<Swing Dev> [9] Review request for 8156217 Selected text is shifted on HiDPI display
Alexander Scherbatiy
alexandr.scherbatiy at oracle.com
Mon Aug 15 18:48:11 UTC 2016
On 15/08/16 21:43, Phil Race wrote:
> Why is the caret support added in here ? Same for the modelToView
> That will just hold this up as the reasoning behind needing those
> changes is not something
> I have yet been able to convince myself about - even after reading
> your last email.
The main change for the Caret public API (methods
Caret.getMagicCaretPosition2D()/setMagicCaretPosition2D(Point2D p)) is
not included in the current fix. I only moved the new methods
JTextComponent.modelToView2D(int pos)/viewToModel2D(Point2D pt) from the
fix for the Caret to this fix. These methods are used not only for caret
but in other cases like mouse handling, text dragging and others.
Thanks,
Alexandr.
>
> -phil.
>
>
>
> On 08/15/2016 04:13 AM, Alexandr Scherbatiy wrote:
>>
>> Hello,
>>
>> Could you review the updated fix?
>> webrev which contains only change in public API:
>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.05/public-api
>> webrev with contains all changes:
>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.05/all
>>
>> - methods with int coordinates are deprecated
>> - public isUseFloatingPointAPI()/setUseFloatingPointAPI() methods
>> are added to the PlainView and WrappedPlainView classes
>> - JTextComponent.modelToView2D(int pos)/viewToModel2D(Point2D pt)
>> public methods from fix JDK-8163124 Add floating point API support to
>> javax.swing.text.Caret
>> are added
>> - some @implSpec descriptions are removed from the new text drawing
>> methods with floating point arguments
>> - Built-in L&Fs are updated to use floating point API in standard
>> Java text components
>>
>> Thanks,
>> Alexandr.
>>
>> On 7/28/2016 5:38 PM, Alexandr Scherbatiy wrote:
>>>
>>> See comments inline.
>>>
>>> On 7/26/2016 11:57 PM, Phil Race wrote:
>>>> I have a lot of doubts about this as well as trouble getting my
>>>> head around all of it.
>>>>
>>>> Given that apps need to 'buy in' to the floating point I am not
>>>> sure what we are gaining
>>>> but I need to make sure I understand the problem.
>>>>
>>>> It affects only the methods that the 3rd party code can over-ride
>>>> in subclasses and that are called by the JDK internal code.
>>>>
>>>> There are just two protected methods that matter :-
>>>> PlainView.drawSelectedText(..)
>>>> and
>>>> PlainView.drawUnselectedText(..)
>>>>
>>>> The hidpi precison matters since they are drawing a sub-range of
>>>> the text.
>>>> Is there any other method that matters / is used in this way ?
>>> I have found the following methods which relate to text drawing,
>>> can be overridden and could have floating point coordinates:
>>>
>>> javax.swing.text.PlainView.drawLine(...)
>>> javax.swing.text.PlainView.lineToRect(...)
>>> javax.swing.text.PasswordView.drawEchoCharacter(...)
>>>
>>> javax.swing.plaf.TextUI.modelToView(...)
>>> javax.swing.plaf.TextUI.viewToModel(...)
>>> javax.swing.plaf.TextUI.getToolTipText(...)
>>>
>>> There is also a method which relates to a caret position in a text:
>>> javax.swing.text.DefaultCaret.setMagicCaretPosition(Point p)
>>> This requires additional investigation because DefaultCaret extends
>>> Rectangle and so its coordinates can't be float.
>>>
>>>>
>>>> Since 3rd party code is not over-riding these they will get the JDK
>>>> super-class version, thus losing any customisation they might have done
>>>> in the no-longer-called int version.
>>>>
>>>> Assuming that is correct, what customisation would be lost and how
>>>> much does it matter?
>>>
>>> The example is javax.swing.text.PasswordView class which overrides
>>> drawSelectedText(...)/drawUnselectedText(...) methods and draws echo
>>> chars instead of text.
>>> The similar can be done in a custom component:
>>> --------
>>> public class CustomPasswordField extends FieldView {
>>>
>>> @Override
>>> protected int drawSelectedText(Graphics g, int x, int y, int
>>> p0, int p1) throws BadLocationException {
>>> // draw echo chars
>>> }
>>> }
>>> --------
>>>
>>> Switching to support new methods with floating point coordinates
>>> will lead that real text will be shown for old applications in
>>> password fields.
>>>>
>>>> My prefernce is to deprecate the int versions and always call the
>>>> float versions
>>>> rather than the opt-in approach.
>>>>
>>>> Actually my real preference would be to come up with something that
>>>> does
>>>> not involve drawing the text in chunks like this.
>>>>
>>>> ie Swing should use AttributedCharacterIterator .. it looks like
>>>> the code to
>>>> do this might already be there !
>>>>
>>>> 106 private float drawElement(int lineIndex, Element elem, Graphics g,
>>>> 107 float x, float y, boolean fractionalCharBounds)
>>>> 108 throws BadLocationException
>>>> 109 {
>>>> 110 int p0 = elem.getStartOffset();
>>>> 111 int p1 = elem.getEndOffset();
>>>> 112 p1 = Math.min(getDocument().getLength(), p1);
>>>> 113
>>>> 114 if (lineIndex == 0) {
>>>> 115 x += firstLineOffset;
>>>> 116 }
>>>> 117 AttributeSet attr = elem.getAttributes();
>>>> 118 if (Utilities.isComposedTextAttributeDefined(attr)) {
>>>> 119 g.setColor(unselected);
>>>> 120 x = Utilities.drawComposedText(this, attr, g, x, y,
>>>> 121 p0-elem.getStartOffset(),
>>>> 122 p1-elem.getStartOffset());
>>>> 123 } else {
>>>>
>>>> In fact what *that* illustrates is that applications already cannot
>>>> expect
>>>> their over-ridden methods to be called, so this fix is trying to
>>>> fix something
>>>> that can't be fixed.
>>> The javadoc for the "protected PlainView.drawLine(...)" method is:
>>> ---------
>>> /**
>>> * Renders a line of text, suppressing whitespace at the end
>>> * and expanding any tabs. This is implemented to make calls
>>> * to the methods {@code drawUnselectedText} and
>>> * {@code drawSelectedText} so that the way selected and
>>> * unselected text are rendered can be customized.
>>> ---------
>>>
>>> Applications can rely on this behaviour and stopping to call the
>>> drawSelectedText(...)/drawUnselectedText(...) methods with int
>>> coordinates will be incompatible change.
>>>
>>>>
>>>> So why can't we do that ? Just deprecate those int methods, don't add
>>>> the float methods and use ACI ..
>>> New float methods allow to easily migrate on new API for
>>> applications without significant changes.
>>>
>>>> BTW getTabSize() is supposed to be a character count isn't it ? Not
>>>> a pixel
>>>> count. So why does it need a float version.
>>> Could you review the updated fix:
>>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.04
>>>
>>> - methods with int coordinates which can be overridden are
>>> deprecated
>>> - getFractionalTabSize() method is removed
>>>
>>> Thanks,
>>> Alexandr.
>>>>
>>>> -phil
>>>>
>>>> On 06/30/2016 08:50 AM, Alexandr Scherbatiy wrote:
>>>>> On 6/28/2016 8:14 PM, Alan Snyder wrote:
>>>>>> Suppose an application is only partially fixed to use/override
>>>>>> the floating point methods. Perhaps it uses a library that has
>>>>>> not been fixed.
>>>>>>
>>>>>> Is there a more fine grained way to detect programmer awareness
>>>>>> or lack of awareness of the new methods?
>>>>>
>>>>> Here is a slightly updated version which adds public
>>>>> isUseFloatingPointAPI()/setUseFloatingPointAPI() methods to the
>>>>> PlainView and WrappedPlainView classes:
>>>>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.02
>>>>>
>>>>> Using the floating point API is disabled by default and enabled
>>>>> for standard Swing text component classes. This has advantage that
>>>>> selection will work for text component in users applications on
>>>>> HiDPI display.
>>>>>
>>>>> But it still has the same problem. Applications which use custom
>>>>> View classes needs to updated them to implement corresponding text
>>>>> drawing methods with floating point arguments and enable the
>>>>> floating point API usage.
>>>>>
>>>>> Thanks,
>>>>> Alexandr.
>>>>>
>>>>>>
>>>>>> Alan
>>>>>>
>>>>>>
>>>>>>> On Jun 28, 2016, at 9:59 AM, Alexandr Scherbatiy
>>>>>>> <alexandr.scherbatiy at oracle.com
>>>>>>> <mailto:alexandr.scherbatiy at oracle.com>> wrote:
>>>>>>>
>>>>>>>
>>>>>>> Hello,
>>>>>>>
>>>>>>> I tried to merge this fix with the 8132119 Provide public API
>>>>>>> for text related methods in SwingUtilities2
>>>>>>> and found a flow in the used algorithm.
