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