add 'before_hr callback' script callback

modules/processing.py

@@ -1074,6 +1074,9 @@ class StableDiffusionProcessingTxt2Img(StableDiffusionProcessing):
 
         sd_models.apply_token_merging(self.sd_model, self.get_token_merging_ratio(for_hr=True))
 
+        if self.scripts is not None:
+            self.scripts.before_hr(self)
+
         samples = self.sampler.sample_img2img(self, samples, noise, self.hr_c, self.hr_uc, steps=self.hr_second_pass_steps or self.steps, image_conditioning=image_conditioning)
 
         sd_models.apply_token_merging(self.sd_model, self.get_token_merging_ratio())

modules/scripts.py

@@ -186,6 +186,11 @@ class Script:
 
         return f'script_{tabname}{title}_{item_id}'
 
+    def before_hr(self, p ,*args):
+        """
+        This function is called before hires fix start.
+        """
+        pass
 
 current_basedir = paths.script_path
 
@@ -548,6 +553,15 @@ class ScriptRunner:
                     self.scripts[si].args_to = args_to
 
 
+    def before_hr(self, p):
+        for script in self.alwayson_scripts:
+            try:
+                script_args = p.script_args[script.args_from:script.args_to]
+                script.before_hr(p, *script_args)
+            except Exception:
+                errors.report(f"Error running before_hr: {script.filename}", exc_info=True)
+
+
 scripts_txt2img: ScriptRunner = None
 scripts_img2img: ScriptRunner = None
 scripts_postproc: scripts_postprocessing.ScriptPostprocessingRunner = None