# Copyright 2026 The HuggingFace Team. All rights reserved.

#

# 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

#

# http://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.

from dataclasses import dataclass

from typing import Any

import torch

import torch.nn as nn

from ...configuration_utils import ConfigMixin, register_to_config

from ...loaders import PeftAdapterMixin, UNet2DConditionLoadersMixin

from ...loaders.single_file_model import FromOriginalModelMixin

from ...utils import (

BaseOutput,

apply_lora_scale,

deprecate,

logging,

)

from ...utils.torch_utils import maybe_adjust_dtype_for_device

from ..activations import get_activation

from ..attention import AttentionMixin

from ..attention_processor import (

ADDED_KV_ATTENTION_PROCESSORS,

CROSS_ATTENTION_PROCESSORS,

Attention,

AttnAddedKVProcessor,

AttnProcessor,

FusedAttnProcessor2_0,

)

from ..embeddings import (

GaussianFourierProjection,

GLIGENTextBoundingboxProjection,

ImageHintTimeEmbedding,

ImageProjection,

ImageTimeEmbedding,

TextImageProjection,

TextImageTimeEmbedding,

TextTimeEmbedding,

TimestepEmbedding,

Timesteps,

)

from ..modeling_utils import ModelMixin

from .unet_2d_blocks import (

get_down_block,

get_mid_block,

get_up_block,

)

logger = logging.get_logger(__name__) # pylint: disable=invalid-name

@dataclass

class UNet2DConditionOutput(BaseOutput):

"""

The output of [`UNet2DConditionModel`].

Args:

sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)`):

The hidden states output conditioned on `encoder_hidden_states` input. Output of last layer of model.

"""

sample: torch.Tensor = None

class UNet2DConditionModel(

ModelMixin, AttentionMixin, ConfigMixin, FromOriginalModelMixin, UNet2DConditionLoadersMixin, PeftAdapterMixin

):

r"""

A conditional 2D UNet model that takes a noisy sample, conditional state, and a timestep and returns a sample

shaped output.

This model inherits from [`ModelMixin`]. Check the superclass documentation for it's generic methods implemented

for all models (such as downloading or saving).

Parameters:

sample_size (`int` or `tuple[int, int]`, *optional*, defaults to `None`):

Height and width of input/output sample.

in_channels (`int`, *optional*, defaults to 4): Number of channels in the input sample.

out_channels (`int`, *optional*, defaults to 4): Number of channels in the output.

center_input_sample (`bool`, *optional*, defaults to `False`): Whether to center the input sample.

flip_sin_to_cos (`bool`, *optional*, defaults to `True`):

Whether to flip the sin to cos in the time embedding.

freq_shift (`int`, *optional*, defaults to 0): The frequency shift to apply to the time embedding.

down_block_types (`tuple[str]`, *optional*, defaults to `("CrossAttnDownBlock2D", "CrossAttnDownBlock2D", "CrossAttnDownBlock2D", "DownBlock2D")`):

The tuple of downsample blocks to use.

mid_block_type (`str`, *optional*, defaults to `"UNetMidBlock2DCrossAttn"`):

Block type for middle of UNet, it can be one of `UNetMidBlock2DCrossAttn`, `UNetMidBlock2D`, or

`UNetMidBlock2DSimpleCrossAttn`. If `None`, the mid block layer is skipped.

up_block_types (`tuple[str]`, *optional*, defaults to `("UpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D", "CrossAttnUpBlock2D")`):

The tuple of upsample blocks to use.

only_cross_attention(`bool` or `tuple[bool]`, *optional*, default to `False`):

Whether to include self-attention in the basic transformer blocks, see

[`~models.attention.BasicTransformerBlock`].

block_out_channels (`tuple[int]`, *optional*, defaults to `(320, 640, 1280, 1280)`):

The tuple of output channels for each block.

layers_per_block (`int`, *optional*, defaults to 2): The number of layers per block.

downsample_padding (`int`, *optional*, defaults to 1): The padding to use for the downsampling convolution.

mid_block_scale_factor (`float`, *optional*, defaults to 1.0): The scale factor to use for the mid block.

dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.

act_fn (`str`, *optional*, defaults to `"silu"`): The activation function to use.

norm_num_groups (`int`, *optional*, defaults to 32): The number of groups to use for the normalization.

If `None`, normalization and activation layers is skipped in post-processing.

norm_eps (`float`, *optional*, defaults to 1e-5): The epsilon to use for the normalization.

cross_attention_dim (`int` or `tuple[int]`, *optional*, defaults to 1280):

The dimension of the cross attention features.

transformer_layers_per_block (`int`, `tuple[int]`, or `tuple[tuple]` , *optional*, defaults to 1):

The number of transformer blocks of type [`~models.attention.BasicTransformerBlock`]. Only relevant for

[`~models.unets.unet_2d_blocks.CrossAttnDownBlock2D`], [`~models.unets.unet_2d_blocks.CrossAttnUpBlock2D`],

[`~models.unets.unet_2d_blocks.UNetMidBlock2DCrossAttn`].

reverse_transformer_layers_per_block : (`tuple[tuple]`, *optional*, defaults to None):

The number of transformer blocks of type [`~models.attention.BasicTransformerBlock`], in the upsampling

blocks of the U-Net. Only relevant if `transformer_layers_per_block` is of type `tuple[tuple]` and for

[`~models.unets.unet_2d_blocks.CrossAttnDownBlock2D`], [`~models.unets.unet_2d_blocks.CrossAttnUpBlock2D`],

