Qt for Android

Qt for Android enables you to run Qt 5 applications Android devices. All Qt modules (essential and add-on) are supported except Qt WebEngine, Qt Serial Port, and the platform-specific ones (Qt Mac Extras, Qt Windows Extras, and Qt X11 Extras).

在Windows或者Linux平臺上可以用QtWebEngine模塊實作網頁預覽和列印成PDF檔案，用起來很方便，生成的檔案質量也比較好，但在Android平臺上QtWebEngine模塊不能用，想要顯示網頁可以用QtWebView模塊，不支持列印成PDF，嘗試用QTextDocument和QPrinter將html轉為PDF，發現QTextDocument不支持CSS樣式，生成的PDF檔案排版是錯的，

查看QtWebView在Android平臺上的實作，可以發現其用的就是Android的WebView控制元件實作的網頁顯示，嘗試在Android平臺上實作html生成PDF，找到了這篇文章https://www.jianshu.com/p/d82bd61b11a4，驗證后可行，需要依賴第三方庫DexMaker，可以用谷歌實作的 implementation 'com.google.dexmaker:dexmaker:1.2'，庫檔案名為dexmaker-1.2.jar，

修改QT原始碼，在Android平臺上實作html轉PDF的功能

• 修改$QtSrc/qtwebview/src/jar/src/org/qtproject/qt5/android/view/QtAndroidWebViewController.java檔案

  /****************************************************************************
  **
  ** Copyright (C) 2015 The Qt Company Ltd.
  ** Contact: http://www.qt.io/licensing/
  **
  ** This file is part of the QtWebView module of the Qt Toolkit.
  **
  ** $QT_BEGIN_LICENSE:LGPL3$
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  ** Licensees holding valid commercial Qt licenses may use this file in
  ** accordance with the commercial license agreement provided with the
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  ** a written agreement between you and The Qt Company. For licensing terms
  ** and conditions see http://www.qt.io/terms-conditions. For further
  ** information use the contact form at http://www.qt.io/contact-us.
  **
  ** GNU Lesser General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU Lesser
  ** General Public License version 3 as published by the Free Software
  ** Foundation and appearing in the file LICENSE.LGPLv3 included in the
  ** packaging of this file. Please review the following information to
  ** ensure the GNU Lesser General Public License version 3 requirements
  ** will be met: https://www.gnu.org/licenses/lgpl.html.
  **
  ** GNU General Public License Usage
  ** Alternatively, this file may be used under the terms of the GNU
  ** General Public License version 2.0 or later as published by the Free
  ** Software Foundation and appearing in the file LICENSE.GPL included in
  ** the packaging of this file. Please review the following information to
  ** ensure the GNU General Public License version 2.0 requirements will be
  ** met: http://www.gnu.org/licenses/gpl-2.0.html.
  **
  ** $QT_END_LICENSE$
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  ****************************************************************************/
  
  package org.qtproject.qt5.android.view;
  
  import android.content.pm.PackageManager;
  import android.view.View;
  import android.webkit.GeolocationPermissions;
  import android.webkit.URLUtil;
  import android.webkit.ValueCallback;
  import android.annotation.SuppressLint;
  import android.content.Context;
  import android.os.Bundle;
  import android.os.CancellationSignal;
  import android.os.ParcelFileDescriptor;
  import android.print.PageRange;
  import android.print.PrintAttributes;
  import android.print.PrintDocumentAdapter;
  import android.webkit.WebView;
  import android.webkit.WebViewClient;
  import android.webkit.WebChromeClient;
  
  import java.lang.Runnable;
  
  import android.app.Activity;
  import android.content.Intent;
  import android.net.Uri;
  
  import java.lang.String;
  
  import android.webkit.WebSettings;
  import android.webkit.WebSettings.PluginState;
  import android.graphics.Bitmap;
  
  import java.util.concurrent.Semaphore;
  import java.io.File;
  import java.io.IOException;
  import java.lang.reflect.InvocationHandler;
  import java.lang.reflect.Method;
  
