Feature: save PDF to device

app/src/main/AndroidManifest.xml

@@ -6,6 +6,8 @@
         android:name="android.hardware.camera"
         android:required="false" />
     <uses-permission android:name="android.permission.CAMERA" />
+    <!-- Required (on Android 9 and lower) to save files -->
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
 
     <application
         android:allowBackup="true"

app/src/main/java/org/mydomain/myscan/MainActivity.kt

@@ -3,7 +3,9 @@ package org.mydomain.myscan
 import android.content.Context
 import android.content.Intent
 import android.graphics.Bitmap
+import android.media.MediaScannerConnection
 import android.os.Bundle
+import android.os.Environment
 import android.util.Log
 import android.widget.Toast
 import androidx.activity.ComponentActivity
@@ -23,6 +25,8 @@ import org.mydomain.myscan.view.CameraScreen
 import org.mydomain.myscan.view.PagePreviewScreen
 import org.opencv.android.OpenCVLoader
 import java.io.File
+import java.io.FileOutputStream
+import java.io.IOException
 
 class MainActivity : ComponentActivity() {
 
@@ -48,7 +52,8 @@ class MainActivity : ComponentActivity() {
                                     image = screen.image,
                                     isProcessing = screen.isProcessing,
                                     onBackPressed = { viewModel.navigateTo(Screen.Camera) },
-                                    onSavePressed = createPdfAndShare(context)
+                                    onSavePressed = createPdfAndSave(context),
+                                    onSharePressed = createPdfAndShare(context),
                                 )
                             }
                         }
@@ -61,7 +66,18 @@ class MainActivity : ComponentActivity() {
     private fun createPdfAndShare(context: Context): (Bitmap) -> Unit = { bitmap ->
         val outputDir = File(cacheDir, "pdfs").apply { mkdirs() }
         val outputFile = File(outputDir, "scan_${System.currentTimeMillis()}.pdf")
-        val success = createPdfFromBitmaps(listOf(bitmap), outputFile)
+        val document = createPdfFromBitmaps(listOf(bitmap))
+        var success = true
+        try {
+            FileOutputStream(outputFile).use { outputStream ->
+                document.writeTo(outputStream)
+            }
+        } catch (_: IOException) {
+            Toast.makeText(context, "Failed to share PDF", Toast.LENGTH_SHORT).show()
+            success = false
+        } finally {
+            document.close()
+        }
         if (success) {
             val uri = FileProvider.getUriForFile(
                 context,
@@ -74,8 +90,30 @@ class MainActivity : ComponentActivity() {
                 addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION)
             }
             startActivity(Intent.createChooser(shareIntent, "Share PDF"))
-        } else {
+        }
+    }
+
+    fun createPdfAndSave(context: Context): (Bitmap) -> Unit = { bitmap ->
+        val document = createPdfFromBitmaps(listOf(bitmap))
+        try {
+            val downloadsDir = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS)
+            if (!downloadsDir.exists()) downloadsDir.mkdirs()
+            val file = File(downloadsDir, "scan_${System.currentTimeMillis()}.pdf")
+            val outputStream = FileOutputStream(file)
+            document.writeTo(outputStream)
+            outputStream.flush()
+            outputStream.close()
+
+            MediaScannerConnection.scanFile(
+                context, arrayOf(file.absolutePath), arrayOf("application/pdf"), null
+            )
+
+            Toast.makeText(context, "Saved PDF in Downloads", Toast.LENGTH_SHORT).show()
+        } catch (e: Exception) {
+            Log.e("MyScan", "Failed to save PDF", e)
             Toast.makeText(context, "Failed to save PDF", Toast.LENGTH_SHORT).show()
+        } finally {
+            document.close()
         }
     }
 

app/src/main/java/org/mydomain/myscan/PdfGeneration.kt

@@ -3,37 +3,24 @@ package org.mydomain.myscan
 import android.graphics.Bitmap
 import android.graphics.BitmapFactory
 import android.graphics.pdf.PdfDocument
-import android.util.Log
 import androidx.core.graphics.scale
 import java.io.ByteArrayOutputStream
-import java.io.File
-import java.io.FileOutputStream
-import java.io.IOException
 import kotlin.math.max
 
-fun createPdfFromBitmaps(bitmaps: List<Bitmap>, outputFile: File): Boolean {
+fun createPdfFromBitmaps (bitmaps: List<Bitmap>): PdfDocument {
     val document = PdfDocument()
-    try {
-        for ((index, bitmap) in bitmaps.map { resizeImage(it) }.withIndex()) {
-            val jpegStream = ByteArrayOutputStream()
-            bitmap.compress(Bitmap.CompressFormat.JPEG, 72, jpegStream)
-            val compressedBytes = jpegStream.toByteArray()
-            val compressedBitmap = BitmapFactory.decodeByteArray(compressedBytes, 0, compressedBytes.size)
-            val pageInfo = PdfDocument.PageInfo.Builder(bitmap.width, bitmap.height, index + 1).create()
-            val page = document.startPage(pageInfo)
-            page.canvas.drawBitmap(compressedBitmap, 0f, 0f, null)
-            document.finishPage(page)
-        }
-        FileOutputStream(outputFile).use { outputStream ->
-            document.writeTo(outputStream)
-        }
-        return true
-    } catch (e: IOException) {
-        Log.e("MyScan", "Error writing PDF: ${e.message}")
-        return false
-    } finally {
-        document.close()
+    for ((index, bitmap) in bitmaps.map { resizeImage(it) }.withIndex()) {
+        val jpegStream = ByteArrayOutputStream()
+        bitmap.compress(Bitmap.CompressFormat.JPEG, 72, jpegStream)
+        val compressedBytes = jpegStream.toByteArray()
+        val compressedBitmap =
+            BitmapFactory.decodeByteArray(compressedBytes, 0, compressedBytes.size)
+        val pageInfo = PdfDocument.PageInfo.Builder(bitmap.width, bitmap.height, index + 1).create()
+        val page = document.startPage(pageInfo)
+        page.canvas.drawBitmap(compressedBitmap, 0f, 0f, null)
+        document.finishPage(page)
     }
+    return document
 }
 
 fun resizeImage(original: Bitmap): Bitmap {

app/src/main/java/org/mydomain/myscan/view/PagePreview.kt

@@ -3,8 +3,11 @@ package org.mydomain.myscan.view
 import android.graphics.Bitmap
 import androidx.compose.foundation.Image
 import androidx.compose.foundation.layout.Box
+import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.automirrored.filled.ArrowBack
 import androidx.compose.material3.Button
@@ -25,6 +28,7 @@ fun PagePreviewScreen(
     isProcessing: Boolean,
     onBackPressed: () -> Unit,
     onSavePressed: (Bitmap) -> Unit,
+    onSharePressed: (Bitmap) -> Unit,
 ) {
     Box(modifier = Modifier.fillMaxSize()) {
         when {
@@ -41,13 +45,18 @@ fun PagePreviewScreen(
                     modifier = Modifier.fillMaxSize(),
                     contentScale = ContentScale.Fit
                 )
-                Button (
-                    onClick = { onSavePressed(image) },
+                Row(
                     modifier = Modifier
                         .align(Alignment.BottomCenter)
                         .padding(16.dp)
                 ) {
-                    Text("Save as PDF")
+                    Button (onClick = { onSavePressed(image) }) {
+                        Text("Save PDF")
+                    }
+                    Spacer(modifier = Modifier.width(8.dp))
+                    Button (onClick = { onSharePressed(image) }) {
+                        Text("Share PDF")
+                    }
                 }
             }
             else -> {