prevent duplicate release of NSImage

Author: samschott

cocoa/src/toga_cocoa/icons.py

@@ -38,29 +38,20 @@ def __init__(self, interface, path):
         else:
             self.path = path
 
-        try:
-            # We *should* be able to do a direct NSImage.alloc.init...(), but if the
-            # image file is invalid, the init fails, returns NULL, and releases the
-            # Objective-C object. Since we've created an ObjC instance, when the
-            # object passes out of scope, Rubicon tries to free it, which segfaults.
-            # To avoid this, we retain result of the alloc() (overriding the default
-            # Rubicon behavior of alloc), then release that reference once we're
-            # done. If the image was created successfully, we temporarily have a
-            # reference count that is 1 higher than it needs to be; if it fails, we
-            # don't end up with a stray release.
-            image = NSImage.alloc().retain()
-            self.native = image.initWithContentsOfFile(str(path))
-            if self.native is None:
-                raise ValueError(f"Unable to load icon from {path}")
-        finally:
-            # Calling `release` here disabled Rubicon's "release on delete" automation.
-            # We therefore add an explicit `release` call in __del__ if the NSImage was
-            # initialized successfully.
-            image.release()
-
-    def __del__(self):
-        if self.native:
-            self.native.release()
+        # We *should* be able to do a direct NSImage.alloc.init...(), but if the
+        # image file is invalid, the init fails, returns NULL, and releases the
+        # Objective-C object. Since we've created an ObjC instance, when the
+        # object passes out of scope, Rubicon tries to free it, which segfaults.
+        # To avoid this, we retain result of the alloc() (overriding the default
+        # Rubicon behavior of alloc), then release that reference once we're
+        # done. If the image was created successfully, we temporarily have a
+        # reference count that is 1 higher than it needs to be; if it fails, we
+        # don't end up with a stray release.
+        image = NSImage.alloc().retain()
+        self.native = image.initWithContentsOfFile(str(path))
+        if self.native is None:
+            raise ValueError(f"Unable to load icon from {path}")
+        image.release()
 
     def _as_size(self, size):
         image = self.native.copy()

cocoa/src/toga_cocoa/images.py

@@ -23,43 +23,30 @@ class Image:
 
     def __init__(self, interface, path=None, data=None, raw=None):
         self.interface = interface
-        self._needs_release = False
 
-        try:
-            # We *should* be able to do a direct NSImage.alloc.init...(), but if the
-            # image file is invalid, the init fails, returns NULL, and releases the
-            # Objective-C object. Since we've created an ObjC instance, when the object
-            # passes out of scope, Rubicon tries to free it, which segfaults.
-            # To avoid this, we retain result of the alloc() (overriding the default
-            # Rubicon behavior of alloc), then release that reference once we're done.
-            # If the image was created successfully, we temporarily have a reference
-            # count that is 1 higher than it needs to be; if it fails, we don't end up
-            # with a stray release.
-            image = NSImage.alloc().retain()
-            if path:
-                self.native = image.initWithContentsOfFile(str(path))
-                if self.native is None:
-                    raise ValueError(f"Unable to load image from {path}")
-                else:
-                    self._needs_release = True
-            elif data:
-                nsdata = NSData.dataWithBytes(data, length=len(data))
-                self.native = image.initWithData(nsdata)
-                if self.native is None:
-                    raise ValueError("Unable to load image from data")
-                else:
-                    self._needs_release = True
-            else:
-                self.native = raw
-        finally:
-            # Calling `release` here disabled Rubicon's "release on delete" automation.
-            # We therefore add an explicit `release` call in __del__ if the NSImage was
-            # initialized successfully.
-            image.release()
+        # We *should* be able to do a direct NSImage.alloc.init...(), but if the
+        # image file is invalid, the init fails, returns NULL, and releases the
+        # Objective-C object. Since we've created an ObjC instance, when the object
+        # passes out of scope, Rubicon tries to free it, which segfaults.
+        # To avoid this, we retain result of the alloc() (overriding the default
+        # Rubicon behavior of alloc), then release that reference once we're done.
+        # If the image was created successfully, we temporarily have a reference
+        # count that is 1 higher than it needs to be; if it fails, we don't end up
+        # with a stray release.
+        image = NSImage.alloc().retain()
+        if path:
+            self.native = image.initWithContentsOfFile(str(path))
+            if self.native is None:
+                raise ValueError(f"Unable to load image from {path}")
+        elif data:
+            nsdata = NSData.dataWithBytes(data, length=len(data))
+            self.native = image.initWithData(nsdata)
+            if self.native is None:
+                raise ValueError("Unable to load image from data")
+        else:
+            self.native = raw
 
-    def __del__(self):
-        if self._needs_release:
-            self.native.release()
+        image.release()
 
     def get_width(self):
         return self.native.size.width