style: customize vertical and horizontal border characters

New border-char-horizontal and border-char-vertical config settings in
aerc.conf allow users to modify border appearance from the default
1-wide/tall blank space. In stylesets, border.fg now affects the
foreground color when custom characters are defined.

Signed-off-by: Robin Jarry <robin@jarry.cc>

config/aerc.conf.in

@@ -94,6 +94,12 @@ next-message-on-delete=true
 # default: @SHAREDIR@/stylesets/
 stylesets-dirs=@SHAREDIR@/stylesets/
 
+# Uncomment to use box-drawing characters for vertical and horizontal borders.
+#
+# Default: spaces
+# border-char-vertical=│
+# border-char-horizontal=─
+
 # Sets the styleset to use for the aerc ui elements.
 #
 # Default: default

config/config.go

@@ -53,6 +53,9 @@ type UIConfig struct {
 	StyleSetDirs        []string      `ini:"stylesets-dirs" delim:":"`
 	StyleSetName        string        `ini:"styleset-name"`
 	style               StyleSet
+	// customize border appearance
+	BorderCharVertical   rune `ini:"-"`
+	BorderCharHorizontal rune `ini:"-"`
 }
 
 type ContextType int
@@ -358,6 +361,9 @@ func (config *AercConfig) LoadConfig(file *ini.File) error {
 		if err := ui.MapTo(&config.Ui); err != nil {
 			return err
 		}
+		if err := validateBorderChars(ui, &config.Ui); err != nil {
+			return err
+		}
 	}
 	for _, sectionName := range file.SectionStrings() {
 		if !strings.Contains(sectionName, "ui:") {
@@ -372,6 +378,9 @@ func (config *AercConfig) LoadConfig(file *ini.File) error {
 		if err := uiSection.MapTo(&uiSubConfig); err != nil {
 			return err
 		}
+		if err := validateBorderChars(uiSection, &uiSubConfig); err != nil {
+			return err
+		}
 		contextualUi :=
 			UIConfigContext{
 				UiConfig: uiSubConfig,
@@ -461,6 +470,26 @@ func (config *AercConfig) LoadConfig(file *ini.File) error {
 	return nil
 }
 
+func validateBorderChars(section *ini.Section, config *UIConfig) error {
+	for key, val := range section.KeysHash() {
+		switch key {
+		case "border-char-vertical":
+			char := []rune(val)
+			if len(char) != 1 {
+				return fmt.Errorf("%v must be one and only one character", key)
+			}
+			config.BorderCharVertical = char[0]
+		case "border-char-horizontal":
+			char := []rune(val)
+			if len(char) != 1 {
+				return fmt.Errorf("%v must be one and only one character", key)
+			}
+			config.BorderCharHorizontal = char[0]
+		}
+	}
+	return nil
+}
+
 func LoadConfigFromFile(root *string, sharedir string) (*AercConfig, error) {
 	if root == nil {
 		_root := path.Join(xdg.ConfigHome(), "aerc")
@@ -524,6 +553,9 @@ func LoadConfigFromFile(root *string, sharedir string) (*AercConfig, error) {
 			CompletionPopovers:  true,
 			StyleSetDirs:        []string{path.Join(sharedir, "stylesets")},
 			StyleSetName:        "default",
+			// border defaults
+			BorderCharVertical:   ' ',
+			BorderCharHorizontal: ' ',
 		},
 
 		ContextualUis: []UIConfigContext{},

doc/aerc-config.5.scd

@@ -192,6 +192,13 @@ These options are configured in the *[ui]* section of aerc.conf.
 
 	Default: 250ms
 
+*border-char-vertical*
+*border-char-horizontal*
+	Set stylable characters (via the 'border' element) for vertical and
+	horizontal borders.
+
+	Default: spaces
+
 *stylesets-dirs*
 	The directories where the stylesets are stored. The config takes a
 	colon-separated list of dirs.

doc/aerc-stylesets.7.scd

@@ -128,7 +128,7 @@ styling.
 |  spinner
 :  The style for the loading spinner.
 |  border
-:  The style used to draw borders. *Only the background color is used*.
+:  The style used to draw borders. *Only the background color is used unless you customize border-char-vertical and/or border-char-horizontal in aerc.conf*.
 |  selector_default
 :  The default style for the selector ui element.
 |  selector_focused

lib/ui/borders.go

@@ -50,22 +50,25 @@ func (bordered *Bordered) Draw(ctx *Context) {
 	width := ctx.Width()
 	height := ctx.Height()
 	style := bordered.uiConfig.GetStyle(config.STYLE_BORDER)
+	verticalChar := bordered.uiConfig.BorderCharVertical
+	horizontalChar := bordered.uiConfig.BorderCharHorizontal
+
 	if bordered.borders&BORDER_LEFT != 0 {
-		ctx.Fill(0, 0, 1, ctx.Height(), ' ', style)
+		ctx.Fill(0, 0, 1, ctx.Height(), verticalChar, style)
 		x += 1
 		width -= 1
 	}
 	if bordered.borders&BORDER_TOP != 0 {
-		ctx.Fill(0, 0, ctx.Width(), 1, ' ', style)
+		ctx.Fill(0, 0, ctx.Width(), 1, horizontalChar, style)
 		y += 1
 		height -= 1
 	}
 	if bordered.borders&BORDER_RIGHT != 0 {
-		ctx.Fill(ctx.Width()-1, 0, 1, ctx.Height(), ' ', style)
+		ctx.Fill(ctx.Width()-1, 0, 1, ctx.Height(), verticalChar, style)
 		width -= 1
 	}
 	if bordered.borders&BORDER_BOTTOM != 0 {
-		ctx.Fill(0, ctx.Height()-1, ctx.Width(), 1, ' ', style)
+		ctx.Fill(0, ctx.Height()-1, ctx.Width(), 1, horizontalChar, style)
 		height -= 1
 	}
 	subctx := ctx.Subcontext(x, y, width, height)

widgets/compose.go

@@ -679,9 +679,10 @@ func (c *Composer) updateGrid() {
 		c.grid.RemoveChild(c.heditors)
 	}
 	borderStyle := c.config.Ui.GetStyle(config.STYLE_BORDER)
+	borderChar := c.config.Ui.BorderCharHorizontal
 	c.heditors = heditors
 	c.grid.AddChild(c.heditors).At(0, 0)
-	c.grid.AddChild(ui.NewFill(' ', borderStyle)).At(1, 0)
+	c.grid.AddChild(ui.NewFill(borderChar, borderStyle)).At(1, 0)
 }
 
 func (c *Composer) reloadEmail() error {

widgets/msgviewer.go

@@ -106,14 +106,15 @@ func NewMessageViewer(acct *AccountView,
 	}
 
 	borderStyle := acct.UiConfig().GetStyle(config.STYLE_BORDER)
+	borderChar := acct.UiConfig().BorderCharHorizontal
 
 	grid.AddChild(header).At(0, 0)
 	if msg.PGPDetails() != nil {
 		grid.AddChild(NewPGPInfo(msg.PGPDetails(), acct.UiConfig())).At(1, 0)
-		grid.AddChild(ui.NewFill(' ', borderStyle)).At(2, 0)
+		grid.AddChild(ui.NewFill(borderChar, borderStyle)).At(2, 0)
 		grid.AddChild(switcher).At(3, 0)
 	} else {
-		grid.AddChild(ui.NewFill(' ', borderStyle)).At(1, 0)
+		grid.AddChild(ui.NewFill(borderChar, borderStyle)).At(1, 0)
 		grid.AddChild(switcher).At(2, 0)
 	}