From d836166087ae295da654a674f4540dd2547513aa Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Fri, 9 Sep 2022 10:14:59 +0100
Subject: [PATCH] add some more examples

---
 examples/meson.build       |  2 +
 examples/new-from-buffer.c | 54 ++++++++++++++++++++++++++
 examples/progress-cancel.c | 78 ++++++++++++++++++++++++++++++++++++++
 meson.build                |  5 ++-
 meson_options.txt          |  5 +++
 5 files changed, 143 insertions(+), 1 deletion(-)
 create mode 100644 examples/new-from-buffer.c
 create mode 100644 examples/progress-cancel.c

diff --git a/examples/meson.build b/examples/meson.build
index 663deaa0..f75ac3b4 100644
--- a/examples/meson.build
+++ b/examples/meson.build
@@ -1,5 +1,7 @@
 examples = [
     'annotate-animated',
+    'new-from-buffer',
+    'progress-cancel',
 ]
 
 foreach example : examples
diff --git a/examples/new-from-buffer.c b/examples/new-from-buffer.c
new file mode 100644
index 00000000..db3f979a
--- /dev/null
+++ b/examples/new-from-buffer.c
@@ -0,0 +1,54 @@
+/* Read and write formatted images to memory.
+ *
+ * Compile with: 
+ *
+ * 	gcc -g -Wall new-from-buffer.c `pkg-config vips --cflags --libs`
+ *
+ */
+
+#include <vips/vips.h>
+
+int 
+main( int argc, char **argv )
+{
+	gchar *buf;
+	gsize len;
+	int i;
+
+	if( VIPS_INIT( argv[0] ) )
+		vips_error_exit( NULL );
+
+        if( argc != 2 ) 
+		vips_error_exit( "usage: %s FILENAME", argv[0] ); 
+
+	if( !g_file_get_contents( argv[1], &buf, &len, NULL ) )
+		vips_error_exit( NULL );
+
+	for( i = 0; i < 10; i++ ) {
+		VipsImage *image;
+		void *new_buf;
+		size_t new_len;
+
+		printf( "loop %d ...\n", i );
+
+		if( !(image = vips_image_new_from_buffer( buf, len, "", 
+			"access", VIPS_ACCESS_SEQUENTIAL,
+			NULL )) ) 
+			vips_error_exit( NULL );
+
+		if( vips_image_write_to_buffer( image, 
+			".jpg", &new_buf, &new_len, 
+			"Q", 95,
+			NULL ) ) 
+			vips_error_exit( NULL );
+
+		g_object_unref( image );
+		g_free( new_buf );
+	}
+
+	g_free( buf );
+
+	vips_shutdown();
+
+	return( 0 );
+}
diff --git a/examples/progress-cancel.c b/examples/progress-cancel.c
new file mode 100644
index 00000000..86b7b51c
--- /dev/null
+++ b/examples/progress-cancel.c
@@ -0,0 +1,78 @@
+/* Show progress feedback and computation cancel.
+ *
+ * compile with
+ *
+ * gcc -g -Wall progress-cancel.c `pkg-config vips --cflags --libs`
+ */
+
+#include <stdio.h>
+#include <vips/vips.h>
+#include <errno.h>
+
+void 
+preeval_callback( VipsImage *image, VipsProgress *progress, void* pdata )
+{
+	printf( "preeval_callback:\n" );
+}
+
+void 
+eval_callback( VipsImage *image, VipsProgress *progress, void* pdata )
+{
+	printf( "eval_callback: percent = %d\n", progress->percent );
+
+	if( progress->percent >= 25 ) {
+		printf( "calling vips_image_set_kill() ...\n" );
+		vips_image_set_kill( image, TRUE );
+	}
+}
+
+void 
+posteval_callback( VipsImage *image, VipsProgress *progress, void* pdata )
+{
+	printf( "posteval_callback: finished in %.3gs\n", 
+                g_timer_elapsed( progress->start, NULL ) );
+}
+
+int 
+main( int argc, char **argv )
+{
+	VipsImage *image;
+	VipsImage *out;
+	void *output;
+	size_t output_length;
+
+	if( VIPS_INIT( argv[0] ) )
+		vips_error_exit( NULL );
+
+        if( argc != 3 ) 
+		vips_error_exit( "usage: %s INPUT-FILE OUTPUT-FILE", argv[0] ); 
+
+	if( !(image = vips_image_new_from_file( argv[1], 
+		"access", VIPS_ACCESS_SEQUENTIAL, 
+		NULL )) )
+		vips_error_exit( NULL );
+
+	if( vips_resize( image, &out, 0.5, NULL ) )
+		vips_error_exit( NULL );
+
+	vips_image_set_progress( out, TRUE );
+	g_signal_connect( out, "preeval", 
+                G_CALLBACK( preeval_callback ), NULL );
+	g_signal_connect( out, "eval", 
+                G_CALLBACK( eval_callback ), NULL );
+	g_signal_connect( out, "posteval", 
+                G_CALLBACK( posteval_callback ), NULL );
+
+	output = NULL;
+	if( vips_image_write_to_buffer( out, argv[2], &output, &output_length, 
+		NULL ) ) 
+		printf( "error return from vips_image_write_to_buffer()\n" );
+
+	g_object_unref( out );
+	g_object_unref( image );
+	if( output )
+		g_free( output );
+	vips_shutdown();
+
+	return 0;
+}
diff --git a/meson.build b/meson.build
index 6dd1c10e..f241dd73 100644
--- a/meson.build
+++ b/meson.build
@@ -633,6 +633,7 @@ build_summary = {
      'enable gtk-doc': [get_option('gtk_doc')],
      'enable doxygen': [get_option('doxygen')],
      'enable introspection': [get_option('introspection')],
+     'enable examples': [get_option('examples')],
      'enable RAD load/save': [get_option('radiance')],
      'enable Analyze7 load/save': [get_option('analyze')],
      'enable PPM load/save': [get_option('ppm')],
@@ -686,6 +687,8 @@ subdir('cplusplus')
 subdir('man')
 subdir('po')
 subdir('tools')
-subdir('examples')
+if get_option('examples')
+  subdir('examples')
+endif
 subdir('test')
 subdir('fuzz')
diff --git a/meson_options.txt b/meson_options.txt
index 0fa8f645..5afc5ef5 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -5,6 +5,11 @@ option('deprecated',
   value: true, 
   description: 'Build deprecated components')
 
+option('examples', 
+  type: 'boolean', 
+  value: true, 
+  description: 'Build example programs')
+
 option('doxygen', 
   type: 'boolean', 
   value: false,