diffusers/models/controlnets/controlnet_sana.py

# Copyright 2025 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
from torch import nn

from ...configuration_utils import ConfigMixin, register_to_config
from ...loaders import PeftAdapterMixin
from ...utils import BaseOutput, apply_lora_scale, logging
from ..attention import AttentionMixin
from ..embeddings import PatchEmbed, PixArtAlphaTextProjection
from ..modeling_outputs import Transformer2DModelOutput
from ..modeling_utils import ModelMixin
from ..normalization import AdaLayerNormSingle, RMSNorm
from ..transformers.sana_transformer import SanaTransformerBlock
from .controlnet import zero_module


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


@dataclass
class SanaControlNetOutput(BaseOutput):
    controlnet_block_samples: tuple[torch.Tensor]


class SanaControlNetModel(ModelMixin, AttentionMixin, ConfigMixin, PeftAdapterMixin):
    _supports_gradient_checkpointing = True
    _no_split_modules = ["SanaTransformerBlock", "PatchEmbed"]
    _skip_layerwise_casting_patterns = ["patch_embed", "norm"]

    @register_to_config
    def __init__(
        self,
        in_channels: int = 32,
        out_channels: int | None = 32,
        num_attention_heads: int = 70,
        attention_head_dim: int = 32,
        num_layers: int = 7,
        num_cross_attention_heads: int | None = 20,
        cross_attention_head_dim: int | None = 112,
        cross_attention_dim: int | None = 2240,
        caption_channels: int = 2304,
        mlp_ratio: float = 2.5,
        dropout: float = 0.0,
        attention_bias: bool = False,
        sample_size: int = 32,
        patch_size: int = 1,
        norm_elementwise_affine: bool = False,
        norm_eps: float = 1e-6,
        interpolation_scale: int | None = None,
    ) -> None:
        super().__init__()

        out_channels = out_channels or in_channels
        inner_dim = num_attention_heads * attention_head_dim

        # 1. Patch Embedding
        self.patch_embed = PatchEmbed(
            height=sample_size,
            width=sample_size,
            patch_size=patch_size,
            in_channels=in_channels,
            embed_dim=inner_dim,
            interpolation_scale=interpolation_scale,
            pos_embed_type="sincos" if interpolation_scale is not None else None,
        )

        # 2. Additional condition embeddings
        self.time_embed = AdaLayerNormSingle(inner_dim)

        self.caption_projection = PixArtAlphaTextProjection(in_features=caption_channels, hidden_size=inner_dim)
        self.caption_norm = RMSNorm(inner_dim, eps=1e-5, elementwise_affine=True)

        # 3. Transformer blocks
        self.transformer_blocks = nn.ModuleList(
            [
                SanaTransformerBlock(
                    inner_dim,
                    num_attention_heads,
                    attention_head_dim,
                    dropout=dropout,
                    num_cross_attention_heads=num_cross_attention_heads,
                    cross_attention_head_dim=cross_attention_head_dim,
                    cross_attention_dim=cross_attention_dim,
                    attention_bias=attention_bias,
                    norm_elementwise_affine=norm_elementwise_affine,
                    norm_eps=norm_eps,
                    mlp_ratio=mlp_ratio,
                )
                for _ in range(num_layers)
            ]
        )

        # controlnet_blocks
        self.controlnet_blocks = nn.ModuleList([])

        self.input_block = zero_module(nn.Linear(inner_dim, inner_dim))
        for _ in range(len(self.transformer_blocks)):
            controlnet_block = nn.Linear(inner_dim, inner_dim)
            controlnet_block = zero_module(controlnet_block)
            self.controlnet_blocks.append(controlnet_block)

