I was not familiar with this "magic caret" but from reading it seems
like it has just one use/purpose.
In the event that someone has multi-line text that you can navigate
around with up/down arrow keys
and that text has lines of varying length, you want a "preferred"
horizontal position for the caret
to be remembered so the caret is placed at that position whenever the
line of text has a length
greater than the caret position. Is there anything more to it than that ?
Obviously the caret needs to be placed correctly in the context of the
text, so the precise position,
even in an all-integer world, is not going to line up on every single
line, unless you have monospaced text.
ie the "pixel" position is going to get converted into a position on the
leading or trailing edge of some glyph
So I wonder, does adding float matter .. is the extra precision valuable
here ?
-phil.
On 08/04/2016 05:44 AM, Alexandr Scherbatiy wrote:
Hello,
Could you review the fix:
bug: https://bugs.openjdk.java.net/browse/JDK-8163124
webrev: http://cr.openjdk.java.net/~alexsch/8163124/webrev.00
The text position can have floating point value on HiDPI display.
The Caret interface should be updated to allow use floating point
positions.
The fix adds the following public API with floating point positions:
javax.swing.text.Caret.getMagicCaretPosition2D()
javax.swing.text.Caret.setMagicCaretPosition2D(Point2D p)
javax.swing.text.JTextComponent.modelToView2D(int pos)
javax.swing.text.JTextComponent.viewToModel2D(Point2D pt)
javax.swing.text.ParagraphView.getClosestPositionTo(int pos,
Position.Bias b, Shape a, int direction, Position.Bias[], int
rowIndex, float x)
The fix replaces
Caret.getMagicCaretPosition()/setMagicCaretPosition(Point p) to
Caret.getMagicCaretPosition2D()/setMagicCaretPosition2D(Point2D p) in
all places
except DefaultCaret because DefaultCaret extends Rectangle so its
coordinates always have int values.
I have filled a separated enhancement for this JDK-8163174 Add
DefaultCaret2D which supports floating point API
To make a custom caret use floating point API it is also necessary
that PlainView.modelToView() returns a rectangle with floating point
values. It can be done after the fix
JDK-8156217 Selected text is shifted on HiDPI display
which implements Utilities.getTabbedTextWidth(Segment s, FontMetrics
metrics, float x, TabExpander e, int startOffset) method.
I have filled a separated issue on it:
JDK-8163175 PlainView.modelToView() method should return Rectangle2D
Thanks,
Alexandr.
