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  1. JDK
  2. JDK-8173323

[macosx] Wrong rendering of rectangle on macOS on Retina display

    Details

    • Subcomponent:
      2d
    • CPU:
      x86
    • OS:
      os_x

      Description

      FULL PRODUCT VERSION :
      java version "1.8.0_121"
      Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
      Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

      ADDITIONAL OS VERSION INFORMATION :
      macOS Sierra 10.12.2

      A DESCRIPTION OF THE PROBLEM :
      Javadoc for java.awt.Graphics class declares that outlines of figures are drawn to the right and bottom of 'ideal' outline path. This doesn't happen when rendering happens on a Retina display - outlines seem to be centered on 'ideal' path instead.
      The same problem is observed on Windows with latest Java 9 builds, when rendering to a HiDPI display with scale factor 2.
      I believe, this is either a bug in the implementation, or in the documentation for java.awt.Graphics class.

      STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
      Run the sample program given below on a macOS computer with Retina display.

      EXPECTED VERSUS ACTUAL BEHAVIOR :
      EXPECTED -
      Black border pixels completely enclose grey inner pixels.
      ACTUAL -
      At the right and at the bottom of the rectangle black pixels are rendered 'inside' grey pixels.

      REPRODUCIBILITY :
      This bug can be reproduced always.

      ---------- BEGIN SOURCE ----------
      import javax.swing.*;
      import java.awt.*;

      public class RectangleTest {
          public static void main(String[] args) {
              SwingUtilities.invokeLater(() -> {
                  JFrame f = new JFrame();
                  f.add(new MyComponent());
                  f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
                  f.setSize(200, 170);
                  f.setLocationRelativeTo(null);
                  f.setVisible(true);
              });
          }

          private static class MyComponent extends JComponent {
              @Override
              protected void paintComponent(Graphics g) {
                  g.setColor(Color.gray);
                  g.fillRect(50, 50, 100, 50);
                  g.setColor(Color.black);
                  g.drawRect(50, 50, 99, 49);
              }
          }
      }

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

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            • Assignee:
              prr Philip Race
              Reporter:
              webbuggrp Webbug Group
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              Dates

              • Created:
                Updated: