feat(genai): add image generation samples (2) (#3282)

Add new image generation samples

- Edit image with text input and image input.
- Generate image and text content with text input.

**All local tests have passed**

---------

Co-authored-by: Juan Dominguez <jdomin@softserveinc.com>

Author: jdomingr

genai/api/GenAI.Samples.Tests/ImageGeneration/ImageGenMultimodalFlashEditImgWithTxtImgTest.cs

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.IO;
+using System.Threading.Tasks;
+using Xunit;
+
+[Collection(nameof(GenAIFixture))]
+public class ImageGenMultimodalFlashEditImgWithTxtImgTest
+{
+    private readonly GenAIFixture _fixture;
+    private readonly ImageGenMultimodalFlashEditImgWithTxtImg _sample;
+
+    public ImageGenMultimodalFlashEditImgWithTxtImgTest(GenAIFixture fixture)
+    {
+        _fixture = fixture;
+        _sample = new ImageGenMultimodalFlashEditImgWithTxtImg();
+    }
+
+    [Fact]
+    public async Task TestImageGenMultimodalFlashEditImgWithTxtImg()
+    {
+        string imageFilePath = Path.GetFullPath("../../../Resources/example-image-eiffel-tower.png");
+        FileInfo response = await _sample.GenerateContent(projectId: _fixture.ProjectId, localImageFilePath: imageFilePath);
+        Assert.NotNull(response);
+        Assert.True(response.Length > 0);
+    }
+}

genai/api/GenAI.Samples.Tests/ImageGeneration/ImageGenMultimodalMmFlashTxtAndImgWithTxtTest.cs

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+using System.IO;
+using System.Threading.Tasks;
+using Xunit;
+
+[Collection(nameof(GenAIFixture))]
+public class ImageGenMultimodalMmFlashTxtAndImgWithTxtTest
+{
+    private readonly GenAIFixture _fixture;
+    private readonly ImageGenMultimodalFlashTxtAndImgWithTxt _sample;
+
+    public ImageGenMultimodalMmFlashTxtAndImgWithTxtTest(GenAIFixture fixture)
+    {
+        _fixture = fixture;
+        _sample = new ImageGenMultimodalFlashTxtAndImgWithTxt();
+    }
+
+    [Fact]
+    public async Task TestImageGenMultimodalFlashTxtAndImgWithTxt()
+    {
+        FileInfo response = await _sample.GenerateContent(_fixture.ProjectId);
+        Assert.NotNull(response);
+        Assert.True(response.Length > 0);
+    }
+}

genai/api/GenAI.Samples.Tests/Resources/example-image-eiffel-tower.png

@@ -0,0 +1,78 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// [START googlegenaisdk_imggen_mmflash_edit_img_with_txt_img]
+
+using Google.GenAI;
+using Google.GenAI.Types;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+
+public class ImageGenMultimodalFlashEditImgWithTxtImg
+{
+    public async Task<FileInfo> GenerateContent(
+        string projectId = "your-project-id",
+        string location = "global",
+        string model = "gemini-2.5-flash-image",
+        string localImageFilePath = "path/to/local_image.png")
+    {
+        await using var client = new Client(project: projectId, location: location, vertexAI: true);
+
+        byte[] imageBytes = File.ReadAllBytes(localImageFilePath);
+
+        GenerateContentResponse response = await client.Models.GenerateContentAsync(
+            model: model,
+            contents: new List<Content>
+            {
+                new Content
+                {
+                    Role= "user",
+                    Parts = new List<Part>
+                    {
+                        new Part { InlineData = new Blob { Data = imageBytes, MimeType = "image/png" } },
+                        new Part { Text = "Edit this image to make it look like a cartoon."}
+                    }
+                }
+            },
+            config: new GenerateContentConfig { ResponseModalities = new List<string> { "TEXT", "IMAGE" } });
+
+        List<Part> parts = response.Candidates?[0]?.Content?.Parts ?? new List<Part>();
+
+        var outputFilename = "bw-example-image.png";
+
+        foreach (Part part in parts)
+        {
+            if (!string.IsNullOrEmpty(part.Text))
+            {
+                Console.WriteLine(part.Text);
+            }
+            else if (part.InlineData?.Data != null)
+            {
+                File.WriteAllBytes(outputFilename, part.InlineData.Data);
+            }
+        }
+
+        FileInfo fileInfo = new FileInfo(Path.GetFullPath(outputFilename));
+        Console.WriteLine($"Created output image using {fileInfo.Length} bytes");
+        // Example response:
+        // Here's the image cartoonized for you! 
+        // Created output image using 1628165 bytes
+        return fileInfo;
+    }
+}
+// [END googlegenaisdk_imggen_mmflash_edit_img_with_txt_img]

genai/api/GenAI.Samples/ImageGeneration/ImageGenMultimodalFlashEditImgWithTxtImg.cs

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+// [START googlegenaisdk_imggen_mmflash_txt_and_img_with_txt]
+
+using Google.GenAI;
+using Google.GenAI.Types;
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Threading.Tasks;
+
+public class ImageGenMultimodalFlashTxtAndImgWithTxt
+{
+    public async Task<FileInfo> GenerateContent(
+        string projectId = "your-project-id",
+        string location = "global",
+        string model = "gemini-2.5-flash-image")
+    {
+        await using var client = new Client(project: projectId, location: location, vertexAI: true);
+
+        GenerateContentResponse response = await client.Models.GenerateContentAsync(
+            model: model,
+            contents: new List<Content>
+            {
+                new Content
+                {
+                    Role= "user",
+                    Parts = new List<Part>
+                    {
+                        new Part { Text = "Generate an illustrated recipe for a paella." },
+                        new Part { Text = "Create images to go alongside the text as you generate the recipe."}
+                    }
+                }
+            },
+            config: new GenerateContentConfig { ResponseModalities = new List<string> { "TEXT", "IMAGE" } });
+
+        List<Part> parts = response.Candidates?[0]?.Content?.Parts ?? new List<Part>();
+
+        using (StreamWriter writer = new StreamWriter("paella-recipe.md"))
+        {
+            int imageCounter = 1;
+            foreach (Part part in parts)
+            {
+                if (!string.IsNullOrEmpty(part.Text))
+                {
+                    writer.WriteLine(part.Text);
+                }
+                else if (part.InlineData?.Data != null)
+                {
+                    string filename = $"example-image-{imageCounter}.png";
+                    File.WriteAllBytes(filename, part.InlineData.Data);
+                    writer.WriteLine($"\n![image]({filename})\n");
+                    imageCounter++;
+                }
+            }
+        }
+
+        FileInfo fileInfo = new FileInfo(Path.GetFullPath("paella-recipe.md"));
+        Console.WriteLine($"Created output image using {fileInfo.Length} bytes");
+        // Example response:
+        // Created output image using 2329 bytes
+        return fileInfo;
+    }
+}
+// [END googlegenaisdk_imggen_mmflash_txt_and_img_with_txt]