Package com.formdev.flatlaf.util

Class HiDPIUtils

java.lang.Object

com.formdev.flatlaf.util.HiDPIUtils

public class HiDPIUtils
extends java.lang.Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	HiDPIUtils.DirtyRegionCallback	For addDirtyRegion(JComponent, int, int, int, int, DirtyRegionCallback).
static class	HiDPIUtils.HiDPIRepaintManager	A repaint manager that fixes a problem in Swing when repainting components at some scale factors (e.g.
static interface	HiDPIUtils.Painter

Field Summary

Fields

Modifier and Type	Field	Description
private static float[]	CORRECTION_INTER
private static float[]	CORRECTION_OPEN_SANS
private static float[]	CORRECTION_SEGOE_UI
private static float[]	CORRECTION_TAHOMA
private static float[]	SCALE_FACTORS
private static java.lang.Boolean	useDebugScaleFactor
private static java.lang.Boolean	useTextYCorrection

Constructor Summary

Constructors

Constructor	Description
HiDPIUtils()

Method Summary

Modifier and Type	Method	Description
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).
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.
private static float	correctionForScaleY(java.awt.Graphics2D g, float[] correction)
static java.awt.Graphics2D	createGraphicsTextYCorrection(java.awt.Graphics2D g)	Creates a graphics object and applies Y correction to string drawing methods.
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.
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.
private static float	getUserScaleFactor()
static void	installHiDPIRepaintManager()	Installs a HiDPIUtils.HiDPIRepaintManager on Windows when running in Java 9+, but only if default repaint manager is currently installed.
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.
private static double	normalize(double value)
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.
static void	paintAtScale1x(java.awt.Graphics2D g, javax.swing.JComponent c, HiDPIUtils.Painter painter)
static void	repaint(java.awt.Component c)	Repaints the given component.
static void	repaint(java.awt.Component c, int x, int y, int width, int height)	Repaints the given component area.
static void	repaint(java.awt.Component c, java.awt.Rectangle r)	Repaints the given component area.
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().
private static int	scaleFactor2index(float scaleFactor)
private static boolean	useDebugScaleFactor()
private static boolean	useTextYCorrection()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

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)

Repaints the given component.

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

Since:

3.5

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