<AWT Dev> <Swing Dev> [12] JDK-8182043: Access to Windows Large Icons

Shashidhara Veerabhadraiah shashidhara.veerabhadraiah at oracle.com
Fri Sep 21 22:22:29 UTC 2018

Hi Alexey, Thanks for your review and below is the new Webrev.



Please see below for inline comments.


Thanks and regards,


From: Alexey Ivanov 
Sent: Friday, September 21, 2018 2:09 PM
To: Shashidhara Veerabhadraiah <shashidhara.veerabhadraiah at oracle.com>; Prasanta Sadhukhan <prasanta.sadhukhan at oracle.com>; swing-dev <swing-dev at openjdk.java.net>; awt-dev <awt-dev at openjdk.java.net>
Subject: Re: <AWT Dev> <Swing Dev> [12] JDK-8182043: Access to Windows Large Icons


Hi Shashi,

What is the purpose of new SystemIcon class?
It's not used anywhere but the provided test. Is this class really needed then?
Is it supposed to become the public API for accessing system icons?
Why can't FileSystemView be used for that purpose as it was proposed in Semyon's review?
[Shashi] SystemIcon is going to be the front face to access the icons and that is the purpose of this class. The reason for choosing this is that FileSystemView class can be used internally and did not wanted to expose it externally too. Externally exposing may cause certain restriction in maintaining the classes hence the indirection.

 259      * Icon for a file, directory, or folder as it would be displayed in
 260      * a system file browser for the requested size.
For getXXX, it's better to start description with "Returns." so it aligns to other similar methods.
However, I see the new method follows description of getIcon(boolean).

[Shashi] Because as you said rightly it follows the getIcon(boolean)

 265      * @param size width and height of the icon in pixels to be scaled(valid range: 1 to 256)
Why is it "to be scaled"? I would expect to get the icon of the requested size. At the same time, the icon can be scaled to the requested size if the requested size is not available.

[Shashi] User has no restriction of mentioning any size but the platform may have a limitation of size. Since we are supporting a set of different versions of platforms, platform may limit the size of the icon to a particular size, in which case it will be scaled to the user requested size.

270     protected Icon getSystemIcon(File f, int size) {
Can't the method be public? It was in Semyon's review.

[Shashi] Because of the indirection, this method can stay as protected. I think it is always good to be of using protected than making everything public. Also that is the advantage of adding the SystemIcon class.

 266      * @return an icon as it would be displayed by a native file chooser
An icon of the requested size (possibly scaled) as.

 275         if(size > 256 || size < 1) {
 276             return null;
 277         }
Please add space between if and the opening parenthesis.
You can throw InvalidArgumentException in this case.
Does size of 1 make any sense?

[Shashi] Done. I can only say that 0 does not make sense. Check is to see that it is not less than 1.

 202     /**
 203      * @param size size of the icon > 0
 204      * @return The icon used to display this shell folder
 205      */
Can you add a short description of the purpose of this method? "Returns the icon of the specified size used to display this shell folder"?
A similar description can be added to the method above it:
198     public Image getIcon(boolean getLargeIcon) {

[Shashi] Updated. Thank you.

 944             hres = pIcon->Extract(szBuf, index, &hIcon, 0, size);
Please use NULL instead of 0. This way it's clear you pass a null pointer rather an integer with value of 0.

[Shashi] Updated.

974     const int MAX_ICON_SIZE = 128;
I also suggest increasing MAX_ICON_SIZE to 256. Otherwise I see no point in allowing 256 as the maximum size at Java level as you'll never have icon of 256×256 even thought the system may have one.

[Shashi] Per me, the problem is that since we support certain older versions of the platforms, it should not cause an exception at the native level. If everyone agrees for the change then we can change that.

1007     private static Image makeIcon(long hIcon, int bsize) {
bsize has no meaning. Prasanta also asked about the name of the parameter.
I suggest using "size" for parameter, and "iconSize" for local variable.

[Shashi] Updated.

1031         int size = getLargeIcon ? 32 : 16; // large icon is 32 pixels else 16 pixels
Create constants for these magic numbers.

[Shashi] Updated.

1080                                         return getShell32Icon(4, size); // pick folder icon
1081                                     } else {
1082                                         return getShell32Icon(1, size); // pick file icon
Also create constants for 4 and 1 as Prasanta suggested.
Creating a constant costs you nothing but makes the code more readable without adding comments.

[Shashi] But my view is that if we start doing for every immediate value, then creation of the object and assignment may have some implications. If it is used more than once, yes definitely create the constant. Please let me know if you think otherwise. This I follow it as a standard by practice. 

1113             if(hIcon <= 0) {
1116                 if(hIcon <= 0) {
Please add space between if and the opening parenthesis.

[Shashi] Updated.

 382                     return Win32ShellFolder2.getShell32Icon(i, key.startsWith("shell32LargeIcon ")?
 383                                                                 32 : 16);
You can use constants declared for icon size in from Win32ShellFolder2 because they're already imported:
  42 import static sun.awt.shell.Win32ShellFolder2.*;

[Shashi] Updated.

Then the code at these lines needs to be updated too:
 129             STANDARD_VIEW_BUTTONS[iconIndex] = (size == 16)
 130                     ? img
 131                     : new MultiResolutionIconImage(16, img);

See http://cr.openjdk.java.net/~ssadetsky/8182043/webrev.01/src/java.desktop/windows/classes/sun/awt/shell/Win32ShellFolderManager2.java.udiff.html


Could you please order the imports? Your IDE would be happy to do it for you.
Could you also add spaces between if and the opening parenthesis?
(Or at least be consistent with it.)

58             ImageIcon icon = (ImageIcon)sysIcon.getSystemIcon(file, size, size);
Casts should be followed by a blank space.

