stats.lua: make page 1 scrollable

This makes page 1 scrollable with up and down keys.

The trick here to avoid a large append parameter refactoring is to
make the append function add the table index only if the newline
character is not empty. Otherwise, new strings are appended to the
existing string.

player/lua/stats.lua

@@ -263,7 +263,10 @@ local function append(s, str, attr)
     attr.prefix = attr.prefix or ""
     attr.no_prefix_markup = attr.no_prefix_markup or false
     attr.prefix = attr.no_prefix_markup and attr.prefix or b(attr.prefix)
-    s[#s+1] = format("%s%s%s%s%s%s", attr.nl, attr.indent,
+
+    local index = #s + (attr.nl == "" and 0 or 1)
+    s[index] = s[index] or ""
+    s[index] = s[index] .. format("%s%s%s%s%s%s", attr.nl, attr.indent,
                      attr.prefix, attr.prefix_sep, no_ASS(str), attr.suffix)
     return true
 end
@@ -640,7 +643,7 @@ end
 
 
 local function add_file(s)
-    append(s, "", {prefix="File:", nl="", indent=""})
+    append(s, "", {prefix="File:", indent=""})
     append_property(s, "filename", {prefix_sep="", nl="", indent=""})
     if not (mp.get_property_osd("filename") == mp.get_property_osd("media-title")) then
         append_property(s, "media-title", {prefix="Title:"})
@@ -884,7 +887,7 @@ local function add_video_out(s)
         return
     end
 
-    append(s, "", {prefix=o.nl .. o.nl .. "Display:", nl="", indent=""})
+    append(s, "", {prefix="Display:", nl=o.nl .. o.nl, indent=""})
     append(s, vo, {prefix_sep="", nl="", indent=""})
     append_property(s, "display-names", {prefix_sep="", prefix="(", suffix=")",
                                          no_prefix_markup=true, nl="", indent=" "})
@@ -937,7 +940,7 @@ local function add_video(s)
         return
     end
 
-    append(s, "", {prefix=o.nl .. o.nl .. "Video:", nl="", indent=""})
+    append(s, "", {prefix="Video:", nl=o.nl .. o.nl, indent=""})
     local track = mp.get_property_native("current-tracks/video")
     if track and append(s, track["codec-desc"], {prefix_sep="", nl="", indent=""}) then
         append(s, track["codec-profile"], {prefix="[", nl="", indent=" ", prefix_sep="",
@@ -997,7 +1000,7 @@ local function add_audio(s)
         return (a == b or a == nil) and a or (a .. " ➜ " .. b)
     end
 
-    append(s, "", {prefix=o.nl .. o.nl .. "Audio:", nl="", indent=""})
+    append(s, "", {prefix="Audio:", nl=o.nl .. o.nl, indent=""})
     local track = mp.get_property_native("current-tracks/audio")
     if track then
         append(s, track["codec-desc"], {prefix_sep="", nl="", indent=""})
@@ -1137,14 +1140,16 @@ end
 
 -- Returns an ASS string with "normal" stats
 local function default_stats()
-    local stats = {}
+    local header, content = {}, {}
     eval_ass_formatting()
-    add_header(stats)
-    add_file(stats)
-    add_video_out(stats)
-    add_video(stats)
-    add_audio(stats)
-    return finalize_page({}, stats, false)
+    add_header(header)
+    local page = pages[o.key_page_1]
+    append(header, "", {prefix=format("%s:%s", page.desc, scroll_hint()), nl="", indent=""})
+    add_file(content)
+    add_video_out(content)
+    add_video(content)
+    add_audio(content)
+    return finalize_page(header, content, true)
 end
 
 -- Returns an ASS string with extended VO stats
@@ -1266,7 +1271,7 @@ local function cache_stats()
     append(stats, info["debug-low-level-seeks"], {prefix = "Media Seeks:"})
     append(stats, info["debug-byte-level-seeks"], {prefix = "Stream Seeks:"})
 
-    append(stats, "", {prefix=o.nl .. o.nl .. "Ranges:", nl="", indent=""})
+    append(stats, "", {prefix="Ranges:", nl=o.nl .. o.nl, indent=""})
 
     append(stats, info["bof-cached"] and "yes" or "no",
            {prefix = "Start Cached:"})
@@ -1306,7 +1311,7 @@ cache_recorder_timer:kill()
 -- Current page and <page key>:<page function> mapping
 curr_page = o.key_page_1
 pages = {
-    [o.key_page_1] = { f = default_stats, desc = "Default" },
+    [o.key_page_1] = { f = default_stats, desc = "Usual Statistics", scroll = true },
     [o.key_page_2] = { f = vo_stats, desc = "Extended Frame Timings", scroll = true },
     [o.key_page_3] = { f = cache_stats, desc = "Cache Statistics" },
     [o.key_page_4] = { f = keybinding_info, desc = "Active Key Bindings", scroll = true },