src/Renderer.ts

   1 /**
   2  * @license MIT
   3  */
   4
   5 import { ITerminal } from './Interfaces';
   6 import { DomElementObjectPool } from './utils/DomElementObjectPool';
   7
   8 /**
   9  * The maximum number of refresh frames to skip when the write buffer is non-
  10  * empty. Note that these frames may be intermingled with frames that are
  11  * skipped via requestAnimationFrame's mechanism.
  12  */
  13 const MAX_REFRESH_FRAME_SKIP = 5;
  14
  15 /**
  16  * Flags used to render terminal text properly.
  17  */
  18 enum FLAGS {
  19   BOLD = 1,
  20   UNDERLINE = 2,
  21   BLINK = 4,
  22   INVERSE = 8,
  23   INVISIBLE = 16
  24 };
  25
  26 let brokenBold: boolean = null;
  27
  28 export class Renderer {
  29   /** A queue of the rows to be refreshed */
  30   private _refreshRowsQueue: {start: number, end: number}[] = [];
  31   private _refreshFramesSkipped = 0;
  32   private _refreshAnimationFrame = null;
  33
  34   private _spanElementObjectPool = new DomElementObjectPool('span');
  35
  36   constructor(private _terminal: ITerminal) {
  37     // Figure out whether boldness affects
  38     // the character width of monospace fonts.
  39     if (brokenBold === null) {
  40       brokenBold = checkBoldBroken((<any>this._terminal).element);
  41     }
  42     this._spanElementObjectPool = new DomElementObjectPool('span');
  43
  44     // TODO: Pull more DOM interactions into Renderer.constructor, element for
  45     // example should be owned by Renderer (and also exposed by Terminal due to
  46     // to established public API).
  47   }
  48
  49   /**
  50    * Queues a refresh between two rows (inclusive), to be done on next animation
  51    * frame.
  52    * @param {number} start The start row.
  53    * @param {number} end The end row.
  54    */
  55   public queueRefresh(start: number, end: number): void {
  56     this._refreshRowsQueue.push({ start: start, end: end });
  57     if (!this._refreshAnimationFrame) {
  58       this._refreshAnimationFrame = window.requestAnimationFrame(this._refreshLoop.bind(this));
  59     }
  60   }
  61
  62   /**
  63    * Performs the refresh loop callback, calling refresh only if a refresh is
  64    * necessary before queueing up the next one.
  65    */
  66   private _refreshLoop(): void {
  67     // Skip MAX_REFRESH_FRAME_SKIP frames if the writeBuffer is non-empty as it
  68     // will need to be immediately refreshed anyway. This saves a lot of
  69     // rendering time as the viewport DOM does not need to be refreshed, no
  70     // scroll events, no layouts, etc.
  71     const skipFrame = this._terminal.writeBuffer.length > 0 && this._refreshFramesSkipped++ <= MAX_REFRESH_FRAME_SKIP;
  72     if (skipFrame) {
  73       this._refreshAnimationFrame = window.requestAnimationFrame(this._refreshLoop.bind(this));
  74       return;
  75     }
  76
  77     this._refreshFramesSkipped = 0;
  78     let start;
  79     let end;
  80     if (this._refreshRowsQueue.length > 4) {
  81       // Just do a full refresh when 5+ refreshes are queued
  82       start = 0;
  83       end = this._terminal.rows - 1;
  84     } else {
  85       // Get start and end rows that need refreshing
  86       start = this._refreshRowsQueue[0].start;
  87       end = this._refreshRowsQueue[0].end;
  88       for (let i = 1; i < this._refreshRowsQueue.length; i++) {
  89         if (this._refreshRowsQueue[i].start < start) {
  90           start = this._refreshRowsQueue[i].start;
  91         }
  92         if (this._refreshRowsQueue[i].end > end) {
  93           end = this._refreshRowsQueue[i].end;
  94         }
  95       }
  96     }
  97     this._refreshRowsQueue = [];
  98     this._refreshAnimationFrame = null;
  99     this._refresh(start, end);
 100   }
 101
 102   /**
 103    * Refreshes (re-renders) terminal content within two rows (inclusive)
 104    *
 105    * Rendering Engine:
 106    *
 107    * In the screen buffer, each character is stored as a an array with a character
 108    * and a 32-bit integer:
 109    *   - First value: a utf-16 character.
 110    *   - Second value:
 111    *   - Next 9 bits: background color (0-511).
 112    *   - Next 9 bits: foreground color (0-511).
