<AWT Dev> [9] Review request for 8132706 [macosx] Toolkit.getImage() throws NPE for null URL

[Alexander Scherbatiy]

On 18/04/16 20:55, Sergey Bylokhov wrote:
> On 18.04.16 18:36, Alexander Scherbatiy wrote:
>> On 4/15/2016 10:55 PM, Sergey Bylokhov wrote:
>>> On 15.04.16 21:49, Phil Race wrote:
>>>> I think that even if no exception is thrown we ought to document what
>>>> happens.
>>>> Which of course means that we need to be sure that it does happen :-)
>>>> And the difference depending on SM may be hard to defend.
>>>> And I am referring to both methods, not just the URL one.
>>>
>>> The spec of checkImage/prepareImage both return incorrect status in
>>> case of null, seems both should throw NPE also. otherwise they report
>>> null as a valid fully loaded image.
>>
>>     Could you give more details why do you think that
>> checkImage/prepareImage methods return incorrect status in case of null
>> file path/URL?
>>     The checkImage just returns a status of an image construction
>> "Information on the flags returned by this method can be found with the
>> discussion of the ImageObserver interface." and the prepareImage()
>> redirects all results to the ImageObserver.
>
> Because the checkImage() return ALLBITS loaded for the null image 
> which means that "all image data is currently available".
> prepareImage() will return true for null, which means that "the image 
> has already been fully prepared"and ready for rendering, note that an 
> observer is not called that there are some errors. At lest this two 
> methods should be investigated.

   The question under discussion is not about null images but about a 
ToolkitImage which has File/URLImageSource with null file/url because 
the Toolkit.getImage((String)null) returns non-null ToolkitImage which 
source points to a null file.

   Thanks,
   Alexandr.

>>
>>    For example the call of Toolkit.getImage(file) method with path which
>> does not point to a file does not lead to the FileNotFoundException. The
>> ToolkitImage is created and just wait for the time when it is loaded.
>> Only during loading the ImageObserver is called with ABORT info flag.
>
> There is a difference between incorrect parameters and some loading 
> errors. For example createImage(byte[] imagedata,...) throws an 
> exception because there is no sense to load the image from null array, 
> the same for URL/File. ImageIO uses the same scheme(throws an 
> exception if it is obvious that load of the image data will fail). 
> Passing a null value to this api is a bug in the program, and it will 
> be good to report it early.
>
>>
>>     The case with null path or URL should follow the same ToolkitImage
>> errors handling rule.
>
>
>>
>>    Thanks,
>>    Alexandr.
>>
>>
>>>
>>>>
>>>> -phil.
>>>>
>>>> On 04/15/2016 11:47 AM, Alexander Scherbatiy wrote:
>>>>> On 15/04/16 22:11, Phil Race wrote:
>>>>>> And it prints the stack trace ??
>>>>>>
>>>>>> This gets even messier.
>>>>>>
>>>>>> Is there anything we can do to have sensible specification of
>>>>>> what happens with null that isn't likely to cause (much) harm ?
>>>>>
>>>>>  I see only two options. Do not throw the NPE as it was before and
>>>>> throw the NPE.
>>>>>  The second one can break some old applications which do not expect
>>>>> that the exception can be thrown in this case.
>>>>>
>>>>>  If the second option is acceptable probably the Toolkit.getImage()
>>>>> javadoc can be updated.
>>>>>
>>>>>  Thanks,
>>>>>  Alexandr.
>>>>>
>>>>>>
>>>>>> -phil.
>>>>>>
>>>>>>
>>>>>> On 04/15/2016 11:10 AM, Alexander Scherbatiy wrote:
>>>>>>> On 15/04/16 20:30, Sergey Bylokhov wrote:
>>>>>>>> How the object of URLImageSource(null) will be useful? I guess we
>>>>>>>> will get some unspecified NPE exceptions if will try to call its
>>>>>>>> methods?
>>>>>>>   I know nothing about the URLImageSource(null) usefulness but
>>>>>>> ImageFetcher swallows the NPE during the image loading in the
>>>>>>> fetchloop() method:
>>>>>>> -------
>>>>>>>             try {
>>>>>>>                 src.doFetch();
>>>>>>>             } catch (Exception e) {
>>>>>>>                 System.err.println("Uncaught error fetching 
>>>>>>> image:");
>>>>>>>                 e.printStackTrace();
>>>>>>>             }
>>>>>>> -------
>>>>>>>
>>>>>>>   Thanks,
>>>>>>>   Alexandr.
>>>>>>>>
>>>>>>>> On 15.04.16 18:02, Alexander Scherbatiy wrote:
>>>>>>>>>
>>>>>>>>> Hello,
>>>>>>>>>
>>>>>>>>> Could you review the fix:
>>>>>>>>>    bug: https://bugs.openjdk.java.net/browse/JDK-8132706
>>>>>>>>>    webrev: http://cr.openjdk.java.net/~alexsch/8132706/webrev.00
>>>>>>>>>
>>>>>>>>>    The fix makes the Toolkit.getDefaultToolkit().getImage(URL)
>>>>>>>>> return a
>>>>>>>>> ToolkitImage based on URLImageSource with null url as it was
>>>>>>>>> before the
>>>>>>>>> fix JDK-8011059.
>>>>>>>>>
>>>>>>>>>    Thanks,
>>>>>>>>>    Alexandr.
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
>