add examples/ dir

plus one example

examples/annotate-animated.c

@@ -0,0 +1,105 @@
+/* Draw something on every frame of an animated image.
+ *
+ * compile with:
+ *
+ * 	gcc -g -Wall annotate-animated.c `pkg-config vips --cflags --libs`
+ *
+ * run with:
+ *
+ *      annotate-animated ~/pics/3198.gif[n=-1] x.webp
+ */
+
+#include <vips/vips.h>
+
+static int
+annotate_image( VipsObject *context, VipsImage *image, VipsImage **out )
+{
+	int page_height = vips_image_get_page_height( image );
+	int n_pages = image->Ysize / page_height;
+	VipsImage **overlay = (VipsImage **)
+		vips_object_local_array( context, n_pages );
+	VipsImage **page = (VipsImage **)
+		vips_object_local_array( context, n_pages );
+	VipsImage **annotated = (VipsImage **)
+		vips_object_local_array( context, n_pages );
+
+	/* Red as RGBA.
+	 */
+	double red[] = { 255, 0, 0, 255 };
+	double transparent[] = { 0, 0, 0, 0 };
+
+	int i;
+
+	/* Split the image into frames.
+	 */
+	for( i = 0; i < n_pages; i++ )
+		if( vips_crop( image, &page[i],
+			0, page_height * i, image->Xsize, page_height, NULL ) )
+			return( -1 );
+
+	/* Make an overlay ... a solid red square, with a transparent hole.
+	 */
+	if( 
+		!(overlay[0] = vips_image_new_from_image( page[0], 
+			red, VIPS_NUMBER( red ) )) ||
+		vips_draw_rect( overlay[0], 
+			transparent, VIPS_NUMBER( transparent ),
+			10, 10, overlay[0]->Xsize - 20, overlay[0]->Ysize - 20,
+			"fill", TRUE,
+			NULL ) )
+		return( -1 );
+
+	/* Draw the overlay on every page.
+	 */
+	for( i = 0; i < n_pages; i++ )
+		if( vips_composite2( page[i], overlay[0], &annotated[i],
+			VIPS_BLEND_MODE_OVER, NULL ) )
+			return( -1 );
+
+	/* Reassemble the frames.
+	 */
+	if( vips_arrayjoin( annotated, out, n_pages, 
+		"across", 1,
+		NULL ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+int 
+main( int argc, char **argv )
+{
+	VipsImage *image;
+	VipsObject *context;
+	VipsImage *x;
+
+	if( VIPS_INIT( "" ) ) 
+		vips_error_exit( NULL ); 
+
+        if( argc != 3 ) 
+		vips_error_exit( "usage: %s xxx.gif[n=-1] yyy.gif", argv[0] ); 
+
+	if( !(image = vips_image_new_from_file( argv[1], 
+		"access", VIPS_ACCESS_SEQUENTIAL,
+		NULL )) )
+		vips_error_exit( NULL ); 
+
+	context = VIPS_OBJECT( vips_image_new() );
+	if( annotate_image( context, image, &x ) ) {
+		g_object_unref( image );
+		g_object_unref( context );
+		vips_error_exit( NULL ); 
+	}
+	g_object_unref( image );
+	g_object_unref( context );
+	image = x;
+
+	if( vips_image_write_to_file( image, argv[2], NULL ) ) {
+		g_object_unref( image );
+		vips_error_exit( NULL ); 
+	}
+
+	g_object_unref( image );
+
+	return( 0 );
+}

examples/meson.build

@@ -0,0 +1,11 @@
+examples = [
+    'annotate-animated',
+]
+
+foreach example : examples
+    executable(example,
+        example + '.c',
+        dependencies: libvips_dep,
+    )
+endforeach
+

meson.build

@@ -686,5 +686,6 @@ subdir('cplusplus')
 subdir('man')
 subdir('po')
 subdir('tools')
+subdir('examples')
 subdir('test')
 subdir('fuzz')