Qt在Android平台上实现html转PDF的功能

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平台上可以用qtwebengine模块实现网页预览和打印成pdf文档，用起来很方便，生成的文档质量也比较好，但在android平台上qtwebengine模块不能用，想要显示网页可以用qtwebview模块，不支持打印成pdf。尝试用qtextdocument和qprinter将html转为pdf，发现qtextdocument不支持css样式，生成的pdf文档排版是错的。

 

查看qtwebview在android平台上的实现，可以发现其用的就是android的webview控件实现的网页显示。尝试在android平台上实现html生成pdf，找到了这篇文章，验证后可行。需要依赖第三方库dexmaker，可以用谷歌实现的 implementation 'com.google.dexmaker:dexmaker:1.2'，库文件名为dexmaker-1.2.jar。

 

修改qt源码，在android平台上实现html转pdf的功能

• 修改$qtsrc/qtwebview/src/jar/src/org/qtproject/qt5/android/view/qtandroidwebviewcontroller.java文件

  /****************************************************************************
  **
  ** 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.
  **
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  ** commercial license usage
  ** 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.
  **
  ** $qt_end_license$
  **
  ****************************************************************************/
  
  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 onloadresource(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 == 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 == 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)打印接口
   2. 增加了 native void c_onpdfprintingfinished(long id, boolean succeed)作为打印完成的回调
   3. 增加了内部类html2pdf实现打印成pdf

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

1. 增加槽函数 void printtopdf(const qstring &filename) q_decl_override;

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

1. 实现槽函数

   void qandroidwebviewprivate::printtopdf(const qstring &filename)
   {
       const qjniobjectprivate &filenamestring = qjniobjectprivate::fromstring(filename);
       m_viewcontroller.callmethod<void>("printtopdf","(ljava/lang/string;)v",filenamestring.object());
   }

2. 实现java代码中打印完成的回调

   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*/)，注册c_onpdfprintingfinished回调函数。

   jninativemethod methods[]数组里增加一项
   {"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++代码、函数、信号等都用#if android宏条件编译）

1. 增加信号void pdfprintingfinished(bool succeed);

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

1. 增加公开槽函数 void printtopdf(const qstring &filename) q_decl_override;
2. 增加信号 void pdfprintingfinished(bool succeed);
3. 增加私有槽函数 void onpdfprintingfinished(bool succeed);

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

1. 构造函数里关联槽函数和信号

   #if android
   connect(m_webview, &qwebview::pdfprintingfinished, this, &qquickwebview::onpdfprintingfinished);
   #endif

2. 实现槽函数printtopdf

   #if android
   void qquickwebview::printtopdf(const qstring &filename)
   {
       m_webview->printtopdf(filename);
   }
   #endif

3. 实现槽函数onpdfprintingfinished

   #if android
   void qquickwebview::onpdfprintingfinished(bool succeed)
   {
       q_emit pdfprintingfinished(succeed);
   }
   #endif

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

1. 增加纯虚函数 virtual void printtopdf(const qstring &filename) = 0;

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

1. qnullwebview类增加

   void printtopdf(const qstring &filename) override
       {q_unused(filename); }

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

1. 增加公开槽函数 void printtopdf(const qstring &filename) q_decl_override;
2. 增加信号 void pdfprintingfinished(bool succeed);
3. 增加私有槽函数 void onpdfprintingfinished(bool succeed);

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

1. 构造函数里关联槽函数和信号

   #if android
   connect(d, &qabstractwebview::pdfprintingfinished, this, &qwebview::onpdfprintingfinished);
   #endif

2. 实现槽函数printtopdf

   #if android
   void qwebview::printtopdf(const qstring &filename)
   {
       d->printtopdf(filename);
   }
   #endif

3. 实现槽函数onpdfprintingfinished

   #if android
   void qwebview::onpdfprintingfinished(bool succeed)
   {
       q_emit pdfprintingfinished(succeed);
   }
   #endif

• 在$qtsrc/qtwebview/src/jar目录下新建lib目录，将dexmaker-1.2.jar文件拷贝到该目录下
• 修改$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
  target.path = $$[qt_install_prefix]/jar
  target.files += $$pwd/lib/dexmaker-1.2.jar
  installs += target

• 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. 增加信号

   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" }
           }

• 配置和编译

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_64，一次只能编译一个架构，注意不同架构要修改安装目录

2. make -j8
3. make install

• 上述软件版本

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 = "打印" + (succeed?"成功":"失败")
              printbtn.enabled = true
          }
      }
  
      button {
          id:printbtn
          text: "打印"
          anchors.bottom: parent.bottom
          anchors.bottommargin: 0
          onclicked: {
              printbtn.enabled = false
              webview.printtopdf("/sdcard/aaa.pdf")
          }
      }
  }

下期预告：在android平台上实现串口读写的功能