilerplate-quartz.c
+++ b/boilerplate/cairo-boilerplate-quartz.c
@@ -57,7 +57,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL,
+	NULL, NULL, NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -68,7 +68,8 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL,
+        FALSE, FALSE, FALSE
     },
 };
 CAIRO_BOILERPLATE (quartz, targets)
diff --git a/boilerplate/cairo-boilerplate-script.c b/boilerplate/cairo-boilerplate-script.c
index 535ca540..f84594d3 100644
--- a/boilerplate/cairo-boilerplate-script.c
+++ b/boilerplate/cairo-boilerplate-script.c
@@ -136,6 +136,6 @@ static const cairo_boilerplate_target_t target[] = {{
     _cairo_boilerplate_script_get_image_surface,
     _cairo_boilerplate_script_surface_write_to_png,
     _cairo_boilerplate_script_cleanup,
-    NULL, FALSE, FALSE, FALSE
+    NULL, NULL, FALSE, FALSE, FALSE
 }};
 CAIRO_BOILERPLATE (script, target)
diff --git a/boilerplate/cairo-boilerplate-skia.c b/boilerplate/cairo-boilerplate-skia.c
index 34c19f15..eb3d4406 100644
--- a/boilerplate/cairo-boilerplate-skia.c
+++ b/boilerplate/cairo-boilerplate-skia.c
@@ -38,7 +38,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, TRUE, FALSE, FALSE
+	NULL, NULL, NULL, TRUE, FALSE, FALSE
     },
     {
 	"skia", "skia", NULL, NULL,
@@ -48,7 +48,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
 };
 CAIRO_BOILERPLATE (skia, targets)
diff --git a/boilerplate/cairo-boilerplate-svg.c b/boilerplate/cairo-boilerplate-svg.c
index a7d6c797..a0bbba6f 100644
--- a/boilerplate/cairo-boilerplate-svg.c
+++ b/boilerplate/cairo-boilerplate-svg.c
@@ -286,7 +286,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_svg_get_image_surface,
 	_cairo_boilerplate_svg_surface_write_to_png,
 	_cairo_boilerplate_svg_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"svg11", "svg", NULL, NULL,
@@ -298,7 +298,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_svg_get_image_surface,
 	_cairo_boilerplate_svg_surface_write_to_png,
 	_cairo_boilerplate_svg_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"svg12", "svg", NULL, NULL,
@@ -310,7 +310,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_svg_get_image_surface,
 	_cairo_boilerplate_svg_surface_write_to_png,
 	_cairo_boilerplate_svg_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"svg12", "svg", NULL, NULL,
@@ -322,7 +322,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_svg_get_image_surface,
 	_cairo_boilerplate_svg_surface_write_to_png,
 	_cairo_boilerplate_svg_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
 #endif
 };
diff --git a/boilerplate/cairo-boilerplate-test-surfaces.c b/boilerplate/cairo-boilerplate-test-surfaces.c
index d3572ec5..993e211d 100644
--- a/boilerplate/cairo-boilerplate-test-surfaces.c
+++ b/boilerplate/cairo-boilerplate-test-surfaces.c
@@ -238,7 +238,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
     {
 	"test-fallback", "image", NULL, NULL,
@@ -249,7 +249,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
     {
 	"test-fallback16", "image", NULL, NULL,
@@ -260,7 +260,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	NULL, /* _cairo_boilerplate_get_image_surface, */
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
     {
 	"test-fallback16", "image", NULL, NULL,
@@ -271,7 +271,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	NULL, /* _cairo_boilerplate_get_image_surface, */
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
 #if CAIRO_HAS_TEST_PAGINATED_SURFACE
     {
@@ -284,7 +284,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_test_paginated_get_image_surface,
 	_cairo_boilerplate_test_paginated_surface_write_to_png,
 	_cairo_boilerplate_test_paginated_cleanup,
-	NULL, FALSE, TRUE, FALSE
