Update README.md

README.md

@@ -339,6 +339,117 @@ Similarly, Zero123:
 
 ### Write a simple ControlNet:
 
+Below is a simple extension to have a completely independent pass of ControlNet that never conflicts any other extensions:
+
+`extensions-builtin/sd_forge_controlnet_example/scripts/sd_forge_controlnet_example.py`
+
+Note that this extension is hidden because it is only for developers. To see it in UI, use `--show-controlnet-example`.
+
+```python
+# Use --show-controlnet-example to see this extension.
+
+import os
+import cv2
+import gradio as gr
+
+from modules import scripts
+from modules.shared_cmd_options import cmd_opts
+from modules.paths import models_path
+from modules.modelloader import load_file_from_url
+from ldm_patched.modules.controlnet import load_controlnet
+from modules_forge.controlnet import apply_controlnet_advanced
+from modules_forge.forge_util import pytorch_to_numpy, numpy_to_pytorch
+
+
+class ControlNetExampleForge(scripts.Script):
+    model = None
+
+    def title(self):
+        return "ControlNet Example for Developers"
+
+    def show(self, is_img2img):
+        # make this extension visible in both txt2img and img2img tab.
+        return scripts.AlwaysVisible
+
+    def ui(self, *args, **kwargs):
+        with gr.Accordion(open=False, label=self.title()):
+            gr.HTML('This is an example controlnet extension for developers.')
+            gr.HTML('You see this extension because you used --show-controlnet-example')
+            input_image = gr.Image(source='upload', type='numpy')
+            funny_slider = gr.Slider(label='This slider does nothing. It just shows you how to transfer parameters.',
+                                     minimum=0.0, maximum=1.0, value=0.5)
+
+        return input_image, funny_slider
+
+    def process(self, p, *script_args, **kwargs):
+        input_image, funny_slider = script_args
+
+        # This slider does nothing. It just shows you how to transfer parameters.
+        del funny_slider
+
+        if input_image is None:
+            return
+
+        model_dir = os.path.join(models_path, 'ControlNet')
+        os.makedirs(model_dir, exist_ok=True)
+        controlnet_canny_path = load_file_from_url(
+            url='https://huggingface.co/lllyasviel/fav_models/resolve/main/fav/control_v11p_sd15_canny_fp16.safetensors',
+            model_dir=model_dir,
+            file_name='control_v11p_sd15_canny_fp16.safetensors'
+        )
+        print('The model [control_v11p_sd15_canny_fp16.safetensors] download finished.')
+
+        self.model = load_controlnet(controlnet_canny_path)
+        print('Controlnet loaded.')
+
+        return
+
+    def process_before_every_sampling(self, p, *script_args, **kwargs):
+        # This will be called before every sampling.
+        # If you use highres fix, this will be called twice.
+
+        input_image, funny_slider = script_args
+
+        if input_image is None or self.model is None:
+            return
+
+        B, C, H, W = kwargs['noise'].shape  # latent_shape
+        height = H * 8
+        width = W * 8
+
+        input_image = cv2.resize(input_image, (width, height))
+        canny_image = cv2.cvtColor(cv2.Canny(input_image, 100, 200), cv2.COLOR_GRAY2RGB)
+
+        # Output preprocessor result. Now called every sampling. Cache in your own way.
+        p.extra_result_images.append(canny_image)
+
+        print('Preprocessor Canny finished.')
+
+        control_image = numpy_to_pytorch(canny_image)
+
+        unet = p.sd_model.forge_objects.unet
+
+        unet = apply_controlnet_advanced(unet=unet, controlnet=self.model, image_bhwc=control_image,
+                                         strength=0.6, start_percent=0.0, end_percent=0.8,
+                                         positive_advanced_weighting=None, negative_advanced_weighting=None)
+
+        p.sd_model.forge_objects.unet = unet
+
+        # Below codes will add some logs to the texts below the image outputs on UI.
+        # The extra_generation_params does not influence results.
+        p.extra_generation_params.update(dict(
+            controlnet_info='You should see these texts below output images!',
+        ))
+
+        return
+
+
+# Use --show-controlnet-example to see this extension.
+if not cmd_opts.show_controlnet_example:
+    del ControlNetExampleForge
+
+```
+
 ![image](https://github.com/lllyasviel/stable-diffusion-webui-forge/assets/19834515/0a703d8b-27df-4608-8b12-aff750f20ffa)