Add support for marshaling pointers

CHANGELOG.rst

@@ -8,6 +8,7 @@
 - add test coverage for type stubs [JoshCLWren]
 - add `Image.pil()` to convert to a PIL image [jonashaag]
 - add `pyvips.concurrency_set()`, `pyvips.concurrency_get()` [NewUserHa]
+- add support for marshaling pointers [kleisauke]
 
 ## Version 3.1.1 (released 9 December 2025)
 

examples/draw_line.py

@@ -0,0 +1,20 @@
+#!/usr/bin/env python3
+
+# import logging
+# logging.basicConfig(level = logging.DEBUG)
+
+import pyvips
+from pyvips import ffi
+
+
+def custom_draw(image, ink, x, y, client):
+    assert ffi.from_handle(client) == 42
+    print(x, y)
+
+
+cb = ffi.callback('VipsDrawPoint', custom_draw)
+client = ffi.new_handle(42)
+
+im = pyvips.Image.black(100, 100)
+im = im.draw_line([100], 0, 0, 100, 0,
+                  draw_point=cb, client=client)  # type: ignore[call-arg]

pyvips/gvalue.py

@@ -31,6 +31,7 @@ class GValue(object):
     guint64_type = type_from_name('guint64')
     gdouble_type = type_from_name('gdouble')
     gstr_type = type_from_name('gchararray')
+    gpointer_type = type_from_name('gpointer')
     genum_type = type_from_name('GEnum')
     gflags_type = type_from_name('GFlags')
     gobject_type = type_from_name('GObject')
@@ -57,6 +58,7 @@ class GValue(object):
         guint64_type: 'int',
         gdouble_type: 'float',
         gstr_type: 'str',
+        gpointer_type: 'ffi.CData',
         refstr_type: 'str',
         genum_type: 'str',
         gflags_type: 'int',
@@ -188,6 +190,8 @@ def set(self, value):
                                           GValue.to_flag(gtype, value))
         elif gtype == GValue.gstr_type:
             gobject_lib.g_value_set_string(self.gvalue, _to_bytes(value))
+        elif gtype == GValue.gpointer_type:
+            gobject_lib.g_value_set_pointer(self.gvalue, value)
         elif gtype == GValue.refstr_type:
             vips_lib.vips_value_set_ref_string(self.gvalue, _to_bytes(value))
         elif fundamental == GValue.gobject_type:
@@ -266,6 +270,8 @@ def get(self):
 
             if pointer != ffi.NULL:
                 result = _to_string(pointer)
+        elif gtype == GValue.gpointer_type:
+            result = gobject_lib.g_value_get_pointer(self.gvalue)
         elif gtype == GValue.refstr_type:
             psize = ffi.new('size_t *')
             pointer = vips_lib.vips_value_get_ref_string(self.gvalue, psize)

pyvips/gvalue.pyi

@@ -13,6 +13,7 @@ class GValue(object):
     guint64_type: ClassVar[int]
     gdouble_type: ClassVar[int]
     gstr_type: ClassVar[int]
+    gpointer_type: ClassVar[int]
     genum_type: ClassVar[int]
     gflags_type: ClassVar[int]
     gobject_type: ClassVar[int]

pyvips/vdecls.py

@@ -99,7 +99,7 @@ def cdefs(features):
             GType gtype, const char* str);
         int vips_flags_from_nick (const char* domain,
             GType gtype, const char* nick);
-        const char *vips_enum_nick (GType gtype, int value);
+        const char* vips_enum_nick (GType gtype, int value);
 
         void g_value_set_boolean (GValue* value, int v_boolean);
         void g_value_set_int (GValue* value, int i);
@@ -108,13 +108,14 @@ def cdefs(features):
         void g_value_set_enum (GValue* value, int e);
         void g_value_set_flags (GValue* value, unsigned int f);
         void g_value_set_string (GValue* value, const char* str);
+        void g_value_set_pointer (GValue* value, void* v_pointer);
         void vips_value_set_ref_string (GValue* value, const char* str);
         void g_value_set_object (GValue* value, void* object);
         void vips_value_set_array_double (GValue* value,
             const double* array, int n );
         void vips_value_set_array_int (GValue* value,
             const int* array, int n );
-        void vips_value_set_array_image (GValue *value, int n);
+        void vips_value_set_array_image (GValue* value, int n);
 
         int g_value_get_boolean (const GValue* value);
         int g_value_get_int (GValue* value);
@@ -123,6 +124,7 @@ def cdefs(features):
         int g_value_get_enum (GValue* value);
         unsigned int g_value_get_flags (GValue* value);
         const char* g_value_get_string (GValue* value);
+        void* g_value_get_pointer (GValue* value);
         const char* vips_value_get_ref_string (const GValue* value,
             size_t* length);
         void* g_value_get_object (GValue* value);
@@ -143,14 +145,14 @@ def cdefs(features):
         } GTypeClass;
 
         typedef struct _GTypeInstance {
-            GTypeClass *g_class;
+            GTypeClass* g_class;
         } GTypeInstance;
 
         typedef struct _GObject {
             GTypeInstance g_type_instance;
 
             unsigned int ref_count;
-            GData *qdata;
+            GData* qdata;
         } GObject;
 
         typedef struct _GParamSpec {
@@ -173,8 +175,8 @@ def cdefs(features):
         typedef struct _GEnumValue {
             int value;
 
