Adding a prompt to help users download Talkback

(Google's open source screen reader) if they go
to the Accessibility settings screen and do not
have any accessibility tools installed.

This is a fix for bug #2250279

res/values/strings.xml

@@ -1752,6 +1752,16 @@ found in the list of installed applications.</string>
     <!-- Warning about disabling accessibility displayed as a dialog message when the user
          selects to disable accessibility. This avoids accidental disabling. -->
     <string name="accessibility_service_disable_warning">Disable accessibility?</string>
+    <!-- Title for the prompt that lets users know that they have no accessibility related apps
+         installed and that they can install TalkBack from Market. -->
+    <string name="accessibility_service_no_apps_title">No accessibility related applications found
+        </string>
+    <!-- Message for the prompt that lets users know that they have no accessibility related apps
+         installed and that they can install TalkBack from Market. -->
+    <string name="accessibility_service_no_apps_message">You do not have any accessibility related
+        applications installed.\n\nYou can download a screen reader for your device from Android
+        Market.\n\nClick "OK" to install the screen reader.</string>
+
 
     <!-- App Fuel Gauge strings -->
     <skip/>

src/com/android/settings/AccessibilitySettings.java

@@ -19,8 +19,14 @@ package com.android.settings;
 import android.app.AlertDialog;
 import android.app.Service;
 import android.content.DialogInterface;
+import android.content.Intent;
+import android.content.pm.ApplicationInfo;
+import android.content.pm.PackageManager;
+import android.content.pm.PackageManager.NameNotFoundException;
 import android.content.pm.ServiceInfo;
+import android.net.Uri;
 import android.os.Bundle;
+import android.os.SystemProperties;
 import android.preference.CheckBoxPreference;
 import android.preference.Preference;
 import android.preference.PreferenceActivity;
@@ -39,6 +45,9 @@ import java.util.Map;
  * Activity with the accessibility settings.
  */
 public class AccessibilitySettings extends PreferenceActivity {
+    private static final String DEFAULT_SCREENREADER_MARKET_LINK =
+        "market://search?q=pname:com.google.android.marvin.talkback";
+
     private final String TOGGLE_ACCESSIBILITY_SERVICE_CHECKBOX =
         "toggle_accessibility_service_checkbox";
 
@@ -108,6 +117,9 @@ public class AccessibilitySettings extends PreferenceActivity {
                 setAccessibilityServicePreferencesState(false);
             }
             mToggleCheckBox.setEnabled(false);
+            // Notify user that they do not have any accessibility apps
+            // installed and direct them to Market to get TalkBack
+            displayNoAppsAlert();
         }
     }
 
@@ -274,4 +286,42 @@ public class AccessibilitySettings extends PreferenceActivity {
             mAccessibilityServicesCategory.addPreference(preference);
         }
     }
+
+    /**
+     * Displays a message telling the user that they do not have any accessibility
+     * related apps installed and that they can get TalkBack (Google's free screen
+     * reader) from Market.
+     */
+    private void displayNoAppsAlert() {
+        try {
+            PackageManager pm = getPackageManager();
+            ApplicationInfo info = pm.getApplicationInfo("com.android.vending", 0);
+        } catch (NameNotFoundException e) {
+            // This is a no-op if the user does not have Android Market
+            return;
+        }
+        AlertDialog.Builder noAppsAlert = new AlertDialog.Builder(this);
+        noAppsAlert.setTitle(R.string.accessibility_service_no_apps_title);
+        noAppsAlert.setMessage(R.string.accessibility_service_no_apps_message);
+
+        noAppsAlert.setPositiveButton(android.R.string.ok,
+            new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface dialog, int which) {
+                    String screenreaderMarketLink =
+                        SystemProperties.get("ro.screenreader.market", DEFAULT_SCREENREADER_MARKET_LINK);
+                    Uri marketUri = Uri.parse(screenreaderMarketLink);
+                    Intent marketIntent = new Intent(Intent.ACTION_VIEW, marketUri);
+                    startActivity(marketIntent);
+                    finish();
+                }
+            });
+
+        noAppsAlert.setNegativeButton(android.R.string.cancel,
+            new DialogInterface.OnClickListener() {
+                public void onClick(DialogInterface dialog, int which) {
+                }
+            });
+
+        noAppsAlert.show();
+    }
 }