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

[Alexander Zuev]

Hi Alexey,

   sorry for late responce, after fixing that initial error with the wrong
icon sizes pulled i found a lot of corner cases that needed some 
additional digging.

On 18-Jun-20 20:56, Alexey Ivanov wrote:
> On 18/06/2020 02:30, Sergey Bylokhov wrote:
>> On 6/17/20 5:50 pm, Sergey Bylokhov wrote:
>>
>>> I guess it is too early to compare behavior before and after the fix 
>>> since the fix has a few bugs.
>>>   - It does not fetch several sizes, as it was expected from the 
>>> code, but load only one native size
>>> and map it to the different resolutions.
>
> Yes, I re-read your message and found this mistake.
> I fixed it locally.
>
> Then I noticed JFileChooser does not really use the new method which 
> returns MRI, so this explains why JFileChooser never adjusts the icons 
> according the screen DPI.
>
> I modified Win32ShellFolder2.getIcon(boolean) to use getIcon(size) 
> instead of getIcon(getAbsolutePath(), getLargeIcon), and now the file 
> icons are updated when JFileChooser window is moved from standard DPI 
> monitor to a High DPI one (150%) and back. I noticed one artefact 
> though: the customised icons from disk drives disappeared, some file 
> icons look clipped, on either monitor.
I also noticed this behavior, some icons retrieved with the extractIcon 
method got clipped or improperly scaled.
I tried to dig deeper and found that it happens when 
pIcon->GetIconLocation function returns "*"
as location of the resource file. I haven't found exact reason for that 
but when this is the case then
getIconBits function always retrieves 32x32 icon no matter what icon 
size we requested.
We then scale it down to 16x16 and the result is unpleasant.
I'm trying to find another way of retrieving the custom icon but for now 
i would say that
for the small icons the approach of getIcon function which uses 
SHGetFileInfo holds better results.

So far the approach that seems to be working is to check if we have a 
high resolution
icon available by requesting icon location. If icon location is not 
known we can get both
low and high resolution icons from SHGetFileInfo and store them in the 
MRI. If high res icon available
then fetch all the standard resolution icons and also return them as MRI.

/Alex