Hello Everyone on Java2D Group
This is a follow-up on the bug fix for JDK-8165212.
Link: https://bugs.openjdk.java.net/browse/JDK-8165212
Title: VolatileImage should not be compatible with GraphicsConfiguration
which transform is changed
First, Thanks to Alexandr for his review suggestions on webrev.00
Root Cause:
Upon any change to display's state (Eg: DPI) the callback method-
displayChanged() is invoked on VolatileSurfaceManager. The callback method
updates the volatile image's surface only if the acceleration is enabled. For
non-accelerated volatile images, the surface isn't updated. This caused the bug
on OSs where user can change screen's DPI on the fly without having to
restart/re-login.
Updates to the Fix:
In the previous fix version (webrev.00), the software surface was re-created
for non-accelerated volatile images as well. This fixed the problem. The
suggestion from Alexandr was to re-create the software surface only when the
affine transformation of GraphicsConfiguration changes. This is incorporated in
the current fix.
It is important to note that, the affine transformation of
GraphicsConfiguration is actually derived from the screen device. When end-user
modifies screen's DPI, the affine transformation is updated on the screen
device first; followed by a call to displayChanged() callback on the listeners.
Henceforth, a copy of the transformation is kept in the volatile surface
manager, to aid in comparing changes to affine transformation (before & after
screen's DPI change)
Kindly review the changes and provide your suggestions at your convenience.
Review link: http://cr.openjdk.java.net/~pnarayanan/8165212/webrev.01/
Thank you for your time in review
Have a good day
Prahalad N.
---
From: Alexandr Scherbatiy
Sent: Friday, October 28, 2016 4:57 PM
To: Prahalad Kumar Narayanan; [email protected]
Subject: Re: [OpenJDK 2D-Dev] [9] Review Request: JDK-8165212 VolatileImage
should not be compatible with GraphicsConfiguration which transform is changed
350 if (!isAccelerationEnabled()) {
351 // Ideally there is no need to re-create a software surface.
But
352 // some OSs allow changes to display state at runtime. Such a
353 // provision would cause mismatch in graphics configuration of
the
354 // display and the surface. Hence we re-create the software
surface
355 // as well.
356 sdBackup = null;
357 sdCurrent = getBackupSurface();
358 }
359 }
It seems that the surface is always recreated when the acceleration is not
enabled. May be it should be only done when the graphics configuration
transform scales are differ from the ones from vImg graphics configuration?
Thanks,
Alexandr.
On 10/14/2016 1:38 PM, Prahalad Kumar Narayanan wrote:
Hello Everyone
Good day to you.
Request your time in reviewing the fix for-
Bug : JDK-8165212
Title : VolatileImage should not be compatible with GraphicsConfiguration
which transform is changed
Description on the bug-
. As per the bug, Volatile Image's graphics configuration is not updated
when the host machine display's DPI is changed at runtime (while still running
the java app). In addition, the method contentsLost() does not return true when
display's DPI is modified.
. It is important to note that, the issue is not reproducible with
D3D/OpenGL backend. It is reproducible with non-accelerated Volatile Image.
Root Cause
. A callback method- displayChanged() in VolatileSurfaceManager.java is
invoked when display's settings (DPI) is modified.
. The callback method, currently, updates the graphics configuration
only for Accelerated volatile image. Graphics configuration is not updated for
non-accelerated system memory based VolatileImage.
. Until recently, there wasn't any need for updating graphics
configuration for non-accelerated volatileImage. However, Win 8.1 and above
provide feature to dynamically update the DPI setting (without requiring for
log-off/ log-in), which causes the current bug.
Bug Fix
. First, the callback method is modified to update graphics configuration
for non-accelerated volatile image also.
. An update to graphics configuration might require re-creation of the
surface. Especially, when the scale factor is increased. Hence the system
memory based backupSurface is re-created here.
. The above change is followed by change to Validate() API, so that the
backup surface re-creation in displayChanged() method, correctly returns
IMAGE_RESTORED from validate() API. This way, the code flow for non-accelerated
Volatile Images behaves just the same way as accelerated volatile images.
. Approximately 81 Jtreg test cases (that contained VolatileImage) were
run on win7, linux, and osx. No new regressions have been found after the
modification.
. In addition, a manual test case has been provided to ensure the proper
functioning of the fix
Kindly review the changes and provide your suggestions
Review link: http://cr.openjdk.java.net/~pnarayanan/8165212/webrev.00/
Thank you for your time in review
Have a good day
Prahalad N.
