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Disabling FRACTIONAL_METRICS on Windows yields incorrect bounds for text PSwing components #191

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GoogleCodeExporter opened this issue Mar 13, 2015 · 14 comments
Open

Disabling FRACTIONAL_METRICS on Windows yields incorrect bounds for text PSwing components #191

GoogleCodeExporter opened this issue Mar 13, 2015 · 14 comments
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auto-migrated Component-Extras Effort-Low Milestone-2.1 OpSys-Linux OpSys-Windows Priority-Medium Toolkit-Piccolo2D.Java Type-Defect Usability

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What steps will reproduce the problem?
1. Run PSwingExample1 on Windows
2. Continuously zoom until the "This is a growable TextArea." text exceeds the 
rightmost bounds of the blue boundary.

What is the expected output? What do you see instead?

The PSwing text shouldn't exceed its bounds.  In other applications, this 
causes the edge of some PSwing components to fall behind other components, 
clipping it so that the rightmost part of the PSwing is hidden.

Note that the problem disappears when commenting out line 474 of PSwing:
g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, 
RenderingHints.VALUE_FRACTIONALMETRICS_OFF);

This line was presumably added to make sure that PSwings on Mac do not render 
with ellipses "...".  However, when we added that workaround we did not know it 
would cause incorrect layout for text PSwings on Windows (and possibly Linux?)

In my working copy, I have applied the change to detect whether the OS is Mac, 
and to disable fractional metrics if and only if the OS is mac:

        //Disable Fractional Metrics on Mac OS because when FRACTIONAL_METRICS are enabled on Mac OS, spurious ellipses
        // are renderer on PSwing text components. Disabling this property on Windows causes incorrect rendering of 
        // adjacent text PSwing nodes.
        if (System.getProperty("os.name").toLowerCase().indexOf("mac") >= 0) {
            g2.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_OFF);
        }

What do others think of this solution?  Could leaving fractional metrics 
enabled in Windows and Linux cause any other buggy behavior?  It would also be 
nice to confirm why this workaround was added in the first place.

Original issue reported on code.google.com by reids%co...@gtempaccount.com on 8 Sep 2010 at 2:51
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The solution you gave seems to be the way to go about it. 

Best case scenario is to have the fractional metrics enabled across the board 
and this gets us far closer to that. Even though it's obviously going against 
the very nature of cross platform Java code, working is working.

Only gotcha there I think is that it would disable it for all mac platforms. 
Are we sure that there are no mac machines for which fractional metrics doesn't 
introduce an ellipsis?

Original comment by allain.lalonde on 8 Sep 2010 at 7:07

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Original comment by heue...@gmail.com on 22 Dec 2010 at 2:06

  • Added labels: Milestone-1.3.1

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Per

http://developer.apple.com/library/mac/documentation/Java/Reference/Java_Propert
iesRef/Articles/JavaSystemProperties.html

There are some system properties on OSX that might affect how text is rendered 
and how this rendering hint is applied:

apple.awt.graphics.EnableQ2DX

    Determines whether hardware acceleration is used to speed up rendering of simple primitives like images, lines, rects, and simple characters. In addition to using this flag, you need to enable Quartz 2D acceleration in the Quartz Debug application, included with the Xcode Developer Tools for Mac OS X.

    This is strictly a developer option. Java applications intended for use on Mac OS X should not rely on the presence of Quartz 2D acceleration.

    The default value is false.

apple.awt.graphics.UseQuartz

    Determines whether Apple’s Quartz renderer is used instead of Sun’s 2D renderer.

    The default value is true for J2SE 5.0 and false for Java SE 6.


Thus the OS check might not be sufficient.

See also Issue 117 which documents my frustration with Piccolo2D text rendering 
in general.