  import android.os.Build;
  
  import java.util.concurrent.TimeUnit;
  
  import com.google.dexmaker.stock.ProxyBuilder;
  
  public class QtAndroidWebViewController
  {
      private final Activity m_activity;
      private final long m_id;
      private boolean busy;
      private boolean m_hasLocationPermission;
      private WebView m_webView = null;
      private static final String TAG = "QtAndroidWebViewController";
      private final int INIT_STATE = 0;
      private final int STARTED_STATE = 1;
      private final int LOADING_STATE = 2;
      private final int FINISHED_STATE = 3;
  
      private volatile int m_loadingState = INIT_STATE;
      private volatile int m_progress = 0;
      private volatile int m_frameCount = 0;
  
      // API 11 methods
      private Method m_webViewOnResume = null;
      private Method m_webViewOnPause = null;
      private Method m_webSettingsSetDisplayZoomControls = null;
  
      // API 19 methods
      private Method m_webViewEvaluateJavascript = null;
  
      // Native callbacks
      private native void c_onPageFinished(long id, String url);
      private native void c_onPageStarted(long id, String url, Bitmap icon);
      private native void c_onProgressChanged(long id, int newProgress);
      private native void c_onReceivedIcon(long id, Bitmap icon);
      private native void c_onReceivedTitle(long id, String title);
      private native void c_onRunJavaScriptResult(long id, long callbackId, String result);
      private native void c_onReceivedError(long id, int errorCode, String description, String url);
      private native void c_onpdfPrintingFinished(long id, boolean succeed);
  
      // We need to block the UI thread in some cases, if it takes to long we should timeout before
      // ANR kicks in... Usually the hard limit is set to 10s and if exceed that then we're in trouble.
      // In general we should not let input events be delayed for more then 500ms (If we're spending more
      // then 200ms somethings off...).
      private final long BLOCKING_TIMEOUT = 250;
  
      private void resetLoadingState(final int state)
      {
          m_progress = 0;
          m_frameCount = 0;
          m_loadingState = state;
      }
  
      private class Html2Pdf {
          private File file;
          private File dexCacheFile;
          private PrintDocumentAdapter printAdapter;
          private PageRange[] ranges;
          private ParcelFileDescriptor descriptor;
      
          private void printToPdf(WebView webView, String fileName) {
              if (webView != null) {
                  file = new File(fileName);
                  dexCacheFile = webView.getContext().getDir("dex", 0);
                  if (!dexCacheFile.exists()) {
                      dexCacheFile.mkdir();
                  }
                  try {
                      if (file.exists()) {
                          file.delete();
                      }
                      file.createNewFile();
                      descriptor = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_WRITE);
                      PrintAttributes attributes = new PrintAttributes.Builder()
                              .setMediaSize(PrintAttributes.MediaSize.ISO_A4)
                              .setResolution(new PrintAttributes.Resolution("id", Context.PRINT_SERVICE, 300, 300))
                              .setColorMode(PrintAttributes.COLOR_MODE_COLOR)
                              .setMinMargins(PrintAttributes.Margins.NO_MARGINS)
                              .build();
                      ranges = new PageRange[]{PageRange.ALL_PAGES};
      
                      printAdapter = webView.createPrintDocumentAdapter();
                      printAdapter.onStart();
                      printAdapter.onLayout(attributes, attributes, new CancellationSignal(), getLayoutResultCallback(new InvocationHandler() {
                          @Override
                          public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                              if (method.getName().equals("onLayoutFinished")) {
                                  onLayoutSuccess();
                              } else {
                                  descriptor.close();
                                  c_onpdfPrintingFinished(m_id, false);
                                  busy = false;
                              }
                              return null;
                          }
                      }, dexCacheFile.getAbsoluteFile()), new Bundle());
                  } catch (IOException e) {
                      if (descriptor != null) {
                          try {
                              descriptor.close();
                          } catch (IOException ex) {
                              ex.printStackTrace();
                          }
                      }
                      c_onpdfPrintingFinished(m_id, false);
                      e.printStackTrace();
                      busy = false;
                  }
              }
          }
      
          private void onLayoutSuccess() throws IOException {
              PrintDocumentAdapter.WriteResultCallback callback = getWriteResultCallback(new InvocationHandler() {
                  @Override
                  public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
                      if (method.getName().equals("onWriteFinished")) {
                          c_onpdfPrintingFinished(m_id, true);
                      } else {
                          c_onpdfPrintingFinished(m_id, false);
                      }
                      busy = false;
                      if (descriptor != null) {
                          try {
                              descriptor.close();
                          } catch (IOException ex) {
                              ex.printStackTrace();
                          }
                      }
                      return null;
                  }
              }, dexCacheFile.getAbsoluteFile());
              printAdapter.onWrite(ranges, descriptor, new CancellationSignal(), callback);
          }
      
          @SuppressLint("NewApi")
          private  PrintDocumentAdapter.LayoutResultCallback getLayoutResultCallback(InvocationHandler invocationHandler, File dexCacheDir) throws IOException {
              return ProxyBuilder.forClass(PrintDocumentAdapter.LayoutResultCallback.class)
                      .dexCache(dexCacheDir)
                      .handler(invocationHandler)
                      .build();
          }
      
          @SuppressLint("NewApi")
          private  PrintDocumentAdapter.WriteResultCallback getWriteResultCallback(InvocationHandler invocationHandler, File dexCacheDir) throws IOException {
              return ProxyBuilder.forClass(PrintDocumentAdapter.WriteResultCallback.class)
                      .dexCache(dexCacheDir)
                      .handler(invocationHandler)
                      .build();
          }    
      }
  
      private class QtAndroidWebViewClient extends WebViewClient
      {
          QtAndroidWebViewClient() { super(); }
  
          @Override
          public boolean shouldOverrideUrlLoading(WebView view, String url)
          {
              // handle http: and http:, etc., as usual
              if (URLUtil.isValidUrl(url))
                  return false;
  
              // try to handle geo:, tel:, mailto: and other schemes
              try {
                  Intent intent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                  view.getContext().startActivity(intent);
                  return true;
              } catch (Exception e) {
                  e.printStackTrace();
              }
  
              return false;
          }
  
          @Override
          public void onl oadResource(WebView view, String url)
          {
              super.onLoadResource(view, url);
          }
  
          @Override
          public void onPageFinished(WebView view, String url)
          {
              super.onPageFinished(view, url);
              m_loadingState = FINISHED_STATE;
              if (m_progress != 100) // onProgressChanged() will notify Qt if we didn't finish here.
                  return;
  
               m_frameCount = 0;
               c_onPageFinished(m_id, url);
          }
  
          @Override
          public void onPageStarted(WebView view, String url, Bitmap favicon)
          {
              super.onPageStarted(view, url, favicon);
              if (++m_frameCount == 1) { // Only call onPageStarted for the first frame.
                  m_loadingState = LOADING_STATE;
                  c_onPageStarted(m_id, url, favicon);
              }
          }
  
          @Override
          public void onReceivedError(WebView view,
                                      int errorCode,
                                      String description,
                                      String url)
          {
              super.onReceivedError(view, errorCode, description, url);
              resetLoadingState(INIT_STATE);
              c_onReceivedError(m_id, errorCode, description, url);
          }
      }
  
      private class QtAndroidWebChromeClient extends WebChromeClient
      {
          QtAndroidWebChromeClient() { super(); }
          @Override
          public void onProgressChanged(WebView view, int newProgress)
          {
              super.onProgressChanged(view, newProgress);
              m_progress = newProgress;
              c_onProgressChanged(m_id, newProgress);
              if (m_loadingState == FINISHED_STATE && m_progress == 100) { // Did we finish?
                  m_frameCount = 0;
                  c_onPageFinished(m_id, view.getUrl());
              }
          }
  
