FULL PRODUCT VERSION :


A DESCRIPTION OF THE PROBLEM :
JTable grid lines are positioned 1 pixel too high or too far left on a 2x HiDPI display.

The grid lines are drawn using drawLine at x-1 or y-1. This produces the intended effect on a 1x display, which is a 1 px line between x-1 and x or between y-1 and y. On a HiDPI display, the line is centered around x-1 or y-1. Should use drawRect.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Create a JTable that displays grid lines and has a non-opaque cell renderer. View on a HiDPI display.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
The grid lines should be painted between the cell backgrounds.
ACTUAL -
The grid lines are painted 1 pixel too high or too far left, and are thus partially overlapped by the cell backgrounds.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
package test;

import javax.swing.*;
import javax.swing.table.*;
import java.awt.*;

public class TestTableGrid
{
JFrame fr;

public TestTableGrid()
{
fr = new JFrame("Test Table Grid");

TableModel dataModel = new AbstractTableModel() {
public int getColumnCount() { return 10; }
public int getRowCount() { return 10;}
public Object getValueAt(int row, int col) { return new Integer(row*col); }
};

DefaultTableCellRenderer r = new DefaultTableCellRenderer();
r.setOpaque(true);
r.setBackground(Color.YELLOW);

JTable t = new JTable(dataModel);
t.setDefaultRenderer(Object.class, r);
t.setGridColor(Color.BLACK);
t.setShowGrid(true);
t.setShowHorizontalLines(true);
t.setShowVerticalLines(true);
fr.setContentPane(t);
fr.setLocation(200, 200);
fr.pack();
fr.setVisible(true);
}

public static void main(String args[])
{
new TestTableGrid();
}
}

---------- END SOURCE ----------