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index.js
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index.js
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'use strict';
var Promise = require('bluebird');
var lwip = require('lwip');
var getBgColor = function (color, format) {
if (format === 'jpg') {
return [color[0], color[1], color[2], 100];
}
return [color[0], color[1], color[2], color[3]];
};
var createCanvas = function (width, height, color) {
return new Promise(function (resolve, reject) {
lwip.create(width, height, color, function (err, image) {
if (!err) {
resolve(image);
}
else {
reject(err);
}
});
});
};
var paste = function (tile, canvas) {
return new Promise(function (resolve, reject) {
lwip.open(tile.contents, tile.type, function (err, img) {
if (err) {
reject(err);
}
else {
canvas.paste(tile.x + tile.offset, tile.y + tile.offset, img, function (e) {
if (!e) {
resolve(canvas);
}
else {
reject(e);
}
});
}
});
});
};
var toBuffer = function (canvas, opt) {
return new Promise(function (resolve, reject) {
var format = opt.options && opt.options.format ? opt.options.format : 'png';
canvas.toBuffer(format, {}, function (err, buf) {
if (!err) {
resolve({
type: format,
mimeType: 'image/' + format,
contents: buf,
width: canvas.width(),
height: canvas.height()
});
}
else {
reject(err);
}
});
});
};
var scaleImage = function (base, type, opt) {
return new Promise(function (resolve, reject) {
lwip.open(base, type, function (err, img) {
if (err) {
reject(err);
}
else {
var interpolation = opt['lwip-interpolation'] || opt.options['lwip-interpolation'] || 'lanczos';
img.scale(opt.scale, interpolation, function (e, image) {
if (!e) {
resolve(image);
}
else {
reject(e);
}
});
}
});
});
};
module.exports = {
create: function (tiles, opt) {
var format = opt.options && opt.options.format ? opt.options.format : 'png';
return createCanvas(opt.width, opt.height, getBgColor(opt.bgColor, format))
.then(function (c) {
return Promise.map(tiles, function (tile) {
return paste(tile, c);
}, {concurrency: 1});
})
.then(function (c) {
return toBuffer(c[0], opt);
});
},
scale: function (base, opt) {
return scaleImage(base.contents, base.type, opt)
.then(function (image) {
return toBuffer(image, opt);
});
}
};