Merge pull request #10196 from dbeaver/text-color#5534

#5534 make cell foreground color contrasting

plugins/org.jkiss.dbeaver.tasks.ui/src/org/jkiss/dbeaver/tasks/ui/view/DatabaseTasksTree.java

@@ -69,8 +69,7 @@ public class DatabaseTasksTree {
         ColorRegistry colorRegistry = UIUtils.getActiveWorkbenchWindow().getWorkbench().getThemeManager().getCurrentTheme().getColorRegistry();
         colorError = colorRegistry.get("org.jkiss.dbeaver.txn.color.reverted.background");
         colorErrorForeground = UIUtils.getContrastColor(colorError);
-        composite.addDisposeListener(e -> colorErrorForeground.dispose());
-
+        
         taskViewer = DialogUtils.createFilteredTree(composite,
             SWT.MULTI | SWT.FULL_SELECTION | (selector ? SWT.BORDER | SWT.CHECK : SWT.NONE),
             new NamedObjectPatternFilter(), TaskUIMessages.db_tasks_tree_text_tasks_type);

plugins/org.jkiss.dbeaver.ui.editors.data/src/org/jkiss/dbeaver/ui/controls/resultset/spreadsheet/SpreadsheetPresentation.java

@@ -1836,15 +1836,11 @@ public class SpreadsheetPresentation extends AbstractPresentation implements IRe
             boolean recordMode = controller.isRecordMode();
             ResultSetRow row = (ResultSetRow) (!recordMode ?  rowElement : colElement);
             DBDAttributeBinding attribute = (DBDAttributeBinding)(!recordMode ?  colElement : rowElement);
-
             Color fg = controller.getLabelProvider().getCellForeground(attribute, row);
             if (fg != null) {
                 return fg;
             }
-            if (foregroundDefault == null) {
-                foregroundDefault = controller.getDefaultForeground();
-            }
-            return foregroundDefault;
+            return UIUtils.getContrastColor(getCellBackground(colElement, rowElement, false));
         }
 
         @Nullable

plugins/org.jkiss.dbeaver.ui/src/org/jkiss/dbeaver/ui/UIUtils.java

@@ -89,6 +89,8 @@ public class UIUtils {
     private static final Log log = Log.getLog(UIUtils.class);
 
     public static final String INLINE_WIDGET_EDITOR_ID = "org.jkiss.dbeaver.ui.InlineWidgetEditor";
+    private static final Color COLOR_BLACK = new Color(null, 0, 0, 0);
+    private static final Color COLOR_WHITE = new Color(null, 255, 255, 255);
 
     private static SharedTextColors sharedTextColors = new SharedTextColors();
     private static SharedFonts sharedFonts = new SharedFonts();
@@ -1928,16 +1930,18 @@ public class UIUtils {
     /**
      * Calculate the Contrast color based on Luma(brightness)
      * https://en.wikipedia.org/wiki/Luma_(video)
+     *
+     * Do not dispose returned color.
      */
     public static Color getContrastColor(Color color) {
-        if (color == null)
-            return new Color(null, 0, 0, 0);
-
+        if (color == null) {
+            return COLOR_BLACK;
+        }
         double luminance = 1 - (0.299 * color.getRed() + 0.587 * color.getGreen() + 0.114 * color.getBlue()) / 255;
-
-        int c = (luminance > 0.5) ? 255 : 0;
-
-        return new Color(null, c, c, c);
+        if (luminance > 0.5) {
+            return COLOR_WHITE;
+        }
+        return COLOR_BLACK;
     }  
 
     public static void openWebBrowser(String url)