video-snap
Version:
Get multiple snapshots from video in a browser
222 lines (221 loc) • 10.2 kB
JavaScript
"use strict";
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
return new (P || (P = Promise))(function (resolve, reject) {
function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
step((generator = generator.apply(thisArg, _arguments || [])).next());
});
};
var __generator = (this && this.__generator) || function (thisArg, body) {
var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
function verb(n) { return function (v) { return step([n, v]); }; }
function step(op) {
if (f) throw new TypeError("Generator is already executing.");
while (_) try {
if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
if (y = 0, t) op = [op[0] & 2, t.value];
switch (op[0]) {
case 0: case 1: t = op; break;
case 4: _.label++; return { value: op[1], done: false };
case 5: _.label++; y = op[1]; op = [0]; continue;
case 7: op = _.ops.pop(); _.trys.pop(); continue;
default:
if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
if (t[2]) _.ops.pop();
_.trys.pop(); continue;
}
op = body.call(thisArg, _);
} catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
}
};
Object.defineProperty(exports, "__esModule", { value: true });
var VIDEO_READY_STATE = 4;
var VideoSnap = /** @class */ (function () {
/**
* @param videoSourceUrl - URL to a video
*/
function VideoSnap(videoSourceUrl) {
this.video = document.createElement('video');
this.canvas = document.createElement('canvas');
var context = this.canvas.getContext('2d');
if (!context) {
throw new Error('Could not create canvas context');
}
this.context = context;
this.video.src = videoSourceUrl;
}
/** Wait for video to rewind to targetTime and resolve Promise */
VideoSnap.rewindVideo = function (video, targetTime) {
return new Promise(function (resolve) {
var handler = function () {
video.removeEventListener('seeked', handler);
resolve();
};
video.addEventListener('seeked', handler);
video.currentTime = targetTime;
});
};
/**
* Asynchronously take snapshots from video provided in constructor.
* Specific number of snapshots equally distributed to whole video length.
*
* @param {number} numberOfFrames - number of images video should be sliced to
* @param {Config} config - configuration for snapshots;
*
* @return Promise with array of Blob URLs to captured images.
*/
VideoSnap.prototype.getFrames = function (numberOfFrames, config) {
if (config === void 0) { config = {}; }
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
if (!(this.video.readyState !== VIDEO_READY_STATE)) return [3 /*break*/, 2];
return [4 /*yield*/, this.waitVideoLoading(config.maxVideoLoadTime)];
case 1:
_a.sent();
_a.label = 2;
case 2:
// Match canvas and video size
this.canvas.height = this.video.videoHeight;
this.canvas.width = this.video.videoWidth;
return [2 /*return*/, this.getEvenlyDistributedImages(numberOfFrames, config)];
}
});
});
};
/**
* Capture image from specific time of the video provided in constructor;
*
* @param time - time of the video where image should be taken
* @param config - image capture params
*
* @return Promise with Blob URL to captured image.
*/
VideoSnap.prototype.getFrameFrom = function (time, config) {
if (config === void 0) { config = {}; }
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
if (!(this.video.readyState !== VIDEO_READY_STATE)) return [3 /*break*/, 2];
return [4 /*yield*/, this.waitVideoLoading(config.maxVideoLoadTime)];
case 1:
_a.sent();
_a.label = 2;
case 2:
// Match canvas and video size
this.canvas.height = this.video.videoHeight;
this.canvas.width = this.video.videoWidth;
return [4 /*yield*/, this.captureImage(time, config.imageQuality)];
case 3: return [2 /*return*/, _a.sent()];
}
});
});
};
/**
* Wait until video loaded, then resolves Promise
* Rejects Promise on error
* Rejects Promise if wait time exceeded maxWaitTime (if specified)
* */
VideoSnap.prototype.waitVideoLoading = function (maxWaitTime) {
var _this = this;
return new Promise(function (resolve, reject) {
var onLoadedHandler = function () {
removeListeners();
resolve();
};
var onErrorHandler = function () {
removeListeners();
reject('Error loading video');
};
var removeListeners = function () {
_this.video.removeEventListener('error', onErrorHandler);
_this.video.removeEventListener('loadedmetadata', onLoadedHandler);
};
_this.video.addEventListener('loadedmetadata', onLoadedHandler);
_this.video.addEventListener('error', onErrorHandler);
if (maxWaitTime) {
setTimeout(onErrorHandler, maxWaitTime);
}
});
};
/**
* Make specific amount of snapshots evenly distributed from start to end of the video.
*
* @param numberOfImages - amount of snapshots to make
* @param config - configuration object
*
* @return Promise with array of Blob url's to images
*/
VideoSnap.prototype.getEvenlyDistributedImages = function (numberOfImages, config) {
return __awaiter(this, void 0, void 0, function () {
var images, step, i, image;
return __generator(this, function (_a) {
switch (_a.label) {
case 0:
images = [];
step = this.video.duration / numberOfImages;
i = 0;
_a.label = 1;
case 1:
if (!(i < numberOfImages)) return [3 /*break*/, 4];
return [4 /*yield*/, this.captureImage(step * i, config.imageQuality)];
case 2:
image = _a.sent();
images.push(image);
_a.label = 3;
case 3:
i++;
return [3 /*break*/, 1];
case 4: return [2 /*return*/, images];
}
});
});
};
/**
* Set video to a specific time and wait while video rewind.
* Then draw image on canvas and convert it to Blob URL
*/
VideoSnap.prototype.captureImage = function (time, quality) {
if (quality === void 0) { quality = 1; }
return __awaiter(this, void 0, void 0, function () {
return __generator(this, function (_a) {
switch (_a.label) {
case 0: return [4 /*yield*/, VideoSnap.rewindVideo(this.video, time)];
case 1:
_a.sent();
this.context.clearRect(0, 0, this.canvas.width, this.canvas.height);
this.context.drawImage(this.video, 0, 0, this.canvas.width, this.canvas.height);
return [2 /*return*/, this.convertCanvasImageToBlobUrl(this.canvas, quality)];
}
});
});
};
/**
* Convert image from canvas into Blob url in JPG (PNG in Edge)
*/
VideoSnap.prototype.convertCanvasImageToBlobUrl = function (canvas, quality) {
return new Promise(function (resolve) {
if (canvas.toBlob) {
canvas.toBlob(function (blob) { return resolve(window.URL.createObjectURL(blob)); }, 'image/jpeg', quality);
}
else if (canvas.msToBlob) {
var blob = canvas.msToBlob();
resolve(window.URL.createObjectURL(blob));
}
else {
throw new Error('canvas.toBlob and canvas.msToBlob are not supported');
}
});
};
return VideoSnap;
}());
exports.VideoSnap = VideoSnap;