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import { OCRRequest, OCRResponse } from "@/shared/ocr-request";
const OFFSCREEN_DOCUMENT_PATH = "offscreen/ocr/index.html";
// Function to ensure the offscreen document is open
/**
* Ensures the offscreen OCR document is open. If it already exists
* this is a no-op.
*/
async function setupOffscreenDocument(): Promise<void> {
if (await chrome.offscreen.hasDocument()) {
return; // Offscreen document already open
}
await chrome.offscreen.createDocument({
url: OFFSCREEN_DOCUMENT_PATH,
reasons: [chrome.offscreen.Reason.CLIPBOARD],
justification: "Performing OCR with Tesseract.js in a long-running context."
});
}
// Listen for messages from content scripts (and popup if applicable)
/**
* Listens for `"OCR"` messages from content scripts. Forwards the
* image data URL to an offscreen document for Tesseract.js processing
* and sends the recognised text back to the caller.
*/
chrome.runtime.onMessage.addListener(function(message: OCRRequest, _sender, sendResponse): boolean {
if (message.type === "OCR" && message.dataURL) {
void (async function(): Promise<void> {
try {
// Ensure the offscreen document is open
await setupOffscreenDocument();
// Send the OCR request to the offscreen document
const offscreenResponse = await chrome.runtime.sendMessage<OCRRequest, OCRResponse>({
type: "OFFSCREEN_OCR_REQUEST",
dataURL: message.dataURL
});
sendResponse(offscreenResponse);
} catch(error) {
sendResponse({ success: false, error: (error as Error).message });
}
})();
return true; // Indicate async response
}
return false;
});
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