I am trying to place the screenshot image into html canvas but not being able to. I have taken screenshot of current tab by using following chrome API. Trying to make a chrome extension.
/* background.js */
let id = 100;
//calling chrome api
chrome.browserAction.onClicked.addListener(() => {
chrome.tabs.captureVisibleTab((screenshotUrl) => {
const viewTabUrl = chrome.extension.getURL('screenshot.html?id=' + id++)
let targetId = null;
//checking if the opened tab id is the same as the target id
chrome.tabs.onUpdated.addListener(function listener(tabId, changedProps) {
if (tabId != targetId || changedProps.status != "complete")
return;
chrome.tabs.onUpdated.removeListener(listener);
const views = chrome.extension.getViews();
for (let i = 0; i < views.length; i++) {
let view = views[i];
if (view.location.href == viewTabUrl) {
view.setScreenshotUrl(screenshotUrl);
return;
}
}
});
//chrome tabs create method
//no listener on create event because the tab’s URL may not be set at the time this event is fired
chrome.tabs.create({ url: viewTabUrl }, (tab) => {
targetId = tab.id;
});
});
});
But not able to call the image from the function
function setScreenshotUrl(url) {
document.getElementById('target').src = url;
};
var cnv = document.getElementById("conv");
cnv.onclick = function() {
var x = document.getElementById("target").src;
document.getElementById("demo").innerHTML = x;
};
window.addEventListener('load', function() {
var c = document.getElementById("myCanvas");
var ctx = c.getContext("2d");
var img = document.getElementById("target");
ctx.drawImage(img, 10, 10, 300, 175, 0, 0, 100, 175);
});
The problem was image was not ready at windows on load event, verified by checking the innerHTML of the image, while if I try to do the same thing in onClick event, the image is successfully loaded into canvas.