Support the Imagen image generation model from Google Cloud Vertex AI (…

…langchain4j#456)

langchain4j-core/src/main/java/dev/langchain4j/internal/ValidationUtils.java

@@ -128,4 +128,19 @@ public static int ensureBetween(Integer i, int min, int max, String name) {
         }
         return i;
     }
+    /**
+     * Ensures that the given Long value is in {@code [min, max]}.
+     * @param i The value to check.
+     * @param min The minimum value.
+     * @param max The maximum value.
+     * @param name The value name to be used in the exception.
+     * @return The value if it is in {@code [min, max]}.
+     * @throws IllegalArgumentException if the value is not in {@code [min, max]}.
+     */
+    public static long ensureBetween(Long i, long min, long max, String name) {
+        if (i == null || i < min || i > max) {
+            throw illegalArgument("%s must be between %s and %s, but is: %s", name, min, max, i);
+        }
+        return i;
+    }
 }

langchain4j-core/src/main/java/dev/langchain4j/model/image/ImageModel.java

@@ -29,4 +29,28 @@ public interface ImageModel {
     default Response<List<Image>> generate(String prompt, int n) {
         throw new IllegalArgumentException("Operation is not supported");
     }
+
+    /**
+     * Given an existing image, edit this image following the given prompt.
+     *
+     * @param image  The image to be edited.
+     * @param prompt The prompt to edit the image.
+     * @return The generated image Response.
+     */
+    default Response<Image> edit(Image image, String prompt) {
+        throw new IllegalArgumentException("Operation is not supported");
+    }
+
+    /**
+     * Given an existing image, edit this image following the given prompt and
+     * apply the changes only to the part of the image specified by the given mask.
+     *
+     * @param image  The image to be edited.
+     * @param mask   The image mask to apply to delimit the area to edit.
+     * @param prompt The prompt to edit the image.
+     * @return The generated image Response.
+     */
+    default Response<Image> edit(Image image, Image mask, String prompt) {
+        throw new IllegalArgumentException("Operation is not supported");
+    }
 }

langchain4j-core/src/test/java/dev/langchain4j/model/image/ImageModelTest.java

@@ -39,6 +39,14 @@ public void test_not_supported() {
         assertThatThrownBy(() -> model.generate("prompt", 1))
                 .isInstanceOf(IllegalArgumentException.class)
                 .hasMessage("Operation is not supported");
+
+        assertThatThrownBy(() -> model.edit(null, "prompt"))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessage("Operation is not supported");
+
+        assertThatThrownBy(() -> model.edit(null, null, "prompt"))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessage("Operation is not supported");
     }
 
     @Test