detect true color

1 files changed, 22 insertions, 6 deletions

diff --git a/xmake/core/base/colors.lua b/xmake/core/base/colors.lua
index d0fedcd81..9fe7790ae 100644
--- a/xmake/core/base/colors.lua
+++ b/xmake/core/base/colors.lua
@@ -116,16 +116,32 @@ function colors.has256()
     end
 
     -- this is supported if exists ANSICON envirnoment variable on windows
-    return os.getenv("ANSICON") 
+    colors._ANSICON = colors._ANSICON or os.getenv("ANSICON")
+    return colors._ANSICON
 end
 
--- support 24bits true colors
+-- support 24bits true color
+--
+-- There's no reliable way, and ncurses/terminfo's maintainer expressed he has no intent on introducing support. 
+-- S-Lang author added a check for $COLORTERM containing either "truecolor" or "24bit" (case sensitive).
+-- In turn, VTE, Konsole and iTerm2 set this variable to "truecolor" (it's been there in VTE for a while, 
+-- it's relatively new and maybe still git-only in Konsole and iTerm2).
+--
+-- This is obviously not a reliable method, and is not forwarded via sudo, ssh etc. However, whenever it errs, 
+-- it errs on the safe side: does not advertise support whereas it's actually supported. 
+-- App developers can freely choose to check for this same variable, or introduce their own method
+-- (e.g. an option in their config file), whichever matches better the overall design of the given app. 
+-- Checking $COLORTERM is recommended though, since that would lead to a more unique desktop experience 
+-- where the user has to set one variable only and it takes effect across all the apps, rather than something 
+-- separately for each app.
+--
 function colors.truecolor()
 
-    -- this is supported if be not windows
-    if os.host() ~= "windows" then
---        return true
-    end
+    -- get $COLORTERM
+    colors._COLORTERM = colors._COLORTERM or os.getenv("COLORTERM") or ""
+
+    -- support true color?
+    return colors._COLORTERM:find("truecolor", 1, true) or colors._COLORTERM:find("24bit", 1, true)
 end
 
 -- make rainbow color code by the index of characters