NEZ-316 fix: alert message current 查询处理labels为空的情况 & alert message图表添加阈值提示

nezha-fronted/src/components/charts/line-chart-block.vue

@@ -1146,6 +1146,7 @@
                             }
                           },
                           lineStyle:{
+                            color:'#d64f40',
                             width:2,
                             type:'dotted'
                           },
@@ -1236,10 +1237,15 @@
           });
         });
       },
-      computeDistance:function(value){
-        let temp=value+'';
-        let length=temp.length *12 -20;
-        return Number('-'+length)
+      computeDistance:function(str){
+        var width = 0;
+        var html = document.createElement('span');
+        html.innerText = str;
+        html.className = 'getTextWidth';
+        document.querySelector('body').appendChild(html);
+        width = document.querySelector('.getTextWidth').offsetWidth;
+        document.querySelector('.getTextWidth').remove();
+        return Number('-'+width);
       },
       showLoad(chartItem) {
         //设置高度