bd028579
 易尊强
2/28
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
|
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];
}
}
}
|
