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- export var DEFAULT_FONT_SIZE = 12;
- export var DEFAULT_FONT_FAMILY = 'sans-serif';
- export var DEFAULT_FONT = DEFAULT_FONT_SIZE + "px " + DEFAULT_FONT_FAMILY;
- var OFFSET = 20;
- var SCALE = 100;
- var defaultWidthMapStr = "007LLmW'55;N0500LLLLLLLLLL00NNNLzWW\\\\WQb\\0FWLg\\bWb\\WQ\\WrWWQ000CL5LLFLL0LL**F*gLLLL5F0LF\\FFF5.5N";
- function getTextWidthMap(mapStr) {
- var map = {};
- if (typeof JSON === 'undefined') {
- return map;
- }
- for (var i = 0; i < mapStr.length; i++) {
- var char = String.fromCharCode(i + 32);
- var size = (mapStr.charCodeAt(i) - OFFSET) / SCALE;
- map[char] = size;
- }
- return map;
- }
- export var DEFAULT_TEXT_WIDTH_MAP = getTextWidthMap(defaultWidthMapStr);
- export var platformApi = {
- createCanvas: function () {
- return typeof document !== 'undefined'
- && document.createElement('canvas');
- },
- measureText: (function () {
- var _ctx;
- var _cachedFont;
- return function (text, font) {
- if (!_ctx) {
- var canvas = platformApi.createCanvas();
- _ctx = canvas && canvas.getContext('2d');
- }
- if (_ctx) {
- if (_cachedFont !== font) {
- _cachedFont = _ctx.font = font || DEFAULT_FONT;
- }
- return _ctx.measureText(text);
- }
- else {
- text = text || '';
- font = font || DEFAULT_FONT;
- var res = /(\d+)px/.exec(font);
- var fontSize = res && +res[1] || DEFAULT_FONT_SIZE;
- var width = 0;
- if (font.indexOf('mono') >= 0) {
- width = fontSize * text.length;
- }
- else {
- for (var i = 0; i < text.length; i++) {
- var preCalcWidth = DEFAULT_TEXT_WIDTH_MAP[text[i]];
- width += preCalcWidth == null ? fontSize : (preCalcWidth * fontSize);
- }
- }
- return { width: width };
- }
- };
- })(),
- loadImage: function (src, onload, onerror) {
- var image = new Image();
- image.onload = onload;
- image.onerror = onerror;
- image.src = src;
- return image;
- }
- };
- export function setPlatformAPI(newPlatformApis) {
- for (var key in platformApi) {
- if (newPlatformApis[key]) {
- platformApi[key] = newPlatformApis[key];
- }
- }
- }
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