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// Copyright 2019 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
import (
runewidth "github.com/mattn/go-runewidth"
)
type cell struct {
currMain rune
currComb []rune
currStyle Style
lastMain rune
lastStyle Style
lastComb []rune
width int
}
// CellBuffer represents a two dimensional array of character cells.
// This is primarily intended for use by Screen implementors; it
// contains much of the common code they need. To create one, just
// declare a variable of its type; no explicit initialization is necessary.
//
// CellBuffer is not thread safe.
type CellBuffer struct {
w int
h int
cells []cell
}
// SetContent sets the contents (primary rune, combining runes,
// and style) for a cell at a given location.
func (cb *CellBuffer) SetContent(x int, y int,
mainc rune, combc []rune, style Style) {
if x >= 0 && y >= 0 && x < cb.w && y < cb.h {
c := &cb.cells[(y*cb.w)+x]
c.currComb = append([]rune{}, combc...)
if c.currMain != mainc {
c.width = runewidth.RuneWidth(mainc)
}
c.currMain = mainc
c.currStyle = style
}
}
// GetContent returns the contents of a character cell, including the
// primary rune, any combining character runes (which will usually be
// nil), the style, and the display width in cells. (The width can be
// either 1, normally, or 2 for East Asian full-width characters.)
func (cb *CellBuffer) GetContent(x, y int) (rune, []rune, Style, int) {
var mainc rune
var combc []rune
var style Style
var width int
if x >= 0 && y >= 0 && x < cb.w && y < cb.h {
c := &cb.cells[(y*cb.w)+x]
mainc, combc, style = c.currMain, c.currComb, c.currStyle
if width = c.width; width == 0 || mainc < ' ' {
width = 1
mainc = ' '
}
}
return mainc, combc, style, width
}
// Size returns the (width, height) in cells of the buffer.
func (cb *CellBuffer) Size() (int, int) {
return cb.w, cb.h
}
// Invalidate marks all characters within the buffer as dirty.
func (cb *CellBuffer) Invalidate() {
for i := range cb.cells {
cb.cells[i].lastMain = rune(0)
}
}
// Dirty checks if a character at the given location needs an
// to be refreshed on the physical display. This returns true
// if the cell content is different since the last time it was
// marked clean.
func (cb *CellBuffer) Dirty(x, y int) bool {
if x >= 0 && y >= 0 && x < cb.w && y < cb.h {
c := &cb.cells[(y*cb.w)+x]
if c.lastMain == rune(0) {
return true
}
if c.lastMain != c.currMain {
return true
}
if c.lastStyle != c.currStyle {
return true
}
if len(c.lastComb) != len(c.currComb) {
return true
}
for i := range c.lastComb {
if c.lastComb[i] != c.currComb[i] {
return true
}
}
}
return false
}
// SetDirty is normally used to indicate that a cell has
// been displayed (in which case dirty is false), or to manually
// force a cell to be marked dirty.
func (cb *CellBuffer) SetDirty(x, y int, dirty bool) {
if x >= 0 && y >= 0 && x < cb.w && y < cb.h {
c := &cb.cells[(y*cb.w)+x]
if dirty {
c.lastMain = rune(0)
} else {
if c.currMain == rune(0) {
c.currMain = ' '
}
c.lastMain = c.currMain
c.lastComb = c.currComb
c.lastStyle = c.currStyle
}
}
}
// Resize is used to resize the cells array, with different dimensions,
// while preserving the original contents. The cells will be invalidated
// so that they can be redrawn.
func (cb *CellBuffer) Resize(w, h int) {
if cb.h == h && cb.w == w {
return
}
newc := make([]cell, w*h)
for y := 0; y < h && y < cb.h; y++ {
for x := 0; x < w && x < cb.w; x++ {
oc := &cb.cells[(y*cb.w)+x]
nc := &newc[(y*w)+x]
nc.currMain = oc.currMain
nc.currComb = oc.currComb
nc.currStyle = oc.currStyle
nc.width = oc.width
nc.lastMain = rune(0)
}
}
cb.cells = newc
cb.h = h
cb.w = w
}
// Fill fills the entire cell buffer array with the specified character
// and style. Normally choose ' ' to clear the screen. This API doesn't
// support combining characters, or characters with a width larger than one.
func (cb *CellBuffer) Fill(r rune, style Style) {
for i := range cb.cells {
c := &cb.cells[i]
c.currMain = r
c.currComb = nil
c.currStyle = style
c.width = 1
}
}
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