Text and element colors of default theme change to be black on white terminals

Ref #181

CHANGELOG.md

@@ -16,6 +16,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Specifying `default` in the theme config uses the terminal's default background color, including transparency (#244, #245)
 - Redirects occur automatically if it only adds a trailing slash (#271)
 - Non-gemini links are underlined by default to help color blind users (#189)
+- Text and element colors of default theme change to be black on white terminals (#181)
 
 ### Changed
 - Bookmarks are stored using XML in the XBEL format, old bookmarks are transferred (#68)
@@ -24,7 +25,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - The user's terminal theme colors are used by default (#181)
 
 ## Removed
-- Favicon support removed (#199)
+- Favicon support (#199)
 - The default Amfora theme, get it back [here](https://github.com/makeworld-the-better-one/amfora/blob/master/contrib/themes/amfora.toml)
 
 ### Fixed

NOTES.md

@@ -6,7 +6,6 @@
 ## Upstream Bugs
 - Bookmark keys aren't deleted, just set to `""`
   - Waiting on [this viper PR](https://github.com/spf13/viper/pull/519) to be merged
-- [cview.Styles not being used](https://code.rocketnine.space/tslocum/cview/issues/47) - issue is circumvented in Amfora
 - [ANSI conversion is messed up](https://code.rocketnine.space/tslocum/cview/issues/48)
 - [WordWrap is broken in some cases](https://code.rocketnine.space/tslocum/cview/issues/27) - close #156 if this is fixed
 - [Prevent panic when reformatting](https://code.rocketnine.space/tslocum/cview/issues/50) - can't reliably reproduce or debug

config/config.go

@@ -15,6 +15,7 @@ import (
 	"github.com/gdamore/tcell/v2"
 	"github.com/makeworld-the-better-one/amfora/cache"
 	homedir "github.com/mitchellh/go-homedir"
+	"github.com/muesli/termenv"
 	"github.com/rkoesters/xdg/basedir"
 	"github.com/rkoesters/xdg/userdirs"
 	"github.com/spf13/viper"
@@ -59,6 +60,11 @@ var MediaHandlers = make(map[string]MediaHandler)
 // Defaults to ScrollBarAuto on an invalid value
 var ScrollBar cview.ScrollBarVisibility
 
+// Whether the user's terminal is dark or light
+// Defaults to dark, but is determined in Init()
+// Used to prevent white text on a white background with the default theme
+var hasDarkTerminalBackground bool
+
 func Init() error {
 
 	// *** Set paths ***
@@ -370,7 +376,14 @@ func Init() error {
 	}
 	if viper.GetBool("a-general.color") {
 		cview.Styles.PrimitiveBackgroundColor = GetColor("bg")
-	} // Otherwise it's black by default
+	} else {
+		// No colors allowed, set backgroud to black instead of default
+		themeMu.Lock()
+		theme["bg"] = tcell.ColorBlack
+		cview.Styles.PrimitiveBackgroundColor = tcell.ColorBlack
+	}
+
+	hasDarkTerminalBackground = termenv.HasDarkBackground()
 
 	// Parse HTTP command
 	HTTPCommand = viper.GetStringSlice("a-general.http")

config/theme.go

@@ -11,27 +11,43 @@ import (
 // UI element tcell.Colors are mapped to a string key, such as "error" or "tab_bg"
 // These are the same keys used in the config file.
 
+// Special color with no real color value
+// Used for a default foreground color
+// White is the terminal background is black, black if the terminal background is white
+// Converted to a real color in this file before being sent out to other modules
+const ColorFg = tcell.ColorSpecial | 2
+
+// The same as ColorFg, but inverted
+const ColorBg = tcell.ColorSpecial | 3
+
 var themeMu = sync.RWMutex{}
 var theme = map[string]tcell.Color{
+	// Map these for special uses in code
+	"ColorBg": ColorBg,
+	"ColorFg": ColorFg,
+
 	// Default values below
 	// Only the 16 Xterm system tcell.Colors are used, because those are the tcell.Colors overrided
 	// by the user's default terminal theme
 
 	// Used for cview.Styles.PrimitiveBackgroundColor
 	// Set to tcell.ColorDefault because that allows transparent terminals to work
-	// The rest of this theme assumes that the background is equivalent to tcell.Color zero, or black.
+	// The rest of this theme assumes that the background is equivalent to black, but
+	// white colors switched to black later if the background is determined to be white.
+	//
+	// Also, this is set to tcell.ColorBlack in config.go if colors are disabled in the config.
 	"bg": tcell.ColorDefault,
 
 	"tab_num":         tcell.ColorTeal,
-	"tab_divider":     tcell.ColorWhite,
+	"tab_divider":     ColorFg,
 	"bottombar_label": tcell.ColorTeal,
-	"bottombar_text":  tcell.ColorBlack,
+	"bottombar_text":  ColorBg,
-	"bottombar_bg":    tcell.ColorWhite,
+	"bottombar_bg":    ColorFg,
-	"scrollbar":       tcell.ColorWhite,
+	"scrollbar":       ColorFg,
 
 	// Modals
-	"btn_bg":   tcell.ColorTeal, // All modal buttons
+	"btn_bg":   tcell.ColorTeal,  // All modal buttons
-	"btn_text": tcell.ColorWhite,
+	"btn_text": tcell.ColorWhite, // White instead of ColorFg because background is known to be Teal
 
 	"dl_choice_modal_bg":      tcell.ColorOlive,
 	"dl_choice_modal_text":    tcell.ColorWhite,
@@ -65,10 +81,10 @@ var theme = map[string]tcell.Color{
 	"amfora_link":       tcell.ColorBlue,
 	"foreign_link":      tcell.ColorPurple,
 	"link_number":       tcell.ColorSilver,
-	"regular_text":      tcell.ColorWhite,
+	"regular_text":      ColorFg,
-	"quote_text":        tcell.ColorWhite,
+	"quote_text":        ColorFg,
-	"preformatted_text": tcell.ColorWhite,
+	"preformatted_text": ColorFg,
-	"list_text":         tcell.ColorWhite,
+	"list_text":         ColorFg,
 }
 
 func SetColor(key string, color tcell.Color) {
@@ -83,7 +99,23 @@ func SetColor(key string, color tcell.Color) {
 func GetColor(key string) tcell.Color {
 	themeMu.RLock()
 	defer themeMu.RUnlock()
-	return theme[key]
+
+	color := theme[key]
+
+	if color == ColorFg {
+		if hasDarkTerminalBackground {
+			return tcell.ColorWhite
+		}
+		return tcell.ColorBlack
+	}
+	if color == ColorBg {
+		if hasDarkTerminalBackground {
+			return tcell.ColorBlack
+		}
+		return tcell.ColorWhite
+	}
+
+	return color
 }
 
 // colorToString converts a color to a string for use in a cview tag
@@ -92,6 +124,19 @@ func colorToString(color tcell.Color) string {
 		return "-"
 	}
 
+	if color == ColorFg {
+		if hasDarkTerminalBackground {
+			return "white"
+		}
+		return "black"
+	}
+	if color == ColorBg {
+		if hasDarkTerminalBackground {
+			return "black"
+		}
+		return "white"
+	}
+
 	if color&tcell.ColorIsRGB == 0 {
 		// tcell.Color is not RGB/TrueColor, it's a tcell.Color from the default terminal
 		// theme as set above
@@ -99,6 +144,7 @@ func colorToString(color tcell.Color) string {
 		return ColorToColorName[color]
 	}
 
+	// Color set by user, must be respected exactly so hex code is used
 	return fmt.Sprintf("#%06x", color.Hex())
 }
 

display/display.go

@@ -96,8 +96,6 @@ func Init(version, commit, builtBy string) {
 	layout.AddItem(bottomBar, 1, 1, false)
 
 	if viper.GetBool("a-general.color") {
-		layout.SetBackgroundColor(config.GetColor("bg"))
-
 		bottomBar.SetBackgroundColor(config.GetColor("bottombar_bg"))
 		bottomBar.SetLabelColor(config.GetColor("bottombar_label"))
 		bottomBar.SetFieldBackgroundColor(config.GetColor("bottombar_bg"))
@@ -106,7 +104,7 @@ func Init(version, commit, builtBy string) {
 		browser.SetTabBackgroundColor(config.GetColor("bg"))
 		browser.SetTabBackgroundColorFocused(config.GetColor("tab_num"))
 		browser.SetTabTextColor(config.GetColor("tab_num"))
-		browser.SetTabTextColorFocused(config.GetTextColor("bg", "tab_num"))
+		browser.SetTabTextColorFocused(config.GetColor("ColorBg"))
 		browser.SetTabSwitcherDivider(
 			"",
 			fmt.Sprintf("[%s:%s]|[-]", config.GetColorString("tab_divider"), config.GetColorString("bg")),

go.mod

@@ -13,6 +13,7 @@ require (
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/mitchellh/mapstructure v1.3.1 // indirect
 	github.com/mmcdole/gofeed v1.1.2
+	github.com/muesli/termenv v0.9.0
 	github.com/pelletier/go-toml v1.8.0 // indirect
 	github.com/rkoesters/xdg v0.0.0-20181125232953-edd15b846f9b
 	github.com/schollz/progressbar/v3 v3.8.0

go.sum

@@ -143,6 +143,8 @@ github.com/makeworld-the-better-one/go-gemini v0.11.0/go.mod h1:F+3x+R1xeYK90jMt
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=
 github.com/mattn/go-isatty v0.0.3/go.mod h1:M+lRXTBqGeGNdLjl/ufCoiOlB5xdOkqRJdNxMWT7Zi4=
 github.com/mattn/go-isatty v0.0.12/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
+github.com/mattn/go-isatty v0.0.13 h1:qdl+GuBjcsKKDco5BsxPJlId98mSWNKqYA+Co0SC1yA=
+github.com/mattn/go-isatty v0.0.13/go.mod h1:cbi8OIDigv2wuxKPP5vlRcQ1OAZbq2CE4Kysco4FUpU=
 github.com/mattn/go-runewidth v0.0.10/go.mod h1:RAqKPSqVFrSLVXbA8x7dzmKdmGzieGRCM46jaSJTDAk=
 github.com/mattn/go-runewidth v0.0.13 h1:lTGmDsbAYt5DmK6OnoV7EuIF1wEIFAcxld6ypU4OSgU=
 github.com/mattn/go-runewidth v0.0.13/go.mod h1:Jdepj2loyihRzMpdS35Xk/zdY8IAYHsh153qUoGf23w=
@@ -171,6 +173,8 @@ github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd/go.mod h1:6dJ
 github.com/modern-go/reflect2 v0.0.0-20180701023420-4b7aa43c6742/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
 github.com/modern-go/reflect2 v1.0.1 h1:9f412s+6RmYXLWZSEzVVgPGK7C2PphHj5RJrvfx9AWI=
 github.com/modern-go/reflect2 v1.0.1/go.mod h1:bx2lNnkwVCuqBIxFjflWJWanXIb3RllmbCylyMrvgv0=
+github.com/muesli/termenv v0.9.0 h1:wnbOaGz+LUR3jNT0zOzinPnyDaCZUQRZj9GxK8eRVl8=
+github.com/muesli/termenv v0.9.0/go.mod h1:R/LzAKf+suGs4IsO95y7+7DpFHO0KABgnZqtlyx2mBw=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
 github.com/oklog/ulid v1.3.1/go.mod h1:CirwcVhetQ6Lv90oh/F+FBtV6XMibvdAFo93nm5qn4U=
 github.com/pascaldekloe/goe v0.0.0-20180627143212-57f6aae5913c/go.mod h1:lzWF7FIEvWOWxwDKqyGYQf6ZUaNfKdP144TG7ZOy1lc=