[`~models.unets.unet_2d_blocks.UNetMidBlock2DCrossAttn`].

encoder_hid_dim (`int`, *optional*, defaults to None):

If `encoder_hid_dim_type` is defined, `encoder_hidden_states` will be projected from `encoder_hid_dim`

dimension to `cross_attention_dim`.

encoder_hid_dim_type (`str`, *optional*, defaults to `None`):

If given, the `encoder_hidden_states` and potentially other embeddings are down-projected to text

embeddings of dimension `cross_attention` according to `encoder_hid_dim_type`.

attention_head_dim (`int`, *optional*, defaults to 8): The dimension of the attention heads.

num_attention_heads (`int`, *optional*):

The number of attention heads. If not defined, defaults to `attention_head_dim`

resnet_time_scale_shift (`str`, *optional*, defaults to `"default"`): Time scale shift config

for ResNet blocks (see [`~models.resnet.ResnetBlock2D`]). Choose from `default` or `scale_shift`.

class_embed_type (`str`, *optional*, defaults to `None`):

The type of class embedding to use which is ultimately summed with the time embeddings. Choose from `None`,

`"timestep"`, `"identity"`, `"projection"`, or `"simple_projection"`.

addition_embed_type (`str`, *optional*, defaults to `None`):

Configures an optional embedding which will be summed with the time embeddings. Choose from `None` or

"text". "text" will use the `TextTimeEmbedding` layer.

addition_time_embed_dim: (`int`, *optional*, defaults to `None`):

Dimension for the timestep embeddings.

num_class_embeds (`int`, *optional*, defaults to `None`):

Input dimension of the learnable embedding matrix to be projected to `time_embed_dim`, when performing

class conditioning with `class_embed_type` equal to `None`.

time_embedding_type (`str`, *optional*, defaults to `positional`):

The type of position embedding to use for timesteps. Choose from `positional` or `fourier`.

time_embedding_dim (`int`, *optional*, defaults to `None`):

An optional override for the dimension of the projected time embedding.

time_embedding_act_fn (`str`, *optional*, defaults to `None`):

Optional activation function to use only once on the time embeddings before they are passed to the rest of

the UNet. Choose from `silu`, `mish`, `gelu`, and `swish`.

timestep_post_act (`str`, *optional*, defaults to `None`):

The second activation function to use in timestep embedding. Choose from `silu`, `mish` and `gelu`.

time_cond_proj_dim (`int`, *optional*, defaults to `None`):

The dimension of `cond_proj` layer in the timestep embedding.

conv_in_kernel (`int`, *optional*, default to `3`): The kernel size of `conv_in` layer.

conv_out_kernel (`int`, *optional*, default to `3`): The kernel size of `conv_out` layer.

projection_class_embeddings_input_dim (`int`, *optional*): The dimension of the `class_labels` input when

`class_embed_type="projection"`. Required when `class_embed_type="projection"`.

class_embeddings_concat (`bool`, *optional*, defaults to `False`): Whether to concatenate the time

embeddings with the class embeddings.

mid_block_only_cross_attention (`bool`, *optional*, defaults to `None`):

Whether to use cross attention with the mid block when using the `UNetMidBlock2DSimpleCrossAttn`. If

`only_cross_attention` is given as a single boolean and `mid_block_only_cross_attention` is `None`, the

`only_cross_attention` value is used as the value for `mid_block_only_cross_attention`. Default to `False`

otherwise.

"""

_supports_gradient_checkpointing = True

_no_split_modules = ["BasicTransformerBlock", "ResnetBlock2D", "CrossAttnUpBlock2D", "UpBlock2D"]

_skip_layerwise_casting_patterns = ["norm"]

_repeated_blocks = ["BasicTransformerBlock"]

@register_to_config

def __init__(

self,

sample_size: int | tuple[int, int] | None = None,

in_channels: int = 4,

out_channels: int = 4,

center_input_sample: bool = False,

flip_sin_to_cos: bool = True,

freq_shift: int = 0,

down_block_types: tuple[str, ...] = (

"CrossAttnDownBlock2D",

"CrossAttnDownBlock2D",

"CrossAttnDownBlock2D",

"DownBlock2D",

),

mid_block_type: str | None = "UNetMidBlock2DCrossAttn",

up_block_types: tuple[str, ...] = (

"UpBlock2D",

"CrossAttnUpBlock2D",

"CrossAttnUpBlock2D",

"CrossAttnUpBlock2D",

),

only_cross_attention: bool | tuple[bool] = False,

block_out_channels: tuple[int, ...] = (320, 640, 1280, 1280),

layers_per_block: int | tuple[int] = 2,

downsample_padding: int = 1,

mid_block_scale_factor: float = 1,

dropout: float = 0.0,

act_fn: str = "silu",

norm_num_groups: int | None = 32,

norm_eps: float = 1e-5,

cross_attention_dim: int | tuple[int] = 1280,

transformer_layers_per_block: int | tuple[int] | tuple[tuple] = 1,

reverse_transformer_layers_per_block: tuple[tuple[int]] | None = None,

encoder_hid_dim: int | None = None,

encoder_hid_dim_type: str | None = None,

attention_head_dim: int | tuple[int] = 8,

num_attention_heads: int | tuple[int] | None = None,

dual_cross_attention: bool = False,

use_linear_projection: bool = False,

class_embed_type: str | None = None,

addition_embed_type: str | None = None,

addition_time_embed_dim: int | None = None,

num_class_embeds: int | None = None,

upcast_attention: bool = False,

resnet_time_scale_shift: str = "default",

resnet_skip_time_act: bool = False,

resnet_out_scale_factor: float = 1.0,

time_embedding_type: str = "positional",

time_embedding_dim: int | None = None,

time_embedding_act_fn: str | None = None,

timestep_post_act: str | None = None,

time_cond_proj_dim: int | None = None,

conv_in_kernel: int = 3,

conv_out_kernel: int = 3,

projection_class_embeddings_input_dim: int | None = None,

attention_type: str = "default",

class_embeddings_concat: bool = False,

mid_block_only_cross_attention: bool | None = None,

cross_attention_norm: str | None = None,

addition_embed_type_num_heads: int = 64,

):

