fixes for comments, plus adding subject references and style customization

Author: David Motsonashvili

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/FirebaseAISamples.kt

@@ -1,6 +1,9 @@
 package com.google.firebase.quickstart.ai
 
+import android.content.Context
+import android.content.res.Resources
 import android.graphics.Bitmap
+import android.graphics.BitmapFactory
 import com.google.firebase.ai.ImagenModel
 import com.google.firebase.ai.type.Dimensions
 import com.google.firebase.ai.type.FunctionDeclaration
@@ -10,6 +13,9 @@ import com.google.firebase.ai.type.ImagenEditMode
 import com.google.firebase.ai.type.ImagenEditingConfig
 import com.google.firebase.ai.type.ImagenMaskReference
 import com.google.firebase.ai.type.ImagenRawImage
+import com.google.firebase.ai.type.ImagenStyleReference
+import com.google.firebase.ai.type.ImagenSubjectReference
+import com.google.firebase.ai.type.ImagenSubjectReferenceType
 import com.google.firebase.ai.type.PublicPreviewAPI
 import com.google.firebase.ai.type.ResponseModality
 import com.google.firebase.ai.type.Schema
@@ -142,21 +148,24 @@ val FIREBASE_AI_SAMPLES = listOf(
             text(
                 "A photo of a modern building with water in the background"
             )
+        },
+        allowEmptyPrompt = false,
+        generateImages = { model: ImagenModel, inputText: String, _: Bitmap? ->
+            model.generateImages(
+                inputText
+            )
         }
     ),
     Sample(
         title = "Imagen 3 - Inpainting",
         description = "Replace the background of an image using Imagen 3",
-        modelName= "imagen-3.0-capability-001",
+        modelName = "imagen-3.0-capability-001",
         backend = GenerativeBackend.vertexAI(),
         navRoute = "imagen",
         categories = listOf(Category.IMAGE),
-        initialPrompt = content {
-            text(
-                "A sunny beach"
-            )
-        },
+        initialPrompt = content { text("A sunny beach") },
         includeAttach = true,
+        allowEmptyPrompt = true,
         generateImages = { model: ImagenModel, inputText: String, bitmap: Bitmap? ->
             model.editImage(
                 listOf(ImagenRawImage(bitmap!!.toImagenInlineImage()), ImagenBackgroundMask()),
@@ -168,16 +177,13 @@ val FIREBASE_AI_SAMPLES = listOf(
     Sample(
         title = "Imagen 3 - Outpainting",
         description = "Expand an image by drawing in more background",
-        modelName= "imagen-3.0-capability-001",
+        modelName = "imagen-3.0-capability-001",
         backend = GenerativeBackend.vertexAI(),
         navRoute = "imagen",
         categories = listOf(Category.IMAGE),
-        initialPrompt = content {
-            text(
-                ""
-            )
-        },
+        initialPrompt = content { text("") },
         includeAttach = true,
+        allowEmptyPrompt = true,
         generateImages = { model: ImagenModel, inputText: String, bitmap: Bitmap? ->
             val dimensions = Dimensions(bitmap!!.width * 2, bitmap.height * 2)
             model.editImage(
@@ -187,6 +193,50 @@ val FIREBASE_AI_SAMPLES = listOf(
             )
         }
     ),
+    Sample(
+        title = "Imagen 3 - Subject Reference",
+        description = "generate an image using a referenced subject (must be an animal)",
+        modelName = "imagen-3.0-capability-001",
+        backend = GenerativeBackend.vertexAI(),
+        navRoute = "imagen",
+        categories = listOf(Category.IMAGE),
+        initialPrompt = content { text("<subject> flying through space") },
+        includeAttach = true,
+        allowEmptyPrompt = false,
+        generateImages = { model: ImagenModel, inputText: String, bitmap: Bitmap? ->
+            model.editImage(
+                listOf(
+                    ImagenSubjectReference(
+                        referenceId = 1,
+                        image = bitmap!!.toImagenInlineImage(),
+                        subjectType = ImagenSubjectReferenceType.ANIMAL,
+                        description = "An animal"
+                    )
+                ),
+                "Create an image about An animal [1] to match the description: " +
+                        inputText.replace("<subject>", "An animal [1]"),
+            )
+        }
+    ),
+    Sample(
+        title = "Imagen 3 - Style Transfer",
+        description = "Change the art style of an cat picture using a reference",
+        modelName = "imagen-3.0-capability-001",
+        backend = GenerativeBackend.vertexAI(),
+        navRoute = "imagen",
+        categories = listOf(Category.IMAGE),
+        initialPrompt = content { text("A picture of a cat") },
+        includeAttach = true,
+        allowEmptyPrompt = true,
+        generateImages = { model: ImagenModel, inputText: String, bitmap: Bitmap? ->
+            model.editImage(
+                listOf(
+                    ImagenRawImage(MainActivity.catImage.toImagenInlineImage()),
+                    ImagenStyleReference(bitmap!!.toImagenInlineImage(), 1, "an art style")),
+                "Generate an image in an art style [1] based on the following caption: $inputText",
+            )
+        }
+    ),
     Sample(
         title = "Gemini 2.0 Flash - image generation",
         description = "Generate and/or edit images using Gemini 2.0 Flash",

