<AWT Dev> RFR: 8182043 Access to Windows Large Icons

[Philip Race]

Icon has API that returns size.
I was wondering how problematic this is for returning an Icon backed by 
an MRI
But this being a Swing API I suspect the reason for it is so Swing can 
lay out.
So it does not want to know the real icon size in "device" pixels.
That would actually be a problem not a benefit. It wants to know the 
user coordinate size for layout.
I think it also means that the size can't change when you drag between 
display devices with
different UI scales.

So maybe we can do this properly with an MRI backed Icon and just return 
whatever is the base image size.
Also it means that maybe we don't need a new API at all.
I've not understood all of the reasoning behind many of the suggestions 
(going back years)
very well but if this can be done without API it would be very helpful 
in general.
No problem backporting and apps will get the benefit without re-coding.

If this is not possible can someone summarise why it is absolutely 
impossible.

Going back the submitter needed to dig out the hi-res icon because we 
didn't do it for them but
that doesn't mean it is what he wants to do, it is what he had to do. 
He'll have to re-code
regardless because of using internal APIs.

So if we re-phrase the problem as "automatically pick the best image at 
*display* time
without requiring applications to re-code", what would this look like 
and what is lost ?

Would it look like no API change, and the only thing that is lost is 
what does not actually
exist (API for the application to dig in to internals) ?

-phil.

On 6/15/20, 9:40 PM, Sergey Bylokhov wrote:
> Hi, Alexander.
>
> Some generic questions about the general approach:
>  - Did you experiment using LookupIconIdFromDirectoryEx? This method 
> was referred in the previous email.
>  - Did you check how the performance will be affected if we always 
> load a few icons, all icons, or if we try to load them on
>    the fly when the user request some size from the MRI?
>  - As far as I understand to access the list of icons the user will 
> need to use instanceof MRI, can we improve it somehow?
>    Probably add example to the javadoc, and to the test?
>  - What about returning the array of icons, will that solution be 
> simpler/faster then using MRI or not?
>  - Did you try to merge implementation of 
> getSystemIcon(File)/getSystemIcon(File, size)?
>  - I think we need to improve the spec for the new method:
>    * "width and height of the icon in pixels to be scaled" -  what 
> does it mean "to be scaled", is
>      the returned icon will always have this size in pixels?
>    * "Whenever possible the icon returned will be a multi-resolution 
> icon image
>       with maximum quality icon provided by the system and the size 
> stored
>       reflecting the size requested by the user. That will allow nice 
> scaling
>       with differen magnification factors." Does our implementation 
> follow this spec?
>
> On 6/9/20 2:24 pm, Alexander Zuev wrote:
>>    while generally agree i'm not sure that we need to populate ALL of 
>> the resolutions for every sing> icon we request. So my idea that you 
>> can see in the new webrev is to create the true MRI which will
>> hold all standatd resolutions within the range of half of requested 
>> icon size and double of it. That would
>> cover magnification factors from 50% to 200%. I tested it and the 
>> icons in the standard JFioleChooser looks
>> pretty good on display with different magnification factors.
>
>  - Looks like in the fix we always use the "size" passed by the user 
> when we call getShell32Icon() so we
> always fetch the same icons from the native?
>  - The change in the makeIcon reverts back the fix for JDK-8151385, 
> can you please confirm that those fix
>    still works as expected?
>  - The new parameter "size" in the makeIcon(long hIcon, int size) is 
> unused.
>