+	NULL, NULL, FALSE, TRUE, FALSE
     },
     {
 	"test-paginated", "image", NULL, NULL,
@@ -296,7 +296,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_test_paginated_get_image_surface,
 	_cairo_boilerplate_test_paginated_surface_write_to_png,
 	_cairo_boilerplate_test_paginated_cleanup,
-	NULL, FALSE, TRUE, FALSE
+	NULL, NULL, FALSE, TRUE, FALSE
     },
 #endif
 #if CAIRO_HAS_TEST_WRAPPING_SURFACE
@@ -309,7 +309,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
 #endif
 #if CAIRO_HAS_TEST_NULL_SURFACE
@@ -321,7 +321,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_test_null_create_surface,
 	NULL, NULL,
 	NULL, NULL, NULL,
-	NULL,
+	NULL, NULL,
 	TRUE, TRUE, FALSE
     },
 #endif
diff --git a/boilerplate/cairo-boilerplate-vg.c b/boilerplate/cairo-boilerplate-vg.c
index 9803dcc1..d5a13729 100644
--- a/boilerplate/cairo-boilerplate-vg.c
+++ b/boilerplate/cairo-boilerplate-vg.c
@@ -312,6 +312,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_vg_cleanup_glx,
 	_cairo_boilerplate_vg_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -324,6 +325,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_vg_cleanup_glx,
 	_cairo_boilerplate_vg_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 #endif
@@ -338,6 +340,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_vg_cleanup_egl,
 	_cairo_boilerplate_vg_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -350,6 +353,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_vg_cleanup_egl,
 	_cairo_boilerplate_vg_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 #endif
diff --git a/boilerplate/cairo-boilerplate-wgl.c b/boilerplate/cairo-boilerplate-wgl.c
index 35e317eb..2215659f 100644
--- a/boilerplate/cairo-boilerplate-wgl.c
+++ b/boilerplate/cairo-boilerplate-wgl.c
@@ -218,6 +218,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_wgl_cleanup,
 	_cairo_boilerplate_wgl_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -231,6 +232,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_wgl_cleanup,
 	_cairo_boilerplate_wgl_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 };
diff --git a/boilerplate/cairo-boilerplate-win32-printing.c b/boilerplate/cairo-boilerplate-win32-printing.c
index e1509951..0d706204 100644
--- a/boilerplate/cairo-boilerplate-win32-printing.c
+++ b/boilerplate/cairo-boilerplate-win32-printing.c
@@ -354,7 +354,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_win32_printing_get_image_surface,
 	_cairo_boilerplate_win32_printing_surface_write_to_png,
 	_cairo_boilerplate_win32_printing_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
     {
 	"win32-printing", "win32", ".ps", NULL,
@@ -365,7 +365,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	_cairo_boilerplate_win32_printing_get_image_surface,
 	_cairo_boilerplate_win32_printing_surface_write_to_png,
 	_cairo_boilerplate_win32_printing_cleanup,
-	NULL, FALSE, TRUE, TRUE
+	NULL, NULL, FALSE, TRUE, TRUE
     },
 #endif
 };
diff --git a/boilerplate/cairo-boilerplate-win32.c b/boilerplate/cairo-boilerplate-win32.c
index 72176c87..5194befc 100644
--- a/boilerplate/cairo-boilerplate-win32.c
+++ b/boilerplate/cairo-boilerplate-win32.c
@@ -57,7 +57,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, TRUE, FALSE, FALSE
+	NULL, NULL, NULL, TRUE, FALSE, FALSE
     },
     /* Testing the win32 surface isn't interesting, since for
      * ARGB images it just chains to the image backend
@@ -70,7 +70,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL, FALSE, FALSE, FALSE
+	NULL, NULL, NULL, FALSE, FALSE, FALSE
     },
 };
 CAIRO_BOILERPLATE (win32, targets)
diff --git a/boilerplate/cairo-boilerplate-xcb.c b/boilerplate/cairo-boilerplate-xcb.c
index b16b1998..0cac82b1 100644