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/MainActivity.kt

@@ -1,5 +1,7 @@
 package com.google.firebase.quickstart.ai
 
+import android.graphics.Bitmap
+import android.graphics.BitmapFactory
 import android.os.Bundle
 import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
@@ -22,6 +24,7 @@ import androidx.navigation.NavDestination
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
 import androidx.navigation.compose.rememberNavController
+import com.google.firebase.ai.type.toImagenInlineImage
 import com.google.firebase.quickstart.ai.feature.live.StreamRealtimeRoute
 import com.google.firebase.quickstart.ai.feature.live.StreamRealtimeScreen
 import com.google.firebase.quickstart.ai.feature.media.imagen.ImagenRoute
@@ -36,6 +39,7 @@ class MainActivity : ComponentActivity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         enableEdgeToEdge()
+        catImage = BitmapFactory.decodeResource(applicationContext.resources, R.drawable.cat)
         setContent {
             val navController = rememberNavController()
 
@@ -86,7 +90,7 @@ class MainActivity : ComponentActivity() {
                         composable<ChatRoute> {
                             ChatScreen()
                         }
-                        // Imagn Samples
+                        // Imagen Samples
                         composable<ImagenRoute> {
                             ImagenScreen()
                         }
@@ -110,4 +114,7 @@ class MainActivity : ComponentActivity() {
             })
         }
     }
+    companion object{
+        lateinit var catImage: Bitmap
+    }
 }

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/feature/media/imagen/ImagenScreen.kt

@@ -47,6 +47,7 @@ fun ImagenScreen(
     val isLoading by imagenViewModel.isLoading.collectAsStateWithLifecycle()
     val generatedImages by imagenViewModel.generatedBitmaps.collectAsStateWithLifecycle()
     val includeAttach by imagenViewModel.includeAttach.collectAsStateWithLifecycle()
+    val allowEmptyPrompt by imagenViewModel.allowEmptyPrompt.collectAsStateWithLifecycle()
     val context = LocalContext.current
     val contentResolver = context.contentResolver
     val openDocument = rememberLauncherForActivityResult(ActivityResultContracts.OpenDocument()) { optionalUri: Uri? ->
@@ -65,7 +66,7 @@ fun ImagenScreen(
 
             contentResolver.openInputStream(uri)?.use { stream ->
                 val bytes = stream.readBytes()
-                imagenViewModel.attachImage(bytes, fileName)
+                imagenViewModel.attachImage(bytes)
             }
         }
     }
@@ -96,13 +97,13 @@ fun ImagenScreen(
                     modifier = Modifier
                         .padding(end = 16.dp, bottom = 16.dp)
                         .align(Alignment.End)
-
-
                 ) { Text("Attach") }
             }
             TextButton(
                 onClick = {
-                    imagenViewModel.generateImages(imagenPrompt)
+                    if (allowEmptyPrompt || imagenPrompt.isNotBlank()) {
+                        imagenViewModel.generateImages(imagenPrompt)
+                    }
                 },
                 modifier = Modifier
                     .padding(end = 16.dp, bottom = 16.dp)

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/feature/media/imagen/ImagenViewModel.kt

@@ -41,6 +41,9 @@ class ImagenViewModel(
     private val _includeAttach = MutableStateFlow(sample.includeAttach)
     val includeAttach: StateFlow<Boolean> = _includeAttach
 
+    private val _allowEmptyPrompt = MutableStateFlow(sample.allowEmptyPrompt)
+    val allowEmptyPrompt: StateFlow<Boolean> = _allowEmptyPrompt
+
     private val _generatedBitmaps = MutableStateFlow(listOf<Bitmap>())
     val generatedBitmaps: StateFlow<List<Bitmap>> = _generatedBitmaps
 
@@ -71,14 +74,7 @@ class ImagenViewModel(
         viewModelScope.launch {
             _isLoading.value = true
             try {
-                val generateImages = sample.generateImages
-                val imageResponse = if (generateImages == null) {
-                    imagenModel.generateImages(
-                        inputText
-                    )
-                } else {
-                    generateImages(imagenModel, inputText, attachedImage)
-                }
+                val imageResponse = sample.generateImages!!(imagenModel, inputText, attachedImage)
                 _generatedBitmaps.value = imageResponse.images.map { it.asBitmap() }
                 _errorMessage.value = null // clear error message
             } catch (e: Exception) {
@@ -91,7 +87,6 @@ class ImagenViewModel(
 
     fun attachImage(
         fileInBytes: ByteArray,
-        fileName: String? = "Unnamed file"
     ) {
         attachedImage = BitmapFactory.decodeByteArray(fileInBytes, 0, fileInBytes.size)
     }

firebase-ai/app/src/main/java/com/google/firebase/quickstart/ai/ui/navigation/Sample.kt

@@ -1,5 +1,6 @@
 package com.google.firebase.quickstart.ai.ui.navigation
 
+import android.content.Context
 import android.graphics.Bitmap
 import com.google.firebase.ai.ImagenModel
 import com.google.firebase.ai.type.Content
@@ -38,5 +39,6 @@ data class Sample(
     val chatHistory: List<Content> = emptyList(),
     val tools: List<Tool>? = null,
     val includeAttach: Boolean = false,
+    val allowEmptyPrompt: Boolean = false,
     val generateImages: (suspend (ImagenModel, String, Bitmap?) -> ImagenGenerationResponse<ImagenInlineImage>)? = null
 )