<AWT Dev> <Swing Dev> [10] Review request for 8182043: Access to Windows Large Icons

Semyon Sadetsky semyon.sadetsky at oracle.com
Thu Sep 28 17:57:14 UTC 2017

Hi Sergey,

On 9/27/2017 12:22 PM, Sergey Bylokhov wrote:
> On 9/26/17 14:37, Semyon Sadetsky wrote:
>>> This means that on HiDPI screen the FILE_ICON_LARGE works in similar 
>>> way as FILE_ICON_SMALL on non-HiDPI screen, and the meaning of the 
>>> FILE_ICON_SMALL on HiDPI is unclear, because it is half of the 
>>> correct size.
>> Small and large don't have any special meanings for HiDPI. They are 
>> some conditional sizes established by the native platform for the 
>> current screen resolution.
> The question what is the current screens resolution when you have two 
> screens?
We should relay on the native platform always. So, the icon size 
returned by the native API is the correct approach. And possibility to 
use any other sizes is provided as well.
>> Why is it half of the correct size? It is the same size as for 
>> non-HiDPI and that is the correct size because otherwise java UI 
>> component that is HiDPI unaware would paint icons 2 times bigger in 
>> size than it is required. But the resolution of small/large icons may 
>> differs in case of HiDPI because it is determined by the size of the 
>> images returned by the native platform by the small/large icon queries.
> It is half of the correct size because on HiDPI it is better to use 
> hidpi icons instead of lowdpi. Will the HiDPI unaware apps draw x2 
> icons correctly or not depends from our implementation. If we will 
> return the MRI then it will be drawn in correct size even if the 
> bigger(HiDPI) image will be used.
This is not true. MRI has a basic size which uniquely determines its 
painted size in component coordinates. The size painted in component 
will be the same for all scales this is how HiDPI works in java.
>>> For example one of the consumer of this new API is WindowsFileView.
>>> How the code below should be changed to work on a different screens, 
>>> and request the proper icon?
>>> WindowsFileChooserUI.java
>>> 1316 icon = getFileChooser().getFileSystemView().getSystemIcon(f);
>> Why it should be changed? The code is requesting the proper icon.
> Because this method returns an icon of 16x16 pixels, which will be 
> rescaled to 32x32 pixels in paint operation.
The size should be equal 16x16 otherwise the component view will be 
distorted. But painted resolution is determined by native platform. The 
native platform may return icon of any size. If the size of the icon 
differs from 16x16 (32x32 for example) then it will be wrapped by MRI of 
16x16 size.


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