Looking a bit further, and I noticed this code has recently been
rewritten. The old code used StringBuffer and wasn't that easy to read,
but the new code although easier to read seems to contain several
changes in how things used to work.
The most noticable is that it doesn't stop after it finds the first
mnemonic (probably because it is now building a new string and stopping
half way would result in an incomplete string -- the old code instead
would delete parts from a copy so it could stop early, although that has
some bugs too I noticed).
The new code therefore finds the last mnemonic instead of the first, but
unfortunately, there is an off by one error that becomes gradually worse
as more underscores are encountered.
Compare the outputs (Input: How_to_test_mnemonics):
Old version
(https://github.com/openjdk/jfx/blob/jfx16/modules/javafx.controls/src/main/java/com/sun/javafx/scene/control/behavior/TextBinding.java):
=========================
Resulting Label = Howto_test_mnemonics; mnemonicIndex = 3; mnemonic = t
Current version (master):
=========================
Resulting Label = Howtotestmnemonics; mnemonicIndex = 11; mnemonic = m
It looks like a significant change in how things used to work which the
tests didn't catch at all.
--John
On 29/10/2021 21:45, John Hendrikx wrote:
Hm, I can confirm it appears under the "e", also under Windows, but I
suspect the platform will make no difference.
I tested a bit further, and I found the following:
1) The mnemonic key seems to be "m", and it appears under the "e"
because it deleted two more underscores (index is off by 2). What makes
this hard to discover however is my second finding:
2) Checkbox doesn't toggle at all when you use the correct mnemonic, a
Button however works.
3) If you add an "onAction" to the Checkbox that prints something on the
console, you can see the mnemonic working, but the Checkbox is still not
toggled.
I checked the mnemonic parsing code, and if you run it in isolation, it
finds the first underscore and has the correct index
(TextBinding#parseAndSplit). I stopped there, but perhaps the code
actually runs for each underscore found (it updates the text, perhaps
this triggers another parsing run).
--John
On 29/10/2021 19:53, Scott Palmer wrote:
I looked in the bug database and while there are lots of bugs reported
against the mnemonic parsing, they claim to be fixed.
After noticing something peculiar on a control in my app (it was
showing a
file path and I hadn't disabled the mnemonic parsing) I did some tests.
The documentation is unclear on what should happen if multiple
underscores
are in the text. It just says if the mnemonic parsing character '_'
appears that the key combination will be based on the succeeding
character. I presume that it should pick only ONE of the underscores and
subsequent character, either the first or the last would make sense.
However, the behavior is that an unrelated character is shown as the
mnemonic and even it doesn't actually do anything. Tested with JDK
17.0.1
and JavaFX 17.0.1.
Does this behave as expected for you?
package mnemonic_parsing_bug;
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.CheckBox;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class Main extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) throws Exception {
Label titleLabel = new Label("""
The CheckBox below has text set to 'How_to_Test_Mnemonics'.
On Windows press the Alt key to see where the underlined
character appears.
It shows under the 'e' in Mnemonics for me, and I can't
figure
out
what key combination (if any) actually does something.
[JavaFX Version %s]""".formatted(System.getProperty(
"javafx.version")) );
titleLabel.setMnemonicParsing(false);
CheckBox mnemonicCB = new CheckBox("How_to_Test_Mnemonics");
mnemonicCB.setMnemonicParsing(true);
VBox box = new VBox(8,titleLabel, mnemonicCB);
box.setPadding(new Insets(16));
Scene scene = new Scene(box);
primaryStage.setTitle("Mnemonic Parsing Bug");
primaryStage.setScene(scene);
primaryStage.show();
}
}
