This is a collection of QML multithreading examples.
线程 is a collection of QML multithreading examples.
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Threaded ListModel 包含 ListView 和 ListModel 。 ListModel object is updated asynchronously in another thread, and the results propagate back to the main thread. A timer requests updates from the worker thread periodically:
Timer { id: timer interval: 2000; repeat: true running: true triggeredOnStart: true onTriggered: { var msg = {'action': 'appendCurrentTime', 'model': listModel}; worker.sendMessage(msg); } }
Inside the worker thread, the ListModel is synchronized once the data is finished loading:
WorkerScript.onMessage = function(msg) { if (msg.action == 'appendCurrentTime') { var data = {'time': new Date().toTimeString()}; msg.model.append(data); msg.model.sync(); // updates the changes to the list } }
WorkerScript contains an example of using a WorkerScript to offload expensive calculations into another thread. This keeps the UI from being blocked. This example calculates numbers in Pascal's Triangle, and not in a very optimal way, so it will often take several seconds to complete the calculation. By doing this in a WorkerScript in another thread, the UI is not blocked during this time.
When the UI needs another value, a request is sent to the WorkerScript :
Spinner { id: rowSpinner label: "Row" onValueChanged: { resultText.text = "Loading..."; myWorker.sendMessage( { row: rowSpinner.value, column: columnSpinner.value } ); } }
The workerscript then is free to take a really long time to calculate it:
WorkerScript.onMessage = function(message) { //Calculate result (may take a while, using a naive algorithm) var calculatedResult = triangle(message.row, message.column); //Send result back to main thread WorkerScript.sendMessage( { row: message.row, column: message.column, result: calculatedResult} ); }
When it's done, the result returns to the main scene via the WorkerScript 类型:
WorkerScript { id: myWorker source: "workerscript.mjs" onMessage: (messageObject) => { if (messageObject.row == rowSpinner.value && messageObject.column == columnSpinner.value){ //Not an old result if (messageObject.result == -1) resultText.text = "Column must be <= Row"; else resultText.text = messageObject.result; } } }