How to get ScrollPane vertical positions? #1108
Comments
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You can try the following: scroll.estimatedScrollYProperty().addListener
(
// Need runLater otherwise getTotalHeightEstimate sometimes reports
// NullPointerException when setting the text area with text ?
y -> Platform.runLater( () ->
{
double currentAbsolutePos = ((Var<Double>) y).getValue();
double totalEstimatedHeight = scroll.getTotalHeightEstimate();
double viewPortHeight = scroll.getHeight();
double fractionalPos = currentAbsolutePos / (totalEstimatedHeight - viewPortHeight);
if ( fractionalPos == 0.0 )
{
System.out.println( "top" );
}
else if ( fractionalPos >= 1 )
{
System.out.println( "bottom" );
}
}
)); |
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@Jugen Thank you for your solution. The only problem - I don't like |
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@Jugen Getting scroll position is one of the most used features (for example, someElement.scrollTop is used very often in JS), so it will be always necessary to have a solid solution. |
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Please try and leave out the |
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Your solution seems to work (I get I need to get scroll position in a window that shows log information. Nobody can paste there text (I mean Ctrl+V) manually, but automatically added text can be rather large. |
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Okay here is a better version that doesn't have the NPE problem: scroll.estimatedScrollYProperty().addListener( (ob,ov,currentAbsolutePos) ->
{
double viewPortHeight = scroll.getHeight();
double totalEstimatedHeight = (double) scroll.totalHeightEstimateProperty().getOrSupply( () -> 1.0 );
double fractionalPos = (double) currentAbsolutePos / (totalEstimatedHeight - viewPortHeight);
if ( fractionalPos == 0.0 )
{
System.out.println( "top" );
}
else if ( fractionalPos >= 1 )
{
System.out.println( "bottom" );
}
}); |
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@Jugen Thank you very much for your help. You solution seems to be OK, but once I got |
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Yes, sometimes I get fractionalPos = 0.9999......, maybe the problem is that when I scroll to bottom this way: there is 1 or 2 pixels left to bottom. I mean, I can't scroll to real bottom using code. So, when I check if it is a bottom, I get |
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So maybe try either |
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@Jugen Yes, thank you. This is the way I went. |
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I have a TextArea and a ScrollPane:
And I need to know when my vertical bar is at the highest and the lowest positions. By other words when vertical scroll bar is on top or bottom. Something like this:
I've found several issues related to this problem but still have no solution. Could anyone say how to do it?
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