[OpenJDK 2D-Dev] [9] Review request for 8163854 Add ToolkitImage.getImage() method which loads an image with schema variant

Alexandr Scherbatiy alexandr.scherbatiy at oracle.com
Thu Sep 22 17:41:04 UTC 2016

On 9/22/2016 11:30 AM, Jim Graham wrote:
> It gets further complicated, though, when you consider that we 
> probably need the dimensions of the base image for any metrics 
> reporting anyway.
> Consider a 25x25 image with variants.  If the user supplies a 125pct 
> variant then they will need an image that is 31.25 pixels in size.  Do 
> they use a 31 pixel image or a 32 pixel image?  And if they offer one 
> of those with the suffix that tells us that it is a 125pct image, then 
> when we try to report the size, do we report it as:
> 31/1.25 == 24.8 pixels == do we report 24 or 25?
> 32/1.25 == 25.6 pixels == do we report 25 or 26?
> In the end, we can't really report anything until we load the base 
> image and discover that we should be reporting 25x25 to the observer 
> and scaling all SOME_BITS notifications based on 25/31 or 25/32...
> Given that we need the original base image size to do anything useful, 
> it may be much more feasible to handle things as Phil suggests...
   I have filled an issue on it:
     JDK-8166566 Improper toolkit resolution variant scale should be 
properly handled.


>             ...jim
> On 9/21/16 5:48 PM, Jim Graham wrote:
>> I think this is a good point.  The only gotcha would appear to be 
>> handling the ImageObserver notifications and the
>> prepareImage() calls.
>> The ImageObserver should get the variant's dimensions as one of the 
>> first notifications, though if they trigger an image
>> load and then add an observer later, I'm not sure if it will get the 
>> back-notifications or not.  Also, it would need to
>> know the base image dimensions, but the base image may not be loaded 
>> yet due to lazy loading and/or receiving the data
>> for the @Nx version of the image before you receive the data for the 
>> regular version.  All of those add complexity with
>> trying to figure out how to notify an observer of incoming information.
>> So, lazy loading may make this approach infeasible.  Alexandr?
>>                 ...jim
>> On 9/21/16 11:47 AM, Philip Race wrote:
>>> Hi,
>>> When the application is specifying the set of images from which
>>> to build the MRI you ask the app to specify a "schema" (probably not 
>>> the
>>> right name given that it is per-file), and a floating point scale.
>>> I don't see why we need to ask the app to name the files
>>> in accordance with our schema in this case .. it should just be
>>> able to list the set of files. It looks redundant to an app developer
>>> to say "150pct" is scale "1.5".
>>> Obviously the ideal is the image is exactly what the naming convention
>>> implies it is, but what if it is not ?
>>> This issue does exist already even in JDK 8 .. if the
>>> @2x image is really 1.5X the @1 image
>>> Consider what happens if this contradicts the floating point scale ?
>>> It appears to me that as implemented, in practice, the app could 
>>> call it "@XXX",
>>> and once @XXX has been used to find the file, the only thing that 
>>> actually
>>> matters is the floating point scale.
>>> So the naming schema is not important when they provide the scale.
>>> But we still have the issue that the *actual* image size may not be
>>> what they said it was  - either explicitly or by convention.
>>> Supposing what is claimed to be a 1.5x1.5 scale image is actually
>>> 1.0x2.0 times the size of the base image ? It is not even uniform.
>>> Ultimately what needs to "win" is the w:h ratio of the base image
>>> and we generally would want to pick whichever image best works
>>> for the actual device scale, based on the *real* dimensions of
>>> the hi-res image, don't we ?
>>> In which case, I'd expect us to work out the scale automatically.
>>> At which point why do we even need the app to tell us anything
>>> except the (full) names of the files where to get the set of images,
>>> with the first one being the base .. or perhaps it should always
>>> be the "smallest".
>>> Otherwise if any are in fact smaller (or the same as) BASE .. do we 
>>> just discard them ?
>>> -phil.
>>> On 9/19/16, 12:03 PM, Alexander Scherbatiy wrote:
>>>> Hello,
>>>> Could you review the updated fix:
>>>>   http://cr.openjdk.java.net/~alexsch/8163854/webrev.01
>>>> The fix includes support for resolution variants loading by 
>>>> getImage() method for built-in toolkits using the
>>>> following media resolution naming scheme (qualifier, scale): 
>>>> ("@125pct", 1.25), ("@150pct", 1.5), ("@200pct" or "@2x",
>>>> 2), ("@250pct", 2.5), ("@300pct" or "@3x", 3).
>>>> Thanks,
>>>> Alexandr.
>>>> On 25/08/16 05:39, Philip Race wrote:
>>>>> FWIW I think the most important image loading use case
>>>>> is that some generic resource loading code - perhaps JDK code - 
>>>>> will get a URL for where
>>>>> the resources are and go hunting. It is never going to call this 
>>>>> API .. so
>>>>> it had better be an optimisation and not a necessity
>>>>> -phil.
>>>>> On 8/24/16, 5:24 PM, Philip Race wrote:
>>>>>> Alexander,
>>>>>> Were  the existing Toolkit.getImage(String/URL) APIs not enhanced to
>>>>>> do this for you automatically ? I suppose I thought they were but
>>>>>> they can't be since you are using getImage(String) here.
>>>>>> IMO that would be more important than this.
>>>>>> And in any case I don't see why this is solved only for local files.
>>>>>> I am *not* asking for that right now. I am asking if the existing 
>>>>>> Toolkit APIs
>>>>>> can load a multi-res image and if not, why not  and can we fix 
>>>>>> that instead ..
>>>>>> -phil.
>>>>>> On 8/24/16, 9:36 AM, Alexander Scherbatiy wrote:
>>>>>>> Hello,
>>>>>>> Could you review the fix:
>>>>>>>   bug: https://bugs.openjdk.java.net/browse/JDK-8163854
>>>>>>>   webrev: http://cr.openjdk.java.net/~alexsch/8163854/webrev.00
>>>>>>>   The public API which allows to load an image with resolution 
>>>>>>> variants based on the provided media resolution
>>>>>>> naming scheme is added:
>>>>>>>   - Toolkit.MediaResolutionNamingScheme class
>>>>>>>   - Toolkit.getImageUsingNamingSchemes(String fileName, 
>>>>>>> MediaResolutionNamingScheme... namingSchemes)
>>>>>>>   A simple example for images which use naming scheme @150pct 
>>>>>>> for scale 1.5 and @2x for scale 2 is:
>>>>>>>     image_name.ext
>>>>>>>     image_name at 150pct.ext
>>>>>>>     image_name at 2x.ext
>>>>>>>     Toolkit toolkit = Toolkit.getDefaultToolkit();
>>>>>>>     Image image = toolkit.getImageUsingNamingSchemes(fileName,
>>>>>>>             new Toolkit.MediaResolutionNamingScheme(“@150pct”, 
>>>>>>> 1.5f),
>>>>>>>             new Toolkit.MediaResolutionNamingScheme(“@2x", 2f)
>>>>>>>     );
>>>>>>>   Thanks,
>>>>>>>   Alexandr.

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