Add Save option to the image view screen

app/src/main/AndroidManifest.xml

@@ -5,6 +5,9 @@
     <uses-permission android:name="android.permission.INTERNET"/>
     <uses-permission android:name="android.permission.READ_MEDIA_IMAGES"/>
     <uses-permission android:name="android.permission.CAMERA" />
+    <!-- Used for SDK < 29 -->
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"
+        tools:ignore="ScopedStorage" />
 
     <application
         android:allowBackup="false"

app/src/main/java/com/vitorpamplona/amethyst/ui/actions/ImageSaver.kt

@@ -0,0 +1,147 @@
+package com.vitorpamplona.amethyst.ui.actions
+
+import android.content.ContentResolver
+import android.content.ContentValues
+import android.content.Context
+import android.content.Intent
+import android.os.Build
+import android.os.Environment
+import android.provider.MediaStore
+import androidx.annotation.RequiresApi
+import androidx.core.net.toUri
+import okhttp3.*
+import okio.BufferedSource
+import okio.IOException
+import okio.sink
+import java.io.File
+
+
+object ImageSaver {
+    /**
+     * Saves the image to the gallery.
+     * May require a storage permission.
+     *
+     * @see PICTURES_SUBDIRECTORY
+     */
+    fun saveImage(
+        url: String,
+        context: Context,
+        onSuccess: () -> Any?,
+        onError: (Throwable) -> Any?,
+    ) {
+        val client = OkHttpClient.Builder().build()
+
+        val request = Request.Builder()
+            .get()
+            .url(url)
+            .build()
+
+        client.newCall(request).enqueue(object : Callback {
+            override fun onFailure(call: Call, e: IOException) {
+                e.printStackTrace()
+                onError(e)
+            }
+
+            override fun onResponse(call: Call, response: Response) {
+                try {
+                    check(response.isSuccessful)
+
+                    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q) {
+                        val contentType = response.header("Content-Type")
+                        checkNotNull(contentType) {
+                            "Can't find out the content type"
+                        }
+
+                        saveContentQ(
+                            displayName = File(url).nameWithoutExtension,
+                            contentType = contentType,
+                            contentSource = response.body.source(),
+                            contentResolver = context.contentResolver,
+                        )
+                    } else {
+                        saveContentDefault(
+                            fileName = File(url).name,
+                            contentSource = response.body.source(),
+                            context = context,
+                        )
+                    }
+                    onSuccess()
+                } catch (e: Exception) {
+                    e.printStackTrace()
+                    onError(e)
+                }
+            }
+        })
+    }
+
+    @RequiresApi(Build.VERSION_CODES.Q)
+    private fun saveContentQ(
+        displayName: String,
+        contentType: String,
+        contentSource: BufferedSource,
+        contentResolver: ContentResolver,
+    ) {
+        val contentValues = ContentValues().apply {
+            put(MediaStore.MediaColumns.DISPLAY_NAME, displayName)
+            put(MediaStore.MediaColumns.MIME_TYPE, contentType)
+            put(
+                MediaStore.MediaColumns.RELATIVE_PATH,
+                Environment.DIRECTORY_PICTURES + File.separatorChar + PICTURES_SUBDIRECTORY
+            )
+        }
+
+        val uri =
+            contentResolver.insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, contentValues)
+        checkNotNull(uri) {
+            "Can't insert the new content"
+        }
+
+        try {
+            val outputStream = contentResolver.openOutputStream(uri)
+            checkNotNull(outputStream) {
+                "Can't open the content output stream"
+            }
+
+            outputStream.use {
+                contentSource.readAll(it.sink())
+            }
+        } catch (e: Exception) {
+            contentResolver.delete(uri, null, null)
+            throw e
+        }
+    }
+
+    private fun saveContentDefault(
+        fileName: String,
+        contentSource: BufferedSource,
+        context: Context,
+    ) {
+        val subdirectory = File(
+            Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES),
+            PICTURES_SUBDIRECTORY
+        )
+
+        if (!subdirectory.exists()) {
+            subdirectory.mkdirs()
+        }
+
+        val outputFile = File(subdirectory, fileName)
+
+        outputFile
+            .outputStream()
+            .use {
+                contentSource.readAll(it.sink())
+            }
+
+        // Call the media scanner manually, so the image
+        // appears in the gallery faster.
+        context.sendBroadcast(
+            Intent(
+                Intent.ACTION_MEDIA_SCANNER_SCAN_FILE,
+                outputFile.toUri()
+            )
+        )
+    }
+
+    private const val PICTURES_SUBDIRECTORY = "Amethyst"
+}