          @Override
          public void onReceivedIcon(WebView view, Bitmap icon)
          {
              super.onReceivedIcon(view, icon);
              c_onReceivedIcon(m_id, icon);
          }
  
          @Override
          public void onReceivedTitle(WebView view, String title)
          {
              super.onReceivedTitle(view, title);
              c_onReceivedTitle(m_id, title);
          }
  
          @Override
          public void onGeolocationPermissionsShowPrompt(String origin, GeolocationPermissions.Callback callback)
          {
              callback.invoke(origin, m_hasLocationPermission, false);
          }
      }
  
      public QtAndroidWebViewController(final Activity activity, final long id)
      {
          m_activity = activity;
          m_id = id;
          final Semaphore sem = new Semaphore(0);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() {
                  m_webView = new WebView(m_activity);
                  m_hasLocationPermission = hasLocationPermission(m_webView);
                  WebSettings webSettings = m_webView.getSettings();
  
                  if (Build.VERSION.SDK_INT > 10) {
                      try {
                          m_webViewOnResume = m_webView.getClass().getMethod("onResume");
                          m_webViewOnPause = m_webView.getClass().getMethod("onPause");
                          m_webSettingsSetDisplayZoomControls = webSettings.getClass().getMethod("setDisplayZoomControls", boolean.class);
                          if (Build.VERSION.SDK_INT > 18) {
                              m_webViewEvaluateJavascript = m_webView.getClass().getMethod("evaluateJavascript",
                                                                                           String.class,
                                                                                           ValueCallback.class);
                          }
                      } catch (Exception e) { /* Do nothing */ e.printStackTrace(); }
                  }
  
                  //allowing access to location without actual ACCESS_FINE_LOCATION may throw security exception
                  webSettings.setGeolocationEnabled(m_hasLocationPermission);
  
                  webSettings.setJavaScriptEnabled(true);
                  if (m_webSettingsSetDisplayZoomControls != null) {
                      try { m_webSettingsSetDisplayZoomControls.invoke(webSettings, false); } catch (Exception e) { e.printStackTrace(); }
                  }
                  webSettings.setBuiltInZoomControls(true);
                  webSettings.setPluginState(PluginState.ON);
                  m_webView.setWebViewClient((WebViewClient)new QtAndroidWebViewClient());
                  m_webView.setWebChromeClient((WebChromeClient)new QtAndroidWebChromeClient());
                  sem.release();
              }
          });
  
          try {
              sem.acquire();
          } catch (Exception e) {
              e.printStackTrace();
          }
      }
  
      public void loadUrl(final String url)
      {
          if (url == null) {
              return;
          }
  
          resetLoadingState(STARTED_STATE);
          c_onPageStarted(m_id, url, null);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.loadUrl(url); }
          });
      }
  
      public void loadData(final String data, final String mimeType, final String encoding)
      {
          if (data =https://www.cnblogs.com/ALittleDruid/p/= null)
              return;
  
          resetLoadingState(STARTED_STATE);
          c_onPageStarted(m_id, null, null);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.loadData(data, mimeType, encoding); }
          });
      }
  
      public void loadDataWithBaseURL(final String baseUrl,
                                      final String data,
                                      final String mimeType,
                                      final String encoding,
                                      final String historyUrl)
      {
          if (data =https://www.cnblogs.com/ALittleDruid/p/= null)
              return;
  
          resetLoadingState(STARTED_STATE);
          c_onPageStarted(m_id, null, null);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.loadDataWithBaseURL(baseUrl, data, mimeType, encoding, historyUrl); }
          });
      }
  
      public void goBack()
      {
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.goBack(); }
          });
      }
  
      public boolean canGoBack()
      {
          final boolean[] back = {false};
          final Semaphore sem = new Semaphore(0);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { back[0] = m_webView.canGoBack(); sem.release(); }
          });
  
          try {
              sem.tryAcquire(BLOCKING_TIMEOUT, TimeUnit.MILLISECONDS);
          } catch (Exception e) {
              e.printStackTrace();
          }
  
          return back[0];
      }
  
      public void goForward()
      {
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.goForward(); }
          });
      }
  
