export var DEFAULT_FONT_SIZE = 12;
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export var DEFAULT_FONT_FAMILY = 'sans-serif';
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export var DEFAULT_FONT = DEFAULT_FONT_SIZE + "px " + DEFAULT_FONT_FAMILY;
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var OFFSET = 20;
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var SCALE = 100;
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var defaultWidthMapStr = "007LLmW'55;N0500LLLLLLLLLL00NNNLzWW\\\\WQb\\0FWLg\\bWb\\WQ\\WrWWQ000CL5LLFLL0LL**F*gLLLL5F0LF\\FFF5.5N";
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function getTextWidthMap(mapStr) {
|
var map = {};
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if (typeof JSON === 'undefined') {
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return map;
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}
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for (var i = 0; i < mapStr.length; i++) {
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var char = String.fromCharCode(i + 32);
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var size = (mapStr.charCodeAt(i) - OFFSET) / SCALE;
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map[char] = size;
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}
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return map;
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}
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export var DEFAULT_TEXT_WIDTH_MAP = getTextWidthMap(defaultWidthMapStr);
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export var platformApi = {
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createCanvas: function () {
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return typeof document !== 'undefined'
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&& document.createElement('canvas');
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},
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measureText: (function () {
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var _ctx;
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var _cachedFont;
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return function (text, font) {
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if (!_ctx) {
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var canvas = platformApi.createCanvas();
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_ctx = canvas && canvas.getContext('2d');
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}
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if (_ctx) {
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if (_cachedFont !== font) {
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_cachedFont = _ctx.font = font || DEFAULT_FONT;
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}
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return _ctx.measureText(text);
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}
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else {
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text = text || '';
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font = font || DEFAULT_FONT;
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var res = /^([0-9]*?)px$/.exec(font);
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var fontSize = +(res && res[1]) || DEFAULT_FONT_SIZE;
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var width = 0;
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if (font.indexOf('mono') >= 0) {
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width = fontSize * text.length;
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}
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else {
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for (var i = 0; i < text.length; i++) {
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var preCalcWidth = DEFAULT_TEXT_WIDTH_MAP[text[i]];
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width += preCalcWidth == null ? fontSize : (preCalcWidth * fontSize);
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}
|
}
|
return { width: width };
|
}
|
};
|
})(),
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loadImage: function (src, onload, onerror) {
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var image = new Image();
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image.onload = onload;
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image.onerror = onerror;
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image.src = src;
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return image;
|
}
|
};
|
export function setPlatformAPI(newPlatformApis) {
|
for (var key in platformApi) {
|
if (newPlatformApis[key]) {
|
platformApi[key] = newPlatformApis[key];
|
}
|
}
|
}
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