Class HiDPIUtils


  • public class HiDPIUtils
    extends java.lang.Object
    • Field Detail

      • useTextYCorrection

        private static java.lang.Boolean useTextYCorrection
      • SCALE_FACTORS

        private static final float[] SCALE_FACTORS
      • CORRECTION_SEGOE_UI

        private static final float[] CORRECTION_SEGOE_UI
      • CORRECTION_TAHOMA

        private static final float[] CORRECTION_TAHOMA
      • CORRECTION_INTER

        private static final float[] CORRECTION_INTER
      • CORRECTION_OPEN_SANS

        private static final float[] CORRECTION_OPEN_SANS
      • useDebugScaleFactor

        private static java.lang.Boolean useDebugScaleFactor
    • Constructor Detail

      • HiDPIUtils

        public HiDPIUtils()
    • Method Detail

      • paintAtScale1x

        public static void paintAtScale1x​(java.awt.Graphics2D g,
                                          javax.swing.JComponent c,
                                          HiDPIUtils.Painter painter)
      • paintAtScale1x

        public static void paintAtScale1x​(java.awt.Graphics2D g,
                                          int x,
                                          int y,
                                          int width,
                                          int height,
                                          HiDPIUtils.Painter painter)
        Paint at system scale factor 1x to avoid rounding issues at 125%, 150% and 175% scaling.

        Scales the given Graphics2D down to 100% and invokes the given painter passing scaled x, y, width and height.

        Uses the same scaling calculation as the JRE uses.

      • scale

        private static java.awt.geom.Rectangle2D.Double scale​(double scaleX,
                                                              double scaleY,
                                                              double px,
                                                              double py,
                                                              int width,
                                                              int height)
        Scales a rectangle in the same way as the JRE does in sun.java2d.pipe.PixelToParallelogramConverter.fillRectangle(), which is used by Graphics.fillRect().
      • normalize

        private static double normalize​(double value)
      • useTextYCorrection

        private static boolean useTextYCorrection()
      • computeTextYCorrection

        public static float computeTextYCorrection​(java.awt.Graphics2D g)
        When painting text on HiDPI screens and the JRE scales, then the text is painted too far down on some operating systems. The higher the system scale factor is, the more.

        This method computes a correction value for the Y position.

      • correctionForScaleY

        private static float correctionForScaleY​(java.awt.Graphics2D g,
                                                 float[] correction)
      • scaleFactor2index

        private static int scaleFactor2index​(float scaleFactor)
      • useDebugScaleFactor

        private static boolean useDebugScaleFactor()
      • getUserScaleFactor

        private static float getUserScaleFactor()
      • drawStringWithYCorrection

        public static void drawStringWithYCorrection​(javax.swing.JComponent c,
                                                     java.awt.Graphics2D g,
                                                     java.lang.String text,
                                                     int x,
                                                     int y)
        Applies Y correction and draws the given string at the specified location. The provided component is used to query text properties and anti-aliasing hints.

        Use this method instead of Graphics.drawString(String, int, int) for correct anti-aliasing.

        Replacement for SwingUtilities2.drawString().

      • drawStringUnderlineCharAtWithYCorrection

        public static void drawStringUnderlineCharAtWithYCorrection​(javax.swing.JComponent c,
                                                                    java.awt.Graphics2D g,
                                                                    java.lang.String text,
                                                                    int underlinedIndex,
                                                                    int x,
                                                                    int y)
        Applies Y correction and draws the given string at the specified location underlining the specified character. The provided component is used to query text properties and anti-aliasing hints.

        Replacement for SwingUtilities2.drawStringUnderlineCharAt().

      • createGraphicsTextYCorrection

        public static java.awt.Graphics2D createGraphicsTextYCorrection​(java.awt.Graphics2D g)
        Creates a graphics object and applies Y correction to string drawing methods. If no Y correction is necessary, the passed in graphics object is returned.
      • repaint

        public static void repaint​(java.awt.Component c,
                                   java.awt.Rectangle r)
        Repaints the given component area.

        See repaint(Component, int, int, int, int) for more details.

        Since:
        3.5
      • repaint

        public static void repaint​(java.awt.Component c,
                                   int x,
                                   int y,
                                   int width,
                                   int height)
        Repaints the given component area.

        Invokes Component.repaint(int, int, int, int) on the given component,

        Use this method, instead of Component.repaint(...), to fix a problem in Swing when using scale factors that end on .25 or .75 (e.g. 1.25, 1.75, 2.25, etc) and repainting single components, which may not repaint right and/or bottom 1px edge of component.

        The problem may occur under following conditions:

        • using Java 9 or later
        • system scale factor is 125%, 175%, 225%, ... (Windows only; Java on macOS and Linux does not support fractional scale factors)
        • repaint whole component or right/bottom area of component
        • component is opaque; or component is contained in a opaque container that has same right/bottom bounds as component
        • component has bounds that Java/Swing scales different when repainting components
        Since:
        3.5
      • needsSpecialRepaint

        private static boolean needsSpecialRepaint​(java.awt.Component c,
                                                   int x,
                                                   int y,
                                                   int width,
                                                   int height)
        There is a problem in Swing, when using scale factors that end on .25 or .75 (e.g. 1.25, 1.75, 2.25, etc) and repainting single components, which may not repaint right and/or bottom 1px edge of component.

        The component is first painted to an in-memory image, and then that image is copied to the screen. See javax.swing.RepaintManager.PaintManager#paintDoubleBufferedFPScales().

        There are two clipping rectangles involved when copying the image to the screen: sun.java2d.SunGraphics2D#devClip and sun.java2d.SunGraphics2D#usrClip.

        devClip is the device clipping in physical pixels. It gets the bounds of the painting component, which is either the passed component, or if it is non-opaque, then the first opaque ancestor of the passed component. It is calculated in sun.java2d.SunGraphics2D#constrain() while getting a graphics context via JComponent.getGraphics().

        usrClip is the user clipping, which is set via Graphics clipping methods. This is done in javax.swing.RepaintManager.PaintManager#paintDoubleBufferedFPScales().

        The intersection of devClip and usrClip (computed in sun.java2d.SunGraphics2D#validateCompClip()) is used to copy the image to the screen.

        Unfortunately different scaling/rounding strategies are used to calculate the two clipping rectangles, which is the reason of the issue.

        devClip (see sun.java2d.SunGraphics2D#constrain()):

        
         int devX = (int) (x * scale);
         int devWidth = Math.round( width * scale )
         
        usrClip (see javax.swing.RepaintManager.PaintManager#paintDoubleBufferedFPScales()):
        
         int usrX = (int) Math.ceil( (x * scale) - 0.5 );
         int usrWidth = ((int) Math.ceil( ((x + width) * scale) - 0.5 )) - usrX;
         
        X/Y coordinates are always rounded down for devClip, but rounded up for usrClip. Width/height calculation is also different.
      • installHiDPIRepaintManager

        public static void installHiDPIRepaintManager()
        Installs a HiDPIUtils.HiDPIRepaintManager on Windows when running in Java 9+, but only if default repaint manager is currently installed.

        Invoke once on application startup. Compatible with all/other LaFs.

        Since:
        3.5
      • addDirtyRegion

        public static void addDirtyRegion​(javax.swing.JComponent c,
                                          int x,
                                          int y,
                                          int width,
                                          int height,
                                          HiDPIUtils.DirtyRegionCallback callback)
        Similar to repaint(Component, int, int, int, int), but invokes callback instead of invoking Component.repaint(int, int, int, int).

        For use in custom repaint managers.

        Since:
        3.5