>>>>>>>
>>>>>>> For each method that uses integer coordinates the fix adds a
>>>>>>> pair with floating point arguments.
>>>>>>> The fix 8156217 uses only methods with floating point values to
>>>>>>> correctly handle a selected text.
>>>>>>> This leads that overridden method with integer arguments in
>>>>>>> user code is not called anymore.
>>>>>>>
>>>>>>> I think that this can be handled in the following way:
>>>>>>> - Add a property that enables to use methods with floating
>>>>>>> point arguments in Swing.
>>>>>>> By default it is false and all work as before. The issue with
>>>>>>> selected text is reproduced.
>>>>>>> An application with enabled property does not have issue with
>>>>>>> the selected text but a user should override
>>>>>>> all methods with floating point values if he uses
>>>>>>> corresponding methods with integer values.
>>>>>>>
>>>>>>> Here is a proposed solution where new public system property
>>>>>>> "javax.swing.floatingPoints.enabled" is added:
>>>>>>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.01
>>>>>>>
>>>>>>> - Fix the enhancement JDK-8157461 Glyph image rendering for
>>>>>>> HiDPI displays
>>>>>>>
>>>>>>> Thanks,
>>>>>>> Alexandr.
>>>>>>>
>>>>>>> On 6/16/2016 6:07 PM, Alexandr Scherbatiy wrote:
>>>>>>>> On 6/16/2016 4:47 PM, Alexandr Scherbatiy wrote:
>>>>>>>>>
>>>>>>>>> I tried to look deeper in the code and it seems there is a
>>>>>>>>> rounding issue when float values are summed up.
>>>>>>>>>
>>>>>>>>> Suppose a transform with scale 1.5 is used and the 'a' char
>>>>>>>>> advance is 10 in a dev space.
>>>>>>>>> The 'a' char has advance 10 / 1.5 = 6.666666666666667 as
>>>>>>>>> double value and 6.6666665 when it is cast to float in user space.
>>>>>>>>> The width of a string which consists of 15 'a' chars is 15 *
>>>>>>>>> 6.6666665 = 100.000000.
>>>>>>>>> But the same width calculated as sum of each glyph advance in
>>>>>>>>> StandardGlyphVector.initPositions() method is 99.999992.
>>>>>>>>> --------------
>>>>>>>>> double scale = 1.5;
>>>>>>>>> float advance = (float) (10 / scale);
>>>>>>>>> int N = 15;
>>>>>>>>> System.out.printf("%d * %f = %f\n", N, advance, N *
>>>>>>>>> advance);
>>>>>>>>> float sum = 0;
>>>>>>>>> for (int i = 0; i < N; i++) {
>>>>>>>>> sum += advance;
>>>>>>>>> }
>>>>>>>>> System.out.printf("sum: %f\n", sum);
>>>>>>>>> --------------
>>>>>>>>>
>>>>>>>>> Because of this a string drawn from float position 99.999998
>>>>>>>>> is shifted one pixel left which affects the text selection
>>>>>>>>> code in Swing:
>>>>>>>>> ------------------------
>>>>>>>>> g.scale(1.5, 1.5);
>>>>>>>>> String TEXT = "aaaaaaaaaaaaaaaa";
>>>>>>>>> Rectangle2D rect = font.getStringBounds(TEXT, 0,
>>>>>>>>> index, g.getFontMetrics().getFontRenderContext());
>>>>>>>>> float selectedTextPosition = (float) rect.getWidth();
>>>>>>>>> // 99.999992
>>>>>>>>> g.drawString(TEXT.substring(0, index), x, y); //
>>>>>>>>> non-selected text
>>>>>>>>> g.drawString(TEXT.substring(index, TEXT.length()), x +
>>>>>>>>> selectedTextPosition, y); // selected text is shifted to one
>>>>>>>>> pixel left
>>>>>>>>> ------------------------
>>>>>>>> The last step is how coordinates are scaled in
>>>>>>>> Graphics2D.drawString() method.
>>>>>>>> If the graphics has scale 1.5 and zero translate the
>>>>>>>> transformed coordinates are:
>>>>>>>> (99.999992 + 0) * 1.5 = 149.999985
>>>>>>>> (100.000000 + 0) * 1.5 = 150.000000
>>>>>>>>
>>>>>>>> Both of them are rounded to the same value.
