Project: Eclipse_Platform_UI
Bug 184345 [Forms] ColumnLayout calculates number of columns incorrectly
Reported: 2007-04-26 18:10:25 | Status: resolved fixed

In package org.eclipse.ui.forms.widgets, class ColumnLayout, method layout, I believe the number of columns is calculated incorrectly. This can cause the columns to be considerably wider than they should be. The line is: int ncolumns = (carea.width - leftMargin - rightMargin - horizontalSpacing) / (cwidth + horizontalSpacing); I think it should be: int ncolumns = (carea.width - leftMargin - rightMargin + horizontalSpacing) / (cwidth + horizontalSpacing); because the horizontalSpacing is only between columns, and not also on the outsides of the columns. (i.e. There are only ncolumns-1 horizontalSpacing's.) The derivation is: ncolumns * cwidth + (ncolumns-1) * horizontalSpacing = carea.width - leftMargin - rightMargin ==> ncolumns * cwidth + ncolumns * horizontalSpacing = carea.width - leftMargin - rightMargin + horizontalSpacing ==> ncolumns * (cwidth + horizontalSpacing) = carea.width - leftMargin - rightMargin + horizontalSpacing

Files changed in fix:
bundles/org.eclipse.ui.forms/src/org/eclipse/ui/forms/widgets/ColumnLayout.java