super().__init__()

self.sample_size = sample_size

if num_attention_heads is not None:

raise ValueError(

"At the moment it is not possible to define the number of attention heads via `num_attention_heads` because of a naming issue as described in https://github.com/huggingface/diffusers/issues/2011#issuecomment-1547958131. Passing `num_attention_heads` will only be supported in diffusers v0.19."

)

# If `num_attention_heads` is not defined (which is the case for most models)

# it will default to `attention_head_dim`. This looks weird upon first reading it and it is.

# The reason for this behavior is to correct for incorrectly named variables that were introduced

# when this library was created. The incorrect naming was only discovered much later in https://github.com/huggingface/diffusers/issues/2011#issuecomment-1547958131

# Changing `attention_head_dim` to `num_attention_heads` for 40,000+ configurations is too backwards breaking

# which is why we correct for the naming here.

num_attention_heads = num_attention_heads or attention_head_dim

# Check inputs

self._check_config(

down_block_types=down_block_types,

up_block_types=up_block_types,

only_cross_attention=only_cross_attention,

block_out_channels=block_out_channels,

layers_per_block=layers_per_block,

cross_attention_dim=cross_attention_dim,

transformer_layers_per_block=transformer_layers_per_block,

reverse_transformer_layers_per_block=reverse_transformer_layers_per_block,

attention_head_dim=attention_head_dim,

num_attention_heads=num_attention_heads,

)

# input

conv_in_padding = (conv_in_kernel - 1) // 2

self.conv_in = nn.Conv2d(

in_channels, block_out_channels[0], kernel_size=conv_in_kernel, padding=conv_in_padding

)

# time

time_embed_dim, timestep_input_dim = self._set_time_proj(

time_embedding_type,

block_out_channels=block_out_channels,

flip_sin_to_cos=flip_sin_to_cos,

freq_shift=freq_shift,

time_embedding_dim=time_embedding_dim,

)

self.time_embedding = TimestepEmbedding(

timestep_input_dim,

time_embed_dim,

act_fn=act_fn,

post_act_fn=timestep_post_act,

cond_proj_dim=time_cond_proj_dim,

)

self._set_encoder_hid_proj(

encoder_hid_dim_type,

cross_attention_dim=cross_attention_dim,

encoder_hid_dim=encoder_hid_dim,

)

# class embedding

self._set_class_embedding(

class_embed_type,

act_fn=act_fn,

num_class_embeds=num_class_embeds,

projection_class_embeddings_input_dim=projection_class_embeddings_input_dim,

time_embed_dim=time_embed_dim,

timestep_input_dim=timestep_input_dim,

)

self._set_add_embedding(

addition_embed_type,

addition_embed_type_num_heads=addition_embed_type_num_heads,

addition_time_embed_dim=addition_time_embed_dim,

cross_attention_dim=cross_attention_dim,

encoder_hid_dim=encoder_hid_dim,

flip_sin_to_cos=flip_sin_to_cos,

freq_shift=freq_shift,

projection_class_embeddings_input_dim=projection_class_embeddings_input_dim,

time_embed_dim=time_embed_dim,

)

if time_embedding_act_fn is None:

self.time_embed_act = None

else:

self.time_embed_act = get_activation(time_embedding_act_fn)

self.down_blocks = nn.ModuleList([])

self.up_blocks = nn.ModuleList([])

if isinstance(only_cross_attention, bool):

if mid_block_only_cross_attention is None:

mid_block_only_cross_attention = only_cross_attention

only_cross_attention = [only_cross_attention] * len(down_block_types)

if mid_block_only_cross_attention is None:

mid_block_only_cross_attention = False

if isinstance(num_attention_heads, int):

num_attention_heads = (num_attention_heads,) * len(down_block_types)

if isinstance(attention_head_dim, int):

attention_head_dim = (attention_head_dim,) * len(down_block_types)

if isinstance(cross_attention_dim, int):

cross_attention_dim = (cross_attention_dim,) * len(down_block_types)

if isinstance(layers_per_block, int):

layers_per_block = [layers_per_block] * len(down_block_types)

if isinstance(transformer_layers_per_block, int):

transformer_layers_per_block = [transformer_layers_per_block] * len(down_block_types)

if class_embeddings_concat:

