[refactor] refactor after review

src/diffusers/pipelines/flux/pipeline_flux_fill.py

@@ -225,9 +225,10 @@ def __init__(
         # Flux latents are turned into 2x2 patches and packed. This means the latent width and height has to be divisible
         # by the patch size. So the vae scale factor is multiplied by the patch size to account for this
         self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor * 2)
+        latent_channels = self.vae.config.latent_channels if getattr(self, "vae", None) else 16
         self.mask_processor = VaeImageProcessor(
             vae_scale_factor=self.vae_scale_factor * 2,
-            vae_latent_channels=self.vae.config.latent_channels,
+            vae_latent_channels=latent_channels,
             do_normalize=False,
             do_binarize=True,
             do_convert_grayscale=True,
@@ -656,7 +657,7 @@ def disable_vae_tiling(self):
         """
         self.vae.disable_tiling()
 
-    # Copied from diffusers.pipelines.flux.pipeline_flux.FluxPipeline.prepare_latents
+    # Copied from diffusers.pipelines.flux.pipeline_flux.FluxImg2ImgPipeline.prepare_latents
     def prepare_latents(
         self,
         image,
@@ -670,20 +671,24 @@ def prepare_latents(
         generator,
         latents=None,
     ):
+        if isinstance(generator, list) and len(generator) != batch_size:
+            raise ValueError(
+                f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
+                f" size of {batch_size}. Make sure the batch size matches the length of the generators."
+            )
+
         # VAE applies 8x compression on images but we must also account for packing which requires
         # latent height and width to be divisible by 2.
         height = 2 * (int(height) // (self.vae_scale_factor * 2))
         width = 2 * (int(width) // (self.vae_scale_factor * 2))
-
         shape = (batch_size, num_channels_latents, height, width)
+        latent_image_ids = self._prepare_latent_image_ids(batch_size, height // 2, width // 2, device, dtype)
+
+        if latents is not None:
+            return latents.to(device=device, dtype=dtype), latent_image_ids
 
-        # if latents is not None:
         image = image.to(device=device, dtype=dtype)
         image_latents = self._encode_vae_image(image=image, generator=generator)
-
-        latent_image_ids = self._prepare_latent_image_ids(
-            batch_size, height // 2, width // 2, device, dtype
-        )
         if batch_size > image_latents.shape[0] and batch_size % image_latents.shape[0] == 0:
             # expand init_latents for batch_size
             additional_image_per_prompt = batch_size // image_latents.shape[0]
@@ -695,19 +700,10 @@ def prepare_latents(
         else:
             image_latents = torch.cat([image_latents], dim=0)
 
-        if latents is None:
-            noise = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
-            latents = self.scheduler.scale_noise(image_latents, timestep, noise)
-        else:
-            noise = latents.to(device)
-            latents = noise
-
-        noise = self._pack_latents(noise, batch_size, num_channels_latents, height, width)
-        image_latents = self._pack_latents(
-            image_latents, batch_size, num_channels_latents, height, width
-        )
+        noise = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
+        latents = self.scheduler.scale_noise(image_latents, timestep, noise)
         latents = self._pack_latents(latents, batch_size, num_channels_latents, height, width)
-        return latents, noise, image_latents, latent_image_ids
+        return latents, latent_image_ids
 
     @property
     def guidance_scale(self):
@@ -866,7 +862,6 @@ def __call__(
         self._joint_attention_kwargs = joint_attention_kwargs
         self._interrupt = False
 
-        original_image = image
         init_image = self.image_processor.preprocess(image, height=height, width=width)
         init_image = init_image.to(dtype=torch.float32)
 
@@ -935,7 +930,7 @@ def __call__(
 
         # 5. Prepare latent variables
         num_channels_latents = self.vae.config.latent_channels
-        latents, noise, image_latents, latent_image_ids = self.prepare_latents(
+        latents, latent_image_ids = self.prepare_latents(
             init_image,
             latent_timestep,
             batch_size * num_images_per_prompt,