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ComboBox: improved location of selected item in popup if list is large and scrollable

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This commit is contained in:
Karl Tauber
2023-07-30 14:01:24 +02:00
parent 9db3dfff26
commit b3fb63c9f5
2 changed files with 25 additions and 0 deletions
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23
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatComboBoxUI.java
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@@ -986,6 +986,29 @@ public class FlatComboBoxUI
}
}
// improve location of selected item in popup if list is large and scrollable
if( list.getHeight() == 0 ) {
// If popup is shown for the first time (or after a laf switch) and is scrollable,
// then BasicComboPopup scrolls the selected item to the top of the visible area.
// But for usability it would be better to have selected item somewhere
// in the middle of the visible area so that the user can see items above
// the selected item, which are usually more "important".
int selectedIndex = list.getSelectedIndex();
if( selectedIndex >= 1 ) {
int maximumRowCount = comboBox.getMaximumRowCount();
if( selectedIndex < maximumRowCount ) {
// selected item is in the first visible items --> scroll to top
list.scrollRectToVisible( new Rectangle() );
} else {
// scroll the selected item to the middle of the visible area
int firstVisibleIndex = Math.max( selectedIndex - (maximumRowCount / 2), 0 );
if( firstVisibleIndex > 0 )
list.ensureIndexIsVisible( firstVisibleIndex );
}
}
}
super.show( invoker, x, y );
}