diff --git a/chart.py b/chart.py
index 70e4392..150b74d 100644
--- a/chart.py
+++ b/chart.py
@@ -313,13 +313,20 @@ class QuantChart:
             return
 
         total_bars = len(df)
-        # TODO: k线拉到最早会报错
-        if bars_after < 0:
-            start_idx = max(0, int(bars_before))
-            end_idx = total_bars
-        else:
-            start_idx = int(bars_before)
-            end_idx = max(0, int(total_bars - bars_after))
+        # 计算可见范围的起始和结束索引
+        # if bars_after < 0:
+        #     start_idx = max(0, int(bars_before))
+        #     end_idx = total_bars
+        # elif bars_before < 0:
+        #     start_idx = 0
+        #     end_idx = max(0, int(total_bars - bars_after))
+        # else:
+        #     start_idx = int(bars_before)
+        #     end_idx = max(0, int(total_bars - bars_after))
+
+        start_idx = max(0, int(bars_before))
+        end_idx = max(0, int(total_bars - max(0, int(bars_after))))
+
         df_range = df.iloc[start_idx:end_idx]
         # logger.info(
         #     f"Calculating POC for bars {start_idx} to {end_idx}, total_bars={total_bars}, bars_before={bars_before}, bars_after={bars_after}"
@@ -335,10 +342,6 @@ class QuantChart:
         poc_line = chart.horizontal_line(
             price=poc, color="#FF0000", width=4, style="solid", text=f"{poc:.2f}"
         )
-        # chart.legend(
-        #     visible=True,
-        #     text=f"POC: {poc:.2f}, poc_range_profit%: {profit:.1f}%, visible_tf_cnt: {len(df_range)}",
-        # )
         legend_text = f"POC: {poc:.2f}, poc_range_profit%: {profit:.1f}%, visible_tf_cnt: {len(df_range)}"
         self.update_legend(chart=chart, key=poc_line_name, text=legend_text)