Provide Explicit "isDarkTheme" Attribute

Up to now we had some heuristics to check if a theme is a dark
theme. This now makes this explicit.

- Add attribute to extension point
- Fill this attribute for the platforms dark theme
- Remove heuristics and now check this explicit flag

Author: BeckerWdf

bundles/org.eclipse.e4.ui.css.swt.theme/schema/org.eclipse.e4.ui.css.swt.theme.exsd

@@ -134,6 +134,13 @@
                </documentation>
             </annotation>
          </attribute>
+         <attribute name="isDarkTheme" type="boolean">
+            <annotation>
+               <documentation>
+                  Set this to true if the theme uses dark background.
+               </documentation>
+            </annotation>
+         </attribute>
       </complexType>
    </element>
 

bundles/org.eclipse.e4.ui.css.swt.theme/src/org/eclipse/e4/ui/css/swt/internal/theme/Theme.java

@@ -19,6 +19,7 @@ public class Theme implements ITheme {
 	private String id;
 	private String label;
 	private String osVersion;
+	private String isDark;
 
 	public Theme(String id, String label) {
 		this.id = id;
@@ -43,10 +44,23 @@ public String getOsVersion() {
 		return this.osVersion;
 	}
 
+	@Override
+	public boolean IsDark() {
+		return Boolean.parseBoolean(isDark);
+	}
+
+	public void setIsDark(String isDark) {
+		if (isDark == null) {
+			this.isDark = "false";
+		} else {
+			this.isDark = isDark;
+		}
+	}
+
 	@Override
 	public String toString() {
 		return "Theme [id=" + id + ", label='" + label + "', osVersion="
-				+ osVersion + "]";
+				+ osVersion + " isDark=" + isDark + "]";
 	}
 
 

bundles/org.eclipse.e4.ui.css.swt.theme/src/org/eclipse/e4/ui/css/swt/internal/theme/ThemeEngine.java

@@ -121,6 +121,7 @@ public ThemeEngine(Display display) {
 						String id = ce.getAttribute("id");
 						String os = ce.getAttribute("os");
 						String version = ce.getAttribute("os_version");
+						String isDarkTheme = ce.getAttribute("isDarkTheme");
 
 						/*
 						 * Code to support e4 dark theme on Mac 10.13 and older. For e4 dark theme on
@@ -154,7 +155,8 @@ public ThemeEngine(Display display) {
 							basestylesheeturi = "platform:/plugin/" + ce.getContributor().getName() + "/"
 									+ basestylesheeturi;
 						}
-						registerTheme(themeId, label, basestylesheeturi, version);
+
+						registerTheme(themeId, label, basestylesheeturi, version, isDarkTheme);
 
 						//check for modified files
 						if (modifiedFiles != null) {
@@ -250,11 +252,11 @@ private boolean isOsVersionMatch(String osVersionList) {
 	@Override
 	public synchronized ITheme registerTheme(String id, String label, String basestylesheetURI)
 			throws IllegalArgumentException {
-		return  registerTheme(id, label, basestylesheetURI, "");
+		return registerTheme(id, label, basestylesheetURI, "", "");
 	}
 
 	public synchronized ITheme registerTheme(String id, String label,
-			String basestylesheetURI, String osVersion) throws IllegalArgumentException {
+			String basestylesheetURI, String osVersion, String isDark) throws IllegalArgumentException {
 		for (Theme t : themes) {
 			if (t.getId().equals(id)) {
 				throw new IllegalArgumentException("A theme with the id '" + id
@@ -265,6 +267,9 @@ public synchronized ITheme registerTheme(String id, String label,
 		if (osVersion != "") {
 			theme.setOsVersion(osVersion);
 		}
+		if (isDark != "") {
+			theme.setIsDark(isDark);
+		}
 		themes.add(theme);
 		registerStyle(id, basestylesheetURI, false);
 		return theme;
@@ -598,7 +603,7 @@ public void restore(String alternateTheme) {
 			}
 		}
 
-		boolean hasDarkTheme = getThemes().stream().anyMatch(t -> t.getId().startsWith(E4_DARK_THEME_ID));
+		boolean hasDarkTheme = getThemes().stream().anyMatch(t -> t.IsDark());
 		boolean overrideWithDarkTheme = false;
 		if (hasDarkTheme) {
 			if (prefThemeId != null) {

bundles/org.eclipse.e4.ui.css.swt.theme/src/org/eclipse/e4/ui/css/swt/theme/ITheme.java

@@ -26,4 +26,10 @@ public interface ITheme {
 	 * @return the label
 	 */
 	String getLabel();
+
+	/**
+	 *
+	 * @return does the theme use a dark background color
+	 */
+	boolean IsDark();
 }

bundles/org.eclipse.ui.themes/plugin.xml

@@ -9,29 +9,33 @@
             label="%theme.classic">
       </theme>
     <theme
-        basestylesheeturi="css/e4-dark_linux.css"
-        id="org.eclipse.e4.ui.css.theme.e4_dark"
-        label="%theme.dark"
-        os="linux">
+          basestylesheeturi="css/e4-dark_linux.css"
+          id="org.eclipse.e4.ui.css.theme.e4_dark"
+          isDarkTheme="true"
+          label="%theme.dark"
+          os="linux">
     </theme>
     <theme
-        basestylesheeturi="css/e4-dark_win.css"
-        id="org.eclipse.e4.ui.css.theme.e4_dark"
-        label="%theme.dark"
-        os="win32">
+          basestylesheeturi="css/e4-dark_win.css"
+          id="org.eclipse.e4.ui.css.theme.e4_dark"
+          isDarkTheme="true"
+          label="%theme.dark"
+          os="win32">
     </theme>
     <theme
-        basestylesheeturi="css/e4-dark_mac1013.css"
-        id="org.eclipse.e4.ui.css.theme.e4_dark"
-        label="%theme.dark"
-        os="macosx"
-        os_version="10.11,10.12,10.13">
+          basestylesheeturi="css/e4-dark_mac1013.css"
+          id="org.eclipse.e4.ui.css.theme.e4_dark"
+          isDarkTheme="true"
+          label="%theme.dark"
+          os="macosx"
+          os_version="10.11,10.12,10.13">
     </theme>
     <theme
-        basestylesheeturi="css/e4-dark_mac.css"
-        id="org.eclipse.e4.ui.css.theme.e4_dark"
-        label="%theme.dark"
-        os="macosx">
+          basestylesheeturi="css/e4-dark_mac.css"
+          id="org.eclipse.e4.ui.css.theme.e4_dark"
+          isDarkTheme="true"
+          label="%theme.dark"
+          os="macosx">
     </theme>
       <theme
             basestylesheeturi="css/e4_default_gtk.css"