 113    *   - Next 14 bits: a mask for misc. flags:
 114    *     - 1=bold
 115    *     - 2=underline
 116    *     - 4=blink
 117    *     - 8=inverse
 118    *     - 16=invisible
 119    *
 120    * @param {number} start The row to start from (between 0 and terminal's height terminal - 1)
 121    * @param {number} end The row to end at (between fromRow and terminal's height terminal - 1)
 122    */
 123   private _refresh(start: number, end: number): void {
 124     // If this is a big refresh, remove the terminal rows from the DOM for faster calculations
 125     let parent;
 126     if (end - start >= this._terminal.rows / 2) {
 127       parent = this._terminal.element.parentNode;
 128       if (parent) {
 129         this._terminal.element.removeChild(this._terminal.rowContainer);
 130       }
 131     }
 132
 133     let width = this._terminal.cols;
 134     let y = start;
 135
 136     if (end >= this._terminal.rows) {
 137       this._terminal.log('`end` is too large. Most likely a bad CSR.');
 138       end = this._terminal.rows - 1;
 139     }
 140
 141     for (; y <= end; y++) {
 142       let row = y + this._terminal.buffer.ydisp;
 143
 144       let line = this._terminal.buffer.lines.get(row);
 145
 146       let x;
 147       if (this._terminal.buffer.y === y - (this._terminal.buffer.ybase - this._terminal.buffer.ydisp) &&
 148           this._terminal.cursorState &&
 149           !this._terminal.cursorHidden) {
 150         x = this._terminal.buffer.x;
 151       } else {
 152         x = -1;
 153       }
 154
 155       let attr = this._terminal.defAttr;
 156
 157       const documentFragment = document.createDocumentFragment();
 158       let innerHTML = '';
 159       let currentElement;
 160
 161       // Return the row's spans to the pool
 162       while (this._terminal.children[y].children.length) {
 163         const child = this._terminal.children[y].children[0];
 164         this._terminal.children[y].removeChild(child);
 165         this._spanElementObjectPool.release(<HTMLElement>child);
 166       }
 167
 168       for (let i = 0; i < width; i++) {
 169         // TODO: Could data be a more specific type?
 170         let data: any = line[i][0];
 171         const ch = line[i][1];
 172         const ch_width: any = line[i][2];
 173         const isCursor: boolean = i === x;
 174         if (!ch_width) {
 175           continue;
 176         }
 177
 178         if (data !== attr || isCursor) {
 179           if (attr !== this._terminal.defAttr && !isCursor) {
 180             if (innerHTML) {
 181               currentElement.innerHTML = innerHTML;
 182               innerHTML = '';
 183             }
 184             documentFragment.appendChild(currentElement);
 185             currentElement = null;
 186           }
 187           if (data !== this._terminal.defAttr || isCursor) {
 188             if (innerHTML && !currentElement) {
 189               currentElement = this._spanElementObjectPool.acquire();
 190             }
 191             if (currentElement) {
 192               if (innerHTML) {
 193                 currentElement.innerHTML = innerHTML;
 194                 innerHTML = '';
 195               }
 196               documentFragment.appendChild(currentElement);
 197             }
 198             currentElement = this._spanElementObjectPool.acquire();
 199
 200             let bg = data & 0x1ff;
 201             let fg = (data >> 9) & 0x1ff;
 202             let flags = data >> 18;
 203
 204             if (isCursor) {
 205               currentElement.classList.add('reverse-video');
 206               currentElement.classList.add('terminal-cursor');
 207             }
 208
 209             if (flags & FLAGS.BOLD) {
 210               if (!brokenBold) {
 211                 currentElement.classList.add('xterm-bold');
 212               }
 213               // See: XTerm*boldColors
 214               if (fg < 8) {
 215                 fg += 8;
 216               }
 217             }
 218
 219             if (flags & FLAGS.UNDERLINE) {
 220               currentElement.classList.add('xterm-underline');
 221             }
 222
 223             if (flags & FLAGS.BLINK) {
 224               currentElement.classList.add('xterm-blink');
 225             }
 226
 227             // If inverse flag is on, then swap the foreground and background variables.
 228             if (flags & FLAGS.INVERSE) {
 229               let temp = bg;
 230               bg = fg;
 231               fg = temp;
 232               // Should inverse just be before the above boldColors effect instead?
 233               if ((flags & 1) && fg < 8) {
 234                 fg += 8;
 235               }
 236             }
 237
 238             if (flags & FLAGS.INVISIBLE && !isCursor) {
 239               currentElement.classList.add('xterm-hidden');
 240             }
 241
 242             /**
 243              * Weird situation: Invert flag used black foreground and white background results
 244              * in invalid background color, positioned at the 256 index of the 256 terminal
 245              * color map. Pin the colors manually in such a case.
 246              *
 247              * Source: https://github.com/sourcelair/xterm.js/issues/57
 248              */
 249             if (flags & FLAGS.INVERSE) {
 250               if (bg === 257) {
 251                 bg = 15;
 252               }
 253               if (fg === 256) {
 254                 fg = 0;
 255               }
 256             }
 257
 258             if (bg < 256) {
 259               currentElement.classList.add(`xterm-bg-color-${bg}`);
 260             }
 261
 262             if (fg < 256) {
 263               currentElement.classList.add(`xterm-color-${fg}`);
 264             }
 265
 266           }
 267         }
 268
 269         if (ch_width === 2) {
 270           // Wrap wide characters so they're sized correctly. It's more difficult to release these
 271           // from the object pool so just create new ones via innerHTML.
