--- title: Synchronizing QML Properties with a C++ Singleton... description: A tutorial demonstrates how to synchronize QML properties across dynamically instantiated UI elements using a C++ singleton message broker. The pattern relies... canonical: https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Synchronizing QML Properties with a C++ Singleton Message Broker | daily.dev og:description: A tutorial demonstrates how to synchronize QML properties across dynamically instantiated UI elements using a C++ singleton message broker. The pattern relies... og:url: https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb og:image: https://api.daily.dev/og/posts/MtzOiH7Cb.png og:image:alt: Synchronizing QML Properties with a C++ Singleton Message Broker og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Synchronizing QML Properties with a C++ Singleton Message Broker **[KDAB Blog](https://daily.dev/sources/kdab)** · 2 min read · 0 upvotes · 0 comments ## Summary A tutorial demonstrates how to synchronize QML properties across dynamically instantiated UI elements using a C++ singleton message broker. The pattern relies on signal-slot connections rather than passing values through a component hierarchy, which becomes unwieldy when connecting dynamically created items to each other. Each dynamically instantiated item has a C++ backend class that shares a common broker, exposing properties to QML via Q_PROPERTY and updating them through signal handlers. The example use case is a small app that opens synchronized per-monitor color windows used as makeshift fill lighting for video or photos. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### How do I synchronize QML properties across dynamically instantiated items in Qt? Use a C++ singleton message broker class that all dynamically created items share, rather than passing values through the component hierarchy. Each item gets a C++ model or backend class that connects to the shared broker's signals, exposes properties via Q_PROPERTY, and updates them through the control's signal handlers, avoiding brittle hierarchical bindings. _Developers wiring up dynamic QML components can find more Qt architecture patterns like this on daily.dev._ ## Similar posts on daily.dev - [Qt Widgets to Qt Quick, An Application Journey Part 3](https://daily.dev/posts/qt-widgets-to-qt-quick-an-application-journey-part-3-vdfmbgxpz) · Qt · 0 upvotes · 0 comments --- Tags: [#c++](https://daily.dev/tags/c++), [#design-patterns](https://daily.dev/tags/design-patterns), [#qt](https://daily.dev/tags/qt), [#qml](https://daily.dev/tags/qml) [View this post on daily.dev](https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Synchronizing QML Properties with a C++ Singleton Message Broker","url":"https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb"},"datePublished":"2026-08-31T05:54:38.791Z","dateModified":"2026-08-31T05:55:27.751Z","description":"A tutorial demonstrates how to synchronize QML properties across dynamically instantiated UI elements using a C++ singleton message broker. The pattern relies...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ac12753a325b2071f8ebc91c5c5abe95?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/ac12753a325b2071f8ebc91c5c5abe95?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"KDAB Blog","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"KDAB Blog","logo":"https://media.daily.dev/image/upload/s--A2C_z6sr--/f_auto,q_auto/v1788155671/logos/kdab?_a=BAMAMicg0","url":"https://daily.dev/sources/kdab"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"c++,design-patterns,qt,qml","timeRequired":"PT2M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"KDAB Blog","item":"https://daily.dev/sources/kdab"},{"@type":"ListItem","position":3,"name":"Synchronizing QML Properties with a C++ Singleton Message Broker"}]} {"@context":"https://schema.org","@type":"FAQPage","@id":"https://daily.dev/posts/synchronizing-qml-properties-with-a-c-singleton-message-broker-mtzoih7cb#faq","mainEntity":[{"@type":"Question","name":"How do I synchronize QML properties across dynamically instantiated items in Qt?","acceptedAnswer":{"@type":"Answer","text":"Use a C++ singleton message broker class that all dynamically created items share, rather than passing values through the component hierarchy. Each item gets a C++ model or backend class that connects to the shared broker's signals, exposes properties via Q_PROPERTY, and updates them through the control's signal handlers, avoiding brittle hierarchical bindings. Developers wiring up dynamic QML components can find more Qt architecture patterns like this on daily.dev."}}]} ```