# The time embeddings are concatenated with the class embeddings. The dimension of the

# time embeddings passed to the down, middle, and up blocks is twice the dimension of the

# regular time embeddings

blocks_time_embed_dim = time_embed_dim * 2

else:

blocks_time_embed_dim = time_embed_dim

# down

output_channel = block_out_channels[0]

for i, down_block_type in enumerate(down_block_types):

input_channel = output_channel

output_channel = block_out_channels[i]

is_final_block = i == len(block_out_channels) - 1

down_block = get_down_block(

down_block_type,

num_layers=layers_per_block[i],

transformer_layers_per_block=transformer_layers_per_block[i],

in_channels=input_channel,

out_channels=output_channel,

temb_channels=blocks_time_embed_dim,

add_downsample=not is_final_block,

resnet_eps=norm_eps,

resnet_act_fn=act_fn,

resnet_groups=norm_num_groups,

cross_attention_dim=cross_attention_dim[i],

num_attention_heads=num_attention_heads[i],

downsample_padding=downsample_padding,

dual_cross_attention=dual_cross_attention,

use_linear_projection=use_linear_projection,

only_cross_attention=only_cross_attention[i],

upcast_attention=upcast_attention,

resnet_time_scale_shift=resnet_time_scale_shift,

attention_type=attention_type,

resnet_skip_time_act=resnet_skip_time_act,

resnet_out_scale_factor=resnet_out_scale_factor,

cross_attention_norm=cross_attention_norm,

attention_head_dim=attention_head_dim[i] if attention_head_dim[i] is not None else output_channel,

dropout=dropout,

)

self.down_blocks.append(down_block)

# mid

self.mid_block = get_mid_block(

mid_block_type,

temb_channels=blocks_time_embed_dim,

in_channels=block_out_channels[-1],

resnet_eps=norm_eps,

resnet_act_fn=act_fn,

resnet_groups=norm_num_groups,

output_scale_factor=mid_block_scale_factor,

transformer_layers_per_block=transformer_layers_per_block[-1],

num_attention_heads=num_attention_heads[-1],

cross_attention_dim=cross_attention_dim[-1],

dual_cross_attention=dual_cross_attention,

use_linear_projection=use_linear_projection,

mid_block_only_cross_attention=mid_block_only_cross_attention,

upcast_attention=upcast_attention,

resnet_time_scale_shift=resnet_time_scale_shift,

attention_type=attention_type,

resnet_skip_time_act=resnet_skip_time_act,

cross_attention_norm=cross_attention_norm,

attention_head_dim=attention_head_dim[-1],

dropout=dropout,

)

# count how many layers upsample the images

self.num_upsamplers = 0

# up

reversed_block_out_channels = list(reversed(block_out_channels))

reversed_num_attention_heads = list(reversed(num_attention_heads))

reversed_layers_per_block = list(reversed(layers_per_block))

reversed_cross_attention_dim = list(reversed(cross_attention_dim))

reversed_transformer_layers_per_block = (

list(reversed(transformer_layers_per_block))

if reverse_transformer_layers_per_block is None

else reverse_transformer_layers_per_block

)

only_cross_attention = list(reversed(only_cross_attention))

output_channel = reversed_block_out_channels[0]

for i, up_block_type in enumerate(up_block_types):

is_final_block = i == len(block_out_channels) - 1

prev_output_channel = output_channel

output_channel = reversed_block_out_channels[i]

input_channel = reversed_block_out_channels[min(i + 1, len(block_out_channels) - 1)]

# add upsample block for all BUT final layer

if not is_final_block:

add_upsample = True

self.num_upsamplers += 1

else:

add_upsample = False

up_block = get_up_block(

up_block_type,

num_layers=reversed_layers_per_block[i] + 1,

transformer_layers_per_block=reversed_transformer_layers_per_block[i],

in_channels=input_channel,

out_channels=output_channel,

prev_output_channel=prev_output_channel,

temb_channels=blocks_time_embed_dim,

add_upsample=add_upsample,

resnet_eps=norm_eps,

resnet_act_fn=act_fn,

resolution_idx=i,

resnet_groups=norm_num_groups,

cross_attention_dim=reversed_cross_attention_dim[i],

num_attention_heads=reversed_num_attention_heads[i],

dual_cross_attention=dual_cross_attention,

use_linear_projection=use_linear_projection,

only_cross_attention=only_cross_attention[i],

upcast_attention=upcast_attention,

resnet_time_scale_shift=resnet_time_scale_shift,

attention_type=attention_type,

resnet_skip_time_act=resnet_skip_time_act,

resnet_out_scale_factor=resnet_out_scale_factor,

cross_attention_norm=cross_attention_norm,

attention_head_dim=attention_head_dim[i] if attention_head_dim[i] is not None else output_channel,

dropout=dropout,

)

self.up_blocks.append(up_block)

# out

if norm_num_groups is not None:

self.conv_norm_out = nn.GroupNorm(

num_channels=block_out_channels[0], num_groups=norm_num_groups, eps=norm_eps

)

self.conv_act = get_activation(act_fn)

else:

self.conv_norm_out = None

self.conv_act = None

conv_out_padding = (conv_out_kernel - 1) // 2

self.conv_out = nn.Conv2d(

block_out_channels[0], out_channels, kernel_size=conv_out_kernel, padding=conv_out_padding

)

self._set_pos_net_if_use_gligen(attention_type=attention_type, cross_attention_dim=cross_attention_dim)

def _check_config(

self,

down_block_types: tuple[str, ...],

up_block_types: tuple[str, ...],

only_cross_attention: bool | tuple[bool],

block_out_channels: tuple[int, ...],

layers_per_block: int | tuple[int],

cross_attention_dim: int | tuple[int],

transformer_layers_per_block: int | tuple[int, tuple[tuple[int]]],

reverse_transformer_layers_per_block: bool,

attention_head_dim: int,

num_attention_heads: int | tuple[int] | None,

):

if len(down_block_types) != len(up_block_types):

raise ValueError(

f"Must provide the same number of `down_block_types` as `up_block_types`. `down_block_types`: {down_block_types}. `up_block_types`: {up_block_types}."

