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.