>>>>>>>>
>>>>>>>> If the translate is set to integer 1 value:
>>>>>>>> (99.999992 + 1) * 1.5 = 151.499989 // shifted to one pixel
>>>>>>>> left
>>>>>>>> (100.000000 + 1) * 1.5 = 151.500000
>>>>>>>>
>>>>>>>> A position 99.999992 in user space is rounded to 151 in dev space.
>>>>>>>> A position 100.000000 in user space is rounded to 152 in dev
>>>>>>>> space.
>>>>>>>>
>>>>>>>> And this difference can depend on the translate even it has
>>>>>>>> integer value in user space because it is multiplied on the
>>>>>>>> graphics scale.
>>>>>>>>
>>>>>>>> Thanks,
>>>>>>>> Alexandr.
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Alexandr.
>>>>>>>>>
>>>>>>>>> On 6/2/2016 11:41 PM, Alexandr Scherbatiy wrote:
>>>>>>>>>> On 5/31/2016 10:40 PM, Phil Race wrote:
>>>>>>>>>>>
>>>>>>>>>>> I applied this and it is *much* better but there still seem
>>>>>>>>>>> to be some tiny quirks.
>>>>>>>>>>> When I drag the mouse to select text down and then up again,
>>>>>>>>>>> as I pass the
>>>>>>>>>>> original mouse click point vertically, repaint seem to
>>>>>>>>>>> jiggle vertically by a pixel.
>>>>>>>>>>> Perhaps a rounding issue in the repaint code's calculation
>>>>>>>>>>> of the location of
>>>>>>>>>>> the target y. I think I may see the same in left/right
>>>>>>>>>>> dragging along a line too.
>>>>>>>>>>> So I think this is repaint and not text related. Can you
>>>>>>>>>>> take a look.
>>>>>>>>>>
>>>>>>>>>> I am able to reproduce this only using a floating point
>>>>>>>>>> scale.
>>>>>>>>>> It looks like 2d issue. I used a test which draws a text
>>>>>>>>>> in two pieces. The second piece of the text is shifted from
>>>>>>>>>> the first piece by the floating point size of the the first
>>>>>>>>>> piece of the text.
>>>>>>>>>> -----------
>>>>>>>>>> Rectangle2D rect = font.getStringBounds(TEXT, 0, index,
>>>>>>>>>> g.getFontMetrics().getFontRenderContext());
>>>>>>>>>> float selectedTextPosition = (float) rect.getWidth();
>>>>>>>>>> g.drawString(TEXT.substring(0, index), x, y);
>>>>>>>>>> g.drawString(TEXT.substring(index, TEXT.length()), x +
>>>>>>>>>> selectedTextPosition, y);
>>>>>>>>>> -----------
>>>>>>>>>>
>>>>>>>>>> The second piece of the text can be shifted in the 2 cases:
>>>>>>>>>> a) graphics scale is 1.5 and translation is 1.
>>>>>>>>>> b) graphics scale is 2.25 without applied translation
>>>>>>>>>>
>>>>>>>>>> I have filed an issue on it:
>>>>>>>>>> JDK-8158370 Text drawn from float pointing position and
>>>>>>>>>> with float pointing scale is shifted
>>>>>>>>>> https://bugs.openjdk.java.net/browse/JDK-8158370
>>>>>>>>>>
>>>>>>>>>> Thanks,
>>>>>>>>>> Alexandr.
>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> -phil.
>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>> On 05/06/2016 12:31 PM, Alexandr Scherbatiy wrote:
>>>>>>>>>>>> Hello,
>>>>>>>>>>>>
>>>>>>>>>>>> Could you review the fix:
>>>>>>>>>>>> bug: https://bugs.openjdk.java.net/browse/JDK-8156217
>>>>>>>>>>>> webrev:
>>>>>>>>>>>> http://cr.openjdk.java.net/~alexsch/8156217/webrev.00
>>>>>>>>>>>>
>>>>>>>>>>>> This is the second part of the fix related to the fact
>>>>>>>>>>>> that char width can be fractional in user space.
>>>>>>>>>>>> http://mail.openjdk.java.net/pipermail/swing-dev/2016-May/005814.html
>>>>>>>>>>>>
>>>>>>>>>>>>
>>>>>>>>>>>> The Font.getStringBounds(...) method is used for the
>>>>>>>>>>>> fractional string width calculation by Swing in user space.
>>>>>>>>>>>>
>>>>>>>>>>>> Thanks,
>>>>>>>>>>>> Alexandr.
>>>>>>>>>>>>
>>>>>>>>>>>
>>>>>>>>>>
>>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>
>>>
>>
>
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