)

if len(block_out_channels) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `block_out_channels` as `down_block_types`. `block_out_channels`: {block_out_channels}. `down_block_types`: {down_block_types}."

)

if not isinstance(only_cross_attention, bool) and len(only_cross_attention) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `only_cross_attention` as `down_block_types`. `only_cross_attention`: {only_cross_attention}. `down_block_types`: {down_block_types}."

)

if not isinstance(num_attention_heads, int) and len(num_attention_heads) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `num_attention_heads` as `down_block_types`. `num_attention_heads`: {num_attention_heads}. `down_block_types`: {down_block_types}."

)

if not isinstance(attention_head_dim, int) and len(attention_head_dim) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `attention_head_dim` as `down_block_types`. `attention_head_dim`: {attention_head_dim}. `down_block_types`: {down_block_types}."

)

if isinstance(cross_attention_dim, list) and len(cross_attention_dim) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `cross_attention_dim` as `down_block_types`. `cross_attention_dim`: {cross_attention_dim}. `down_block_types`: {down_block_types}."

)

if not isinstance(layers_per_block, int) and len(layers_per_block) != len(down_block_types):

raise ValueError(

f"Must provide the same number of `layers_per_block` as `down_block_types`. `layers_per_block`: {layers_per_block}. `down_block_types`: {down_block_types}."

)

if isinstance(transformer_layers_per_block, list) and reverse_transformer_layers_per_block is None:

for layer_number_per_block in transformer_layers_per_block:

if isinstance(layer_number_per_block, list):

raise ValueError("Must provide 'reverse_transformer_layers_per_block` if using asymmetrical UNet.")

def _set_time_proj(

self,

time_embedding_type: str,

block_out_channels: int,

flip_sin_to_cos: bool,

freq_shift: float,

time_embedding_dim: int,

) -> tuple[int, int]:

if time_embedding_type == "fourier":

time_embed_dim = time_embedding_dim or block_out_channels[0] * 2

if time_embed_dim % 2 != 0:

raise ValueError(f"`time_embed_dim` should be divisible by 2, but is {time_embed_dim}.")

self.time_proj = GaussianFourierProjection(

time_embed_dim // 2, set_W_to_weight=False, log=False, flip_sin_to_cos=flip_sin_to_cos

)

timestep_input_dim = time_embed_dim

elif time_embedding_type == "positional":

time_embed_dim = time_embedding_dim or block_out_channels[0] * 4

self.time_proj = Timesteps(block_out_channels[0], flip_sin_to_cos, freq_shift)

timestep_input_dim = block_out_channels[0]

else:

raise ValueError(

f"{time_embedding_type} does not exist. Please make sure to use one of `fourier` or `positional`."

)

return time_embed_dim, timestep_input_dim

def _set_encoder_hid_proj(

self,

encoder_hid_dim_type: str | None,

cross_attention_dim: int | tuple[int],

encoder_hid_dim: int | None,

):

if encoder_hid_dim_type is None and encoder_hid_dim is not None:

encoder_hid_dim_type = "text_proj"

self.register_to_config(encoder_hid_dim_type=encoder_hid_dim_type)

logger.info("encoder_hid_dim_type defaults to 'text_proj' as `encoder_hid_dim` is defined.")

if encoder_hid_dim is None and encoder_hid_dim_type is not None:

raise ValueError(

f"`encoder_hid_dim` has to be defined when `encoder_hid_dim_type` is set to {encoder_hid_dim_type}."

)

if encoder_hid_dim_type == "text_proj":

self.encoder_hid_proj = nn.Linear(encoder_hid_dim, cross_attention_dim)

elif encoder_hid_dim_type == "text_image_proj":

# image_embed_dim DOESN'T have to be `cross_attention_dim`. To not clutter the __init__ too much

# they are set to `cross_attention_dim` here as this is exactly the required dimension for the currently only use

# case when `addition_embed_type == "text_image_proj"` (Kandinsky 2.1)`

self.encoder_hid_proj = TextImageProjection(

text_embed_dim=encoder_hid_dim,

image_embed_dim=cross_attention_dim,

cross_attention_dim=cross_attention_dim,

)

elif encoder_hid_dim_type == "image_proj":

# Kandinsky 2.2

self.encoder_hid_proj = ImageProjection(

image_embed_dim=encoder_hid_dim,

cross_attention_dim=cross_attention_dim,

)

elif encoder_hid_dim_type is not None:

raise ValueError(

f"`encoder_hid_dim_type`: {encoder_hid_dim_type} must be None, 'text_proj', 'text_image_proj', or 'image_proj'."

