Extend Browser API to check for custom text location

The contribution provides an API to check if the location is the
location where custom texts are loaded in a browser. By construct,
"about:blank" is used for that purpose. This API can be adapted by the
clients instead of explicitly defining the string and checking.

Contributes to #213

bundles/org.eclipse.swt/Eclipse SWT Browser/common/org/eclipse/swt/browser/Browser.java

@@ -13,6 +13,9 @@
  *******************************************************************************/
 package org.eclipse.swt.browser;
 
+import java.net.*;
+import java.util.*;
+
 import org.eclipse.swt.*;
 import org.eclipse.swt.widgets.*;
 
@@ -1187,6 +1190,21 @@ public boolean setUrl (String url, String postData, String[] headers) {
 	return webBrowser.setUrl (url, postData, headers);
 }
 
+/**
+ * Checks if the location supplied is the location for setting custom text in the browser.
+ * This means, when passing the browser URL to this method after a custom text has been set
+ * via {@link #setText(String)} will yield true as long as no further navigation
+ * to some other location is performed.
+ *
+ * @param location the URL to be checked, must not be null
+ *
+ * @since 3.128
+ */
+public boolean isLocationForCustomText(String location) {
+	checkWidget();
+	return URI.create(Objects.requireNonNull(location)).equals(webBrowser.getUriForCustomText());
+}
+
 /**
  * Stop any loading and rendering activity.
  *

bundles/org.eclipse.swt/Eclipse SWT Browser/common/org/eclipse/swt/browser/WebBrowser.java

@@ -13,6 +13,7 @@
  *******************************************************************************/
 package org.eclipse.swt.browser;
 
+import java.net.*;
 import java.util.*;
 import java.util.List;
 
@@ -36,6 +37,7 @@ abstract class WebBrowser {
 
 	static final String ERROR_ID = "org.eclipse.swt.browser.error"; // $NON-NLS-1$
 	static final String EXECUTE_ID = "SWTExecuteTemporaryFunction"; // $NON-NLS-1$
+	private static final URI URI_FOR_CUSTOM_TEXT_PAGE = URI.create("about:blank");
 
 	static List<String[]> NativePendingCookies = new ArrayList<> ();
 	static String CookieName, CookieValue, CookieUrl;
@@ -724,6 +726,10 @@ public void setBrowser (Browser browser) {
 	this.browser = browser;
 }
 
+URI getUriForCustomText() {
+	return URI_FOR_CUSTOM_TEXT_PAGE;
+}
+
 public abstract boolean setText (String html, boolean trusted);
 
 public abstract boolean setUrl (String url, String postData, String[] headers);

examples/org.eclipse.swt.examples/src/org/eclipse/swt/examples/controlexample/BrowserTab.java

@@ -209,7 +209,7 @@ void disposeExampleWidgets () {
 		/* store the state of the Browser if applicable */
 		if (browser != null) {
 			String url = browser.getUrl();
-			if (url.length() > 0 && !url.equals("about:blank")) { //$NON-NLS-1$
+			if (url.length() > 0 && !browser.isLocationForCustomText(url)) { //$NON-NLS-1$
 				lastUrl = url;
 			} else {
 				String text = browser.getText();

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_browser_Browser.java

@@ -34,6 +34,7 @@
 import java.lang.management.ThreadMXBean;
 import java.net.HttpURLConnection;
 import java.net.MalformedURLException;
+import java.net.URI;
 import java.net.URL;
 import java.nio.file.DirectoryStream;
 import java.nio.file.Files;
@@ -518,6 +519,80 @@ public void changing(LocationEvent event) {
 	for (int i = 0; i < 100; i++) browser.removeLocationListener(listener);
 }
 
