Modular backend - add ControlNet (#6642)

## Summary

ControlNet code from #6577.

## Related Issues / Discussions

#6606

https://invokeai.notion.site/Modular-Stable-Diffusion-Backend-Design-Document-e8952daab5d5472faecdc4a72d377b0d

## QA Instructions

Run with and without set `USE_MODULAR_DENOISE` environment.

## Merge Plan

Merge #6641 firstly, to be able see output difference properly.
If you think that there should be some kind of tests - feel free to add.

## Checklist

- [x] _The PR has a short but descriptive title, suitable for a
changelog_
- [ ] _Tests added / updated (if applicable)_
- [ ] _Documentation added / updated (if applicable)_

invokeai/app/invocations/denoise_latents.py

@@ -58,6 +58,7 @@ from invokeai.backend.stable_diffusion.diffusion.conditioning_data import (
 from invokeai.backend.stable_diffusion.diffusion.custom_atttention import CustomAttnProcessor2_0
 from invokeai.backend.stable_diffusion.diffusion_backend import StableDiffusionBackend
 from invokeai.backend.stable_diffusion.extension_callback_type import ExtensionCallbackType
+from invokeai.backend.stable_diffusion.extensions.controlnet import ControlNetExt
 from invokeai.backend.stable_diffusion.extensions.freeu import FreeUExt
 from invokeai.backend.stable_diffusion.extensions.preview import PreviewExt
 from invokeai.backend.stable_diffusion.extensions.rescale_cfg import RescaleCFGExt
@@ -465,6 +466,38 @@ class DenoiseLatentsInvocation(BaseInvocation):
 
         return controlnet_data
 
+    @staticmethod
+    def parse_controlnet_field(
+        exit_stack: ExitStack,
+        context: InvocationContext,
+        control_input: ControlField | list[ControlField] | None,
+        ext_manager: ExtensionsManager,
+    ) -> None:
+        # Normalize control_input to a list.
+        control_list: list[ControlField]
+        if isinstance(control_input, ControlField):
+            control_list = [control_input]
+        elif isinstance(control_input, list):
+            control_list = control_input
+        elif control_input is None:
+            control_list = []
+        else:
+            raise ValueError(f"Unexpected control_input type: {type(control_input)}")
+
+        for control_info in control_list:
+            model = exit_stack.enter_context(context.models.load(control_info.control_model))
+            ext_manager.add_extension(
+                ControlNetExt(
+                    model=model,
+                    image=context.images.get_pil(control_info.image.image_name),
+                    weight=control_info.control_weight,
+                    begin_step_percent=control_info.begin_step_percent,
+                    end_step_percent=control_info.end_step_percent,
+                    control_mode=control_info.control_mode,
+                    resize_mode=control_info.resize_mode,
+                )
+            )
+
     def prep_ip_adapter_image_prompts(
         self,
         context: InvocationContext,
@@ -800,22 +833,30 @@ class DenoiseLatentsInvocation(BaseInvocation):
         if self.unet.freeu_config:
             ext_manager.add_extension(FreeUExt(self.unet.freeu_config))
 
-        # ext: t2i/ip adapter
-        ext_manager.run_callback(ExtensionCallbackType.SETUP, denoise_ctx)
+        # context for loading additional models
+        with ExitStack() as exit_stack:
+            # later should be smth like:
+            # for extension_field in self.extensions:
+            #    ext = extension_field.to_extension(exit_stack, context, ext_manager)
+            #    ext_manager.add_extension(ext)
+            self.parse_controlnet_field(exit_stack, context, self.control, ext_manager)
 
