viewLineRenderer.ts

/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/
'use strict';

import {ViewLineToken} from 'vs/editor/common/core/viewLineToken';

export class RenderLineInput {
	_renderLineInputBrand: void;

	lineContent: string;
	tabSize: number;
	spaceWidth: number;
	stopRenderingLineAfter: number;
	renderWhitespace: boolean;
	parts: ViewLineToken[];

	constructor(
		lineContent: string,
		tabSize: number,
		spaceWidth: number,
		stopRenderingLineAfter: number,
		renderWhitespace: boolean,
		parts: ViewLineToken[]
	) {
		this.lineContent = lineContent;
		this.tabSize = tabSize;
		this.spaceWidth = spaceWidth;
		this.stopRenderingLineAfter = stopRenderingLineAfter;
		this.renderWhitespace = renderWhitespace;
		this.parts = parts;
	}
}

export class RenderLineOutput {
	_renderLineOutputBrand: void;
	charOffsetInPart: number[];
	lastRenderedPartIndex: number;
	output: string;

	constructor(charOffsetInPart: number[], lastRenderedPartIndex: number, output: string) {
		this.charOffsetInPart = charOffsetInPart;
		this.lastRenderedPartIndex = lastRenderedPartIndex;
		this.output = output;
	}
}

const _space = ' '.charCodeAt(0);
const _tab = '\t'.charCodeAt(0);
const _lowerThan = '<'.charCodeAt(0);
const _greaterThan = '>'.charCodeAt(0);
const _ampersand = '&'.charCodeAt(0);
const _carriageReturn = '\r'.charCodeAt(0);
const _lineSeparator = '\u2028'.charCodeAt(0); //http://www.fileformat.info/info/unicode/char/2028/index.htm
const _bom = 65279;

export function renderLine(input:RenderLineInput): RenderLineOutput {
	const lineText = input.lineContent;
	const lineTextLength = lineText.length;
	const tabSize = input.tabSize;
	const spaceWidth = input.spaceWidth;
	const actualLineParts = input.parts;
	const renderWhitespace = input.renderWhitespace;
	const charBreakIndex = (input.stopRenderingLineAfter === -1 ? lineTextLength : input.stopRenderingLineAfter - 1);

	if (lineTextLength === 0) {
		return new RenderLineOutput(
			[],
			0,
			// This is basically for IE's hit test to work
			'<span><span>&nbsp;</span></span>'
		);
	}

	if (actualLineParts.length === 0) {
		throw new Error('Cannot render non empty line without line parts!');
	}

	return renderLineActual(lineText, lineTextLength, tabSize, spaceWidth, actualLineParts.slice(0), renderWhitespace, charBreakIndex);
}

function isWhitespace(type:string): boolean {
	return (type.indexOf('whitespace') >= 0);
}

function isIndentGuide(type:string): boolean {
	return (type.indexOf('indent-guide') >= 0);
}

function renderLineActual(lineText:string, lineTextLength:number, tabSize:number, spaceWidth:number, actualLineParts:ViewLineToken[], renderWhitespace:boolean, charBreakIndex:number): RenderLineOutput {
	lineTextLength = +lineTextLength;
	tabSize = +tabSize;
	charBreakIndex = +charBreakIndex;

	let charIndex = 0;
	let out = '';
	let charOffsetInPartArr: number[] = [];
	let charOffsetInPart = 0;
	let tabsCharDelta = 0;

	out += '<span>';
	for (let partIndex = 0, partIndexLen = actualLineParts.length; partIndex < partIndexLen; partIndex++) {
		let part = actualLineParts[partIndex];

		let parsRendersWhitespace = (renderWhitespace && isWhitespace(part.type));
		let partIsFixedWidth = parsRendersWhitespace || isIndentGuide(part.type);

		let toCharIndex = lineTextLength;
		if (partIndex + 1 < partIndexLen) {
			let nextPart = actualLineParts[partIndex + 1];
			toCharIndex = Math.min(lineTextLength, nextPart.startIndex);
		}

		charOffsetInPart = 0;
		if (partIsFixedWidth) {

			let partContentCnt = 0;
			let partContent = '';
			for (; charIndex < toCharIndex; charIndex++) {
				charOffsetInPartArr[charIndex] = charOffsetInPart;
				let charCode = lineText.charCodeAt(charIndex);

				if (charCode === _tab) {
					let insertSpacesCount = tabSize - (charIndex + tabsCharDelta) % tabSize;
					tabsCharDelta += insertSpacesCount - 1;
					charOffsetInPart += insertSpacesCount - 1;
					if (insertSpacesCount > 0) {
						partContent += parsRendersWhitespace ? '&rarr;' : '&nbsp;';
						partContentCnt++;
						insertSpacesCount--;
					}
					while (insertSpacesCount > 0) {
						partContent += '&nbsp;';
						partContentCnt++;
						insertSpacesCount--;
					}
				} else {
					// must be _space
					partContent += parsRendersWhitespace ? '&middot;' : '&nbsp;';
					partContentCnt++;
				}

				charOffsetInPart ++;

				if (charIndex >= charBreakIndex) {
					out += '<span class="token '+part.type+'" style="width:'+(spaceWidth * partContentCnt)+'px">';
					out += partContent;
					out += '&hellip;</span></span>';
					charOffsetInPartArr[charIndex] = charOffsetInPart;
					return new RenderLineOutput(
						charOffsetInPartArr,
						partIndex,
						out
					);
				}
			}
			out += '<span class="token '+part.type+'" style="width:'+(spaceWidth * partContentCnt)+'px">';
			out += partContent;
			out += '</span>';
		} else {
			out += '<span class="token ';
			out += part.type;
			out += '">';

			for (; charIndex < toCharIndex; charIndex++) {
				charOffsetInPartArr[charIndex] = charOffsetInPart;
				let charCode = lineText.charCodeAt(charIndex);

				switch (charCode) {
					case _tab:
						let insertSpacesCount = tabSize - (charIndex + tabsCharDelta) % tabSize;
						tabsCharDelta += insertSpacesCount - 1;
						charOffsetInPart += insertSpacesCount - 1;
						while (insertSpacesCount > 0) {
							out += '&nbsp;';
							insertSpacesCount--;
						}
						break;

					case _space:
						out += '&nbsp;';
						break;

					case _lowerThan:
						out += '&lt;';
						break;

					case _greaterThan:
						out += '&gt;';
						break;

					case _ampersand:
						out += '&amp;';
						break;

					case 0:
						out += '&#00;';
						break;

					case _bom:
					case _lineSeparator:
						out += '\ufffd';
						break;

					case _carriageReturn:
						// zero width space, because carriage return would introduce a line break
						out += '&#8203';
						break;

					default:
						out += lineText.charAt(charIndex);
				}

				charOffsetInPart ++;

				if (charIndex >= charBreakIndex) {
					out += '&hellip;</span></span>';
					charOffsetInPartArr[charIndex] = charOffsetInPart;
					return new RenderLineOutput(
						charOffsetInPartArr,
						partIndex,
						out
					);
				}
			}

			out += '</span>';
		}

	}
	out += '</span>';

	// When getting client rects for the last character, we will position the
	// text range at the end of the span, insteaf of at the beginning of next span
	charOffsetInPartArr.push(charOffsetInPart);

	return new RenderLineOutput(
		charOffsetInPartArr,
		actualLineParts.length - 1,
		out
	);
}