+@Test
+public void test_isLocationForCustomText_setUrlAfterDisposedThrowsSwtException() {
+	Browser testBrowser = createBrowser(shell, SWT.NONE);
+	testBrowser.dispose();
+	assertThrows(SWTException.class, () -> testBrowser.isLocationForCustomText("about:blank"));
+}
+
+@Test
+public void test_isLocationForCustomText_isSetUrlNotCustomTextUrlAfterSetText() {
+	assumeFalse("behavior is not (yet) supported by Edge browser", isEdge);	// Edge doesn't fire a changed event if the URL is the same as the previous location.
+	URI url = getValidUrl();
+	AtomicBoolean locationChanged = new AtomicBoolean(false);
+	browser.addLocationListener(changedAdapter(event -> {
+			locationChanged.set(true);
+	}));
+
+	browser.setText("Custom text");
+	assertTrue("Time Out: The Browser didn't navigate to the URL", waitForPassCondition(locationChanged::get));
+	locationChanged.set(false);
+	browser.setUrl(url.toASCIIString());
+	assertTrue("Time Out: The Browser didn't navigate to the URL", waitForPassCondition(locationChanged::get));
+	assertEquals("Url is wrongly considered Custom Text Url", URI.create(browser.getUrl()), url);
+	assertFalse("The navigated URL is falsly indicated to be the custom text URL", browser.isLocationForCustomText(browser.getUrl()));
+}
+
+@Test
+public void test_isLocationForCustomText_isFirstSetTextURLStillCustomTextUrlAfterSetUrl() {
+	assumeFalse("behavior is not (yet) supported by Edge browser", isEdge);	// Edge doesn't fire a changed event if the URL is the same as the previous location.
+	AtomicBoolean locationChanged = new AtomicBoolean(false);
+	browser.addLocationListener(changedAdapter(event -> locationChanged.set(true)));
+	URI url = getValidUrl();
+	browser.setText("Custom text");
+	assertTrue(waitForPassCondition(locationChanged::get));
+	String firstUrl = browser.getUrl();
+	locationChanged.set(false);
+	browser.setUrl(url.toASCIIString());
+	assertTrue("Time Out: The Browser didn't navigate to the URL", waitForPassCondition(locationChanged::get));
+	assertTrue(browser.isLocationForCustomText(firstUrl));
+	assertFalse(browser.isLocationForCustomText(browser.getUrl()));
+}
+
+private URI getValidUrl() {
+	String pluginPath = System.getProperty("PLUGIN_PATH");
+	URI url;
+	// Depending on how the jUnit test is ran, (gui/maven/ant), url for local file needs to be acquired differently.
+	if (pluginPath != null) {
+		url = URI.create(pluginPath + "/data/testWebsiteWithTitle.html");
+	} else {
+		// used when ran from Eclipse gui.
+		url = URI.create(Test_org_eclipse_swt_browser_Browser.class.getClassLoader().getResource("testWebsiteWithTitle.html").toString());
+	}
+	return url;
+}
+
+@Test
+public void test_isLocationForCustomText_isSetUrlNotCustomTextUrl() {
+	AtomicBoolean locationChanged = new AtomicBoolean(false);
+	browser.addLocationListener(changedAdapter(event -> locationChanged.set(true)));
+	URI url = getValidUrl();
+	browser.setUrl(url.toASCIIString());
+	waitForPassCondition(locationChanged::get);
+	assertFalse("Url is wrongly considered Custom Text Url", browser.isLocationForCustomText(browser.getUrl()));
+}
+
+@Test
+public void test_isLocationForCustomText() {
+	assumeFalse("behavior is not (yet) supported by Edge browser", isEdge);	// Edge doesn't fire a changed event if the URL is the same as the previous location.
+	AtomicBoolean locationChanged = new AtomicBoolean(false);
+	browser.addLocationListener(changedAdapter(e -> locationChanged.set(true)));
+	browser.setText("Hello world");
+	assertTrue("Timeout: LocationListener.changing() event was never fired", waitForPassCondition(locationChanged::get));
+	assertTrue("Custom Text URI was not loaded on setText", browser.isLocationForCustomText(browser.getUrl()));
+}
+
 @Test
 public void test_LocationListener_changing() {
 	AtomicBoolean changingFired = new AtomicBoolean(false);