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Qt 6.12 was released on 30 September 2026 as an LTS version. Qt highlights native QML hot reload and Qt Canvas Painter, an imperative 2D drawing API designed for GPU rendering through Qt’s Rendering Hardware Interface (QRhi). The important maturity distinction: the core Canvas Painter module is maintained, while its new QtCanvas2D QML API remains in Technology Preview.
What does Qt 6.12 LTS include?
Qt’s release announcement describes Qt 6.12 as a Long-Term Support release and says Qt LTS versions receive maintenance over a five-year period. That is Qt’s stated maintenance model; it does not by itself establish support terms, licensing obligations, or compliance status for a particular project.
Alongside the headline features, Qt identifies official HarmonyOS support as an LTS platform. For exact module and platform changes, consult the versioned Qt 6.12 change log.
How does QML hot reload work?
Qt says the QML Engine now has native hot reload support: developers can preview a running QML application as they edit its code. Qt names Qt Creator and the qmlpreview command-line tool as ways to access the live-preview workflow. The release materials do not quantify reload latency or establish that every edit can be applied without restarting, so behavior should be checked in the context of a particular project and edit.
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Is Qt Canvas Painter supported or still in Technology Preview?
They are separate maturity cases. Qt describes the core Qt Canvas Painter module as out of Technology Preview and maintained. The new QtCanvas2D QML API built on it remains in Technology Preview. Qt presents Canvas2D as a modern architectural replacement for Qt Quick Canvas, but preview status means it should not be treated as having the same maturity as the core module.
What the core module does
Canvas Painter is an imperative, painter-like 2D API for C++ and QML. Qt designed it for GPU rendering through QRhi, and it can use shaders for visual effects. Its API generally follows HTML Canvas 2D conventions, with differences; consult Qt’s Qt 6.12 documentation for the version-specific details.
What Canvas2D adds
QtCanvas2D lets JavaScript draw shapes using the Canvas Painter rendering path. Because Qt still labels this QML API Technology Preview, teams should assess its current API and project suitability before depending on it for production functionality.
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1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsWhat changes matter for graphs and visualizations?
Qt 6.12 offers Canvas Painter as an optional rendering backend for 2D graphs. It is enabled at configure time with -feature-graphs-2d-high-performance-backend; it is not described as the default. Qt’s release announcement says it wants feedback before making the backend the default.
The change log also lists support for SVG path strings through QCanvasPath::addPath() and new fill-rule support. These additions may be relevant to applications building 2D paths or graphs, but Qt’s cited release materials provide no independent benchmark or quantified performance result. A GPU-oriented backend is a design choice, not proof of a specific speedup for a given workload.
How should a team assess an upgrade?
Qt 6.12’s headline features are most relevant when a project needs a longer maintenance horizon under its applicable Qt terms, a target platform covered by the release, live QML preview, or imperative 2D drawing. Before adopting it, check the following against the application rather than assuming that an LTS label or a feature name settles the decision:
- Confirm the maintenance and support terms that apply to the project’s Qt license and distribution.
- Verify target-platform requirements, including whether the newly highlighted HarmonyOS support is relevant to the product.
- Separate stable core Canvas Painter use from reliance on the Technology Preview QtCanvas2D API.
- Evaluate the configure-time graphs backend with representative data and rendering needs; no universal performance gain is established by the release announcement.
- Plan migration and validation for the existing application. The release materials do not establish a project-specific migration effort or guarantee that hot reload will apply every edit without a restart.
What Qt says about CRA compliance
Qt says its commercial Qt 6.12 release is compliant with the EU Cyber Resilience Act (CRA), while also stating that this does not automatically make a customer’s finished product compliant. Customers retain their own CRA responsibilities. Treat this as Qt’s statement about its commercial release, not as legal advice or a blanket assurance about an application built with Qt.
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