CSharp:Android App - Appunti

Accesso al cloud Google

Doc

• Google Drive API v3, applicazione Console developers.google.com
• Google API Client Libraries .NET developers.google.com
• Implementare autenticazione google in app syncfusion.com
• Xamarin.Essentials: Web Authenticator docs.microsoft.com
• Esempio funzionante e testato di Upload di un file: www.c-sharpcorner.com
• Download a file from Google Drive codeproject.com
• Keytool per SH1 del certificato per App Android: stackoverflow.com
• Accesso a OneDrive Drive, DropBox da Xamarin Forms forums.xamarin.com

é Google Drive spiegazione ed esempio edandersen.com

• Esempio OAuth2 x Google Drive timothelariviere.com
• Broadcast receiver docs.microsoft.com intercettare tutti gli eventi da SO.

Condivisione file

• Condividere un file
• Sharing with NFC
• condividere file con Google Drive
• Google Drive rendere owner un altro utente
•  ! Google Drive share

Visualizzazione di immagini

L'oggetto da usare è ImageView, si va ad agire sulle proprietà:

• SetImageURI , per via programmatica oppure
• android:src , nello XAML nel file xml di progettazione lato UI.

Per poter funzionare occorrerà impostare prima i diritti di accesso alle risorse del fileSystem. Vedere esempio qui (http://wiki.aino.it/index.php?title=CSharp:Android_App_-_primi_step#Permessi_.5C_Autorizzazioni Primi step autorizzazioni)

Esempio

Segue codice di esempio adattato da esempio preso su internet c-sharpcorner.com e che corrisponde al progetto di tipo xamarin native. activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:orientation="vertical"  
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:minWidth="25px"
    android:minHeight="25px">
    <TextView  
         android:id="@+id/TxtViewTitle"  
         android:layout_width="wrap_content"  
         android:layout_height="wrap_content"  
         android:text="Android ImageView Example"  
         android:textSize="22sp"  
         android:textStyle="bold" />

    <ImageView
        android:id="@+id/ImageDocView"
        android:src="@android:drawable/ic_menu_compass"
        android:layout_width="200dp"
        android:layout_height="200dp"
        android:layout_gravity="center_horizontal"
        android:contentDescription="description" />

    <Button   
         android:id="@+id/BtnImgLoadCustom"
         android:text="Custom"  
         android:layout_width="match_parent"  
         android:layout_height="wrap_content"  />  
    <Button    
         android:id="@+id/BtnFromGallery"
         android:text="From Galley"  
         android:layout_width="match_parent"  
         android:layout_height="wrap_content" />  
</LinearLayout>

using Android;
using Android.App;
using Android.Content;
using Android.Content.PM;
using Android.OS;
using Android.Runtime;
using Android.Support.V4.App;
using Android.Support.V4.Content;
using Android.Support.V7.App;
using Android.Widget;
using Bank_Document.Core;
using System;
using System.IO;
using System.Threading.Tasks;
 
namespace Bank_Document
{
    [Activity(Label = "@string/app_name"
                , Theme = "@style/AppTheme"
                , MainLauncher = true)]
    public class MainActivity : AppCompatActivity
    {
        public static readonly int PickImageId = 1000;
        TextView TxtViewTitle;
        ImageView ImageDocView;
        Button BtnImgLoadCustom;
        Button BtnFromGallery;
 
        protected override void OnCreate(Bundle savedInstanceState)
        {
            base.OnCreate(savedInstanceState);
            Xamarin.Essentials.Platform.Init(this, savedInstanceState);
            // Set our view from the "main" layout resource
            SetContentView(Resource.Layout.activity_main);
 
            //---Parte di personalizzazione
            TxtViewTitle = FindViewById<TextView>(Resource.Id.TxtViewTitle);
            ImageDocView = FindViewById<ImageView>(Resource.Id.ImageDocView);
            BtnImgLoadCustom = FindViewById<Button>(Resource.Id.BtnImgLoadCustom);
            BtnFromGallery = FindViewById<Button>(Resource.Id.BtnFromGallery);
 
            BtnImgLoadCustom.Click += BtnImgLoadCustom_Click;
            BtnFromGallery.Click += BtnFromGallery_Click;
 
