Target platform editor - Only resolve target platform if changed

When you leave the Source tab, the editor takes the entire text (XML)
from that tab and reconstructs a new internal Target Definition model
(ITargetDefinition).

This new model is compared to the current target definition model and if
it is the same, the resolving of the target platform is not triggered.

Author: vogella

ui/org.eclipse.pde.ui/src/org/eclipse/pde/internal/ui/editor/targetdefinition/TargetEditor.java

@@ -57,13 +57,15 @@
 import org.eclipse.osgi.util.NLS;
 import org.eclipse.pde.core.target.ITargetDefinition;
 import org.eclipse.pde.core.target.ITargetHandle;
+import org.eclipse.pde.core.target.ITargetLocation;
 import org.eclipse.pde.core.target.ITargetPlatformService;
 import org.eclipse.pde.core.target.LoadTargetDefinitionJob;
 import org.eclipse.pde.core.target.TargetEvents;
 import org.eclipse.pde.internal.core.ICoreConstants;
 import org.eclipse.pde.internal.core.PDECore;
 import org.eclipse.pde.internal.core.PDEPreferencesManager;
 import org.eclipse.pde.internal.core.target.P2TargetUtils;
+import org.eclipse.pde.internal.core.target.TargetDefinition;
 import org.eclipse.pde.internal.core.target.TargetDefinitionPersistenceHelper;
 import org.eclipse.pde.internal.core.target.TargetPlatformService;
 import org.eclipse.pde.internal.core.target.WorkspaceFileTargetHandle;
@@ -161,10 +163,27 @@ protected void addPages() {
 	protected void pageChange(int newPageIndex) {
 		try {
 			if (newPageIndex != fSourceTabIndex && getCurrentPage() == fSourceTabIndex) {
-				InputStream stream = new ByteArrayInputStream(fTargetDocument.get().getBytes(StandardCharsets.UTF_8));
-				TargetDefinitionPersistenceHelper.initFromXML(getTarget(), stream);
-				if (!getTarget().isResolved()) {
-					getTargetChangedListener().contentsChanged(getTarget(), this, true, false);
+				String text = fTargetDocument.get();
+				byte[] bytes = text.getBytes(StandardCharsets.UTF_8);
+				InputStream stream = new ByteArrayInputStream(bytes);
+				ITargetDefinition currentTarget = getTarget();
+				ITargetPlatformService service = PDECore.getDefault().acquireService(ITargetPlatformService.class);
+				ITargetDefinition newTarget = service.newTarget();
+				TargetDefinitionPersistenceHelper.initFromXML(newTarget, stream);
+				if (currentTarget instanceof TargetDefinition && ((TargetDefinition) currentTarget).isContentEqual(newTarget)) {
+					ITargetLocation[] oldLocations = currentTarget.getTargetLocations();
+					boolean wasResolved = currentTarget.isResolved();
+					stream.reset();
+					TargetDefinitionPersistenceHelper.initFromXML(currentTarget, stream);
+					if (wasResolved) {
+						currentTarget.setTargetLocations(oldLocations);
+					}
+				} else {
+					stream.reset();
+					TargetDefinitionPersistenceHelper.initFromXML(currentTarget, stream);
+					if (!getTarget().isResolved()) {
+						getTargetChangedListener().contentsChanged(getTarget(), this, true, false);
+					}
 				}
 			}
 			super.pageChange(newPageIndex);