[Enhance] add negative prompt for sd inferencer (open-mmlab#2021)

add negative prompt for sd

mmagic/apis/inferencers/text2image_inferencer.py

@@ -15,18 +15,23 @@ class Text2ImageInferencer(BaseMMagicInferencer):
     """inferencer that predicts with text2image models."""
 
     func_kwargs = dict(
-        preprocess=['text', 'control'],
+        preprocess=['text', 'control', 'negative_prompt'],
         forward=[],
         visualize=['result_out_dir'],
         postprocess=[])
 
     extra_parameters = dict(height=None, width=None, seed=1)
 
-    def preprocess(self, text: InputsType, control: str = None) -> Dict:
+    def preprocess(self,
+                   text: InputsType,
+                   control: str = None,
+                   negative_prompt: InputsType = None) -> Dict:
         """Process the inputs into a model-feedable format.
 
         Args:
             text(InputsType): text input for text-to-image model.
+            control(str): control img dir for controlnet.
+            negative_prompt(InputsType): negative prompt.
 
         Returns:
             result(Dict): Results of preprocess.
@@ -43,6 +48,9 @@ def preprocess(self, text: InputsType, control: str = None) -> Dict:
             result['control'] = control_img
             result.pop('seed', None)
 
+        if negative_prompt:
+            result['negative_prompt'] = negative_prompt
+
         return result
 
     def forward(self, inputs: InputsType) -> PredType: