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jquery.canvasResize.js
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jquery.canvasResize.js
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/*
* jQuery canvasResize plugin
*
* Version: 1.2.0
* Date (d/m/y): 02/10/12
* Update (d/m/y): 14/05/13
* Original author: @gokercebeci
* Licensed under the MIT license
* - This plugin working with jquery.exif.js
* (It's under the MPL License http://www.nihilogic.dk/licenses/mpl-license.txt)
* Demo: http://ios6-image-resize.gokercebeci.com/
*
* - I fixed iOS6 Safari's image file rendering issue for large size image (over mega-pixel)
* using few functions from https://github.com/stomita/ios-imagefile-megapixel
* (detectSubsampling, )
* And fixed orientation issue by edited http://blog.nihilogic.dk/2008/05/jquery-exif-data-plugin.html
* Thanks, Shinichi Tomita and Jacob Seidelin
*/
(function($) {
var pluginName = 'canvasResize',
methods = {
newsize: function(w, h, W, H, C) {
var c = C ? 'h' : '';
if ((W && w > W) || (H && h > H)) {
var r = w / h;
if ((r >= 1 || H === 0) && W && !C) {
w = W;
h = (W / r) >> 0;
} else if (C && r <= (W / H)) {
w = W;
h = (W / r) >> 0;
c = 'w';
} else {
w = (H * r) >> 0;
h = H;
}
}
return {
'width': w,
'height': h,
'cropped': c
};
},
dataURLtoBlob: function(data) {
var mimeString = data.split(',')[0].split(':')[1].split(';')[0];
var byteString = atob(data.split(',')[1]);
var ab = new ArrayBuffer(byteString.length);
var ia = new Uint8Array(ab);
for (var i = 0; i < byteString.length; i++) {
ia[i] = byteString.charCodeAt(i);
}
var bb = (window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder);
if (bb) {
// console.log('BlobBuilder');
bb = new (window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder)();
bb.append(ab);
return bb.getBlob(mimeString);
} else {
// console.log('Blob');
bb = new Blob([ab], {
'type': (mimeString)
});
return bb;
}
},
/**
* Detect subsampling in loaded image.
* In iOS, larger images than 2M pixels may be subsampled in rendering.
*/
detectSubsampling: function(img) {
var iw = img.width, ih = img.height;
if (iw * ih > 1048576) { // subsampling may happen over megapixel image
var canvas = document.createElement('canvas');
canvas.width = canvas.height = 1;
var ctx = canvas.getContext('2d');
ctx.drawImage(img, -iw + 1, 0);
// subsampled image becomes half smaller in rendering size.
// check alpha channel value to confirm image is covering edge pixel or not.
// if alpha value is 0 image is not covering, hence subsampled.
return ctx.getImageData(0, 0, 1, 1).data[3] === 0;
} else {
return false;
}
},
/**
* Update the orientation according to the specified rotation angle
*/
rotate: function(orientation, angle) {
var o = {
// nothing
1: {90: 6, 180: 3, 270: 8},
// horizontal flip
2: {90: 7, 180: 4, 270: 5},
// 180 rotate left
3: {90: 8, 180: 1, 270: 6},
// vertical flip
4: {90: 5, 180: 2, 270: 7},
// vertical flip + 90 rotate right
5: {90: 2, 180: 7, 270: 4},
// 90 rotate right
6: {90: 3, 180: 8, 270: 1},
// horizontal flip + 90 rotate right
7: {90: 4, 180: 5, 270: 2},
// 90 rotate left
8: {90: 1, 180: 6, 270: 3}
};
return o[orientation][angle] ? o[orientation][angle] : orientation;
},
/**
* Transform canvas coordination according to specified frame size and orientation
* Orientation value is from EXIF tag
*/
transformCoordinate: function(canvas, width, height, orientation) {
//console.log(width, height);
switch (orientation) {
case 5:
case 6:
case 7:
case 8:
canvas.width = height;
canvas.height = width;
break;
default:
canvas.width = width;
canvas.height = height;
}
var ctx = canvas.getContext('2d');
switch (orientation) {
case 1:
// nothing
break;
case 2:
// horizontal flip
ctx.translate(width, 0);
ctx.scale(-1, 1);
break;
case 3:
// 180 rotate left
ctx.translate(width, height);
ctx.rotate(Math.PI);
break;
case 4:
// vertical flip
ctx.translate(0, height);
ctx.scale(1, -1);
break;
case 5:
// vertical flip + 90 rotate right
ctx.rotate(0.5 * Math.PI);
ctx.scale(1, -1);
break;
case 6:
// 90 rotate right
ctx.rotate(0.5 * Math.PI);
ctx.translate(0, -height);
break;
case 7:
// horizontal flip + 90 rotate right
ctx.rotate(0.5 * Math.PI);
ctx.translate(width, -height);
ctx.scale(-1, 1);
break;
case 8:
// 90 rotate left
ctx.rotate(-0.5 * Math.PI);
ctx.translate(-width, 0);
break;
default:
break;
}
},
/**
* Detecting vertical squash in loaded image.
