TUN-3201: Create base cloudflared UI structure

vendor/github.com/gdamore/tcell/style.go

@@ -0,0 +1,126 @@
+// Copyright 2015 The TCell Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use file except in compliance with the License.
+// You may obtain a copy of the license at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package tcell
+
+// Style represents a complete text style, including both foreground
+// and background color.  We encode it in a 64-bit int for efficiency.
+// The coding is (MSB): <7b flags><1b><24b fgcolor><7b attr><1b><24b bgcolor>.
+// The <1b> is set true to indicate that the color is an RGB color, rather
+// than a named index.
+//
+// This gives 24bit color options, if it ever becomes truly necessary.
+// However, applications must not rely on this encoding.
+//
+// Note that not all terminals can display all colors or attributes, and
+// many might have specific incompatibilities between specific attributes
+// and color combinations.
+//
+// The intention is to extend styles to support paletting, in which case
+// some flag bit(s) would be set, and the foreground and background colors
+// would be replaced with a palette number and palette index.
+//
+// To use Style, just declare a variable of its type.
+type Style int64
+
+// StyleDefault represents a default style, based upon the context.
+// It is the zero value.
+const StyleDefault Style = 0
+
+// styleFlags -- used internally for now.
+const (
+	styleBgSet = 1 << (iota + 57)
+	styleFgSet
+	stylePalette
+)
+
+// Foreground returns a new style based on s, with the foreground color set
+// as requested.  ColorDefault can be used to select the global default.
+func (s Style) Foreground(c Color) Style {
+	if c == ColorDefault {
+		return (s &^ (0x1ffffff00000000 | styleFgSet))
+	}
+	return (s &^ Style(0x1ffffff00000000)) |
+		((Style(c) & 0x1ffffff) << 32) | styleFgSet
+}
+
+// Background returns a new style based on s, with the background color set
+// as requested.  ColorDefault can be used to select the global default.
+func (s Style) Background(c Color) Style {
+	if c == ColorDefault {
+		return (s &^ (0x1ffffff | styleBgSet))
+	}
+	return (s &^ (0x1ffffff)) | (Style(c) & 0x1ffffff) | styleBgSet
+}
+
+// Decompose breaks a style up, returning the foreground, background,
+// and other attributes.
+func (s Style) Decompose() (fg Color, bg Color, attr AttrMask) {
+	if s&styleFgSet != 0 {
+		fg = Color(s>>32) & 0x1ffffff
+	} else {
+		fg = ColorDefault
+	}
+	if s&styleBgSet != 0 {
+		bg = Color(s & 0x1ffffff)
+	} else {
+		bg = ColorDefault
+	}
+	attr = AttrMask(s) & attrAll
+
+	return fg, bg, attr
+}
+
+func (s Style) setAttrs(attrs Style, on bool) Style {
+	if on {
+		return s | attrs
+	}
+	return s &^ attrs
+}
+
+// Normal returns the style with all attributes disabled.
+func (s Style) Normal() Style {
+	return s &^ Style(attrAll)
+}
+
+// Bold returns a new style based on s, with the bold attribute set
+// as requested.
+func (s Style) Bold(on bool) Style {
+	return s.setAttrs(Style(AttrBold), on)
+}
+
+// Blink returns a new style based on s, with the blink attribute set
+// as requested.
+func (s Style) Blink(on bool) Style {
+	return s.setAttrs(Style(AttrBlink), on)
+}
+
+// Dim returns a new style based on s, with the dim attribute set
+// as requested.
+func (s Style) Dim(on bool) Style {
+	return s.setAttrs(Style(AttrDim), on)
+}
+
+// Reverse returns a new style based on s, with the reverse attribute set
+// as requested.  (Reverse usually changes the foreground and background
+// colors.)
+func (s Style) Reverse(on bool) Style {
+	return s.setAttrs(Style(AttrReverse), on)
+}
+
+// Underline returns a new style based on s, with the underline attribute set
+// as requested.
+func (s Style) Underline(on bool) Style {
+	return s.setAttrs(Style(AttrUnderline), on)
+}