Merge pull request #934 from sdroege/pixbuf-transfer-none-subclass-returns

gdk-pixbuf: Ensure that transfer-none return values in subclassing ar…

Author: sdroege

gdk-pixbuf/Cargo.toml

@@ -32,6 +32,7 @@ bitflags = "1.3"
 ffi = { package = "gdk-pixbuf-sys", path = "sys" }
 glib = { path = "../glib" }
 gio = { path = "../gio" }
+once_cell = "1"
 
 [dev-dependencies]
 gir-format-check = "^0.1"

gdk-pixbuf/src/subclass/pixbuf_animation.rs

@@ -5,7 +5,8 @@
 
 use std::{mem::MaybeUninit, time::Duration};
 
-use glib::{subclass::prelude::*, translate::*, Cast};
+use glib::{prelude::*, subclass::prelude::*, translate::*};
+use once_cell::sync::Lazy;
 
 use crate::{Pixbuf, PixbufAnimation, PixbufAnimationIter};
 
@@ -153,13 +154,32 @@ unsafe extern "C" fn animation_get_size<T: PixbufAnimationImpl>(
     }
 }
 
+static STATIC_IMAGE_QUARK: Lazy<glib::Quark> =
+    Lazy::new(|| glib::Quark::from_str("gtk-rs-subclass-static-image"));
+
 unsafe extern "C" fn animation_get_static_image<T: PixbufAnimationImpl>(
     ptr: *mut ffi::GdkPixbufAnimation,
 ) -> *mut ffi::GdkPixbuf {
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
-    imp.static_image().to_glib_none().0
+    let instance = imp.obj();
+    let static_image = imp.static_image();
+    // Ensure that a) the static image stays alive as long as the animation instance and b) that
+    // the same static image is returned every time. This is a requirement by the gdk-pixbuf API.
+    if let Some(old_image) = instance.qdata::<Option<Pixbuf>>(*STATIC_IMAGE_QUARK) {
+        let old_image = old_image.as_ref();
+
+        if let Some(old_image) = old_image {
+            assert_eq!(
+                Some(old_image),
+                static_image.as_ref(),
+                "Did not return same static image again"
+            );
+        }
+    }
+    instance.set_qdata(*STATIC_IMAGE_QUARK, static_image.clone());
+    static_image.to_glib_none().0
 }
 
 unsafe extern "C" fn animation_get_iter<T: PixbufAnimationImpl>(

gdk-pixbuf/src/subclass/pixbuf_animation_iter.rs

@@ -5,7 +5,8 @@
 
 use std::time::Duration;
 
-use glib::{subclass::prelude::*, translate::*, Cast};
+use glib::{prelude::*, subclass::prelude::*, translate::*};
+use once_cell::sync::Lazy;
 
 use crate::{Pixbuf, PixbufAnimationIter};
 
@@ -138,13 +139,19 @@ unsafe extern "C" fn animation_iter_get_delay_time<T: PixbufAnimationIterImpl>(
     imp.delay_time().map(|t| t.as_millis() as i32).unwrap_or(-1)
 }
 
+static PIXBUF_QUARK: Lazy<glib::Quark> =
+    Lazy::new(|| glib::Quark::from_str("gtk-rs-subclass-pixbuf"));
+
 unsafe extern "C" fn animation_iter_get_pixbuf<T: PixbufAnimationIterImpl>(
     ptr: *mut ffi::GdkPixbufAnimationIter,
 ) -> *mut ffi::GdkPixbuf {
     let instance = &*(ptr as *mut T::Instance);
     let imp = instance.imp();
 
-    imp.pixbuf().to_glib_none().0
+    let pixbuf = imp.pixbuf();
+    // Ensure that the pixbuf stays alive until the next call
+    imp.obj().set_qdata(*PIXBUF_QUARK, pixbuf.clone());
+    pixbuf.to_glib_none().0
 }
 
 unsafe extern "C" fn animation_iter_on_currently_loading_frame<T: PixbufAnimationIterImpl>(