<AWT Dev> RFR: 8265761: Font with missed font family name is not properly printed on Windows

[Alexander Scherbatiy]

On Fri, 23 Apr 2021 07:02:45 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> PDFBox 1.8 uses [Graphics2D.drawGlyphVector()](https://github.com/apache/pdfbox/blob/41ae21bd4c3f304373d3b05f63af5325df248019/pdfbox/src/main/java/org/apache/pdfbox/pdmodel/font/PDSimpleFont.java#L352)  method with scaled glyphs to print a text and PDF 2.0 uses [Graphics2D.fill()](https://github.com/apache/pdfbox/blob/4f14dee47ff821e44d9e2ff11532959d95e94d5b/pdfbox/src/main/java/org/apache/pdfbox/rendering/PageDrawer.java#L512) to print glyphs path. Both methods finally calls WPathGraphics.convertToWPath(...) in jdk on Windows which call GDI FillPath.
>> 
>> Using a custom PageDrawer to draw a text in PDFBox with Graphics2D.drawString() method reveals the fact that some pdf documents which are properly printed by PDFBox 1.8 and PDF 2.0 on Linux and Windows have issues with printing them on Windows.
>> 
>> The reason is that such docs use fonts which have empty font family name.
>> The awt_PrintJob.jFontToWFontA(...) method is not able to select the required font when the passed font family name is empty.
>> https://github.com/openjdk/jdk/blob/7c37c022a1664437bf8d2c8d76ad039521f3ffa7/src/java.desktop/windows/native/libawt/windows/awt_PrintJob.cpp#L2264 
>> 
>> The proposed solution returns false from WPrinterJob.setFont(...) method when the font family is empty so the text printing falls back to printing a text by GDI FillPath method:
>> https://github.com/openjdk/jdk/blob/6d49cc3b655433d00e967fdcec3f3759412cd925/src/java.desktop/windows/classes/sun/awt/windows/WPrinterJob.java#L1157
>> 
>> To reproduce the issue I created a simple [SampleBowMissedFamilyName.ttf](https://bugs.openjdk.java.net/secure/attachment/94344/SampleBowMissedFamilyName.ttf) font which contains only capital letters "ABCDEF" and saved it with empty font family name.
>> 
>> Here is a simple [PrintFontSample.java](https://bugs.openjdk.java.net/secure/attachment/94343/PrintFontSample.java) program that helps to reproduce the issue using the SampleBowMissedFamilyName.ttf font.
>> 
>> The PrintFontSample program draws a text using three methods:
>> - Graphics2D.drawString(...)
>> - Graphics2D.drawGlyphVector(...)
>> - Graphics2D.drawGlyphVector(...) using transformed glyphs 
>> 
>> Running the program with jdk 16 on Windows (without the fix)
>>>  java PrintFontSample SampleBowMissedFamilyName.ttf
>> 
>> shows that the first and the second lines are not properly printed: [sample-doc-without-fix.pdf](https://bugs.openjdk.java.net/secure/attachment/94345/sample-doc-without-fix.pdf)
>> Running the program with the fix properly prints all three lines: [sample-doc-with-fix.pdf](https://bugs.openjdk.java.net/secure/attachment/94349/sample-doc-with-fix.pdf)
>> 
>> The provided manual test uses the created SampleBowMissedFamilyName.ttf font with empty font family name.
>
> src/java.desktop/windows/classes/sun/awt/windows/WPrinterJob.java line 1160:
> 
>> 1158:                               int rotation, float awScale) {
>> 1159: 
>> 1160:         if (family.isEmpty()) {
> 
> Not sure that the non-empty family, but spaces only will work.

Would it be better to use isBlank() instead of isEmpty() to check a font family name is blank?

        if (family.isBlank()) {
            return false;
        }

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PR: https://git.openjdk.java.net/jdk/pull/3631