Save and Open PDF on Android!

[RenanHm]

Hello.. I am saving a PDF file on the Android device as follows:

QString fileName = QFileDialog::getSaveFileName(this, tr("Exportar relatório..."), QString(), tr("PDF (*.pdf);;HTML (*.htm *.html);;Excel (*.csv);;Todos Arquivos (*)"));
    if(fileName.isEmpty())
        return;

printer->setOutputFormat(QPrinter::PdfFormat);
printer->setOutputFileName(fileName);
TE_Rel->document()->print(printer);

This way I use on Windows and now I'm using it on Android.
Apparently the PDF is successfully saved in the APP folder. But I can't view the APP form PDF, which I believe is related to Android permissions.

Given this, I'm trying to open the PDF right after saving. I use the following code to try to open it:

        QString filePath = fileName; //The file exists at that location, I used the same path to create the pdf
        QDesktopServices::openUrl(QUrl::fromLocalFile(filePath));

However, the PDF is not opened through a standard PDF viewer that is installed on the device.

Any other alternative to save and read PDF on Android?

I use QT 5.14.2.
Thanks.

[JoeCFD]

add read and write permissions in your AndroidManifess.xml? You can save your files in QStandardPaths::DocumentsLocation

[RenanHm]

I will add the following permissions:

    <uses-permission android:name="android.permission.ACCESS_CHECKIN_PROPERTIES"/>
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_SETTINGS"/>
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <uses-permission android:name="android.permission.WRITE_PROFILE"/>

But apparently it has no effect.

Whenever I save the PDF, the QFileDialog opens, allowing saving only within the APP folder.

Any idea?

[JoeCFD]

@JoeCFD said in Save and Open PDF on Android!:

QStandardPaths::DocumentsLocation

you assign this path QStandardPaths::DocumentsLocation to QFileDialog

[RenanHm]

Hello.. Okay. Change to:

    QString caminho = QStandardPaths::writableLocation(QStandardPaths::DocumentsLocation);
    QString fileName = QFileDialog::getSaveFileName(this, tr("Exportar relatório..."), caminho, tr("PDF (*.pdf);;HTML (*.htm *.html);;Excel (*.csv);;Todos Arquivos (*)"));
    if(fileName.isEmpty())
        return;

Now open the "Documents" folder. Saves correctly. But I can't open it with my APP through QDesktopServices

[JoeCFD]

not familiar with QDesktopServices. What is the error message?
the following link is a bit old. But it may help a bit.
https://stackoverflow.com/questions/18786919/qt-android-qdesktopservicesopenurl-qurlfromlocalfile-pdf-with
https://bugreports.qt.io/browse/QTBUG-67877

[RenanHm]

W System.err: android.os.FileUriExposedException: file:///storage/emulated/0/Documents/Caduser.pdf exposed beyond app through Intent.getData()
W System.err: at android.os.StrictMode.onFileUriExposed(StrictMode.java:2209)
W System.err: at android.net.Uri.checkFileUriExposed(Uri.java:2402)
W System.err: at android.content.Intent.prepareToLeaveProcess(Intent.java:12108)
W System.err: at android.content.Intent.prepareToLeaveProcess(Intent.java:12057)
W System.err: at android.app.Instrumentation.execStartActivity(Instrumentation.java:1742)
W System.err: at android.app.Activity.startActivityForResult(Activity.java:5473)
W System.err: at android.app.Activity.startActivityForResult(Activity.java:5431)
W System.err: at android.app.Activity.startActivity(Activity.java:5817)
W System.err: at android.app.Activity.startActivity(Activity.java:5770)
W System.err: at org.qtproject.qt5.android.QtNative.openURL(QtNative.java:164)
W System.err: at org.qtproject.qt5.android.QtNative.startQtApplication(Native Method)
W System.err: at org.qtproject.qt5.android.QtNative$7.run(QtNative.java:390)
W System.err: at org.qtproject.qt5.android.QtThread$1.run(QtThread.java:61)
W System.err: at java.lang.Thread.run(Thread.java:1012)

[piervalli]

@RenanHm said in Save and Open PDF on Android!:

W System.err: at java.lang.Thread.run(Thread.java:1012)

Have you checked permission on startup?

#ifdef REQUEST_PERMISSIONS_ON_ANDROID
#include <QtAndroid>

bool requestStoragePermission() {
    using namespace QtAndroid;
    SOPermission sop;
    QStringList permissions = {"android.permission.ACCESS_FINE_LOCATION"};
    const QHash<QString, PermissionResult> results = requestPermissionsSync(permissions);
    auto ok = true;
    auto i = 0;
    while (ok && i< permissions.size()) {
        if (!results.contains(permissions[i]) || results[permissions[i]] == PermissionResult::Denied) {
            qCritical() << "Couldn't get permission: " << permissions[i];
            ok = false;
            --i;
        }
        ++i;
    }
    return ok;
}
#endif

[RenanHm]

Hello.. I performed the test with the function mentioned. Change to permission:

    QStringList permissions = {"android.permission.READ_EXTERNAL_STORAGE"};

It is returned to me that it has permission. But without any practical effect.