)

else:

self.encoder_hid_proj = None

def _set_class_embedding(

self,

class_embed_type: str | None,

act_fn: str,

num_class_embeds: int | None,

projection_class_embeddings_input_dim: int | None,

time_embed_dim: int,

timestep_input_dim: int,

):

if class_embed_type is None and num_class_embeds is not None:

self.class_embedding = nn.Embedding(num_class_embeds, time_embed_dim)

elif class_embed_type == "timestep":

self.class_embedding = TimestepEmbedding(timestep_input_dim, time_embed_dim, act_fn=act_fn)

elif class_embed_type == "identity":

self.class_embedding = nn.Identity(time_embed_dim, time_embed_dim)

elif class_embed_type == "projection":

if projection_class_embeddings_input_dim is None:

raise ValueError(

"`class_embed_type`: 'projection' requires `projection_class_embeddings_input_dim` be set"

)

# The projection `class_embed_type` is the same as the timestep `class_embed_type` except

# 1. the `class_labels` inputs are not first converted to sinusoidal embeddings

# 2. it projects from an arbitrary input dimension.

#

# Note that `TimestepEmbedding` is quite general, being mainly linear layers and activations.

# When used for embedding actual timesteps, the timesteps are first converted to sinusoidal embeddings.

# As a result, `TimestepEmbedding` can be passed arbitrary vectors.

self.class_embedding = TimestepEmbedding(projection_class_embeddings_input_dim, time_embed_dim)

elif class_embed_type == "simple_projection":

if projection_class_embeddings_input_dim is None:

raise ValueError(

"`class_embed_type`: 'simple_projection' requires `projection_class_embeddings_input_dim` be set"

)

self.class_embedding = nn.Linear(projection_class_embeddings_input_dim, time_embed_dim)

else:

self.class_embedding = None

def _set_add_embedding(

self,

addition_embed_type: str,

addition_embed_type_num_heads: int,

addition_time_embed_dim: int | None,

flip_sin_to_cos: bool,

freq_shift: float,

cross_attention_dim: int | None,

encoder_hid_dim: int | None,

projection_class_embeddings_input_dim: int | None,

time_embed_dim: int,

):

if addition_embed_type == "text":

if encoder_hid_dim is not None:

text_time_embedding_from_dim = encoder_hid_dim

else:

text_time_embedding_from_dim = cross_attention_dim

self.add_embedding = TextTimeEmbedding(

text_time_embedding_from_dim, time_embed_dim, num_heads=addition_embed_type_num_heads

)

elif addition_embed_type == "text_image":

# text_embed_dim and image_embed_dim DON'T have to be `cross_attention_dim`. To not clutter the __init__ too much

# they are set to `cross_attention_dim` here as this is exactly the required dimension for the currently only use

# case when `addition_embed_type == "text_image"` (Kandinsky 2.1)`

self.add_embedding = TextImageTimeEmbedding(

text_embed_dim=cross_attention_dim, image_embed_dim=cross_attention_dim, time_embed_dim=time_embed_dim

)

elif addition_embed_type == "text_time":

self.add_time_proj = Timesteps(addition_time_embed_dim, flip_sin_to_cos, freq_shift)

self.add_embedding = TimestepEmbedding(projection_class_embeddings_input_dim, time_embed_dim)

elif addition_embed_type == "image":

# Kandinsky 2.2

self.add_embedding = ImageTimeEmbedding(image_embed_dim=encoder_hid_dim, time_embed_dim=time_embed_dim)

elif addition_embed_type == "image_hint":

# Kandinsky 2.2 ControlNet

self.add_embedding = ImageHintTimeEmbedding(image_embed_dim=encoder_hid_dim, time_embed_dim=time_embed_dim)

elif addition_embed_type is not None:

raise ValueError(

f"`addition_embed_type`: {addition_embed_type} must be None, 'text', 'text_image', 'text_time', 'image', or 'image_hint'."

)

def _set_pos_net_if_use_gligen(self, attention_type: str, cross_attention_dim: int):

if attention_type in ["gated", "gated-text-image"]:

positive_len = 768

if isinstance(cross_attention_dim, int):

positive_len = cross_attention_dim

elif isinstance(cross_attention_dim, (list, tuple)):

positive_len = cross_attention_dim[0]

feature_type = "text-only" if attention_type == "gated" else "text-image"

self.position_net = GLIGENTextBoundingboxProjection(

positive_len=positive_len, out_dim=cross_attention_dim, feature_type=feature_type

)

def set_default_attn_processor(self):

"""

Disables custom attention processors and sets the default attention implementation.

"""

if all(proc.__class__ in ADDED_KV_ATTENTION_PROCESSORS for proc in self.attn_processors.values()):

processor = AttnAddedKVProcessor()

elif all(proc.__class__ in CROSS_ATTENTION_PROCESSORS for proc in self.attn_processors.values()):

processor = AttnProcessor()

else:

raise ValueError(

f"Cannot call `set_default_attn_processor` when attention processors are of type {next(iter(self.attn_processors.values()))}"

)

self.set_attn_processor(processor)

def set_attention_slice(self, slice_size: str | int | list[int] = "auto"):

r"""

Enable sliced attention computation.

When this option is enabled, the attention module splits the input tensor in slices to compute attention in

several steps. This is useful for saving some memory in exchange for a small decrease in speed.

Args:

slice_size (`str` or `int` or `list(int)`, *optional*, defaults to `"auto"`):

When `"auto"`, input to the attention heads is halved, so attention is computed in two steps. If

`"max"`, maximum amount of memory is saved by running only one slice at a time. If a number is

provided, uses as many slices as `attention_head_dim // slice_size`. In this case, `attention_head_dim`

must be a multiple of `slice_size`.

