1 // canvas转dataURL：canvas对象、转换格式、图像品质
2 function canvasToDataURL(canvas, format, quality){
3 return canvas.toDataURL(format||'image/jpeg', quality||1.0);
4 }
5 // DataURL转canvas
6 function dataURLToCanvas(dataurl, cb){
7 var canvas = document.createElement('CANVAS');
8 var ctx = canvas.getContext('2d');
9 var img = new Image();
10 img.onload = function(){
11 canvas.width = img.width;
12 canvas.height = img.height;
13 ctx.drawImage(img, 0, 0);
14 cb(canvas);
15 };
16 img.src = dataurl;
17 }
18 /*-----------------------------------------------------------------------*/
19 // image转canvas：图片地址
20 function imageToCanvas(src, cb){
21 var canvas = document.createElement('CANVAS');
22 var ctx = canvas.getContext('2d');
23 var img = new Image();
24 img.src = src;
25 img.onload = function (){
26 canvas.width = img.width;
27 canvas.height = img.height;
28 ctx.drawImage(img, 0, 0);
29 cb(canvas);
30 };
31 }
32 // canvas转image
33 function canvasToImage(canvas){
34 var img = new Image();
35 img.src = canvas.toDataURL('image/jpeg', 1.0);
36 return img;
37 }
38 /*-----------------------------------------------------------------------*/
39 // File/Blob对象转DataURL
40 function fileOrBlobToDataURL(obj, cb){
41 var a = new FileReader();
42 a.readAsDataURL(obj);
43 a.onload = function (e){
44 cb(e.target.result);
45 };
46 }
47 // DataURL转Blob对象
48 function dataURLToBlob(dataurl){
49 var arr = dataurl.split(',');
50 var mime = arr[0].match(/:(.*?);/)[1];
51 var bstr = atob(arr[1]);
52 var n = bstr.length;
53 var u8arr = new Uint8Array(n);
54 while(n--){
55 u8arr[n] = bstr.charCodeAt(n);
56 }
57 return new Blob([u8arr], {type:mime});
58 }
59 /*-----------------------------------------------------------------------*/
60 // Blob转image
61 function blobToImage(blob, cb){
62 fileOrBlobToDataURL(blob, function (dataurl){
63 var img = new Image();
64 img.src = dataurl;
65 cb(img);
66 });
67 }
68 // image转Blob
69 function imageToBlob(src, cb){
70 imageToCanvas(src, function (canvas){
71 cb(dataURLToBlob(canvasToDataURL(canvas)));
72 });
73 }
74 /*-----------------------------------------------------------------------*/
75 // Blob转canvas
76 function BlobToCanvas(blob, cb){
77 fileOrBlobToDataURL(blob, function (dataurl){
78 dataURLToCanvas(dataurl, cb);
79 });
80 }
81 // canvas转Blob
82 function canvasToBlob(canvas, cb){
83 cb(dataURLToBlob(canvasToDataURL(canvas)));
84 }
85 /*-----------------------------------------------------------------------*/
86 // image转dataURL
87 function imageToDataURL(src, cb){
88 imageToCanvas(src, function (canvas){
89 cb(canvasToDataURL(canvas));
90 });
91 }
92 // dataURL转image，这个不需要转，直接给了src就能用
93 function dataURLToImage(dataurl){
94 var img = new Image();
95 img.src = d;
96 return img;
97 }