app/src/main/java/com/vitorpamplona/amethyst/ui/actions/SaveToGallery.kt

@@ -0,0 +1,83 @@
+package com.vitorpamplona.amethyst.ui.actions
+
+import android.Manifest
+import android.os.Build
+import android.widget.Toast
+import androidx.compose.foundation.shape.RoundedCornerShape
+import androidx.compose.material.Button
+import androidx.compose.material.ButtonDefaults
+import androidx.compose.material.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.rememberCoroutineScope
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.platform.LocalContext
+import androidx.compose.ui.unit.dp
+import com.google.accompanist.permissions.ExperimentalPermissionsApi
+import com.google.accompanist.permissions.isGranted
+import com.google.accompanist.permissions.rememberPermissionState
+import kotlinx.coroutines.launch
+
+/**
+ * A button to save the remote image to the gallery.
+ * May require a storage permission.
+ *
+ * @param url URL of the image
+ */
+@OptIn(ExperimentalPermissionsApi::class)
+@Composable
+fun SaveToGallery(url: String) {
+    val localContext = LocalContext.current
+    val scope = rememberCoroutineScope()
+
+    fun saveImage() {
+        ImageSaver.saveImage(
+            context = localContext,
+            url = url,
+            onSuccess = {
+                scope.launch {
+                    Toast.makeText(
+                        localContext,
+                        "Image saved to the gallery",
+                        Toast.LENGTH_SHORT
+                    )
+                        .show()
+                }
+            },
+            onError = {
+                scope.launch {
+                    Toast.makeText(
+                        localContext,
+                        "Failed to save the image",
+                        Toast.LENGTH_SHORT
+                    )
+                        .show()
+                }
+            }
+        )
+    }
+
+    val writeStoragePermissionState = rememberPermissionState(
+        Manifest.permission.WRITE_EXTERNAL_STORAGE
+    ) { isGranted ->
+        if (isGranted) {
+            saveImage()
+        }
+    }
+
+    Button(
+        onClick = {
+            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.Q || writeStoragePermissionState.status.isGranted) {
+                saveImage()
+            } else {
+                writeStoragePermissionState.launchPermissionRequest()
+            }
+        },
+        shape = RoundedCornerShape(20.dp),
+        colors = ButtonDefaults
+            .buttonColors(
+                backgroundColor = Color.Gray
+            )
+    ) {
+        Text(text = "Save", color = Color.White)
+    }
+}

app/src/main/java/com/vitorpamplona/amethyst/ui/components/ZoomableImageView.kt

@@ -2,35 +2,26 @@ package com.vitorpamplona.amethyst.ui.components
 
 import androidx.compose.foundation.ExperimentalFoundationApi
 import androidx.compose.foundation.border
-import androidx.compose.foundation.clickable
 import androidx.compose.foundation.combinedClickable
-import androidx.compose.foundation.layout.Arrangement
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.fillMaxSize
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.shape.RoundedCornerShape
 import androidx.compose.material.MaterialTheme
 import androidx.compose.material.Surface
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
-import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
+import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.ExperimentalComposeUiApi
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
 import androidx.compose.ui.layout.ContentScale
 import androidx.compose.ui.platform.LocalClipboardManager
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.text.AnnotatedString
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.window.Dialog
 import androidx.compose.ui.window.DialogProperties
 import coil.compose.AsyncImage
 import com.vitorpamplona.amethyst.ui.actions.CloseButton
-import nostr.postr.toNpub
+import com.vitorpamplona.amethyst.ui.actions.SaveToGallery
 
 @Composable
 @OptIn(ExperimentalComposeUiApi::class, ExperimentalFoundationApi::class)
@@ -75,6 +66,8 @@ fun ZoomableImageView(word: String) {
             CloseButton(onCancel = {
               dialogOpen = false
             })
+
+            SaveToGallery(url = word)
           }
 
           ZoomableAsyncImage(word)