-        unet_info = context.models.load(self.unet.unet)
-        assert isinstance(unet_info.model, UNet2DConditionModel)
-        with (
-            unet_info.model_on_device() as (cached_weights, unet),
-            ModelPatcher.patch_unet_attention_processor(unet, denoise_ctx.inputs.attention_processor_cls),
-            # ext: controlnet
-            ext_manager.patch_extensions(unet),
-            # ext: freeu, seamless, ip adapter, lora
-            ext_manager.patch_unet(unet, cached_weights),
-        ):
-            sd_backend = StableDiffusionBackend(unet, scheduler)
-            denoise_ctx.unet = unet
-            result_latents = sd_backend.latents_from_embeddings(denoise_ctx, ext_manager)
+            # ext: t2i/ip adapter
+            ext_manager.run_callback(ExtensionCallbackType.SETUP, denoise_ctx)
+
+            unet_info = context.models.load(self.unet.unet)
+            assert isinstance(unet_info.model, UNet2DConditionModel)
+            with (
+                unet_info.model_on_device() as (cached_weights, unet),
+                ModelPatcher.patch_unet_attention_processor(unet, denoise_ctx.inputs.attention_processor_cls),
+                # ext: controlnet
+                ext_manager.patch_extensions(denoise_ctx),
+                # ext: freeu, seamless, ip adapter, lora
+                ext_manager.patch_unet(unet, cached_weights),
+            ):
+                sd_backend = StableDiffusionBackend(unet, scheduler)
+                denoise_ctx.unet = unet
+                result_latents = sd_backend.latents_from_embeddings(denoise_ctx, ext_manager)
 
         # https://discuss.huggingface.co/t/memory-usage-by-later-pipeline-stages/23699
         result_latents = result_latents.detach().to("cpu")

invokeai/backend/stable_diffusion/extensions/base.py

@@ -52,7 +52,7 @@ class ExtensionBase:
         return self._callbacks
 
     @contextmanager
-    def patch_extension(self, context: DenoiseContext):
+    def patch_extension(self, ctx: DenoiseContext):
         yield None
 
