8256264: Printed GlyphVector outline with low DPI has bad quality on Windows

[AlexanderScherbatiy]

Printing text using GlyphVector outline has bad quality on printers with low DPI on Windows.
The GDI system used for text printing on Windows accepts only integer path coordinates.
Rounding GlyphVector outline coordinates leads to distorted printed text.

To reproduce the issue run the PrintGlyphVectorOutlineSample file on Windows and select a low DPI
printer in the printer dialog. The sample prints two lines, one using Graphics drawString() method and another by
filling GlyphVector outline. Chars on the second line are distorted.

It is also possible to reproduce the issue running the sample and printing the text to PDF: fill-glyph-vector-outline.png

The proposed fix introduce "sun.java2d.print.enablePathPrecisionScale" property which being enabled
scales the GDI WorldTransform down and GlyphVector outline coordinates up.
This allows to keep some digits after a dot from being rounded.
The value for scaling is chosen to be 1000 in the same way how it is used by String trunc(float f) method from PSPrinterJob class on Linux:

jdk/src/java.desktop/share/classes/sun/print/PSPrinterJob.java

Line 1489 in ed615e3

String trunc(float f) {

See the fill-glyph-vector-outline-enable-path-scale-factor.png screenshot which shows how the GlyphVector outline is filled after the fix with the enabled "sun.java2d.print.enablePathPrecisionScale" option.

fill-glyph-vector-outline-diff.png shows difference of GlyphVector outline printing before and after the fix.

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Progress

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Issue

• JDK-8256264: Printed GlyphVector outline with low DPI has bad quality on Windows

Reviewers

• Sergey Bylokhov (@mrserb - Reviewer)

Download

$ git fetch https://git.openjdk.java.net/jdk pull/1183/head:pull/1183
$ git checkout pull/1183

[bridgekeeper]

👋 Welcome back alexsch! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

@AlexanderScherbatiy The following labels will be automatically applied to this pull request:

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[mlbridge]

Webrevs

• 02: Full - Incremental (b6885e5)
• 01: Full - Incremental (f79b801)
• 00: Full (120ae32)

[mrserb]

I am not sure that we need the additional property for things other than possibly to workaround some possible bugs. I am fine if we will use the scaled version all the time, does it have any drawbacks?

[AlexanderScherbatiy]

I prepared a simple print test sample which uses 4 different fonts (plain and bold) with different sizes and prints 640 lines on 10 pages.

I run the sample with and without the fix to PDF and measured the time which is used by the deviceFill() method (it both converts the shape to path and fills it):

jdk/src/java.desktop/windows/classes/sun/awt/windows/WPathGraphics.java

Line 1489 in b21b96d

protected void deviceFill(PathIterator pathIter, Color color) {

The average time without the fix: 2.77s (min 2.74s, max 2,78)
The average time with the fix: 2.76s (min 2.74s, max 2.77)

I removed the sun.java2d.print.enablePathPrecisionScale property from the fix.

[mrserb]

I removed the sun.java2d.print.enablePathPrecisionScale property from the fix.

You forgot to delete it from the test.

[AlexanderScherbatiy]

The sun.java2d.print.enablePathPrecisionScale property is removed from the PathPrecisionScaleFactorTest test.

[openjdk]

@AlexanderScherbatiy This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8256264: Printed GlyphVector outline with low DPI has bad quality on Windows

Reviewed-by: serb

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 378 new commits pushed to the master branch:

• 2b4a423: 8255542: Attribute length of Module, ModulePackages and other attributes is ignored
• ca40267: 8257509: Strengthen requirements to call G1HeapVerifier::verify(VerifyOption)
• 4a85514: 8257182: JCK test failures in integer / long rotation tests
• f33808f: 8257631: C2: Assertion failure in ArrayCopyNode::get_count() during late inlining
• 417e7e6: 8257632: C2: Late inlining attempt on a call with a dead memory crashes
• 6845fee: 8257625: C2: Harden input checks in vector intrinsics
• 4390f2c: 8257630: C2: ReplacedNodes doesn't handle non-CFG multi nodes
• d08c612: 8257708: Remove redundant unmodifiableSet wrapper from already immutable set returned by Collections.singleton
• 49f9e57: 8257734: Extraneous output in HmacSHA3_512 constructor
• f83fd4a: 8257438: Avoid adding duplicate values into extendedKeyCodesSet
• ... and 368 more: https://git.openjdk.java.net/jdk/compare/ec08b3f28d133c2cc8a9cb8396c5bfa36333ff98...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

[AlexanderScherbatiy]

/integrate

[openjdk]

@AlexanderScherbatiy Since your change was applied there have been 378 commits pushed to the master branch:

• 2b4a423: 8255542: Attribute length of Module, ModulePackages and other attributes is ignored
• ca40267: 8257509: Strengthen requirements to call G1HeapVerifier::verify(VerifyOption)
• 4a85514: 8257182: JCK test failures in integer / long rotation tests
• f33808f: 8257631: C2: Assertion failure in ArrayCopyNode::get_count() during late inlining
• 417e7e6: 8257632: C2: Late inlining attempt on a call with a dead memory crashes
• 6845fee: 8257625: C2: Harden input checks in vector intrinsics
• 4390f2c: 8257630: C2: ReplacedNodes doesn't handle non-CFG multi nodes
• d08c612: 8257708: Remove redundant unmodifiableSet wrapper from already immutable set returned by Collections.singleton
• 49f9e57: 8257734: Extraneous output in HmacSHA3_512 constructor
• f83fd4a: 8257438: Avoid adding duplicate values into extendedKeyCodesSet
• ... and 368 more: https://git.openjdk.java.net/jdk/compare/ec08b3f28d133c2cc8a9cb8396c5bfa36333ff98...master

Your commit was automatically rebased without conflicts.

Pushed as commit d6dd440.

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