Searching more.. I found that in the most recent versions of Android it is now necessary to use "Provider".

https://bugreports.qt.io/browse/QTBUG-67877
https://bugreports.qt.io/browse/QTBUG-85238

Following the guidelines for using the Provider, I add in the Manifest:

<provider
            android:name="androidx.core.content.FileProvider"
            android:authorities="com.example.myapp.fileprovider"
            android:grantUriPermissions="true"
            android:exported="false">
            <meta-data
                android:name="android.support.FILE_PROVIDER_PATHS"
                android:resource="@xml/filepaths" />
        </provider>

I also include the "filepaths" file in the "xml" folder.
But the error always occurs when opening the APP:

E AndroidRuntime: FATAL EXCEPTION: main
E AndroidRuntime: Process: com.digitalsof.totallocapp, PID: 4718
E AndroidRuntime: java.lang.RuntimeException: Unable to get provider androidx.core.content.FileProvider: java.lang.ClassNotFoundException: Didn't find class "androidx.core.content.FileProvider" on path: DexPathList[[zip file "/data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/base.apk"],nativeLibraryDirectories=[/data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/lib/arm64, /data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/base.apk!/lib/arm64-v8a, /system/lib64, /system/system_ext/lib64]]
E AndroidRuntime: 	at android.app.ActivityThread.installProvider(ActivityThread.java:8231)
E AndroidRuntime: 	at android.app.ActivityThread.installContentProviders(ActivityThread.java:7728)
E AndroidRuntime: 	at android.app.ActivityThread.handleBindApplication(ActivityThread.java:7482)
E AndroidRuntime: 	at android.app.ActivityThread.access$1600(ActivityThread.java:310)
E AndroidRuntime: 	at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2281)
E AndroidRuntime: 	at android.os.Handler.dispatchMessage(Handler.java:106)
E AndroidRuntime: 	at android.os.Looper.loopOnce(Looper.java:226)
E AndroidRuntime: 	at android.os.Looper.loop(Looper.java:313)
E AndroidRuntime: 	at android.app.ActivityThread.main(ActivityThread.java:8669)
E AndroidRuntime: 	at java.lang.reflect.Method.invoke(Native Method)
E AndroidRuntime: 	at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
E AndroidRuntime: 	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)
E AndroidRuntime: Caused by: java.lang.ClassNotFoundException: Didn't find class "androidx.core.content.FileProvider" on path: DexPathList[[zip file "/data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/base.apk"],nativeLibraryDirectories=[/data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/lib/arm64, /data/app/~~qh7wYdLZU6AvVfgP104ckQ==/com.digitalsof.totallocapp-pzAvkKqAw1X05TWYviFvnA==/base.apk!/lib/arm64-v8a, /system/lib64, /system/system_ext/lib64]]
E AndroidRuntime: 	at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:259)
E AndroidRuntime: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:379)
E AndroidRuntime: 	at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
E AndroidRuntime: 	at android.app.AppComponentFactory.instantiateProvider(AppComponentFactory.java:147)
E AndroidRuntime: 	at android.app.ActivityThread.installProvider(ActivityThread.java:8215)
E AndroidRuntime: 	... 11 more

Any idea?

[piervalli]

@RenanHm
In the my app I haved inserted in the all permission that we need .
const QStringList m_permissionsNameListAndroid = {"android.permission.ACCESS_FINE_LOCATION","android.permission.ACCESS_COARSE_LOCATION","android.permission.READ_EXTERNAL_STORAGE","android.permission.WRITE_EXTERNAL_STORAGE","android.permission.CHANGE_WIFI_STATE","android.permission.READ_PHONE_STATE","android.permission.ACCESS_WIFI_STATE","android.permission.BLUETOOTH","android.permission.BLUETOOTH_ADMIN","android.permission.VIBRATE","android.permission.RECEIVE_BOOT_COMPLETED"};

For Android > 10 I have ceate this function to create an file on directory. So You can test, if you can write on directory. I neved opened a url but I think the way is create a function java.

For example
//https://trendoceans.com/how-to-open-pdf-programmatically-using-intent-in-android/

For open the url
public static String directoryDownLoad() {
Context context = m_instance.getApplicationContext();
File path = android.os.Environment.getExternalStoragePublicDirectory(
android.os.Environment.DIRECTORY_DOWNLOADS);
Log.v(m_instance.TAG,"directoryDownLoad"+path.getAbsolutePath());
return path.getAbsolutePath();
}

Id

[RenanHm]

I'm managing to save the PDF, as I went above.
The problem is in opening the PDF.

From what I researched, the "Provider" should be created and call the native java class through "QAndroidJniObject".

But I can't move forward when I edit the Manifest file as above.

[piervalli]

@RenanHm
In this case usually I create a basic project with Android Studio to open a pdf. Then you can push the function in activity that you have extended in Qt for Android

[RenanHm]

@piervalli said in Save and Open PDF on Android!:

In this case usually I create a basic project with Android Studio to open a pdf. Then you can push the function in activity that you have extended in Qt for Android

I understood. I am going to try..

[RenanHm]

I'm having the same problem with printing documents on Android... QT doesn't recognize the drivers installed... it just gives the option to save to PDF... Do you know anything about this?

[piervalli]

@RenanHm
I am remember that the printer is not supported on Android, I think that you need same way.

[RenanHm]

@piervalli Got it.. I'll research about it. Thanks.