[CodeCamp2023-305] Improve Visualizer Rendering Speed with OpenCV Backend

docs/en/design/visualization.md

@@ -13,6 +13,7 @@ Based on the above requirements, we proposed the `Visualizer` and various `VisBa
 
 - For convenience, the APIs provided by the `Visualizer` implement the drawing and storage functions.  As an internal property of `Visualizer`, `VisBackend` will be called by `Visualizer` to write data to different backends.
 - Considering that you may want to write data to multiple backends after drawing, `Visualizer` can be configured with multiple backends. When the user calls the storage API of the `Visualizer`, it will traverse and call all the specified APIs of `VisBackend` internally.
+- Considering the difference in drawing performance, the drawing `backend` is an internal property of `Visualizer`, and users can choose a drawing backend according to the usage scenario to balance drawing performance and richness of drawing functions.
 
 The UML diagram of the two is as follows.
 

docs/zh_cn/design/visualization.md

@@ -13,6 +13,7 @@
 
 - 为了方便调用，Visualizer 提供的接口实现了绘制和存储的功能。可视化存储后端 VisBackend 作为 Visualizer 的内部属性，会在需要的时候被 Visualizer 调用，将数据存到不同的后端
 - 考虑到绘制后会希望存储到多个后端，Visualizer 可以配置多个 VisBackend，当用户调用 Visualizer 的存储接口时候，Visualizer 内部会遍历的调用 VisBackend 存储接口
+- 考虑到绘图性能的差异，绘图后端 backend 作为 Visualizer 的内部属性，用户可根据使用场景选择绘图后端，以达到绘图性能和绘图功能丰富性的平衡
 
 两者的 UML 关系图如下
 

mmengine/visualization/utils.py

@@ -95,7 +95,8 @@ def color_val_matplotlib(
     colors: Union[str, tuple, List[Union[str, tuple]]]
 ) -> Union[str, tuple, List[Union[str, tuple]]]:
     """Convert various input in RGB order to normalized RGB matplotlib color
-    tuples,
+    tuples.
+
     Args:
         colors (Union[str, tuple, List[Union[str, tuple]]]): Color inputs
     Returns:
@@ -120,6 +121,35 @@ def color_val_matplotlib(
         raise TypeError(f'Invalid type for color: {type(colors)}')
 
 
+def color_val_opencv(
+    colors: Union[str, tuple, List[Union[str, tuple]]]
+) -> Union[tuple, List[tuple]]:
+    """Convert various input in RGB order to RGB color tuples.
+
+    Args:
+        colors (Union[str, tuple, List[Union[str, tuple]]]): Color inputs
+    Returns:
+        Union[str, tuple, List[Union[str, tuple]]]: A tuple of 3 ints
+        indicating RGB channels.
+    """
+    if isinstance(colors, str):
+        colors = color_str2rgb(colors)
+        return colors
+    elif isinstance(colors, tuple):
+        assert len(colors) == 3
+        for channel in colors:
+            assert 0 <= channel <= 255
+        return colors
+    elif isinstance(colors, list):
+        colors = [
+            color_val_opencv(color)  # type:ignore
+            for color in colors
+        ]
+        return colors  # type:ignore
+    else:
+        raise TypeError(f'Invalid type for color: {type(colors)}')
+
+
 def color_str2rgb(color: str) -> tuple:
     """Convert Matplotlib str color to an RGB color which range is 0 to 255,
     silently dropping the alpha channel.