src/Buffer.ts

   1 /**
   2  * @license MIT
   3  */
   4
   5 import { ITerminal, IBuffer } from './Interfaces';
   6 import { CircularList } from './utils/CircularList';
   7
   8 /**
   9  * This class represents a terminal buffer (an internal state of the terminal), where the
  10  * following information is stored (in high-level):
  11  *   - text content of this particular buffer
  12  *   - cursor position
  13  *   - scroll position
  14  */
  15 export class Buffer implements IBuffer {
  16   private _lines: CircularList<[number, string, number][]>;
  17
  18   public ydisp: number;
  19   public ybase: number;
  20   public y: number;
  21   public x: number;
  22   public scrollBottom: number;
  23   public scrollTop: number;
  24   public tabs: any;
  25   public savedY: number;
  26   public savedX: number;
  27
  28   /**
  29    * Create a new Buffer.
  30    * @param {Terminal} _terminal - The terminal the Buffer will belong to
  31    * @param {number} ydisp - The scroll position of the Buffer in the viewport
  32    * @param {number} ybase - The scroll position of the y cursor (ybase + y = the y position within the Buffer)
  33    * @param {number} y - The cursor's y position after ybase
  34    * @param {number} x - The cursor's x position after ybase
  35    */
  36   constructor(
  37     private _terminal: ITerminal
  38   ) {
  39     this.clear();
  40   }
  41
  42   public get lines(): CircularList<[number, string, number][]> {
  43     return this._lines;
  44   }
  45
  46   public fillViewportRows(): void {
  47     if (this._lines.length === 0) {
  48       let i = this._terminal.rows;
  49       while (i--) {
  50         this.lines.push(this._terminal.blankLine());
  51       }
  52     }
  53   }
  54
  55   public clear(): void {
  56     this.ydisp = 0;
  57     this.ybase = 0;
  58     this.y = 0;
  59     this.x = 0;
  60     this.scrollBottom = 0;
  61     this.scrollTop = 0;
  62     this.tabs = {};
  63     this._lines = new CircularList<[number, string, number][]>(this._terminal.scrollback);
  64     this.scrollBottom = this._terminal.rows - 1;
  65   }
  66
  67   public resize(newCols: number, newRows: number): void {
  68     // Don't resize the buffer if it's empty and hasn't been used yet.
  69     if (this._lines.length === 0) {
  70       return;
  71     }
  72
  73     // Deal with columns increasing (we don't do anything when columns reduce)
  74     if (this._terminal.cols < newCols) {
  75       const ch: [number, string, number] = [this._terminal.defAttr, ' ', 1]; // does xterm use the default attr?
  76       for (let i = 0; i < this._lines.length; i++) {
  77         if (this._lines.get(i) === undefined) {
  78           this._lines.set(i, this._terminal.blankLine());
  79         }
  80         while (this._lines.get(i).length < newCols) {
  81           this._lines.get(i).push(ch);
  82         }
  83       }
  84     }
  85
  86     // Resize rows in both directions as needed
  87     let addToY = 0;
  88     if (this._terminal.rows < newRows) {
  89       for (let y = this._terminal.rows; y < newRows; y++) {
  90         if (this._lines.length < newRows + this.ybase) {
  91           if (this.ybase > 0 && this._lines.length <= this.ybase + this.y + addToY + 1) {
  92             // There is room above the buffer and there are no empty elements below the line,
  93             // scroll up
  94             this.ybase--;
  95             addToY++;
  96             if (this.ydisp > 0) {
  97               // Viewport is at the top of the buffer, must increase downwards
  98               this.ydisp--;
  99             }
 100           } else {
 101             // Add a blank line if there is no buffer left at the top to scroll to, or if there
 102             // are blank lines after the cursor
 103             this._lines.push(this._terminal.blankLine());
 104           }
 105         }
 106       }
 107     } else { // (this._terminal.rows >= newRows)
 108       for (let y = this._terminal.rows; y > newRows; y--) {
 109         if (this._lines.length > newRows + this.ybase) {
 110           if (this._lines.length > this.ybase + this.y + 1) {
 111             // The line is a blank line below the cursor, remove it
 112             this._lines.pop();
 113           } else {
 114             // The line is the cursor, scroll down
 115             this.ybase++;
 116             this.ydisp++;
 117           }
 118         }
 119       }
 120     }
 121
 122     // Make sure that the cursor stays on screen
 123     if (this.y >= newRows) {
 124       this.y = newRows - 1;
 125     }
 126     if (addToY) {
 127       this.y += addToY;
 128     }
 129
 130     if (this.x >= newCols) {
 131       this.x = newCols - 1;
 132     }
 133
 134     this.scrollTop = 0;
 135     this.scrollBottom = newRows - 1;
 136   }
 137 }