            InitializeCustom();
        }
 
        private void InitializeCustom()
        {
            bool isAccessDenied = false;
            string strErrorMsg = string.Empty;
            int nrAttempt4Access = 0;
 
            try
            {
                do
                {
                    strErrorMsg = string.Empty;
                    if (ContextCompat.CheckSelfPermission(this
                                , Manifest.Permission.ReadExternalStorage) != (int)Permission.Granted)
                    {
                        strErrorMsg += "\r\nMissed read permission for external archive";
                        isAccessDenied = true;
                    }
                    if (ContextCompat.CheckSelfPermission(this
                                , Manifest.Permission.WriteExternalStorage) != (int)Permission.Granted)
                    {
                        strErrorMsg += "\r\nMissed write permission for external archive";
                        isAccessDenied = true;
                    }
                    if (isAccessDenied)
                    {
                        var permissions = new string[]
                                            {
                                                Manifest.Permission.ReadExternalStorage,
                                                Manifest.Permission.WriteExternalStorage
                                            };
                        // RequestCode REQUEST_FOLDER_PERMISSION = 9?
                        ActivityCompat.RequestPermissions(this, permissions, 9);
 
                        Task.Delay(4000).Wait(); //Attesa di 4 secondi
                        isAccessDenied = ContextCompat.CheckSelfPermission(this, Manifest.Permission.ReadExternalStorage) != (int)Permission.Granted
                                    || ContextCompat.CheckSelfPermission(this, Manifest.Permission.WriteExternalStorage) != (int)Permission.Granted;
                    }
                } while (isAccessDenied && nrAttempt4Access < 3);
                if (isAccessDenied && nrAttempt4Access == 3)
                {
                    throw new Exception("Permissions are mandatory!\r\n" + strErrorMsg);
                }
            }
            catch (System.Exception ex)
            {
                AManager.MessageBox(this, "InitializeCustom", ex.Message);
            }
        }
 
        private void BtnFromGallery_Click(object sender, System.EventArgs e)
        {
            try
            {
                Intent = new Intent();
                Intent.SetType("image/*");
                Intent.SetAction(Intent.ActionGetContent);
                StartActivityForResult(Intent.CreateChooser(Intent, "Select Picture")
                                    , PickImageId);
            }
            catch (System.Exception ex)
            {
                AManager.MessageBox(this, "BtnFromGallery", ex.Message);
            }
        }
 
        // Create a Method OnActivityResult(it is select the image controller)   
        protected override void OnActivityResult(int requestCode, Result resultCode
                                               , Intent data)
        {
            if ((requestCode == PickImageId) 
                && (resultCode == Result.Ok) 
                && (data != null))
            {
                Android.Net.Uri uri = data.Data;
                string strFileName = Path.GetFileName(uri.Path);
                TxtViewTitle.Text = strFileName;
                ImageDocView.SetImageURI(uri);
            }
        }
 
        private void BtnImgLoadCustom_Click(object sender, System.EventArgs e)
        {
            try
            {
                string rootPath = "/storage/emulated/0/";
                string relativePath = "MiaCartella/Doc/fileImmagine.jpg";
                Java.IO.File fileImage = new Java.IO.File(rootPath + relativePath);
 
                Android.Net.Uri uri = Android.Net.Uri.FromFile(fileImage);
                ImageDocView.SetImageURI(uri);
            }
            catch (System.Exception ex)
            {
                AManager.MessageBox(this, "BtnImgLoadCustom", ex.Message);
            }
        }
 
        //etc... non serve
        public override void OnRequestPermissionsResult(int requestCode, string[] permissions
                                , [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
        {
            Xamarin.Essentials.Platform.OnRequestPermissionsResult(requestCode, permissions
                                                                , grantResults);
 
            base.OnRequestPermissionsResult(requestCode, permissions, grantResults);
        }
    }
}

Si usa un metodo preconfezionato per invocare l'Esplora risorse standard di Android affinché si scelga il file immagine da visualizzare, allo scopo c'è un modo per creare un metodo "Action" preconfezionata, notare i metodi BtnFromGallery_Click (che è l'hadler personalizzato di preparazione) ma soprattutto OnActivityResult!

QR Code

• c-sharpcorner.com

Accesso a Risorse

FingerPrint

• DOC1 learn.microsoft.com
• DOC2 c-sharpcorner.com

Share

La condivisione di risorse con altre App:

• Xamarin.Essentials Share

Mappa e Link

---

C# | Android App

---

Visual Studio | Windows Form | MS SQL | Dizionario

---

Parole chiave: