1 files changed, 33 insertions, 0 deletions
diff --git a/src/io/term.nim b/src/io/term.nim
index 0406907d..518990e3 100644
--- a/src/io/term.nim
+++ b/src/io/term.nim
@@ -42,6 +42,7 @@ type
     cleared: bool
     prevgrid: FixedGrid
     attrs*: WindowAttributes
+    mincontrast: float
     colormode: ColorMode
     formatmode: FormatMode
     smcup: bool
@@ -162,6 +163,32 @@ proc disableAltScreen(term: Terminal): string =
   else:
     return RMCUP()
 
+proc distance(a, b: CellColor): float =
+  let a = if a.rgb:
+    a.rgbcolor
+  elif a == defaultColor:
+    ColorsRGB["black"]
+  else:
+    ANSIColorMap[a.color mod 10]
+  let b = if b.rgb:
+    b.rgbcolor
+  elif b == defaultColor:
+    ColorsRGB["white"]
+  else:
+    ANSIColorMap[b.color mod 10]
+  sqrt(float((a.r - b.r) ^  2 + (a.g - b.b) ^ 2 + (a.g - b.g) ^ 2))
+
+proc invert(color: CellColor, bg: bool): CellColor =
+  if color == defaultColor:
+    if bg:
+      return CellColor(rgb: true, rgbcolor: ColorsRGB["white"])
+    else:
+      return CellColor(rgb: true, rgbcolor: ColorsRGB["black"])
+  elif color.rgb:
+    return CellColor(rgb: true, rgbcolor: RGBColor(0xFFFFFF - uint32(color.rgbcolor)))
+  else:
+    return CellColor(rgb: true, rgbcolor: RGBColor(0xFFFFFF - uint32(ANSIColorMap[color.color mod 10])))
+
 # Use euclidian distance to quantize RGB colors.
 proc approximateANSIColor(rgb: RGBColor, exclude = -1): int =
   var a = 0
@@ -183,6 +210,11 @@ proc processFormat*(term: Terminal, format: var Format, cellf: Format): string =
         result &= SGR(FormatCodes[flag].e)
 
   var cellf = cellf
+  if term.mincontrast >= 0 and distance(cellf.bgcolor, cellf.fgcolor) <= term.mincontrast:
+    cellf.fgcolor = invert(cellf.fgcolor, false)
+    if distance(cellf.bgcolor, cellf.fgcolor) <= term.mincontrast:
+      cellf.fgcolor = defaultColor
+      cellf.bgcolor = defaultColor
   case term.colormode
   of ANSI, EIGHT_BIT:
     if cellf.bgcolor.rgb:
@@ -416,6 +448,7 @@ proc detectTermAttributes(term: Terminal) =
     term.formatmode = term.config.formatmode.get
   if term.config.altscreen.isSome:
     term.smcup = term.config.altscreen.get
+  term.mincontrast = term.config.mincontrast
 
 proc start*(term: Terminal, infile: File) =
   term.infile = infile