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.scherba...@oracle.com
<mailto:alexandr.scherba...@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.