<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def start_capture(self):
 """Start capturing the rectangle."""

        previous_map_tool = self.canvas.mapTool()
        if previous_map_tool != self.tool:
            self.previous_map_tool = previous_map_tool
        self.canvas.setMapTool(self.tool)
        self.hide()