Hi Semyon, Whenever the container is resized we used to update the scroll pane 
sizes/geometry regardless of the scroll bar display policies. This resizing 
make sense for the non SCROLLBARS_NEVER cases as the scroll pane is displayed 
or needed an update. This additional update posed issues for the 
SCROLLBARS_NEVER case where we are not supposed to display the scroll pane per 
the java doc, then why update?

 

Scroll pane geometry gets updated in 2 ways, one thro' setScrollPosition() and 
childResized(). So I derived the conclusion based on the javadoc information 
that since we don't display the scroll pane there is no need to update the 
scroll pane geometry based on the childResized() as it was altering the 
position already set by the setScrollPosition(). This behavior is same as the 
other non SCROLLBARS_NEVER mode and setting the scroll bar display to 
SCROLLBARS_NEVER didn't made any difference.

 

Thanks and regards,
Shashi

 

From: Semyon Sadetsky 
Sent: Friday, February 23, 2018 10:17 PM
To: Shashidhara Veerabhadraiah <shashidhara.veerabhadra...@oracle.com>; 
awt-dev@openjdk.java.net
Subject: Re: <AWT Dev> [11] JDK-8195738: scroll poistion in ScrollPane is reset 
after calling validate()

 

On 2/22/18 8:23 PM, Shashidhara Veerabhadraiah wrote:

Hi Semyon, Thanks for your review comments.

 

Here are those different scroll bar pane modes and their description:

Modifier and Type

Field

Description

static int

HYPERLINK 
"https://docs.oracle.com/javase/9/docs/api/java/awt/ScrollPane.html#SCROLLBARS_ALWAYS"SCROLLBARS_ALWAYS

Specifies that horizontal/vertical scrollbars should always be shown regardless 
of the respective sizes of the scrollpane and child.

static int

HYPERLINK 
"https://docs.oracle.com/javase/9/docs/api/java/awt/ScrollPane.html#SCROLLBARS_AS_NEEDED"SCROLLBARS_AS_NEEDED

Specifies that horizontal/vertical scrollbar should be shown only when the size 
of the child exceeds the size of the scrollpane in the horizontal/vertical 
dimension.

static int

HYPERLINK 
"https://docs.oracle.com/javase/9/docs/api/java/awt/ScrollPane.html#SCROLLBARS_NEVER"SCROLLBARS_NEVER

Specifies that horizontal/vertical scrollbars should never be shown regardless 
of the respective sizes of the scrollpane and child.

 

This javadoc, you've copy-pasted here, doesn't explain why in your fix the 
notification about changed child size is disabled for SCROLLBARS_NEVER case. 

Thanks and regards,
Shashi

 

From: Semyon Sadetsky 
Sent: Thursday, February 22, 2018 11:58 PM
To: Shashidhara Veerabhadraiah HYPERLINK 
"mailto:shashidhara.veerabhadra...@oracle.com";<shashidhara.veerabhadra...@oracle.com>;
 HYPERLINK "mailto:awt-dev@openjdk.java.net"awt-dev@openjdk.java.net
Subject: Re: <AWT Dev> [11] JDK-8195738: scroll poistion in ScrollPane is reset 
after calling validate()

 

Hi Shashi,

Can you clarify what is the principal difference between SCROLLBARS_NEVER and 
other scroll policies that requires to avoid updating the scroll geometry 
according to the inner component size?

--Semyon

On 02/19/2018 11:08 PM, Shashidhara Veerabhadraiah wrote:

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

 

Bug: https://bugs.openjdk.java.net/browse/JDK-8195738

 

Webrev: HYPERLINK 
"http://cr.openjdk.java.net/%7Esveerabhadra/8195738/webrev.00/"http://cr.openjdk.java.net/~sveerabhadra/8195738/webrev.00/

 

Problematic platform: Windows only.

 

Summary: This bug occurs only on windows platform and whereas the behavior is 
different on Mac/Linux platforms. Now after this fix there is common behavior 
across the platforms.

The main problem was with resetting the state of the scroll bars even though 
the scroll bar panes are spawned with SCROLLBARS_NEVER as the scroll bar 
display policy. This resetting should not occur as the scroll bar display 
policy makes the 

scroll bar panes invisible. Hence except the setScrollPosition() calls, we 
don't need to resize/update the scroll bars state upon calling the scroll bars 
validation if SCROLLBARS_NEVER policy is used as the scroll bars are not 
displayed.

 

Thanks and regards,
Shashi

 

 

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