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Hi Alexandr,<br>
<br>
I looked at the testcase <a moz-do-not-send="true"
class="moz-txt-link-freetext"
href="https://bugs.openjdk.java.net/browse/JDK-8162350">8162350</a>
closely and found your explanation below not quite precise...<br>
<br>
When you repaint a letter with an slightly expanded dirty rect,
you've got it as [40-1, 0-1, 80+2, 60+2] = [39, -1, 82, 62]. Let's
count only "x".<br>
As Jim noted, the code to draw is:<br>
<br>
// repainting x,y,w,h
<br>
img = make image (w,h)
<br>
g = img.getGraphics()
<br>
g.setClip(x,y,w,h)
<br>
g.translate(-x,-y)
<br>
component.paint(g)
<br>
destination.drawImage(img, x,y)
<br>
<br>
The transformation matrix of "g" is double (AffineTransform.java).
So, g.translate(-39) translates to -39*1.5=-58.5. The top-left pixel
of the letter [40, 0]=[40*1.5, 0]=[60, 0] thus is painted into
x=[60-58.5]=1.5 of the intermediate "img". And I suspect it's
eventually not rounded up but is floor'ed to x=1. Then, the "img" is
drawn at x=[39]=[39*1.5]=58.5 which I suspect is also eventually
floor'ed to x=58. As the result, the top-left pixel of the letter
appears at x=[58+1]=59, not at x=60. That's the shift. Not sure if
my guess is correct though.<br>
<br>
The Jim's last suggestion seems to address the problem, as it scales
& rounds first and then passes already computed values down.
Does the solution affect RepaintManager only? Or I suspect there
will be a problem with:<br>
<br>
// Not sure if there is a mechanism for this since I think
<br>
// all of the interfaces to get a compatible image are
<br>
// designed to assume that the caller is not scale-aware.
<br>
img = make pixel-sized image (pixelw, pixelh)<br>
<br>
because the comments are true.<br>
<br>
Thanks,<br>
Anton.<br>
<br>
On 9/30/2016 1:22 PM, Alexandr Scherbatiy wrote:<br>
<blockquote
cite="mid:ae559915-f1f1-cc32-3a2b-05bb5d4b1672@oracle.com"
type="cite">
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<br>
Hello Anton,<br>
<br>
Yes, we are working on it.<br>
<br>
For example, there is the known issue DK-8162350 RepaintManager
shifts repainted region when the floating point UI scale is used.<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="https://bugs.openjdk.java.net/browse/JDK-8162350">https://bugs.openjdk.java.net/browse/JDK-8162350</a><br>
<br>
The problem is that the RepaintManager draws a region to a
buffered image at first and draws the image after that to the
window.<br>
Suppose the image has int coordinates and size (x, y, w, h) in the
user space. It should be drawn into the region with coordinates
(x, y, x+width, y+height) = (x1, y1, x2, y2).<br>
If floating point UI scale is used (like 1.5) the region
coordinates are converted to values (1.5 * x1, 1.5 * y1, 1.5 *
x2, 1.5 * y2) in the dev space.<br>
Now these coordinates need to be rounded and the process really
depends on the evenness or oddness of the start and end
coordinates. They both can be rounded to one side or to opposite.
Depending on this some lines near the drawn image region can be
not filled or just wrongly filled.<br>
<br>
If I try to not use a buffered image in the RepaintManager it
seems that some problems are just gone away (internal frame moving
artifacts on the SwingSet2 demo or squares in
MinimalSwingApplication are drawn as squares and not rectangles).<br>
But not all of them. The artifacts during the scrolling in the
SwingSet2 demo still exist.<br>
<br>
I have filled an issue on it just to keep track of them:
JDK-8166954 Drawing artifacts with floating point UI scale<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="https://bugs.openjdk.java.net/browse/JDK-8166954">https://bugs.openjdk.java.net/browse/JDK-8166954</a><br>
<br>
The another problem which we are working on is that a selected
text is just shifted: 8156217 Selected text is shifted on HiDPI
display<br>
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="https://bugs.openjdk.java.net/browse/JDK-8156217">https://bugs.openjdk.java.net/browse/JDK-8156217</a><br>
<br>
To support this we were needed to add some new API which support
floating point coordinates in the View, TextUI and JTextComponent
classes.<br>
The issue is on the review:
<a moz-do-not-send="true" class="moz-txt-link-freetext"
href="http://mail.openjdk.java.net/pipermail/swing-dev/2016-September/006705.html">http://mail.openjdk.java.net/pipermail/swing-dev/2016-September/006705.html</a><br>
<br>
Thanks,<br>
Alexandr.<br>
<br>
<div class="moz-cite-prefix">On 9/28/2016 1:17 PM, Anton Tarasov
wrote:<br>
</div>
<blockquote
cite="mid:e773b694-40aa-513f-158d-14c67f3d0020@jetbrains.com"
type="cite">
<meta http-equiv="content-type" content="text/html;
charset=utf-8">
Hello,<br>
<br>
JDK9 comes with HiDPI support on Windows/Linux which is really
great. As we gave it a try, we found it looking pretty good with
an integer scale (2x) but revealed some rendering flaws with
float scales.<br>
<br>
Let me please demonstrate it with SwingSet2 + JDK9-ea-b137 +
Windows 8.1 in 150% scale (1.5f)<br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/demo1.png">demo1</a><br>
<br>
Dragging Frame-0 behind the pallet makes the pallet wavy.<br>
Also, as Frame-0 moves it may leave traces.<br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/demo2.png">demo2</a><br>
<br>
Unstable look of a control. For instance, these two combos are
decorated differently (and not perfectly).<br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/demo3.png">demo3</a><br>
<br>
Scrolling traces.<br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/demo4.png">demo4</a><br>
<br>
Menu traces.<br>
Colored rendering artifacts.<br>
<br>
Additionally, I'm attaching a test source & pics kindly
provided by Renaud (cc'd) from AndroidStudio. The demo finely
shows problems on the example of primitive rendering.<br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/Scaling-100-percent.png">Scaling
100%</a><br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/Scaling-125-percent.png">Scaling
125%</a><br>
<br>
<a moz-do-not-send="true"
href="http://cr.openjdk.java.net/%7Eant/hidpi_pics/Scaling-150-percent.png">Scaling
150%</a><br>
<br>
It seems like most of the mentioned issues are caused by
inaccurate rounding performed during the rendering cycle.<br>
<br>
So, I'd like to ask you please share your thoughts on it. How
serious is the problem at all (I guess you're aware of it)? What
is solvable on the JDK side, and what is not (e.g. demo2 and the
Renaud's test case)?<br>
Do you have plans to resolve it by jdk9 GA, or earlier/later?
Any technical details behind it are very welcome as well.<br>
<br>
Thanks in advance,<br>
Anton.<br>
</blockquote>
<br>
</blockquote>
<br>
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