 272           innerHTML += `<span class="xterm-wide-char">${ch}</span>`;
 273         } else if (ch.charCodeAt(0) > 255) {
 274           // Wrap any non-wide unicode character as some fonts size them badly
 275           innerHTML += `<span class="xterm-normal-char">${ch}</span>`;
 276         } else {
 277           switch (ch) {
 278             case '&':
 279               innerHTML += '&amp;';
 280               break;
 281             case '<':
 282               innerHTML += '&lt;';
 283               break;
 284             case '>':
 285               innerHTML += '&gt;';
 286               break;
 287             default:
 288               if (ch <= ' ') {
 289                 innerHTML += '&nbsp;';
 290               } else {
 291                 innerHTML += ch;
 292               }
 293               break;
 294           }
 295         }
 296
 297         // The cursor needs its own element, therefore we set attr to -1
 298         // which will cause the next character to be rendered in a new element
 299         attr = isCursor ? -1 : data;
 300
 301       }
 302
 303       if (innerHTML && !currentElement) {
 304         currentElement = this._spanElementObjectPool.acquire();
 305       }
 306       if (currentElement) {
 307         if (innerHTML) {
 308           currentElement.innerHTML = innerHTML;
 309           innerHTML = '';
 310         }
 311         documentFragment.appendChild(currentElement);
 312         currentElement = null;
 313       }
 314
 315       this._terminal.children[y].appendChild(documentFragment);
 316     }
 317
 318     if (parent) {
 319       this._terminal.element.appendChild(this._terminal.rowContainer);
 320     }
 321
 322     this._terminal.emit('refresh', {element: this._terminal.element, start: start, end: end});
 323   };
 324
 325   /**
 326    * Refreshes the selection in the DOM.
 327    * @param start The selection start.
 328    * @param end The selection end.
 329    */
 330   public refreshSelection(start: [number, number], end: [number, number]) {
 331     // Remove all selections
 332     while (this._terminal.selectionContainer.children.length) {
 333       this._terminal.selectionContainer.removeChild(this._terminal.selectionContainer.children[0]);
 334     }
 335
 336     // Selection does not exist
 337     if (!start || !end) {
 338       return;
 339     }
 340
 341     // Translate from buffer position to viewport position
 342     const viewportStartRow = start[1] - this._terminal.buffer.ydisp;
 343     const viewportEndRow = end[1] - this._terminal.buffer.ydisp;
 344     const viewportCappedStartRow = Math.max(viewportStartRow, 0);
 345     const viewportCappedEndRow = Math.min(viewportEndRow, this._terminal.rows - 1);
 346
 347     // No need to draw the selection
 348     if (viewportCappedStartRow >= this._terminal.rows || viewportCappedEndRow < 0) {
 349       return;
 350     }
 351
 352     // Create the selections
 353     const documentFragment = document.createDocumentFragment();
 354     // Draw first row
 355     const startCol = viewportStartRow === viewportCappedStartRow ? start[0] : 0;
 356     const endCol = viewportCappedStartRow === viewportCappedEndRow ? end[0] : this._terminal.cols;
 357     documentFragment.appendChild(this._createSelectionElement(viewportCappedStartRow, startCol, endCol));
 358     // Draw middle rows
 359     const middleRowsCount = viewportCappedEndRow - viewportCappedStartRow - 1;
 360     documentFragment.appendChild(this._createSelectionElement(viewportCappedStartRow + 1, 0, this._terminal.cols, middleRowsCount));
 361     // Draw final row
 362     if (viewportCappedStartRow !== viewportCappedEndRow) {
 363       // Only draw viewportEndRow if it's not the same as viewporttartRow
 364       const endCol = viewportEndRow === viewportCappedEndRow ? end[0] : this._terminal.cols;
 365       documentFragment.appendChild(this._createSelectionElement(viewportCappedEndRow, 0, endCol));
 366     }
 367     this._terminal.selectionContainer.appendChild(documentFragment);
 368   }
 369
 370   /**
 371    * Creates a selection element at the specified position.
 372    * @param row The row of the selection.
 373    * @param colStart The start column.
 374    * @param colEnd The end columns.
 375    */
 376   private _createSelectionElement(row: number, colStart: number, colEnd: number, rowCount: number = 1): HTMLElement {
 377     const element = document.createElement('div');
 378     element.style.height = `${rowCount * this._terminal.charMeasure.height}px`;
 379     element.style.top = `${row * this._terminal.charMeasure.height}px`;
 380     element.style.left = `${colStart * this._terminal.charMeasure.width}px`;
 381     element.style.width = `${this._terminal.charMeasure.width * (colEnd - colStart)}px`;
 382     return element;
 383   }
 384 }
 385
 386
 387 // If bold is broken, we can't use it in the terminal.
 388 function checkBoldBroken(terminal) {
 389   const document = terminal.ownerDocument;
 390   const el = document.createElement('span');
 391   el.innerHTML = 'hello world';
 392   terminal.appendChild(el);
 393   const w1 = el.offsetWidth;
 394   const h1 = el.offsetHeight;
 395   el.style.fontWeight = 'bold';
 396   const w2 = el.offsetWidth;
 397   const h2 = el.offsetHeight;
 398   terminal.removeChild(el);
 399   return w1 !== w2 || h1 !== h2;
 400 }