Various android enhancements - see the changelog

CHANGELOG.md

@@ -1,4 +1,12 @@
 ## ChangeLog
+#### Version 0.7.2 (not yet released)
+- [__change__:] Changed plugin ID to `cordova-plugin-printer`
+- [__change__:] Plugin requires Android KitKat or newer
+- [__change__:] `isAvailable` returns false if no enabled print services can be found (Android)
+- [enhancement:] `isAvailable` returns additional list of available print services (Android)
+- [enhancement:] Support `duplex` attribute (Android)
+
+
 #### Version 0.7.1 (23.04.2015)
 - [bugfix:] `isAvailable` does not block the main thread anymore.
 - [bugfix:] iPad+iOS8 incompatibility (Thanks to __zmagyar__)

plugin.xml

@@ -42,7 +42,8 @@
 
     <!-- cordova -->
     <engines>
-        <engine name="cordova" version=">=6.0.0" />
+        <engine name="cordova" version=">=3.0.0" />
+        <engine name="android-sdk" version=">=19" />
     </engines>
 
     <!-- interface -->

src/android/Printer.java

@@ -21,14 +21,6 @@
 
 package de.appplant.cordova.plugin.printer;
 
-import org.apache.cordova.CallbackContext;
-import org.apache.cordova.CordovaPlugin;
-import org.apache.cordova.PluginResult;
-import org.json.JSONArray;
-import org.json.JSONException;
-import org.json.JSONObject;
-
-import android.annotation.TargetApi;
 import android.app.Activity;
 import android.content.Context;
 import android.os.Build;
@@ -39,7 +31,20 @@ import android.print.PrintManager;
 import android.webkit.WebView;
 import android.webkit.WebViewClient;
 
-@TargetApi(19)
+import org.apache.cordova.CallbackContext;
+import org.apache.cordova.CordovaPlugin;
+import org.apache.cordova.PluginResult;
+import org.json.JSONArray;
+import org.json.JSONException;
+import org.json.JSONObject;
+
+import java.lang.reflect.InvocationTargetException;
+import java.lang.reflect.Method;
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+
 public class Printer extends CordovaPlugin {
 
     private WebView view;
@@ -71,17 +76,14 @@ public class Printer extends CordovaPlugin {
 
         if (action.equalsIgnoreCase("isAvailable")) {
             isAvailable();
-
             return true;
         }
 
         if (action.equalsIgnoreCase("print")) {
             print(args);
-
             return true;
         }
 
-        // Returning false results in a "MethodNotFound" error.
         return false;
     }
 
@@ -93,10 +95,17 @@ public class Printer extends CordovaPlugin {
         cordova.getThreadPool().execute(new Runnable() {
             @Override
             public void run() {
-                Boolean supported   = Build.VERSION.SDK_INT >= Build.VERSION_CODES.KITKAT;
+                List<String> ids  = getEnabledPrintServiceIds();
-                PluginResult result = new PluginResult(PluginResult.Status.OK, supported);
+                Boolean available = ids.size() > 1;
 
-                command.sendPluginResult(result);
+                PluginResult res1 = new PluginResult(
+                        PluginResult.Status.OK, available);
+                PluginResult res2 = new PluginResult(
+                        PluginResult.Status.OK, new JSONArray(ids));
+                PluginResult res  = new PluginResult(
+                        PluginResult.Status.OK, Arrays.asList(res1, res2));
+
+                command.sendPluginResult(res);
             }
         });
     }
@@ -130,11 +139,12 @@ public class Printer extends CordovaPlugin {
         if (content.startsWith("http") || content.startsWith("file:")) {
             view.loadUrl(content);
         } else {
-            //Set base URI to the assets/www folder
             String baseURL = webView.getUrl();
             baseURL        = baseURL.substring(0, baseURL.lastIndexOf('/') + 1);
 
-            view.loadDataWithBaseURL(baseURL, content, "text/html", "UTF-8", null);
+            // Set base URI to the assets/www folder
+            view.loadDataWithBaseURL(
+                    baseURL, content, "text/html", "UTF-8", null);
         }
     }
 
@@ -164,6 +174,7 @@ public class Printer extends CordovaPlugin {
         final String docName    = props.optString("name", DEFAULT_DOC_NAME);
         final boolean landscape = props.optBoolean("landscape", false);
         final boolean graystyle = props.optBoolean("graystyle", false);
+        final String  duplex    = props.optString("duplex", "none");
 
         view.setWebViewClient(new WebViewClient() {
             @Override
@@ -173,27 +184,31 @@ public class Printer extends CordovaPlugin {
 
             @Override
             public void onPageFinished (WebView webView, String url) {
-                // Get a PrintManager instance
+                PrintManager printManager       = getPrintMgr();
-                PrintManager printManager = (PrintManager) cordova.getActivity()
-                        .getSystemService(Context.PRINT_SERVICE);
-
-                // Get a print adapter instance
-                PrintDocumentAdapter printAdapter = webView.createPrintDocumentAdapter();
-
-                // Get a print builder instance
                 PrintAttributes.Builder builder = new PrintAttributes.Builder();
+                PrintDocumentAdapter adapter    = getAdapter(webView, docName);
 
