[OpenJDK 2D-Dev] RFR: 8242004: TextLayout throws Exception with a non-invertible transform

Fri Apr 10 20:51:51 UTC 2020

You're right.
This is because I did not apply the non-invertible transform on the 
graphics and do
what would be more normal which is to call 
Graphics2D.getFontRenderContext() to
create the TextLayout so that it matched. The constructor FRC is for 
layout not rendering.
So in other words unless the non-invertible transform is applied to the 
graphics it doesn't prevent rendering.
In fact this made me looks how we use the inverse Tx and it turns out 
that currently *nothing* uses it.
So I've updated the webrev to remove it entirely along with unused code.

Now the test should cover both cases.
But in this case - default FRC used for rendering - we will get what you 
see.

Updated webrev : http://cr.openjdk.java.net/~prr/8242004.1/

-phil.

On 4/10/20, 8:41 AM, Jayathirth D v wrote:
> Hi Phil,
>
> I see your point of allowing queries on text layout without throwing 
> exceptions.
>
> I was also under the impression that we should not see text getting 
> drawn when we try to draw it using TextLayout with your change.
>
> For more clarification I am adding what I tested :
> I used code from your test case and tried drawing using TextLayout and 
> drawString(). Without your change in both the cases we 
> see NoninvertibleTransformException. After your change in case of 
> TextLayout.draw() we are actually seeing the text but in case of 
> drawString() text is not getting drawn.
>
> _Verification test I used:_
> importjavax.swing.*;
> importjava.awt.*;
> importjava.awt.font.FontRenderContext;
> importjava.awt.font.TextLayout;
> importjava.awt.geom.AffineTransform;
>
> public classNonInvertibleTransformTextTestextendsJPanel {
>
>      public voidpaint(Graphics g) {
>          Graphics2D g2 = (Graphics2D)g;
>
>          AffineTransform at =newAffineTransform(1f,0.0f,-15,0.0,-1,-30);
>
>          // First use case of drawing using TextLayout
>          FontRenderContext frc =newFontRenderContext(at, false, false);
>          Font font =newFont(Font.DIALOG,Font.PLAIN,12);
>          TextLayout tl =newTextLayout("ABC",font,frc);
>          tl.draw(g2,50,50);
>
>          // Second use case of drawing using drawString()
>          //g2.setTransform(at);
>          //g2.drawString("ABC", 50, 50);
>      }
>
>      public static voidmain(String[] args) {
>          JFrame f =newJFrame();
>          f.getContentPane().add(newNonInvertibleTransformTextTest());
>          f.setSize(300,200);
>          f.setVisible(true);
>      }
> }
> May be I am wrongly using TextLayout.draw() to check expected 
> behaviour after the change.
> Please clarify.
>
> Thanks,
> Jay
>
>> On 10-Apr-2020, at 7:45 PM, Philip Race <philip.race at oracle.com 
>> <mailto:philip.race at oracle.com>> wrote:
>>
>> Oh and if you do draw it, it still goes through the GV path so 
>> nothing should draw there.
>>
>> This is what I meant by :
>> > Subsequent rendering of the TextLayoutwill be handled by the other 
>> checks being added.
>>
>> The shape returned might be not be null but I don't think you'll get 
>> more than a line ..
>>
>> -phil.
>>
>> On 4/10/20, 12:57 AM, Philip Race wrote:
>>>
>>>
>>> On 4/9/20, 10:26 PM, Jayathirth D v wrote:
>>>> Hi Phil,
>>>>
>>>> I went through all use cases captured in test case (TextLayout, 
>>>> drawXXXX).
>>>>
>>>> With updated change there is difference in behaviour between how we 
>>>> interpret non-invertible transform between TextLayout.draw() and 
>>>> drawXXXX() API’s.
>>>> In case of TextLayout.draw() we are overriding non-invertible 
>>>> transform and allowing text rendering to happen, but in case of 
>>>> drawXXXX() we just return and doesn’t allow text rendering to 
>>>> continue. Is it okay to have this difference in behaviour?
>>>
>>> It becomes tricky.
>>> Do you have a suggestion ?
>>> Remember that the TextLayout is returned and does not have to be 
>>> drawn, but could be
>>> by both drawing it directly or asking for the outline shape and 
>>> rendering that.
>>> It can also be queried for the layout etc. There needs to be 
>>> something returned that
>>> does not cause other problems. And patently there can't be apps that 
>>> would care because
>>> today they can't get that far.
>>> And there's no defined behaviour in this case.
>>>
>>> So if you have specific code suggestions ..
>>>>
>>>> Also in test case its better if we continue to test all use cases 
>>>> and then fail instead of failing at first instance and added test 
>>>> case needs change in Copyright year from 2015 to 2020.
>>>
>>> oops.
>>>
>>> -phil.
>>>
>>>>
>>>> Thanks,
>>>> Jay
>>>>
>>>>> On 10-Apr-2020, at 7:53 AM, Philip Race <philip.race at oracle.com 
>>>>> <mailto:philip.race at oracle.com>> wrote:
>>>>>
>>>>> D**n copy/paste, yes you correctly inferred the webrev is at
>>>>> <cr-url>/<my openjdk id>/<bugid> ie : 
>>>>> http://cr.openjdk.java.net/~prr/8242004/ 
>>>>> <http://cr.openjdk.java.net/%7Eprr/8242004/>
>>>>>
>>>>> -phil.
>>>>>
>>>>>
>>>>> On 4/9/20, 7:00 PM, Jayathirth D v wrote:
>>>>>> Hi Phil,
>>>>>>
>>>>>> Please share webrev link, you have added JBS link for webrev.
>>>>>> I went to path where you usually share webrev's and found 
>>>>>> http://cr.openjdk.java.net/~prr/8242004/ 
>>>>>> <http://cr.openjdk.java.net/%7Eprr/8242004/>
>>>>>>
>>>>>> Thanks,
>>>>>> Jay
>>>>>>
>>>>>>
>>>>>>> On 10-Apr-2020, at 12:49 AM, Philip Race <philip.race at oracle.com 
>>>>>>> <mailto:philip.race at oracle.com>> wrote:
>>>>>>>
>>>>>>> Any takers ?
>>>>>>>
>>>>>>> -phil
>>>>>>>
>>>>>>> On 4/3/20, 1:29 PM, Philip Race wrote:
>>>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8242004
>>>>>>>> webrev: https://bugs.openjdk.java.net/browse/JDK-8242004
>>>>>>>>
>>>>>>>> Several code paths can end up in the method shown in the bug report
>>>>>>>> with a non-invertible transform.
>>>>>>>>
>>>>>>>> As much as possible, we can prevent them reaching here by 
>>>>>>>> checking in the rendering code.
>>>>>>>>
>>>>>>>> If we do get here, which should now be possible only when 
>>>>>>>> directly creating
>>>>>>>> a TextLayout, we can use a default TX. Subsequent rendering of 
>>>>>>>> the TextLayout
>>>>>>>> will be handled by the other checks being added.
>>>>>>>>
>>>>>>>> A regression test is provided which checks various APIs to make 
>>>>>>>> sure no
>>>>>>>> exception is thrown.
>>>>>>>>
>>>>>>>> -phil.
>>>>>>>>
>>>>>>>>
>>>>>>
>>>>
>
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