      public boolean canGoForward()
      {
          final boolean[] forward = {false};
          final Semaphore sem = new Semaphore(0);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { forward[0] = m_webView.canGoForward(); sem.release(); }
          });
  
          try {
              sem.tryAcquire(BLOCKING_TIMEOUT, TimeUnit.MILLISECONDS);
          } catch (Exception e) {
              e.printStackTrace();
          }
  
          return forward[0];
      }
  
      public void stopLoading()
      {
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.stopLoading(); }
          });
      }
  
      public void reload()
      {
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { m_webView.reload(); }
          });
      }
  
      public String getTitle()
      {
          final String[] title = {""};
          final Semaphore sem = new Semaphore(0);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { title[0] = m_webView.getTitle(); sem.release(); }
          });
  
          try {
              sem.tryAcquire(BLOCKING_TIMEOUT, TimeUnit.MILLISECONDS);
          } catch (Exception e) {
              e.printStackTrace();
          }
  
          return title[0];
      }
  
      public int getProgress()
      {
          return m_progress;
      }
  
      public boolean isLoading()
      {
          return m_loadingState == LOADING_STATE || m_loadingState == STARTED_STATE || (m_progress > 0 && m_progress < 100);
      }
  
      public void runJavaScript(final String script, final long callbackId)
      {
          if (script == null)
              return;
  
          if (Build.VERSION.SDK_INT < 19 || m_webViewEvaluateJavascript == null)
              return;
  
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() {
                  try {
                      m_webViewEvaluateJavascript.invoke(m_webView, script, callbackId == -1 ? null :
                          new ValueCallback<String>() {
                              @Override
                              public void onReceiveValue(String result) {
                                  c_onRunJavaScriptResult(m_id, callbackId, result);
                              }
                          });
                  } catch (Exception e) {
                      e.printStackTrace();
                  }
              }
          });
      }
  
      public String getUrl()
      {
          final String[] url = {""};
          final Semaphore sem = new Semaphore(0);
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { url[0] = m_webView.getUrl(); sem.release(); }
          });
  
          try {
              sem.tryAcquire(BLOCKING_TIMEOUT, TimeUnit.MILLISECONDS);
          } catch (Exception e) {
              e.printStackTrace();
          }
  
          return url[0];
      }
  
      public WebView getWebView()
      {
         return m_webView;
      }
  
      public void onPause()
      {
          if (m_webViewOnPause == null)
              return;
  
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { try { m_webViewOnPause.invoke(m_webView); } catch (Exception e) { e.printStackTrace(); } }
          });
      }
  
      public void onResume()
      {
          if (m_webViewOnResume == null)
              return;
  
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() { try { m_webViewOnResume.invoke(m_webView); } catch (Exception e) { e.printStackTrace(); } }
          });
      }
  
      private static boolean hasLocationPermission(View view)
      {
          final String name = view.getContext().getPackageName();
          final PackageManager pm = view.getContext().getPackageManager();
          return pm.checkPermission("android.permission.ACCESS_FINE_LOCATION", name) == PackageManager.PERMISSION_GRANTED;
      }
  
      public void destroy()
      {
          m_activity.runOnUiThread(new Runnable() {
              @Override
              public void run() {
                  m_webView.destroy();
              }
          });
      }
  
      public void printToPdf(final String fileName){
          if(!busy){
              busy = true;
              m_activity.runOnUiThread(new Runnable() {
                  @Override
                  public void run() { 
                      Html2Pdf html2Pdf = new Html2Pdf();
                      html2Pdf.printToPdf(m_webView, fileName);
                  }
              });
          }else{
              c_onpdfPrintingFinished(m_id,false); 
          }
      }
  
  }

   

1. 主要修改：
   1. 增加了 void printToPdf(final String fileName)列印介面
   2. 增加了 native void c_onpdfPrintingFinished(long id, boolean succeed)作為列印完成的回呼
   3. 增加了內部類Html2Pdf實作列印成PDF