-                // The page does itself set its own margins
                 builder.setMinMargins(PrintAttributes.Margins.NO_MARGINS);
 
-                builder.setColorMode(graystyle ? PrintAttributes.COLOR_MODE_MONOCHROME
+                builder.setColorMode(graystyle
+                        ? PrintAttributes.COLOR_MODE_MONOCHROME
                         : PrintAttributes.COLOR_MODE_COLOR);
 
-                builder.setMediaSize(landscape ? PrintAttributes.MediaSize.UNKNOWN_LANDSCAPE
+                builder.setMediaSize(landscape
+                        ? PrintAttributes.MediaSize.UNKNOWN_LANDSCAPE
                         : PrintAttributes.MediaSize.UNKNOWN_PORTRAIT);
 
-                // Create a print job with name and adapter instance
+                if (!duplex.equals("none") && Build.VERSION.SDK_INT >= 23) {
-                PrintJob job = printManager.print(docName, printAdapter, builder.build());
+                    boolean longEdge = duplex.equals("long");
+                    Method setDuplexModeMethod = getMethod(builder.getClass(),
+                            "setDuplexMode", int.class);
+
+                    invokeMethod(builder, setDuplexModeMethod,
+                            longEdge ? 2 : 4);
+                }
+
+                PrintJob job = printManager.print(
+                        docName, adapter, builder.build());
 
                 invokeCallbackOnceCompletedOrCanceled(job);
 
@@ -221,4 +236,125 @@ public class Printer extends CordovaPlugin {
             }
         });
     }
+
+    /**
+     * Get a PrintManager instance.
+     *
+     * @return A PrintManager instance.
+     */
+    private PrintManager getPrintMgr () {
+        return (PrintManager) cordova.getActivity()
+                .getSystemService(Context.PRINT_SERVICE);
+    }
+
+    /**
+     * Create the print document adapter for the web view component. On
+     * devices older then SDK 21 it will use the deprecated method
+     * `createPrintDocumentAdapter` without arguments and on newer devices
+     * the recommended way.
+     *
+     * @param webView
+     *      The web view which content to print out.
+     * @param docName
+     *      The name of the printed document.
+     * @return
+     *      The created adapter.
+     */
+    private PrintDocumentAdapter getAdapter (WebView webView, String docName) {
+        if (Build.VERSION.SDK_INT >= 21) {
+            Method createPrintDocumentAdapterMethod = getMethod(
+                    WebView.class, "createPrintDocumentAdapter", String.class);
+
+            return (PrintDocumentAdapter) invokeMethod(
+                    webView, createPrintDocumentAdapterMethod, docName);
+        } else {
+            Method createPrintDocumentAdapterMethod = getMethod(
+                    WebView.class, "createPrintDocumentAdapter");
+
+            return (PrintDocumentAdapter) invokeMethod(
+                    webView, createPrintDocumentAdapterMethod);
+        }
+    }
+
+    /**
+     * Get a list of ids of all installed and enabled print services. For
+     * that it uses reflections to call public but hidden methods from the
+     * PrintManager.
+     *
+     * @return A list of found print service ids.
+     */
+    private List<String> getEnabledPrintServiceIds () {
+        try {
+            PrintManager printMgr = getPrintMgr();
+            Class<?> printerCls = Class.forName(
+                    "android.printservice.PrintServiceInfo");
+            Method getPrinterMethod = getMethod(printMgr.getClass(),
+                    "getEnabledPrintServices");
+            Method getIdMethod = getMethod(printerCls,
+                    "getId");
+
+            List printers = (List) invokeMethod(printMgr, getPrinterMethod);
+            ArrayList<String> printerIds = new ArrayList<String>();
+
+            printerIds.add("android.print.pdf");
+
+            if (printers == null)
+                return printerIds;
+
+            for (Object printer : printers) {
+                String printerId = (String) invokeMethod(printer, getIdMethod);
+                printerIds.add(printerId);
+            }
+
+            return printerIds;
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+
+        return Collections.emptyList();
+    }
+
+    /**
+     * Finds the method with given name and set of arguments.
+     *
+     * @param cls
+     *      The class in where to look for the method declaration.
+     * @param name
+     *      The name of the method.
+     * @param params
+     *      The arguments of the method.
+     * @return
+     *      The found method or null.
+     */
+    private Method getMethod (Class<?> cls, String name, Class<?>... params) {
+        try {
+            return cls.getDeclaredMethod(name, params);
+        } catch (NoSuchMethodException e) {
+            return null;
+        }
+    }
+
+    /**
+     * Invokes the method on the given object with the specified arguments.
+     *
+     * @param obj
+     *      An object which class defines the method.
+     * @param method
+     *      The method to invoke.
+     * @param args
+     *      Set of arguments.
+     * @return
+     *      The returned object or null.
+     */
+    private Object invokeMethod (Object obj, Method method, Object... args) {
+        try {
+            return method.invoke(obj, args);
+        } catch (IllegalAccessException e) {
+            e.printStackTrace();
+        } catch (InvocationTargetException e) {
+            e.printStackTrace();
+        }
+
+        return null;
+    }
 }