Original comment by heue...@gmail.com on 2 Mar 2011 at 4:34

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Consider also OpenJDK builds on Mac OSX

http://code.google.com/p/openjdk-osx-build/

Original comment by heue...@gmail.com on 2 Mar 2011 at 6:00

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Here's a summary of this issue to date:

While the default for all platforms seems to be FRACTIONAL_METRICS_ON 
("fm_on"), Piccolo2D explicitly sets FRACTIONAL_METRICS_OFF ("fm_off") for 
painting of PSwing nodes. As I understand it, this decision has been a part of 
the PSwing class for a long while now and the primary motivation for doing this 
is to avoid rendering of ellipses on Mac OS X platforms (by using "fm_off", we 
prevent Mac OS from rendering ellipses for some text renderings that, due to 
fractional metrics calculations can't fully render within their bounds.)

After running several tests, however, it seems that painting w/ "fm_off" causes 
more unpleasant behavior across systems than using the default of "fm_on". On 
all systems, using "fm_off" causes noticeable jittering while zooming. On 
Ubuntu/Java4, ellipses are actually rendered in this mode and not in "fm_on". 
And on Windows 7, using Java4, ellipses are rendered regardless of the setting.

I tested on a subset of {Win7, Snow Leopard, Ubuntu10} x {Java4, Java6} x 
{FRACTIONAL_METRICS_ON, FRACTIONALMETRICS_OFF} and the outcome images will come 
soon attached with tell-tale filenames:

                                   | "fm_off"                                | "fm_on"               
Windows7
    Java4:                         jittering; ellipsed                   no jitter; ellipsed
    Java6:                         jittering                                  slight jittering
Ubuntu10
   Java4:                          jittering; ellipsed                   slight jittering
   Java6 (openjdk):          jittering; slight artifacts         no jitter; noticeable artifacts
Mac/Snow
   Java6:                           jittering                                 slight jittering; ellipsed

It appears impossible to avoid ellipse-rendering using RenderingHints. Also, 
using the default rendering hint "fm_on" yields much better behavior (little or 
no jittering) otherwise.

It seems clients can avoid ellipses by explicitly setting preferred sizes on 
their components, so there is a workaround.

With this data, I believe the *correct* route is to use the default "fm_on" 
rendering hints (which is default on all systems I tested on), which also 
resolves this issue.

I don't believe we can do this, however, in 1.3.* releases as clients may 
already rely on this behavior. 1.3.* clients can workaround this issue by 
overriding paint() behavior (not ideal, I know.)

Looking for P2D developers to comment. My vote is to move this ticket to 2.0 
with the plan of removing our use "fm_off" in 2.0.

Original comment by atdi...@gmail.com on 27 Mar 2011 at 9:23

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Attaching Windows 7 outcomes -- {Java4, Java6} x {"fm_on", "fm_off"}

Original comment by atdi...@gmail.com on 27 Mar 2011 at 9:24

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Attaching Ubuntu outcomes -- {Java4, Java6 (openjdk)} x {"fm_on", "fm_off"}

Original comment by atdi...@gmail.com on 27 Mar 2011 at 9:26

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Attaching Mac OS X (Snow L.) -- {Java6} x {"fm_on", "fm_off"}

Original comment by atdi...@gmail.com on 27 Mar 2011 at 9:27

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Speaking for PhET...

+1 for the proposal to move this ticket to 2.0.  Also OK to default to "fm_on", 
as long as we have some way to globally change to "fm_off" in client code.

Also of note is that we have recently experienced the Mac OS ellipsis problem 
with Arabic characters at font size > 14, with both "fm_on" and "fm_off" 
scenarios.

Original comment by cmal...@pixelzoom.com on 29 Mar 2011 at 12:12

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Are you able to workaround ellipses by explicitly setting preferred bounds on 
the component (giving it larger width)?

Original comment by atdi...@gmail.com on 29 Mar 2011 at 3:18

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Original comment by atdi...@gmail.com on 29 Mar 2011 at 3:18

  • Added labels: Milestone-2.0
  • Removed labels: Milestone-1.3.1

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Yes, I am able to work around ellipses in a component by explicitly increasing 
its preferred width.

Original comment by cmal...@pixelzoom.com on 30 Mar 2011 at 7:17

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Original comment by heue...@gmail.com on 26 Nov 2013 at 9:11

  • Added labels: Milestone-2.1
  • Removed labels: Milestone-2.0

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