--- a/boilerplate/cairo-boilerplate-xcb.c
+++ b/boilerplate/cairo-boilerplate-xcb.c
@@ -623,6 +623,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -636,6 +637,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -649,6 +651,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -662,6 +665,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -675,6 +679,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -688,6 +693,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -701,6 +707,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xcb_cleanup,
 	_cairo_boilerplate_xcb_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 };
diff --git a/boilerplate/cairo-boilerplate-xlib.c b/boilerplate/cairo-boilerplate-xlib.c
index 906b5548..db42d67f 100644
--- a/boilerplate/cairo-boilerplate-xlib.c
+++ b/boilerplate/cairo-boilerplate-xlib.c
@@ -495,6 +495,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xlib_cleanup,
 	_cairo_boilerplate_xlib_synchronize,
+        NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -507,6 +508,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xlib_cleanup,
 	_cairo_boilerplate_xlib_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -519,6 +521,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xlib_cleanup,
 	_cairo_boilerplate_xlib_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 #endif
@@ -535,6 +538,7 @@ static const cairo_boilerplate_target_t targets[] = {
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_xlib_cleanup,
 	_cairo_boilerplate_xlib_synchronize,
+        NULL,
 	FALSE, FALSE, FALSE
     },
 #endif
diff --git a/boilerplate/cairo-boilerplate.c b/boilerplate/cairo-boilerplate.c
index 7bbc1e6e..529a4f21 100644
--- a/boilerplate/cairo-boilerplate.c
+++ b/boilerplate/cairo-boilerplate.c
@@ -326,7 +326,7 @@ static const cairo_boilerplate_target_t builtin_targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL,
+	NULL, NULL, NULL,
 	TRUE, FALSE, FALSE
     },
     {
@@ -336,7 +336,7 @@ static const cairo_boilerplate_target_t builtin_targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL,
+	NULL, NULL, NULL,
 	FALSE, FALSE, FALSE
     },
     {
@@ -346,7 +346,7 @@ static const cairo_boilerplate_target_t builtin_targets[] = {
 	NULL, NULL,
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
-	NULL, NULL,
+	NULL, NULL, NULL,
 	TRUE, FALSE, FALSE
     },
 #if CAIRO_HAS_RECORDING_SURFACE
@@ -359,7 +359,7 @@ static const cairo_boilerplate_target_t builtin_targets[] = {
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_recording_surface_cleanup,
-	NULL,
+	NULL, NULL,
 	FALSE, FALSE, TRUE
     },
     {
@@ -371,7 +371,7 @@ static const cairo_boilerplate_target_t builtin_targets[] = {
 	_cairo_boilerplate_get_image_surface,
 	cairo_surface_write_to_png,
 	_cairo_boilerplate_recording_surface_cleanup,
-	NULL,
+	NULL, NULL,
 	FALSE, FALSE, TRUE
     },
 #endif
diff --git a/boilerplate/cairo-boilerplate.h b/boilerplate/cairo-boilerplate.h
index 38df3b9b..dae17ea4 100644
--- a/boilerplate/cairo-boilerplate.h
+++ b/boilerplate/cairo-boilerplate.h
@@ -149,6 +149,9 @@ typedef void
 typedef void
 (*cairo_boilerplate_wait_t) (void *closure);
 
+typedef char *
+(*cairo_boilerplate_describe_t) (void *closure);
+
 typedef struct _cairo_boilerplate_target {
     const char					*name;
     const char					*basename;
@@ -165,6 +168,7 @@ typedef struct _cairo_boilerplate_target {
     cairo_boilerplate_write_to_png_t		 write_to_png;
     cairo_boilerplate_cleanup_t 		 cleanup;
     cairo_boilerplate_wait_t			 synchronize;
+    cairo_boilerplate_describe_t                 describe;
     cairo_bool_t				 is_measurable;
     cairo_bool_t				 is_vector;
     cairo_bool_t				 is_recording;