<Swing Dev> [13] RFR JDK-8214702:Wrong text position for whitespaced string in printing Swing text
Prasanta Sadhukhan
prasanta.sadhukhan at oracle.com
Tue Feb 26 06:21:27 UTC 2019
Thanks Phil for review. So, you are doubting it will regress swing
printing tests. As you told earlier, I have ran the following regression
test with this fix
(https://bugs.openjdk.java.net/browse/JDK-6488219 The bug above is
covered by java/awt/print/PrinterJob/SwingUIText.java)
and I did not notice any regression. Any other test we have for swing
printing that we can run?
>>Previously we were using DEFAULT_FRC to make it a screen width which
except for maybe needing to be updated for hi-dpi screens is what we want.
This issue was there from jdk1.6. If it is for hidpi screen, we would
have seen it from jdk9 onwards where we supported hidpi, no?
Regards
Prasanta
On 26-Feb-19 3:25 AM, Phil Race wrote:
> The current fix confused me for a while as I could not see how it was
> at all different than the existing code, since I can't imagine when we'd
> ever take the "else" branch here :
> 533 TextLayout layout;
> 534 if (!isFontRenderContextPrintCompatible(frc, deviceFRC)) {
> 535 layout = createTextLayout(c, text, g2d.getFont(), deviceFRC);
> 536 } else {
> 537 layout = createTextLayout(c, text, g2d.getFont(), frc);
> 538 } Eventually when walking through it I noticed this 531
> FontMetrics fm = g2d.getFontMetrics();
> 532 float screenWidth = SwingUtilities2.stringWidth(c, fm ,trimmedText);
>
> "fm" from line 532 is getting a FontMetrics from the PRINTER - ie the
> scaled FontRenderContext.
> It then uses this to calculate the advance width for such a case - ie
> the printer
> but then *assigns it to a variable called screenWidth*.
>
> Previously we were using DEFAULT_FRC to make it a screen width which
> except
> for maybe needing to be updated for hi-dpi screens is what we want.
>
> So in the updated proposed fix the wrong width is passed to
> getJustifiedLayout().
>
> This may not matter here because there is plenty of space, but in
> other cases
> Swing printing will be clipped as a result. And there were many, many,
> bug reports about
> that. Which is why the code is laying out to the screenwidth because
> that is where the
> UI component size available came from. Buttons & Label text are the
> typical cases where
> this showed up.
>
> There maybe other things to change, as well but the incorrect
> screenWidth is the
> main problem I see here.
>
> -phil.
>
> On 2/25/19 12:05 AM, Prasanta Sadhukhan wrote:
>>
>>
>> On 21-Feb-19 4:50 AM, Sergey Bylokhov wrote:
>>> On 13/02/2019 22:53, Prasanta Sadhukhan wrote:
>>>> Hi Sergey,
>>>>
>>>> I believe drawChars() also has same printing issue [and should be
>>>> changed like modified drawString()] but I am not able to test it as
>>>> reproducer testcase uses JLabel whose constructor can only accept
>>>> "String" and not char[] so I can only test drawString(). Using
>>>> drawChars() implementation in drawString() still reproduces the issue.
>>>
>>> Is it possible temporary replace the call to drawString() by the
>>> drawChars(), to check how drawChars() will work?
>> As I told, it behaves similarly to unmodified drawString and the
>> issue can still be seen. I think we should commit this drawString()
>> change in this fix and I can open another bug to investigate
>> drawChars() impl and reproducer. Will that be fine?
>>
>> Regards
>> Prasanta
>>> or probably we can implement drawChars() on top of drawString()?
>>>
>>>>
>>>> Regards
>>>> Prasanta
>>>> On 14-Feb-19 4:12 AM, Sergey Bylokhov wrote:
>>>>> Hi, Prasanta.
>>>>>
>>>>>> I modified the fix to use deviceFRC if not compatible and in sync
>>>>>> with the comment which says "obtain a TextLayout with advances
>>>>>> for the printer graphics FRC"
>>>>>> I used SwingUtilies2.getStringWidth() which calculates the
>>>>>> advances of the string if text layouting is used.
>>>>>>
>>>>>> http://cr.openjdk.java.net/~psadhukhan/8214702/webrev.2/
>>>>>
>>>>> Can you please take a look to the existed drawChars() method,
>>>>> which is implemented in the similar way as drawStringImpl() and
>>>>> new version of drawString(), but they have some small difference.
>>>>> Why we cannot use the same logic?
>>>>>
>>>>> For example in the drawChars:
>>>>> =========
>>>>> FontRenderContext deviceFontRenderContext = g2d.
>>>>> getFontRenderContext();
>>>>> FontRenderContext frc = getFontRenderContext(c);
>>>>> if (frc != null &&
>>>>> !isFontRenderContextPrintCompatible
>>>>> (deviceFontRenderContext, frc)) {
>>>>> String text = new String(data, offset, length);
>>>>> TextLayout layout = new TextLayout(text,
>>>>> g2d.getFont(),
>>>>> deviceFontRenderContext);
>>>>> String trimmedText = trimTrailingSpaces(text);
>>>>> if (!trimmedText.isEmpty()) {
>>>>> float screenWidth = (float)g2d.getFont().
>>>>> getStringBounds(trimmedText,
>>>>> frc).getWidth();
>>>>> layout = layout.getJustifiedLayout(screenWidth);
>>>>>
>>>>> ==========
>>>>> Similar but not the same logic in the fix:
>>>>>
>>>>> 524 FontRenderContext frc = getFontRenderContext(c);
>>>>> 525 if (frc.isAntiAliased() ||
>>>>> frc.usesFractionalMetrics()) {
>>>>> 526 frc = new
>>>>> FontRenderContext(frc.getTransform(), false, false);
>>>>> 527 }
>>>>> 528 FontRenderContext deviceFRC =
>>>>> g2d.getFontRenderContext();
>>>>> 529 String trimmedText = trimTrailingSpaces(text);
>>>>> 530 if (!trimmedText.isEmpty()) {
>>>>> 531 FontMetrics fm = g2d.getFontMetrics();
>>>>> 532 float screenWidth =
>>>>> SwingUtilities2.stringWidth(c, fm ,trimmedText);
>>>>> 533 TextLayout layout;
>>>>> 534 if
>>>>> (!isFontRenderContextPrintCompatible(frc, deviceFRC)) {
>>>>> 535 layout = createTextLayout(c, text,
>>>>> g2d.getFont(), deviceFRC);
>>>>> 536 } else {
>>>>> 537 layout = createTextLayout(c, text,
>>>>> g2d.getFont(), frc);
>>>>> 538 }
>>>>> 540 layout =
>>>>> layout.getJustifiedLayout(screenWidth);
>>>>>
>>>>>
>>>>>
>>>>
>>>
>>>
>>
>
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