"""

sliceable_head_dims = []

def fn_recursive_retrieve_sliceable_dims(module: torch.nn.Module):

if hasattr(module, "set_attention_slice"):

sliceable_head_dims.append(module.sliceable_head_dim)

for child in module.children():

fn_recursive_retrieve_sliceable_dims(child)

# retrieve number of attention layers

for module in self.children():

fn_recursive_retrieve_sliceable_dims(module)

num_sliceable_layers = len(sliceable_head_dims)

if slice_size == "auto":

# half the attention head size is usually a good trade-off between

# speed and memory

slice_size = [dim // 2 for dim in sliceable_head_dims]

elif slice_size == "max":

# make smallest slice possible

slice_size = num_sliceable_layers * [1]

slice_size = num_sliceable_layers * [slice_size] if not isinstance(slice_size, list) else slice_size

if len(slice_size) != len(sliceable_head_dims):

raise ValueError(

f"You have provided {len(slice_size)}, but {self.config} has {len(sliceable_head_dims)} different"

f" attention layers. Make sure to match `len(slice_size)` to be {len(sliceable_head_dims)}."

)

for i in range(len(slice_size)):

size = slice_size[i]

dim = sliceable_head_dims[i]

if size is not None and size > dim:

raise ValueError(f"size {size} has to be smaller or equal to {dim}.")

# Recursively walk through all the children.

# Any children which exposes the set_attention_slice method

# gets the message

def fn_recursive_set_attention_slice(module: torch.nn.Module, slice_size: list[int]):

if hasattr(module, "set_attention_slice"):

module.set_attention_slice(slice_size.pop())

for child in module.children():

fn_recursive_set_attention_slice(child, slice_size)

reversed_slice_size = list(reversed(slice_size))

for module in self.children():

fn_recursive_set_attention_slice(module, reversed_slice_size)

def enable_freeu(self, s1: float, s2: float, b1: float, b2: float):

r"""Enables the FreeU mechanism from https://huggingface.co/papers/2309.11497.

The suffixes after the scaling factors represent the stage blocks where they are being applied.

Please refer to the [official repository](https://github.com/ChenyangSi/FreeU) for combinations of values that

are known to work well for different pipelines such as Stable Diffusion v1, v2, and Stable Diffusion XL.

Args:

s1 (`float`):

Scaling factor for stage 1 to attenuate the contributions of the skip features. This is done to

mitigate the "oversmoothing effect" in the enhanced denoising process.

s2 (`float`):

Scaling factor for stage 2 to attenuate the contributions of the skip features. This is done to

mitigate the "oversmoothing effect" in the enhanced denoising process.

b1 (`float`): Scaling factor for stage 1 to amplify the contributions of backbone features.

b2 (`float`): Scaling factor for stage 2 to amplify the contributions of backbone features.

"""

for i, upsample_block in enumerate(self.up_blocks):

setattr(upsample_block, "s1", s1)

setattr(upsample_block, "s2", s2)

setattr(upsample_block, "b1", b1)

setattr(upsample_block, "b2", b2)

def disable_freeu(self):

"""Disables the FreeU mechanism."""

freeu_keys = {"s1", "s2", "b1", "b2"}

for i, upsample_block in enumerate(self.up_blocks):

for k in freeu_keys:

if hasattr(upsample_block, k) or getattr(upsample_block, k, None) is not None:

setattr(upsample_block, k, None)

def fuse_qkv_projections(self):

"""

Enables fused QKV projections. For self-attention modules, all projection matrices (i.e., query, key, value)

are fused. For cross-attention modules, key and value projection matrices are fused.

> [!WARNING] > This API is 🧪 experimental.

"""

self.original_attn_processors = None

for _, attn_processor in self.attn_processors.items():

if "Added" in str(attn_processor.__class__.__name__):

raise ValueError("`fuse_qkv_projections()` is not supported for models having added KV projections.")

self.original_attn_processors = self.attn_processors

for module in self.modules():

if isinstance(module, Attention):

module.fuse_projections(fuse=True)

self.set_attn_processor(FusedAttnProcessor2_0())

def unfuse_qkv_projections(self):

"""Disables the fused QKV projection if enabled.

> [!WARNING] > This API is 🧪 experimental.

"""

if self.original_attn_processors is not None:

self.set_attn_processor(self.original_attn_processors)

def get_time_embed(self, sample: torch.Tensor, timestep: torch.Tensor | float | int) -> torch.Tensor | None:

timesteps = timestep

if not torch.is_tensor(timesteps):

# TODO: this requires sync between CPU and GPU. So try to pass timesteps as tensors if you can

# This would be a good case for the `match` statement (Python 3.10+)

dtype = maybe_adjust_dtype_for_device(

torch.float64 if isinstance(timestep, float) else torch.int64, sample.device

)

timesteps = torch.tensor([timesteps], dtype=dtype, device=sample.device)

elif len(timesteps.shape) == 0:

timesteps = timesteps[None].to(sample.device)

# broadcast to batch dimension in a way that's compatible with ONNX/Core ML

timesteps = timesteps.expand(sample.shape[0])

t_emb = self.time_proj(timesteps)

# `Timesteps` does not contain any weights and will always return f32 tensors

# but time_embedding might actually be running in fp16. so we need to cast here.

# there might be better ways to encapsulate this.

t_emb = t_emb.to(dtype=sample.dtype)

return t_emb

def get_class_embed(self, sample: torch.Tensor, class_labels: torch.Tensor | None) -> torch.Tensor | None:

class_emb = None

if self.class_embedding is not None:

if class_labels is None:

raise ValueError("class_labels should be provided when num_class_embeds > 0")

if self.config.class_embed_type == "timestep":

class_labels = self.time_proj(class_labels)

# `Timesteps` does not contain any weights and will always return f32 tensors

# there might be better ways to encapsulate this.

class_labels = class_labels.to(dtype=sample.dtype)

class_emb = self.class_embedding(class_labels).to(dtype=sample.dtype)

return class_emb

def get_aug_embed(

self, emb: torch.Tensor, encoder_hidden_states: torch.Tensor, added_cond_kwargs: dict[str, Any]

) -> torch.Tensor | None:

aug_emb = None

if self.config.addition_embed_type == "text":

aug_emb = self.add_embedding(encoder_hidden_states)

elif self.config.addition_embed_type == "text_image":

# Kandinsky 2.1 - style

if "image_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `addition_embed_type` set to 'text_image' which requires the keyword argument `image_embeds` to be passed in `added_cond_kwargs`"

)

image_embs = added_cond_kwargs.get("image_embeds")

text_embs = added_cond_kwargs.get("text_embeds", encoder_hidden_states)

aug_emb = self.add_embedding(text_embs, image_embs)

elif self.config.addition_embed_type == "text_time":

# SDXL - style

if "text_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `addition_embed_type` set to 'text_time' which requires the keyword argument `text_embeds` to be passed in `added_cond_kwargs`"

)

text_embeds = added_cond_kwargs.get("text_embeds")

if "time_ids" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `addition_embed_type` set to 'text_time' which requires the keyword argument `time_ids` to be passed in `added_cond_kwargs`"

)

time_ids = added_cond_kwargs.get("time_ids")

time_embeds = self.add_time_proj(time_ids.flatten())

time_embeds = time_embeds.reshape((text_embeds.shape[0], -1))

add_embeds = torch.concat([text_embeds, time_embeds], dim=-1)

add_embeds = add_embeds.to(emb.dtype)

aug_emb = self.add_embedding(add_embeds)

elif self.config.addition_embed_type == "image":

# Kandinsky 2.2 - style

if "image_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `addition_embed_type` set to 'image' which requires the keyword argument `image_embeds` to be passed in `added_cond_kwargs`"

)

image_embs = added_cond_kwargs.get("image_embeds")

aug_emb = self.add_embedding(image_embs)

elif self.config.addition_embed_type == "image_hint":

# Kandinsky 2.2 ControlNet - style

if "image_embeds" not in added_cond_kwargs or "hint" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `addition_embed_type` set to 'image_hint' which requires the keyword arguments `image_embeds` and `hint` to be passed in `added_cond_kwargs`"

)

image_embs = added_cond_kwargs.get("image_embeds")

hint = added_cond_kwargs.get("hint")

aug_emb = self.add_embedding(image_embs, hint)

return aug_emb

def process_encoder_hidden_states(

self, encoder_hidden_states: torch.Tensor, added_cond_kwargs: dict[str, Any]

) -> torch.Tensor:

if self.encoder_hid_proj is not None and self.config.encoder_hid_dim_type == "text_proj":

encoder_hidden_states = self.encoder_hid_proj(encoder_hidden_states)

elif self.encoder_hid_proj is not None and self.config.encoder_hid_dim_type == "text_image_proj":

# Kandinsky 2.1 - style

if "image_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `encoder_hid_dim_type` set to 'text_image_proj' which requires the keyword argument `image_embeds` to be passed in `added_cond_kwargs`"

)

image_embeds = added_cond_kwargs.get("image_embeds")

encoder_hidden_states = self.encoder_hid_proj(encoder_hidden_states, image_embeds)

elif self.encoder_hid_proj is not None and self.config.encoder_hid_dim_type == "image_proj":

# Kandinsky 2.2 - style

if "image_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `encoder_hid_dim_type` set to 'image_proj' which requires the keyword argument `image_embeds` to be passed in `added_cond_kwargs`"

)

image_embeds = added_cond_kwargs.get("image_embeds")

encoder_hidden_states = self.encoder_hid_proj(image_embeds)

elif self.encoder_hid_proj is not None and self.config.encoder_hid_dim_type == "ip_image_proj":

if "image_embeds" not in added_cond_kwargs:

raise ValueError(

f"{self.__class__} has the config param `encoder_hid_dim_type` set to 'ip_image_proj' which requires the keyword argument `image_embeds` to be passed in `added_cond_kwargs`"

)

if hasattr(self, "text_encoder_hid_proj") and self.text_encoder_hid_proj is not None:

encoder_hidden_states = self.text_encoder_hid_proj(encoder_hidden_states)

image_embeds = added_cond_kwargs.get("image_embeds")

image_embeds = self.encoder_hid_proj(image_embeds)

encoder_hidden_states = (encoder_hidden_states, image_embeds)

return encoder_hidden_states

@apply_lora_scale("cross_attention_kwargs")

def forward(

self,

sample: torch.Tensor,

timestep: torch.Tensor | float | int,

encoder_hidden_states: torch.Tensor,

class_labels: torch.Tensor | None = None,

timestep_cond: torch.Tensor | None = None,

attention_mask: torch.Tensor | None = None,

cross_attention_kwargs: dict[str, Any] | None = None,

added_cond_kwargs: dict[str, torch.Tensor] | None = None,

down_block_additional_residuals: tuple[torch.Tensor] | None = None,

mid_block_additional_residual: torch.Tensor | None = None,

down_intrablock_additional_residuals: tuple[torch.Tensor] | None = None,

encoder_attention_mask: torch.Tensor | None = None,

return_dict: bool = True,

) -> UNet2DConditionOutput | tuple:

r"""

The [`UNet2DConditionModel`] forward method.

Args:

sample (`torch.Tensor`):

The noisy input tensor with the following shape `(batch, channel, height, width)`.