public resize()

in src/Buffer.ts [112:195]
61 lines of code
18 McCabe index (conditional complexity)

  public resize(newCols: number, newRows: number): void {
    // Increase max length if needed before adjustments to allow space to fill
    // as required.
    const newMaxLength = this._getCorrectBufferLength(newRows);
    if (newMaxLength > this.lines.maxLength) {
      this.lines.maxLength = newMaxLength;
    }

    // The following adjustments should only happen if the buffer has been
    // initialized/filled.
    if (this.lines.length > 0) {
      // Deal with columns increasing (we don't do anything when columns reduce)
      if (this._terminal.cols < newCols) {
        const ch: CharData = [DEFAULT_ATTR, NULL_CELL_CHAR, NULL_CELL_WIDTH, NULL_CELL_CODE]; // does xterm use the default attr?
        for (let i = 0; i < this.lines.length; i++) {
          while (this.lines.get(i).length < newCols) {
            this.lines.get(i).push(ch);
          }
        }
      }

      // Resize rows in both directions as needed
      let addToY = 0;
      if (this._terminal.rows < newRows) {
        for (let y = this._terminal.rows; y < newRows; y++) {
          if (this.lines.length < newRows + this.ybase) {
            if (this.ybase > 0 && this.lines.length <= this.ybase + this.y + addToY + 1) {
              // There is room above the buffer and there are no empty elements below the line,
              // scroll up
              this.ybase--;
              addToY++;
              if (this.ydisp > 0) {
                // Viewport is at the top of the buffer, must increase downwards
                this.ydisp--;
              }
            } else {
              // Add a blank line if there is no buffer left at the top to scroll to, or if there
              // are blank lines after the cursor
              this.lines.push(BufferLine.blankLine(newCols, DEFAULT_ATTR));
            }
          }
        }
      } else { // (this._terminal.rows >= newRows)
        for (let y = this._terminal.rows; y > newRows; y--) {
          if (this.lines.length > newRows + this.ybase) {
            if (this.lines.length > this.ybase + this.y + 1) {
              // The line is a blank line below the cursor, remove it
              this.lines.pop();
            } else {
              // The line is the cursor, scroll down
              this.ybase++;
              this.ydisp++;
            }
          }
        }
      }

      // Reduce max length if needed after adjustments, this is done after as it
      // would otherwise cut data from the bottom of the buffer.
      if (newMaxLength < this.lines.maxLength) {
        // Trim from the top of the buffer and adjust ybase and ydisp.
        const amountToTrim = this.lines.length - newMaxLength;
        if (amountToTrim > 0) {
          this.lines.trimStart(amountToTrim);
          this.ybase = Math.max(this.ybase - amountToTrim, 0);
          this.ydisp = Math.max(this.ydisp - amountToTrim, 0);
        }
        this.lines.maxLength = newMaxLength;
      }

      // Make sure that the cursor stays on screen
      this.x = Math.min(this.x, newCols - 1);
      this.y = Math.min(this.y, newRows - 1);
      if (addToY) {
        this.y += addToY;
      }
      this.savedY = Math.min(this.savedY, newRows - 1);
      this.savedX = Math.min(this.savedX, newCols - 1);

      this.scrollTop = 0;
    }

    this.scrollBottom = newRows - 1;
  }