From 7cd0ba6667c62405edf232192f479e2f9118063f Mon Sep 17 00:00:00 2001
From: Falko Schindler <falko@zauberzeug.com>
Date: Fri, 6 Aug 2021 17:11:10 +0200
Subject: [PATCH] readonly log view, max_lines argument, escaping special
 characters

---
 nicegui/elements/log.js | 16 ++++++++++++++--
 nicegui/elements/log.py | 15 +++++++++------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/nicegui/elements/log.js b/nicegui/elements/log.js
index b4fce92ec..c171d1781 100644
--- a/nicegui/elements/log.js
+++ b/nicegui/elements/log.js
@@ -1,13 +1,25 @@
+var num_lines = 0;
+
 Vue.component("log", {
-  template: `<textarea v-bind:id="jp_props.id" :class="jp_props.classes" :style="jp_props.style"></textarea>`,
+  template: `<textarea v-bind:id="jp_props.id" :class="jp_props.classes" :style="jp_props.style" disabled></textarea>`,
   mounted() {
     comp_dict[this.$props.jp_props.id] = this;
   },
   methods: {
     push(line) {
+      const decoded = decodeURI(line);
       const textarea = document.getElementById(this.$props.jp_props.id);
-      textarea.innerHTML += (textarea.innerHTML ? "\n" : "") + line;
+      textarea.innerHTML += (num_lines ? "\n" : "") + decoded;
       textarea.scrollTop = textarea.scrollHeight;
+      num_lines += decoded.split("\n").length;
+
+      const max_lines = this.$props.jp_props.options.max_lines;
+      while (max_lines != null && num_lines > max_lines) {
+        const index = textarea.innerHTML.indexOf("\n");
+        if (index == -1) break;
+        textarea.innerHTML = textarea.innerHTML.slice(index + 1);
+        num_lines -= 1;
+      }
     },
   },
   props: {
diff --git a/nicegui/elements/log.py b/nicegui/elements/log.py
index b909709dd..c39b53cd7 100644
--- a/nicegui/elements/log.py
+++ b/nicegui/elements/log.py
@@ -1,30 +1,33 @@
 import asyncio
+import urllib
 from justpy.htmlcomponents import WebPage
 from .custom_view import CustomView
 from .element import Element
 
 class LogView(CustomView):
 
-    def __init__(self):
+    def __init__(self, max_lines: int):
 
-        super().__init__('log', __file__)
+        super().__init__('log', __file__, max_lines=max_lines)
 
 class Log(Element):
 
-    def __init__(self):
+    def __init__(self, max_lines: int = None):
         """Log view
 
         Create a log view that allows to add new lines without re-transmitting the whole history to the client.
+
+        :param max_lines: maximum number of lines before dropping oldest ones (default: None)
         """
 
-        super().__init__(LogView())
+        super().__init__(LogView(max_lines=max_lines))
 
-        self.classes('border whitespace-pre font-mono')
+        self.classes('border whitespace-pre font-mono').style('opacity: 1 !important')
 
     async def push_async(self, line: str):
 
         await asyncio.gather(*[
-            self.view.run_method(f'push("{line}")', socket)
+            self.view.run_method(f'push("{urllib.parse.quote(line)}")', socket)
             for socket in WebPage.sockets[Element.wp.page_id].values()
         ])