67             else if (icon.getIconWidth() != size) {
else is redundant as the preceding if throws an exception.

[Shashi] Updated.


On 04/09/2018 10:39, Shashidhara Veerabhadraiah wrote:

Hi All, Please find the updated Webrev per the discussion:


HYPERLINK "http://cr.openjdk.java.net/%7Esveerabhadra/8182043/webrev.02/"http://cr.openjdk.java.net/~sveerabhadra/8182043/webrev.02/


Thanks and regards,



From: Shashidhara Veerabhadraiah 
Sent: Monday, July 30, 2018 1:32 PM
To: Prasanta Sadhukhan HYPERLINK "mailto:prasanta.sadhukhan at oracle.com"<prasanta.sadhukhan at oracle.com>; HYPERLINK "mailto:swing-dev at openjdk.java.net"swing-dev at openjdk.java.net; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net
Subject: Re: <AWT Dev> <Swing Dev> [12] JDK-8182043: Access to Windows Large Icons


Hi Prashanta, Thanks for your review. Below are my replies:


HYPERLINK "http://cr.openjdk.java.net/%7Esveerabhadra/8182043/webrev.01/"http://cr.openjdk.java.net/~sveerabhadra/8182043/webrev.01/


Thanks and regards,


From: Prasanta Sadhukhan 
Sent: Friday, July 20, 2018 3:42 PM
To: Shashidhara Veerabhadraiah <HYPERLINK "mailto:shashidhara.veerabhadraiah at oracle.com"shashidhara.veerabhadraiah at oracle.com>; HYPERLINK "mailto:swing-dev at openjdk.java.net"swing-dev at openjdk.java.net; HYPERLINK "mailto:awt-dev at openjdk.java.net"awt-dev at openjdk.java.net
Subject: Re: <Swing Dev> [12] JDK-8182043: Access to Windows Large Icons


Hi Shashi,

The previous review thread is too long so probably need the original reviewer to take a look.
But here are my 2 cents

Can you please explain how the new API is supposed to be used? It says "Scaled icon for a file, directory, or folder as it would be displayed in a system file browser"

                getSystemIcon(File f, int width, int height)
            If the specified width, height is not available, then it will be scaled to available icon size, is it? I do not think the javadoc captures the essence of the api thoroughly.
            For example, if width/height asked for is 100 and we have icon of 96/96 and 128/128, then what it will return, the closest size 96/96 or the next positive one 128/128.

[Shashi] Yes. It will be scaled to the requested size. For the example that you mentioned, it is OS dependent. Typically it will pick up the higher resolution if available and scales it down to the requested level. If the higher resolution icon is not available then it will pick the lower one and scales it up. Hence I just happened to mention it as 'scaled icon' in the explanation.

As per fix of HYPERLINK "https://bugs.openjdk.java.net/browse/JDK-8151385"JDK-8151385, MAX_ICON_SIZE=128 was added so even if you accept width/height as 256 (by your check it will still restrict icon size to 128)...

        287         if((width > 256 || width < 1) || (height > 256 || height < 1)) {
        288             System.err.println("Warning: Icon scaling may be distorted");
        289             throw new IllegalArgumentException("unexpected icon scaling size");
        290         }

            so maybe either increase MAX_ICON_SIZE or adjust your check accordingly. 

[Shashi] The size I have kept is in a similar scale that is available with the OS. Though there is an internal limit of 128, code is present to scale it to 256 if the user wants in such a way.

We normally do not throw unchecked exception (RuntimeException) from public API, so you should consider throwing checked exception instead.

[Shashi] Fixed this.

Also, you need to change javadoc to have @throws instead of @exception

[Shashi] Fixed this.

Also, it was asked, IIUC that the public API used MutliResolutionImage and uses HYPERLINK "https://docs.oracle.com/javase/10/docs/api/java/awt/image/MultiResolutionImage.html#getResolutionVariants%28%29"getResolutionVariants() to select appropriate icon image or let user select it (for case mentioned above, if we are not sure ourselves)

[Shashi] Since the icon is scaled to the levels that was requested and limits are mentioned as part of Javadoc comments. Fixed in the updated Webrev.

·        scaleIconImage, scaleIcon uses lot of common code so we can have a common method

[Shashi] Fixed this.

makeIcon(long hIcon, int bsize).. I guess parameter name bsize does not convey meaning, is it "bestsize"?

[Shashi] Just an alternative and no meaning for that.

·        int size = getLargeIcon ? 32 : 16; and also in Win32ShellFolderManager2. java probably you can have constants for these 2 number
·        Win32ShellFolderManager2
·        1118                         return getShell32Icon(4, size);
·        1119                     } else {
·        1120                         return getShell32Icon(1, size);

You should use constant to be more readable FILE_ICON_ID = 1; FOLDER_ICON_ID = 4;

[Shashi] For the constants, I have newly added some comments explaining that magic number. Adding a new constant is not worth as it is used only once!!


On 7/20/2018 12:02 PM, Shashidhara Veerabhadraiah wrote:

Hi All, Please review a fix for the below bug.


Bug: https://bugs.openjdk.java.net/browse/JDK-8182043


Webrev: HYPERLINK "http://cr.openjdk.java.net/%7Esveerabhadra/8182043/webrev.00/"http://cr.openjdk.java.net/~sveerabhadra/8182043/webrev.00/


History: This fix is derived from an earlier fix proposed under this mail thread: http://mail.openjdk.java.net/pipermail/awt-dev/2017-September/013016.html. Thanks to Semyon for that trial and part of this solution is continued from where it was left off.


Solution details: Large system icons were not able to be extracted because of sun package internal classes are not exposed anymore. This change adds a new api to get access to those icons.


Thanks and regards,



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