Fixed tooltip flickering during fade-in.

core/src/main/java/com/github/weisj/darklaf/ui/DarkPopupFactory.java

@@ -38,9 +38,10 @@ public class DarkPopupFactory extends PopupFactory {
         Popup popup = super.getPopup(owner, contents, x, y);
         boolean isMediumWeight = popup.getClass().getSimpleName().endsWith("MediumWeightPopup");
         boolean isLightWeight = popup.getClass().getSimpleName().endsWith("LightWeightPopup");
+        boolean isBalloonTooltip = contents instanceof JToolTip
+            && ((JToolTip) contents).getBorder() instanceof DarkTooltipBorder;
         if (isMediumWeight || isLightWeight) {
-            if (contents instanceof JToolTip
-                && ((JToolTip) contents).getBorder() instanceof DarkTooltipBorder) {
+            if (isBalloonTooltip) {
                 // null owner forces a heavyweight popup.
                 popup = super.getPopup(null, contents, x, y);
             } else if (isMediumWeight) {
@@ -67,6 +68,9 @@ public class DarkPopupFactory extends PopupFactory {
             } else {
                 Decorations.uninstallPopupWindow(window);
             }
+            if (isBalloonTooltip) {
+                window.setOpacity(0.0f);
+            }
         }
         return popup;
     }

core/src/main/java/com/github/weisj/darklaf/ui/tooltip/DarkTooltipBorder.java

@@ -46,7 +46,6 @@ public class DarkTooltipBorder implements Border {
                                                                        false, true,
                                                                        true, true);
     private final BubbleBorder bubbleBorder;
-    private static final AlphaComposite COMPOSITE = AlphaComposite.getInstance(AlphaComposite.SRC_OVER);
 
     public DarkTooltipBorder() {
         bubbleBorder = new BubbleBorder(UIManager.getColor("ToolTip.borderColor"));
@@ -88,25 +87,10 @@ public class DarkTooltipBorder implements Border {
         }
     }
 
-    protected float getAlpha(final Component c) {
-        if (c instanceof JComponent) {
-            Object alpha = ((JComponent) c).getClientProperty(DarkTooltipUI.KEY_PAINT_ALPHA);
-            if (alpha instanceof Float) {
-                return (float) alpha;
-            }
-        }
-        return DarkTooltipUI.MAX_ALPHA;
-    }
-
     @Override
     public void paintBorder(final Component c, final Graphics g,
                             final int x, final int y, final int width, final int height) {
-        float alpha = getAlpha(c);
-        if (alpha == 0) return;
         GraphicsContext context = new GraphicsContext(g);
-        if (alpha != DarkTooltipUI.MAX_ALPHA) {
-            ((Graphics2D) g).setComposite(COMPOSITE.derive(alpha));
-        }
         if (isPlain(c)) {
             g.setColor(bubbleBorder.getColor());
             DarkUIUtil.drawRect(g, x, y, width, height, 1);

core/src/main/java/com/github/weisj/darklaf/ui/tooltip/DarkTooltipUI.java

@@ -54,10 +54,8 @@ public class DarkTooltipUI extends BasicToolTipUI implements PropertyChangeListe
     public static final String VARIANT_BALLOON = "balloon";
     public static final String VARIANT_PLAIN_BALLOON = "plainBalloon";
     public static final String TIP_TEXT_PROPERTY = "tiptext";
-    public static final String KEY_PAINT_ALPHA = KEY_PREFIX + "paintAlpha";
     public static final String KEY_CONTEXT = KEY_PREFIX + "toolTipContext";
     static final float MAX_ALPHA = 1.0f;
-    private static final AlphaComposite COMPOSITE = AlphaComposite.getInstance(AlphaComposite.SRC_OVER);
     private Animator fadeAnimator;
     private float alpha = 0;
 
@@ -199,12 +197,7 @@ public class DarkTooltipUI extends BasicToolTipUI implements PropertyChangeListe
             fadeAnimator.reset();
             fadeAnimator.resume();
         }
-        toolTip.putClientProperty(KEY_PAINT_ALPHA, alpha);
-        if (alpha == 0) return;
         GraphicsContext config = new GraphicsContext(g);
-        if (alpha != MAX_ALPHA) {
-            ((Graphics2D) g).setComposite(COMPOSITE.derive(alpha));
-        }
         g.setColor(c.getBackground());
         if (c.getBorder() instanceof DarkTooltipBorder) {
             Area area = ((DarkTooltipBorder) c.getBorder()).getBackgroundArea(c, c.getWidth(), c.getHeight());
@@ -374,13 +367,15 @@ public class DarkTooltipUI extends BasicToolTipUI implements PropertyChangeListe
         @Override
         public void paintNow(final int frame, final int totalFrames, final int cycle) {
             alpha = ((float) frame * MAX_ALPHA) / totalFrames;
-            toolTip.paintImmediately(0, 0, toolTip.getWidth(), toolTip.getHeight());
+            Window window = SwingUtilities.getWindowAncestor(toolTip);
+            if (window != null) window.setOpacity(alpha);
         }
 
         @Override
         protected void paintCycleEnd() {
             alpha = MAX_ALPHA;
-            toolTip.paintImmediately(0, 0, toolTip.getWidth(), toolTip.getHeight());
+            Window window = SwingUtilities.getWindowAncestor(toolTip);
+            if (window != null) window.setOpacity(alpha);
         }
     }
 }