Generate QR in background thread.

- Moved the logic to generate the QR Code image from ReceiveTransactionFragment to its ViewModel (ReceiveTransactionViewModel), and used coroutines to send that process to a background thread to make sure this does not freeze the UI.

app/src/main/java/cy/agorise/bitsybitshareswallet/fragments/ReceiveTransactionFragment.kt

@@ -1,10 +1,7 @@
 package cy.agorise.bitsybitshareswallet.fragments
 
-import android.Manifest
 import android.content.Intent
 import android.content.pm.PackageManager
-import android.graphics.Bitmap
-import android.graphics.Color
 import android.os.Bundle
 import android.preference.PreferenceManager
 import android.util.Log
@@ -17,11 +14,6 @@ import androidx.lifecycle.Observer
 import androidx.lifecycle.ViewModelProviders
 import com.crashlytics.android.Crashlytics
 import com.google.common.primitives.UnsignedLong
-import com.google.zxing.BarcodeFormat
-import com.google.zxing.EncodeHintType
-import com.google.zxing.MultiFormatWriter
-import com.google.zxing.WriterException
-import com.google.zxing.common.BitMatrix
 import com.jakewharton.rxbinding3.widget.textChanges
 import cy.agorise.bitsybitshareswallet.R
 import cy.agorise.bitsybitshareswallet.adapters.AssetsAdapter
@@ -43,6 +35,7 @@ import java.text.DecimalFormatSymbols
 import java.util.*
 import java.util.concurrent.TimeUnit
 import kotlin.collections.ArrayList
+import kotlin.math.min
 
 class ReceiveTransactionFragment : ConnectedFragment() {
 
@@ -144,6 +137,10 @@ class ReceiveTransactionFragment : ConnectedFragment() {
                 }
         })
 
+        mViewModel.qrCodeBitmap.observe(this, Observer { bitmap ->
+            ivQR.setImageBitmap(bitmap)
+        })
+
         spAsset.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
             override fun onNothingSelected(parent: AdapterView<*>?) { }
 
@@ -251,7 +248,6 @@ class ReceiveTransactionFragment : ConnectedFragment() {
         }
     }
 
-    // TODO use coroutines to move this process to a background thread
     private fun updateQR() {
         if (mAsset == null) {
             ivQR.setImageDrawable(null)
@@ -276,64 +272,14 @@ class ReceiveTransactionFragment : ConnectedFragment() {
             asset.symbol.replaceFirst("bit", ""), items, "", "")
         Log.d(TAG, "invoice: " + invoice.toJsonString())
         try {
-            val bitmap = encodeAsBitmap(Invoice.toQrCode(invoice), "#139657") // PalmPay green
+            mViewModel.updateInvoice(invoice, min(ivQR.width, ivQR.height))
-            ivQR.setImageBitmap(bitmap)
             updateAmountAddressUI(amount, asset.symbol, asset.precision, mUserAccount!!.name)
-        } catch (e: WriterException) {
-            Log.e(TAG, "WriterException. Msg: " + e.message)
-            Crashlytics.logException(e)
         } catch (e: NullPointerException) {
             Log.e(TAG, "NullPointerException. Msg: " + e.message)
             Crashlytics.logException(e)
         }
     }
 
-    /**
-     * Encodes the provided data as a QR-code. Used to provide payment requests.
-     * @param data: Data containing payment request data as the recipient's address and the requested amount.
-     * @param color: The color used for the QR-code
-     * @return Bitmap with the QR-code encoded data
-     * @throws WriterException if QR Code cannot be generated
-     */
-    @Throws(WriterException::class)
-    internal fun encodeAsBitmap(data: String, color: String): Bitmap? {
-        val result: BitMatrix
-
-        // Get measured width and height of the ImageView where the QR code will be placed and make sure
-        // the final QR code has a squared shape
-        val w = Math.min(ivQR.width, ivQR.height)
-        val h = w
-
-        try {
-            val hints = HashMap<EncodeHintType, Any>()
-            hints[EncodeHintType.MARGIN] = 0
-            result = MultiFormatWriter().encode(
-                data,
-                BarcodeFormat.QR_CODE, w, h, hints
-            )
-        } catch (iae: IllegalArgumentException) {
-            // Unsupported format
-            return null
-        }
-
-        val pixels = IntArray(w * h)
-        for (y in 0 until h) {
-            val offset = y * w
-            for (x in 0 until w) {
-                pixels[offset + x] = if (result.get(x, y)) Color.parseColor(color) else Color.WHITE
-            }
-        }
-
-        return try {
-            val bitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888)
-            bitmap.setPixels(pixels, 0, w, 0, 0, w, h)
-            bitmap
-        } catch (e: IllegalArgumentException) {
-            Crashlytics.logException(e)
-            null
-        }
-    }
-
     /**
      * Updates the UI to show the amount and account to send the payment
      */
@@ -369,7 +315,7 @@ class ReceiveTransactionFragment : ConnectedFragment() {
     }
 