• 修改$QtSrc/qtwebview/src/plugins/android/qandroidwebview_p.h

1. 增加槽函式 void printToPdf(const QString &fileName) Q_DECL_OVERRIDE;

• 修改$QtSrc/qtwebview/src/plugins/android/qandroidwebview.cpp

1. 實作槽函式

   void QAndroidWebViewPrivate::printToPdf(const QString &fileName)
   {
       const QJNIObjectPrivate &fileNameString = QJNIObjectPrivate::fromString(fileName);
       m_viewController.callMethod<void>("printToPdf","(Ljava/lang/String;)V",fileNameString.object());
   }

2. 實作java代碼中列印完成的回呼

   static void c_onpdfPrintingFinished(JNIEnv *env,
                                 jobject thiz,
                                 jlong id,
                                 jboolean succeed)
   {
       Q_UNUSED(env)
       Q_UNUSED(thiz)
       const WebViews &wv = (*g_webViews);
       QAndroidWebViewPrivate *wc = wv[id];
       if (!wc)
           return;
       Q_EMIT wc->pdfPrintingFinished(succeed);
   }

3. 修改JNIEXPORT jint JNI_OnLoad(JavaVM* vm, void* /*reserved*/)，注冊c_onpdfPrintingFinished回呼函式，

   JNINativeMethod methods[]陣列里增加一項
   {"c_onpdfPrintingFinished","(JZ)V",reinterpret_cast<void *>(c_onpdfPrintingFinished)}

• 修改$QtSrc/qtwebview/src/webview/qabstractwebview_p.h（以下增加的所有的C++代碼、函式、信號等都用#if ANDROID宏條件編譯）

1. 增加信號void pdfPrintingFinished(bool succeed);

• 修改$QtSrc/qtwebview/src/webview/qquickwebview_p.h

1. 增加公開槽函式 void printToPdf(const QString &fileName) Q_DECL_OVERRIDE;
2. 增加信號 void pdfPrintingFinished(bool succeed);
3. 增加私有槽函式 void onPdfPrintingFinished(bool succeed);

• 修改$QtSrc/qtwebview/src/webview/qquickwebview.cpp

1. 建構式里關聯槽函式和信號

   #if ANDROID
   connect(m_webView, &QWebView::pdfPrintingFinished, this, &QQuickWebView::onPdfPrintingFinished);
   #endif

2. 實作槽函式printToPdf

   #if ANDROID
   void QQuickWebView::printToPdf(const QString &fileName)
   {
       m_webView->printToPdf(fileName);
   }
   #endif

3. 實作槽函式onPdfPrintingFinished

   #if ANDROID
   void QQuickWebView::onPdfPrintingFinished(bool succeed)
   {
       Q_EMIT pdfPrintingFinished(succeed);
   }
   #endif

• 修改$QtSrc/qtwebview/src/webview/qwebviewinterface_p.h

1. 增加純虛函式 virtual void printToPdf(const QString &fileName) = 0;

• 修改$QtSrc/qtwebview/src/webview/qwebviewfactory.cpp

1. QNullWebView類增加

   void printToPdf(const QString &fileName) override
       {Q_UNUSED(fileName); }

• 修改$QtSrc/qtwebview/src/webview/qwebview_p.h

1. 增加公開槽函式 void printToPdf(const QString &fileName) Q_DECL_OVERRIDE;
2. 增加信號 void pdfPrintingFinished(bool succeed);
3. 增加私有槽函式 void onPdfPrintingFinished(bool succeed);

• 修改$QtSrc/qtwebview/src/webview/qwebview.cpp

1. 建構式里關聯槽函式和信號

   #if ANDROID
   connect(d, &QAbstractWebView::pdfPrintingFinished, this, &QWebView::onPdfPrintingFinished);
   #endif

2. 實作槽函式printToPdf

   #if ANDROID
   void QWebView::printToPdf(const QString &fileName)
   {
       d->printToPdf(fileName);
   }
   #endif

3. 實作槽函式onPdfPrintingFinished

   #if ANDROID
   void QWebView::onPdfPrintingFinished(bool succeed)
   {
       Q_EMIT pdfPrintingFinished(succeed);
   }
   #endif

• 在$QtSrc/qtwebview/src/jar目錄下新建lib目錄，將dexmaker-1.2.jar檔案拷貝到該目錄下
• 修改$QtSrc/qtwebview/src/jar/jar.pro

  TARGET = QtAndroidWebView
  
  load(qt_build_paths)
  CONFIG += java
  DESTDIR = $$MODULE_BASE_OUTDIR/jar
  
  JAVACLASSPATH += $$PWD/src \
      $$PWD/lib/dexmaker-1.2.jar
  
  JAVASOURCES += $$PWD/src/org/qtproject/qt5/android/view/QtAndroidWebViewController.java
  
  # install
  thridpartyjar.files = \
      $$PWD/lib/dexmaker-1.2.jar
  thridpartyjar.path = $$[QT_INSTALL_PREFIX]/jar
  
  target.path = $$[QT_INSTALL_PREFIX]/jar
  INSTALLS += target thridpartyjar

• 修改$QtSrc/qtwebview/src/webview/webview.pro

  ……
  
  QMAKE_DOCS = \
               $$PWD/doc/qtwebview.qdocconf
  
  ANDROID_BUNDLED_JAR_DEPENDENCIES = \
      jar/QtAndroidWebView.jar \
      jar/dexmaker-1.2.jar
  ANDROID_PERMISSIONS = \
      android.permission.ACCESS_FINE_LOCATION
  ANDROID_LIB_DEPENDENCIES = \
      plugins/webview/libqtwebview_android.so
  
  HEADERS += $$PUBLIC_HEADERS $$PRIVATE_HEADERS
  
  load(qt_module)

• 修改$QtSrc/qtwebview/src/imports/plugins.qmltypes

1. 增加信號

   Signal {
               name: "pdfPrintingFinished"
               revision: 1
               Parameter { name: "succeed"; type: "bool" }
           }

2. 增加方法

   Method {
               name: "printToPdf"
               revision: 1
               Parameter { name: "fileName"; type: "string" }
           }

• 配置和編譯

1. ./configure -extprefix $QTInstall/android_arm64_v8a -xplatform android-clang -release -nomake tests -nomake examples -opensource -confirm-license -recheck-all -android-ndk $NDKPATH -android-sdk $AndroidSDKPATH -android-ndk-host linux-x86_64 -android-arch arm64-v8a

   -android-arch支持armeabi, armeabi-v7a, arm64-v8a, x86, x86_64，一次只能編譯一個架構，注意不同架構要修改安裝目錄

2. make -j8
3. make install

• 上述軟體版本

1. QT：5.13.2
2. NDK：r20b(20.1.5948944)
3. Android-buildToolsVersion：29.0.2

• 使用示例

  import QtQuick 2.12
  import QtQuick.Window 2.12
  import QtWebView 1.1
  import QtQuick.Controls 2.12
  
  Window {
      id: window
      visible: true
      width: 1080
      height: 1920
      title: qsTr("Hello World")
      WebView{
          id:webView
          anchors.bottom: printBtn.top
          anchors.right: parent.right
          anchors.left: parent.left
          anchors.top: parent.top
          anchors.bottomMargin: 0
          url:"http://www.qq.com"
          onPdfPrintingFinished: {
              printBtn.text = "列印" + (succeed?"成功":"失敗")
              printBtn.enabled = true
          }
      }
  
      Button {
          id:printBtn
          text: "列印"
          anchors.bottom: parent.bottom
          anchors.bottomMargin: 0
          onClicked: {
              printBtn.enabled = false
              webView.printToPdf("/sdcard/aaa.pdf")
          }
      }
  }

全部修改見https://github.com/ALittleDruid/qtwebview/commit/722a4757dd0acf86846194607a433cd724e9b028

下期預告：在Android平臺上實作串口讀寫的功能

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