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

[Jim Graham]

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...

			...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.
>> It is WID_HIRES/WID_BASE x HGT_HIRES/HGT_BASE
>>
>> 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.
>>>>>>
>>>