-            const char *value_name;
-            const char *value_nick;
+            const char* value_name;
+            const char* value_nick;
         } GEnumValue;
 
         typedef struct _GEnumClass {
@@ -183,22 +185,22 @@ def cdefs(features):
             int minimum;
             int maximum;
             unsigned int n_values;
-            GEnumValue *values;
+            GEnumValue* values;
         } GEnumClass;
 
         typedef struct _GFlagsValue {
             unsigned int value;
 
-            const char *value_name;
-            const char *value_nick;
+            const char* value_name;
+            const char* value_nick;
         } GFlagsValue;
 
         typedef struct _GFlagsClass {
             GTypeClass g_type_class;
 
             unsigned int mask;
             unsigned int n_values;
-            GFlagsValue *values;
+            GFlagsValue* values;
         } GFlagsClass;
 
         void* g_type_class_ref (GType type);
@@ -208,14 +210,14 @@ def cdefs(features):
         void g_object_unref (void* object);
 
         void g_object_set_property (GObject* object,
-            const char *name, GValue* value);
+            const char* name, GValue* value);
         void g_object_get_property (GObject* object,
             const char* name, GValue* value);
 
         void vips_image_invalidate_all (VipsImage* image);
 
-        typedef void (*GCallback)(void);
-        typedef void (*GClosureNotify)(void* data, struct _GClosure *);
+        typedef void (*GCallback) (void);
+        typedef void (*GClosureNotify) (void* data, struct _GClosure* );
         long g_signal_connect_data (GObject* object,
             const char* detailed_signal,
             GCallback c_handler,
@@ -247,7 +249,7 @@ def cdefs(features):
         typedef ... VipsObjectClass;
 
         typedef struct _VipsArgument {
-            GParamSpec *pspec;
+            GParamSpec* pspec;
         } VipsArgument;
 
         typedef struct _VipsArgumentInstance {
@@ -271,14 +273,14 @@ def cdefs(features):
         typedef struct _VipsArgumentClass {
             VipsArgument parent;
 
-            VipsObjectClass *object_class;
+            VipsObjectClass* object_class;
             VipsArgumentFlags flags;
             int priority;
             unsigned int offset;
         } VipsArgumentClass;
 
         int vips_object_get_argument (VipsObject* object,
-            const char *name, GParamSpec** pspec,
+            const char* name, GParamSpec** pspec,
             VipsArgumentClass** argument_class,
             VipsArgumentInstance** argument_instance);
 
@@ -365,7 +367,7 @@ def cdefs(features):
     # vips_value_set_blob_free in a backwards compatible way
     if not features['api']:
         code += '''
-            typedef void (*FreeFn)(void* a);
+            typedef void (*FreeFn) (void* a);
             void vips_value_set_blob (GValue* value,
                 FreeFn free_fn, void* data, size_t length);
         '''
@@ -443,7 +445,7 @@ def cdefs(features):
             extern "Python" void _marshal_finish (VipsTarget*,
                 void*);
 
-            const char* vips_foreign_find_load_source (VipsSource *source);
+            const char* vips_foreign_find_load_source (VipsSource* source);
             const char* vips_foreign_find_save_target (const char* suffix);
 
         '''
@@ -454,16 +456,23 @@ def cdefs(features):
                 void*);
 
             void vips_block_untrusted_set (int state);
-            void vips_operation_block_set (const char *name, int state);
+            void vips_operation_block_set (const char* name, int state);
 
         '''
 
     if _at_least(features, 8, 18):
         code += '''
-            VipsImage *vips_image_get_gainmap(VipsImage *image);
+            VipsImage* vips_image_get_gainmap(VipsImage* image);
 
         '''
 
+    if _at_least(features, 8, 19):
+        code += '''
+            typedef unsigned char VipsPel;
+            typedef void (*VipsDrawPoint) (VipsImage* image, VipsPel* ink,
+                int x, int y, void* client);
+        '''
+
     # we must only define these in API mode ... in ABI mode we need to call
     # these things earlier
     if features['api']:

tests/test_gvalue.py

@@ -78,6 +78,14 @@ def test_string(self):
         value = gv.get()
         assert value == 'banana'
 
+    def test_pointer(self):
+        pointer = pyvips.ffi.new_handle(42)
+        gv = pyvips.GValue()
+        gv.set_type(pyvips.GValue.gpointer_type)
+        gv.set(pointer)
+        value = gv.get()
+        assert pyvips.ffi.from_handle(value) == 42
+
     def test_array_int(self):
         gv = pyvips.GValue()
         gv.set_type(pyvips.GValue.array_int_type)