[eclipse-cdt#159] Add C file image descriptor

fixes eclipse-cdt#159

bundles/org.eclipse.cdt.lsp/plugin.xml

@@ -247,5 +247,11 @@
             isBefore="org.eclipse.lsp4e.operations.hover.LSPTextHover">
       </hoverProvider>
    </extension>
+   <extension
+         point="org.eclipse.cdt.ui.CFileImageProvider">
+      <imageDescriptor
+            class="org.eclipse.cdt.lsp.editor.LspEditorFileImageDescriptor">
+      </imageDescriptor>
+   </extension>
 </plugin>
 

bundles/org.eclipse.cdt.lsp/src/org/eclipse/cdt/lsp/editor/LspEditorFileImageDescriptor.java

@@ -0,0 +1,72 @@
+/*******************************************************************************
+ * Copyright (c) 2023 Contributors to the Eclipse Foundation.
+ * This program and the accompanying materials are made
+ * available under the terms of the Eclipse Public License 2.0
+ * which is available at https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ * Contributors:
+ *   See git history
+ *******************************************************************************/
+package org.eclipse.cdt.lsp.editor;
+
+import java.net.URL;
+import java.util.HashMap;
+
+import org.eclipse.cdt.lsp.LspPlugin;
+import org.eclipse.cdt.lsp.server.ICLanguageServerProvider;
+import org.eclipse.cdt.ui.lsp.ICFileImageDescriptor;
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.runtime.FileLocator;
+import org.eclipse.core.runtime.Path;
+import org.eclipse.core.runtime.Platform;
+import org.eclipse.jface.resource.ImageDescriptor;
+import org.osgi.framework.Bundle;
+
+public class LspEditorFileImageDescriptor implements ICFileImageDescriptor {
+	private final ICLanguageServerProvider cLanguageServerProvider;
+	private static HashMap<String, ImageDescriptor> imageRegistry = new HashMap<>(2);
+	private static final String ICONS_PATH = "$nl$/icons/"; //$NON-NLS-1$
+	public static final String IMG_CFILE = "IMG_CFILE"; //$NON-NLS-1$
+	public static final String IMG_CXXFILE = "IMG_CXXFILE"; //$NON-NLS-1$
+
+	public LspEditorFileImageDescriptor() {
+		cLanguageServerProvider = LspPlugin.getDefault().getCLanguageServerProvider();
+		declareRegistryImage(IMG_CFILE, ICONS_PATH + "c.png"); //$NON-NLS-1$
+		declareRegistryImage(IMG_CXXFILE, ICONS_PATH + "cpp.png"); //$NON-NLS-1$
+	}
+
+	@Override
+	public ImageDescriptor getCImageDescriptor() {
+		return imageRegistry.get(IMG_CFILE);
+	}
+
+	@Override
+	public ImageDescriptor getCXXImageDescriptor() {
+		return imageRegistry.get(IMG_CXXFILE);
+	}
+
+	@Override
+	public ImageDescriptor getHeaderImageDescriptor() {
+		return imageRegistry.get(IMG_CFILE);
+	}
+
+	@Override
+	public boolean isEnabled(IProject project) {
+		return cLanguageServerProvider.isEnabledFor(project);
+	}
+
+	private final void declareRegistryImage(String key, String path) {
+		ImageDescriptor desc = ImageDescriptor.getMissingImageDescriptor();
+		Bundle bundle = Platform.getBundle(LspPlugin.PLUGIN_ID);
+		URL url = null;
+		if (bundle != null) {
+			url = FileLocator.find(bundle, new Path(path), null);
+			if (url != null) {
+				desc = ImageDescriptor.createFromURL(url);
+			}
+		}
+		imageRegistry.put(key, desc);
+	}
+}