* Fixes a bug which squash image vertically while drawing into canvas for some images.
*/
detectVerticalSquash: function(img, iw, ih) {
var canvas = document.createElement('canvas');
canvas.width = 1;
canvas.height = ih;
var ctx = canvas.getContext('2d');
ctx.drawImage(img, 0, 0);
var data = ctx.getImageData(0, 0, 1, ih).data;
// search image edge pixel position in case it is squashed vertically.
var sy = 0;
var ey = ih;
var py = ih;
while (py > sy) {
var alpha = data[(py - 1) * 4 + 3];
if (alpha === 0) {
ey = py;
} else {
sy = py;
}
py = (ey + sy) >> 1;
}
var ratio = py / ih;
return ratio === 0 ? 1 : ratio;
},
callback: function(d) {
return d;
}
},
defaults = {
width: 300,
height: 0,
crop: false,
quality: 80,
'callback': methods.callback
};
function Plugin(file, options) {
this.file = file;
this.options = $.extend({}, defaults, options);
this._defaults = defaults;
this._name = pluginName;
this.init();
}
Plugin.prototype = {
init: function() {
//this.options.init(this);
var $this = this;
var file = this.file;
var reader = new FileReader();
reader.onloadend = function(e) {
var dataURL = e.target.result;
var img = new Image();
img.onload = function(e) {
// Read Orientation Data in EXIF
$(img).exifLoadFromDataURL(function() {
var orientation = $(img).exif('Orientation')[0] || 1;
orientation = methods.rotate(orientation, $this.options.rotate);
// CW or CCW ? replace width and height
var size = (orientation >= 5 && orientation <= 8)
? methods.newsize(img.height, img.width, $this.options.width, $this.options.height, $this.options.crop)
: methods.newsize(img.width, img.height, $this.options.width, $this.options.height, $this.options.crop);
var iw = img.width, ih = img.height;
var width = size.width, height = size.height;
//console.log(iw, ih, size.width, size.height, orientation);
var canvas = document.createElement("canvas");
var ctx = canvas.getContext("2d");
ctx.save();
methods.transformCoordinate(canvas, width, height, orientation);
// over image size
if (methods.detectSubsampling(img)) {
iw /= 2;
ih /= 2;
}
var d = 1024; // size of tiling canvas
var tmpCanvas = document.createElement('canvas');
tmpCanvas.width = tmpCanvas.height = d;
var tmpCtx = tmpCanvas.getContext('2d');
var vertSquashRatio = methods.detectVerticalSquash(img, iw, ih);
var sy = 0;
while (sy < ih) {
var sh = sy + d > ih ? ih - sy : d;
var sx = 0;
while (sx < iw) {
var sw = sx + d > iw ? iw - sx : d;
tmpCtx.clearRect(0, 0, d, d);
tmpCtx.drawImage(img, -sx, -sy);
var dx = Math.floor(sx * width / iw);
var dw = Math.ceil(sw * width / iw);
var dy = Math.floor(sy * height / ih / vertSquashRatio);
var dh = Math.ceil(sh * height / ih / vertSquashRatio);
ctx.drawImage(tmpCanvas, 0, 0, sw, sh, dx, dy, dw, dh);
sx += d;
}
sy += d;
}
ctx.restore();
tmpCanvas = tmpCtx = null;
// if cropped or rotated width and height data replacing issue
var newcanvas = document.createElement('canvas');
newcanvas.width = size.cropped === 'h' ? height : width;
newcanvas.height = size.cropped === 'w' ? width : height;
var x = size.cropped === 'h' ? (height - width) * .5 : 0;
var y = size.cropped === 'w' ? (width - height) * .5 : 0;
newctx = newcanvas.getContext('2d');
newctx.drawImage(canvas, x, y, width, height);
if (file.type === "image/png") {
var data = newcanvas.toDataURL(file.type);
} else {
var data = newcanvas.toDataURL("image/jpeg", ($this.options.quality * .01));
}
// CALLBACK
$this.options.callback(data, width, height);
});
};
img.src = dataURL;
// =====================================================
};
reader.readAsDataURL(file);
}
};
$[pluginName] = function(file, options) {
if (typeof file === 'string')
return methods[file](options);
else
new Plugin(file, options);
};
})(jQuery);