     @contextmanager

invokeai/backend/stable_diffusion/extensions/controlnet.py

@@ -0,0 +1,158 @@
+from __future__ import annotations
+
+import math
+from contextlib import contextmanager
+from typing import TYPE_CHECKING, List, Optional, Union
+
+import torch
+from PIL.Image import Image
+
+from invokeai.app.invocations.constants import LATENT_SCALE_FACTOR
+from invokeai.app.util.controlnet_utils import CONTROLNET_MODE_VALUES, CONTROLNET_RESIZE_VALUES, prepare_control_image
+from invokeai.backend.stable_diffusion.denoise_context import UNetKwargs
+from invokeai.backend.stable_diffusion.diffusion.conditioning_data import ConditioningMode
+from invokeai.backend.stable_diffusion.extension_callback_type import ExtensionCallbackType
+from invokeai.backend.stable_diffusion.extensions.base import ExtensionBase, callback
+
+if TYPE_CHECKING:
+    from invokeai.backend.stable_diffusion.denoise_context import DenoiseContext
+    from invokeai.backend.util.hotfixes import ControlNetModel
+
+
+class ControlNetExt(ExtensionBase):
+    def __init__(
+        self,
+        model: ControlNetModel,
+        image: Image,
+        weight: Union[float, List[float]],
+        begin_step_percent: float,
+        end_step_percent: float,
+        control_mode: CONTROLNET_MODE_VALUES,
+        resize_mode: CONTROLNET_RESIZE_VALUES,
+    ):
+        super().__init__()
+        self._model = model
+        self._image = image
+        self._weight = weight
+        self._begin_step_percent = begin_step_percent
+        self._end_step_percent = end_step_percent
+        self._control_mode = control_mode
+        self._resize_mode = resize_mode
+
+        self._image_tensor: Optional[torch.Tensor] = None
+
+    @contextmanager
+    def patch_extension(self, ctx: DenoiseContext):
+        original_processors = self._model.attn_processors
+        try:
+            self._model.set_attn_processor(ctx.inputs.attention_processor_cls())
+
+            yield None
+        finally:
+            self._model.set_attn_processor(original_processors)
+
+    @callback(ExtensionCallbackType.PRE_DENOISE_LOOP)
+    def resize_image(self, ctx: DenoiseContext):
+        _, _, latent_height, latent_width = ctx.latents.shape
+        image_height = latent_height * LATENT_SCALE_FACTOR
+        image_width = latent_width * LATENT_SCALE_FACTOR
+
+        self._image_tensor = prepare_control_image(
+            image=self._image,
+            do_classifier_free_guidance=False,
+            width=image_width,
+            height=image_height,
+            device=ctx.latents.device,
+            dtype=ctx.latents.dtype,
+            control_mode=self._control_mode,
+            resize_mode=self._resize_mode,
+        )
+
+    @callback(ExtensionCallbackType.PRE_UNET)
+    def pre_unet_step(self, ctx: DenoiseContext):
+        # skip if model not active in current step
+        total_steps = len(ctx.inputs.timesteps)
+        first_step = math.floor(self._begin_step_percent * total_steps)
+        last_step = math.ceil(self._end_step_percent * total_steps)
+        if ctx.step_index < first_step or ctx.step_index > last_step:
+            return
+
+        # convert mode to internal flags
+        soft_injection = self._control_mode in ["more_prompt", "more_control"]
+        cfg_injection = self._control_mode in ["more_control", "unbalanced"]
+
+        # no negative conditioning in cfg_injection mode
+        if cfg_injection:
+            if ctx.conditioning_mode == ConditioningMode.Negative:
+                return
+            down_samples, mid_sample = self._run(ctx, soft_injection, ConditioningMode.Positive)
+
+            if ctx.conditioning_mode == ConditioningMode.Both:
+                # add zeros as samples for negative conditioning
+                down_samples = [torch.cat([torch.zeros_like(d), d]) for d in down_samples]
+                mid_sample = torch.cat([torch.zeros_like(mid_sample), mid_sample])
+
+        else:
+            down_samples, mid_sample = self._run(ctx, soft_injection, ctx.conditioning_mode)
+
+        if (
+            ctx.unet_kwargs.down_block_additional_residuals is None
+            and ctx.unet_kwargs.mid_block_additional_residual is None
+        ):
+            ctx.unet_kwargs.down_block_additional_residuals = down_samples
+            ctx.unet_kwargs.mid_block_additional_residual = mid_sample
+        else:
+            # add controlnet outputs together if have multiple controlnets
+            ctx.unet_kwargs.down_block_additional_residuals = [
+                samples_prev + samples_curr
+                for samples_prev, samples_curr in zip(
+                    ctx.unet_kwargs.down_block_additional_residuals, down_samples, strict=True
+                )
+            ]
+            ctx.unet_kwargs.mid_block_additional_residual += mid_sample
+
+    def _run(self, ctx: DenoiseContext, soft_injection: bool, conditioning_mode: ConditioningMode):
+        total_steps = len(ctx.inputs.timesteps)
+
+        model_input = ctx.latent_model_input
+        image_tensor = self._image_tensor
+        if conditioning_mode == ConditioningMode.Both:
+            model_input = torch.cat([model_input] * 2)
+            image_tensor = torch.cat([image_tensor] * 2)
+
+        cn_unet_kwargs = UNetKwargs(
+            sample=model_input,
+            timestep=ctx.timestep,
+            encoder_hidden_states=None,  # set later by conditioning
+            cross_attention_kwargs=dict(  # noqa: C408
+                percent_through=ctx.step_index / total_steps,
+            ),
+        )
+
+        ctx.inputs.conditioning_data.to_unet_kwargs(cn_unet_kwargs, conditioning_mode=conditioning_mode)
+
+        # get static weight, or weight corresponding to current step
+        weight = self._weight
+        if isinstance(weight, list):
+            weight = weight[ctx.step_index]
+
+        tmp_kwargs = vars(cn_unet_kwargs)
+
+        # Remove kwargs not related to ControlNet unet
+        # ControlNet guidance fields
+        del tmp_kwargs["down_block_additional_residuals"]
+        del tmp_kwargs["mid_block_additional_residual"]
+
+        # T2i Adapter guidance fields
+        del tmp_kwargs["down_intrablock_additional_residuals"]
+
+        # controlnet(s) inference
+        down_samples, mid_sample = self._model(
+            controlnet_cond=image_tensor,
+            conditioning_scale=weight,  # controlnet specific, NOT the guidance scale
+            guess_mode=soft_injection,  # this is still called guess_mode in diffusers ControlNetModel
+            return_dict=False,
+            **vars(cn_unet_kwargs),
+        )
+
+        return down_samples, mid_sample

invokeai/backend/stable_diffusion/extensions_manager.py

@@ -52,13 +52,13 @@ class ExtensionsManager:
             cb.function(ctx)
 
     @contextmanager
-    def patch_extensions(self, context: DenoiseContext):
+    def patch_extensions(self, ctx: DenoiseContext):
         if self._is_canceled and self._is_canceled():
             raise CanceledException
 
         with ExitStack() as exit_stack:
             for ext in self._extensions:
-                exit_stack.enter_context(ext.patch_extension(context))
+                exit_stack.enter_context(ext.patch_extension(ctx))
 
             yield None