Support for manual CLIP loading in StableDiffusionPipeline - txt2img. (#3832)

* Support for manual CLIP loading in StableDiffusionPipeline - txt2img.

* Update src/diffusers/pipelines/stable_diffusion/convert_from_ckpt.py

* Update variables & according docs to match previous style.

* Updated to match style & quality of 'diffusers'

---------
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

src/diffusers/loaders.py

@@ -1339,6 +1339,17 @@ class FromCkptMixin:
                 "ddim"]`.
             load_safety_checker (`bool`, *optional*, defaults to `True`):
                 Whether to load the safety checker or not.
+            text_encoder (`CLIPTextModel`, *optional*, defaults to `None`):
+                An instance of
+                [CLIP](https://huggingface.co/docs/transformers/model_doc/clip#transformers.CLIPTextModel) to use,
+                specifically the [clip-vit-large-patch14](https://huggingface.co/openai/clip-vit-large-patch14)
+                variant. If this parameter is `None`, the function will load a new instance of [CLIP] by itself, if
+                needed.
+            tokenizer (`CLIPTokenizer`, *optional*, defaults to `None`):
+                An instance of
+                [CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer)
+                to use. If this parameter is `None`, the function will load a new instance of [CLIPTokenizer] by
+                itself, if needed.
             kwargs (remaining dictionary of keyword arguments, *optional*):
                 Can be used to overwrite load and saveable variables (for example the pipeline components of the
                 specific pipeline class). The overwritten components are directly passed to the pipelines `__init__`
@@ -1383,6 +1394,8 @@ class FromCkptMixin:
         upcast_attention = kwargs.pop("upcast_attention", None)
         load_safety_checker = kwargs.pop("load_safety_checker", True)
         prediction_type = kwargs.pop("prediction_type", None)
+        text_encoder = kwargs.pop("text_encoder", None)
+        tokenizer = kwargs.pop("tokenizer", None)
 
         torch_dtype = kwargs.pop("torch_dtype", None)
 
@@ -1463,6 +1476,8 @@ class FromCkptMixin:
             upcast_attention=upcast_attention,
             load_safety_checker=load_safety_checker,
             prediction_type=prediction_type,
+            text_encoder=text_encoder,
+            tokenizer=tokenizer,
         )
 
         if torch_dtype is not None:

src/diffusers/pipelines/stable_diffusion/convert_from_ckpt.py

@@ -734,8 +734,12 @@ def convert_ldm_bert_checkpoint(checkpoint, config):
     return hf_model
 
 
-def convert_ldm_clip_checkpoint(checkpoint, local_files_only=False):
-    text_model = CLIPTextModel.from_pretrained("openai/clip-vit-large-patch14", local_files_only=local_files_only)
+def convert_ldm_clip_checkpoint(checkpoint, local_files_only=False, text_encoder=None):
+    text_model = (
+        CLIPTextModel.from_pretrained("openai/clip-vit-large-patch14", local_files_only=local_files_only)
+        if text_encoder is None
+        else text_encoder
+    )
 
     keys = list(checkpoint.keys())
 
@@ -1025,6 +1029,8 @@ def download_from_original_stable_diffusion_ckpt(
     load_safety_checker: bool = True,
     pipeline_class: DiffusionPipeline = None,
     local_files_only=False,
+    text_encoder=None,
+    tokenizer=None,
 ) -> DiffusionPipeline:
     """
     Load a Stable Diffusion pipeline object from a CompVis-style `.ckpt`/`.safetensors` file and (ideally) a `.yaml`
@@ -1072,6 +1078,15 @@ def download_from_original_stable_diffusion_ckpt(
             The pipeline class to use. Pass `None` to determine automatically.
         local_files_only (`bool`, *optional*, defaults to `False`):
             Whether or not to only look at local files (i.e., do not try to download the model).
+        text_encoder (`CLIPTextModel`, *optional*, defaults to `None`):
+            An instance of [CLIP](https://huggingface.co/docs/transformers/model_doc/clip#transformers.CLIPTextModel)
+            to use, specifically the [clip-vit-large-patch14](https://huggingface.co/openai/clip-vit-large-patch14)
+            variant. If this parameter is `None`, the function will load a new instance of [CLIP] by itself, if needed.
+        tokenizer (`CLIPTokenizer`, *optional*, defaults to `None`):
+            An instance of
+            [CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer)
+            to use. If this parameter is `None`, the function will load a new instance of [CLIPTokenizer] by itself, if
+            needed.
         return: A StableDiffusionPipeline object representing the passed-in `.ckpt`/`.safetensors` file.
     """
 
@@ -1327,8 +1342,10 @@ def download_from_original_stable_diffusion_ckpt(
             feature_extractor=feature_extractor,
         )
     elif model_type == "FrozenCLIPEmbedder":
-        text_model = convert_ldm_clip_checkpoint(checkpoint, local_files_only=local_files_only)
-        tokenizer = CLIPTokenizer.from_pretrained("openai/clip-vit-large-patch14")
+        text_model = convert_ldm_clip_checkpoint(
+            checkpoint, local_files_only=local_files_only, text_encoder=text_encoder
+        )
+        tokenizer = CLIPTokenizer.from_pretrained("openai/clip-vit-large-patch14") if tokenizer is None else tokenizer
 
         if load_safety_checker:
             safety_checker = StableDiffusionSafetyChecker.from_pretrained("CompVis/stable-diffusion-safety-checker")