     private fun verifyStoragePermission() {
-        if (ContextCompat.checkSelfPermission(activity!!, Manifest.permission.WRITE_EXTERNAL_STORAGE)
+        if (ContextCompat.checkSelfPermission(activity!!, android.Manifest.permission.WRITE_EXTERNAL_STORAGE)
             != PackageManager.PERMISSION_GRANTED) {
             // Permission is not already granted
             requestPermissions(arrayOf(android.Manifest.permission.WRITE_EXTERNAL_STORAGE),

app/src/main/java/cy/agorise/bitsybitshareswallet/viewmodels/ReceiveTransactionViewModel.kt

@@ -1,18 +1,36 @@
 package cy.agorise.bitsybitshareswallet.viewmodels
 
 import android.app.Application
+import android.graphics.Bitmap
+import android.graphics.Color
+import android.util.Log
 import androidx.lifecycle.AndroidViewModel
 import androidx.lifecycle.LiveData
+import androidx.lifecycle.MutableLiveData
+import androidx.lifecycle.viewModelScope
+import com.google.zxing.BarcodeFormat
+import com.google.zxing.EncodeHintType
+import com.google.zxing.MultiFormatWriter
+import com.google.zxing.WriterException
 import cy.agorise.bitsybitshareswallet.database.entities.Asset
 import cy.agorise.bitsybitshareswallet.database.entities.UserAccount
 import cy.agorise.bitsybitshareswallet.repositories.AssetRepository
 import cy.agorise.bitsybitshareswallet.repositories.UserAccountRepository
+import cy.agorise.graphenej.Invoice
+import kotlinx.coroutines.Dispatchers.Default
+import kotlinx.coroutines.launch
+import kotlinx.coroutines.withContext
+import java.util.HashMap
 
 class ReceiveTransactionViewModel(application: Application) : AndroidViewModel(application) {
 
     private var mUserAccountRepository = UserAccountRepository(application)
     private var mAssetRepository = AssetRepository(application)
 
+    private val _qrCodeBitmap = MutableLiveData<Bitmap>()
+    val qrCodeBitmap: LiveData<Bitmap>
+        get() = _qrCodeBitmap
+
     internal fun getUserAccount(id: String): LiveData<UserAccount> {
         return mUserAccountRepository.getUserAccount(id)
     }
@@ -20,4 +38,48 @@ class ReceiveTransactionViewModel(application: Application) : AndroidViewModel(a
     internal fun getAllNonZero(): LiveData<List<Asset>> {
         return mAssetRepository.getAllNonZero()
     }
+
+    internal fun updateInvoice(invoice: Invoice, size: Int) {
+        viewModelScope.launch {
+            try {
+                _qrCodeBitmap.value = encodeAsBitmap(Invoice.toQrCode(invoice), "#139657", size) // PalmPay green
+            } catch (e: Exception) {
+                Log.d("ReceiveTransactionVM", e.message)
+            }
+        }
+    }
+
+    /**
+     * Encodes the provided data as a QR-code. Used to provide payment requests.
+     * @param data: Data containing payment request data as the recipient's address and the requested amount.
+     * @param color: The color used for the QR-code
+     * @param size: The size in pixels of the QR-code to generate
+     * @return Bitmap with the QR-code encoded data
+     * @throws WriterException if QR Code cannot be generated
+     * @throws IllegalArgumentException IllegalArgumentException
+     */
+    @Throws(WriterException::class, IllegalArgumentException::class)
+    private suspend fun encodeAsBitmap(data: String, color: String, size: Int): Bitmap? =
+        withContext(Default) {
+
+            val hints = HashMap<EncodeHintType, Any>()
+            hints[EncodeHintType.MARGIN] = 0
+            val result = MultiFormatWriter().encode(
+                data,
+                BarcodeFormat.QR_CODE, size, size, hints
+            )
+
+            val pixels = IntArray(size * size)
+            for (y in 0 until size) {
+                val offset = y * size
+                for (x in 0 until size) {
+                    pixels[offset + x] =
+                        if (result.get(x, y)) Color.parseColor(color) else Color.WHITE
+                }
+            }
+
+            val bitmap = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888)
+            bitmap.setPixels(pixels, 0, size, 0, 0, size, size)
+            bitmap
+        }
 }