        self.gradient_checkpointing = False

    @apply_lora_scale("attention_kwargs")
    def forward(
        self,
        hidden_states: torch.Tensor,
        encoder_hidden_states: torch.Tensor,
        timestep: torch.LongTensor,
        controlnet_cond: torch.Tensor,
        conditioning_scale: float = 1.0,
        encoder_attention_mask: torch.Tensor | None = None,
        attention_mask: torch.Tensor | None = None,
        attention_kwargs: dict[str, Any] | None = None,
        return_dict: bool = True,
    ) -> tuple[torch.Tensor, ...] | Transformer2DModelOutput:
        # ensure attention_mask is a bias, and give it a singleton query_tokens dimension.
        #   we may have done this conversion already, e.g. if we came here via UNet2DConditionModel#forward.
        #   we can tell by counting dims; if ndim == 2: it's a mask rather than a bias.
        # expects mask of shape:
        #   [batch, key_tokens]
        # adds singleton query_tokens dimension:
        #   [batch,                    1, key_tokens]
        # this helps to broadcast it as a bias over attention scores, which will be in one of the following shapes:
        #   [batch,  heads, query_tokens, key_tokens] (e.g. torch sdp attn)
        #   [batch * heads, query_tokens, key_tokens] (e.g. xformers or classic attn)
        if attention_mask is not None and attention_mask.ndim == 2:
            # assume that mask is expressed as:
            #   (1 = keep,      0 = discard)
            # convert mask into a bias that can be added to attention scores:
            #       (keep = +0,     discard = -10000.0)
            attention_mask = (1 - attention_mask.to(hidden_states.dtype)) * -10000.0
            attention_mask = attention_mask.unsqueeze(1)

        # convert encoder_attention_mask to a bias the same way we do for attention_mask
        if encoder_attention_mask is not None and encoder_attention_mask.ndim == 2:
            encoder_attention_mask = (1 - encoder_attention_mask.to(hidden_states.dtype)) * -10000.0
            encoder_attention_mask = encoder_attention_mask.unsqueeze(1)

        # 1. Input
        batch_size, num_channels, height, width = hidden_states.shape
        p = self.config.patch_size
        post_patch_height, post_patch_width = height // p, width // p

        hidden_states = self.patch_embed(hidden_states)
        hidden_states = hidden_states + self.input_block(self.patch_embed(controlnet_cond.to(hidden_states.dtype)))

        timestep, embedded_timestep = self.time_embed(
            timestep, batch_size=batch_size, hidden_dtype=hidden_states.dtype
        )

        encoder_hidden_states = self.caption_projection(encoder_hidden_states)
        encoder_hidden_states = encoder_hidden_states.view(batch_size, -1, hidden_states.shape[-1])

        encoder_hidden_states = self.caption_norm(encoder_hidden_states)

        # 2. Transformer blocks
        block_res_samples = ()
        if torch.is_grad_enabled() and self.gradient_checkpointing:
            for block in self.transformer_blocks:
                hidden_states = self._gradient_checkpointing_func(
                    block,
                    hidden_states,
                    attention_mask,
                    encoder_hidden_states,
                    encoder_attention_mask,
                    timestep,
                    post_patch_height,
                    post_patch_width,
                )
                block_res_samples = block_res_samples + (hidden_states,)
        else:
            for block in self.transformer_blocks:
                hidden_states = block(
                    hidden_states,
                    attention_mask,
                    encoder_hidden_states,
                    encoder_attention_mask,
                    timestep,
                    post_patch_height,
                    post_patch_width,
                )
                block_res_samples = block_res_samples + (hidden_states,)

        # 3. ControlNet blocks
        controlnet_block_res_samples = ()
        for block_res_sample, controlnet_block in zip(block_res_samples, self.controlnet_blocks):
            block_res_sample = controlnet_block(block_res_sample)
            controlnet_block_res_samples = controlnet_block_res_samples + (block_res_sample,)

        controlnet_block_res_samples = [sample * conditioning_scale for sample in controlnet_block_res_samples]

        if not return_dict:
            return (controlnet_block_res_samples,)

        return SanaControlNetOutput(controlnet_block_samples=controlnet_block_res_samples)