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Copy pathcalibrator.js
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140 lines (116 loc) · 3.65 KB
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'use strict';
var Promise = require('bluebird'),
fs = require('fs'),
path = require('path'),
_ = require('lodash'),
GeminiError = require('./errors/gemini-error'),
looksSame = require('looks-same'),
clientScriptCalibrate = fs.readFileSync(path.join(__dirname, 'browser', 'client-scripts', 'gemini.calibrate.min.js'), 'utf8'),
DIRECTION = {FORWARD: 'forward', REVERSE: 'reverse'};
/**
* @constructor
*/
function Calibrator() {
this._cache = {};
}
/**
* @param {Browser} browser
* @returns {Promise.<CalibrationResult>}
*/
Calibrator.prototype.calibrate = function(browser) {
var _this = this;
if (this._cache[browser.id]) {
return Promise.resolve(this._cache[browser.id]);
}
return browser.open('about:blank', {resetZoom: false})
.then(function() {
return browser.evalScript(clientScriptCalibrate);
})
.then(function(features) {
return [features, browser.captureViewportImage()];
})
.spread(function(features, image) {
var innerWidth = features.innerWidth,
hasPixelRatio = !!(features.pixelRatio && features.pixelRatio > 1.0),
imageFeatures = _this._analyzeImage(image, {calculateColorLength: hasPixelRatio});
if (!imageFeatures) {
return Promise.reject(new GeminiError(
'Could not calibrate. This could be due to calibration page has failed to open properly'
));
}
_.extend(features, {
top: imageFeatures.viewportStart.y,
left: imageFeatures.viewportStart.x,
usePixelRatio: hasPixelRatio && imageFeatures.colorLength > innerWidth
});
_this._cache[browser.id] = features;
return features;
});
};
Calibrator.prototype._analyzeImage = function(image, params) {
var imageHeight = image.getSize().height;
for (var y = 0; y < imageHeight; y++) {
var result = analyzeRow(y, image, params);
if (result) {
return result;
}
}
return null;
};
function analyzeRow(row, image, params) {
params = params || {};
var markerStart = findMarkerInRow(row, image, DIRECTION.FORWARD);
if (markerStart === -1) {
return null;
}
if (!params.calculateColorLength) {
return {viewportStart: {x: markerStart, y: row}};
}
var markerEnd = findMarkerInRow(row, image, DIRECTION.REVERSE),
colorLength = markerEnd - markerStart + 1;
return {viewportStart: {x: markerStart, y: row}, colorLength: colorLength};
}
function findMarkerInRow(row, image, searchDirection) {
var imageWidth = image.getSize().width,
searchColor = {R: 148, G: 250, B: 0};
if (searchDirection === DIRECTION.REVERSE) {
return searchReverse_();
} else {
return searchForward_();
}
function searchForward_() {
for (var x = 0; x < imageWidth; x++) {
if (compare_(x)) {
return x;
}
}
return -1;
}
function searchReverse_() {
for (var x = imageWidth - 1; x >= 0; x--) {
if (compare_(x)) {
return x;
}
}
return -1;
}
function compare_(x) {
var color = pickRGB(image.getRGBA(x, row));
return looksSame.colors(color, searchColor);
}
}
function pickRGB(rgba) {
return {
R: rgba.r,
G: rgba.g,
B: rgba.b
};
}
/**
* @typedef {Object} CalibrationResult
* @property {Number} top
* @property {Number} left
* @property {Number} right
* @property {Number} bottom
*/
module.exports = Calibrator;