GeezerVison

Adds NativeScript Linux (GTK 4) support to canvas and its plugins, through the Node-API modules the Windows port uses.

Packages

• canvas
  • A GTK 4 widget drives the canvasnative.node Node-API module.
  • 2D, WebGL and WebGL2 run on EGL using GDK's display. Offscreen surfaces use pbuffers, and transferred OffscreenCanvas is supported.
  • WebGPU runs on Vulkan. Its frames are shared with GL through exported memory.
• canvas-svg: a GTK 4 view.
• canvas-media: video and audio play through GStreamer.
• audio-context: works through its Node-API module.
• canvas-gamepad:
  • Reads evdev devices through gilrs, which uses SDL's mapping database. Hot-plug is watched through udev.
  • Reports the standard 17-button / 4-axis layout.
  • Reading /dev/input/event* requires read access. Desktop sessions normally grant it to gamepads.
• canvas-polyfill:
  • fetch works for local files.
  • Blob-URL Workers work on Node-API hosts.
  • The window size is taken from the app window.
• canvas-chartjs: Linux V8 ships without ICU data, so the Intl polyfills are forced on there.
• The x64 and arm64 .node modules are committed under each package's platforms/linux/lib/<arch>. They're built by tools/scripts/build-linux.sh, which needs libudev-dev on the build machine. The arm64 ones were built on Ubuntu 22.04 arm64 (glibc 2.35, GTK 4.6, clang 18) and load in Node 22 on arm64, but haven't been run in a GTK app on arm64 hardware yet.

Cross-platform fixes found along the way

• WebGL:
  • clearBuffer* now takes the buffer enum.
  • bindTransformFeedback now binds the transform feedback.
  • bindVertexArrayOES(null) now unbinds.
• WebGPU: subgroups are no longer advertised, because naga can't enable them yet. WGSL compile errors are now logged.
• 2D:
  • Non-finite values for lineDashOffset, globalAlpha, miterLimit and lineWidth are now ignored.
  • createImageBitmap accepts Blob-like sources.
• Images: an image that fails to decode now fires error.
• Node-API: Windows-only methods are now in their own impl blocks, so the module builds on other hosts.

GPU video frames

• Display: canvas-media decodes into GL textures (glupload ! glcolorconvert) in a GStreamer GL context that shares GDK's, and GTK shows them as GdkGLTextures. If the GL path isn't available it falls back to CPU memory; NS_CANVAS_MEDIA_CPU=1 forces the fallback.
• WebGL: texImage2D / texImage3D with a video does a GPU blit through an EGLImage, guarded by an EGL fence.
• WebGPU: importExternalTexture and copyExternalImageToTexture(video) read Vulkan images that GL imports and fills on the GPU, synchronised by exported semaphores, as on Windows.
  • wgpu's Vulkan backend has no external textures, so texture_external is emulated by binding the frame as a texture_2d<f32>.
• Software decode: mapped frames go to WebGL / WebGPU natively and are uploaded once.
• VA-API: disable-vpp on vaapidecodebin fixes H.264 producing no frames on the Intel iHD driver.

1080p, process CPU:

WebGL texImage2D(video): 0.19 ms per call, down from ~3.9 ms.

Not done: displaying DMABuf frames with GdkDmabufTexture (needs GTK 4.14+) and importing them straight into Vulkan. Both are TODOs.

Tests: media.video 9/9 on both paths, webgpu 19/19, webgl 83/83.

Depends on

• feat: Linux platform (GTK 4) NativeScript#11620: core with the Linux platform.
• feat: linux nativescript-cli#6202: the CLI copies .node modules from a plugin's platforms/linux/lib/<arch>.
• The Linux runtime is not published yet. apps/demo and apps/demo-linux point at a local runtime pack in tools/linux/ (gitignored).

Known gaps

• Draco decoding in a Worker (three)
• webgpu_backdrop renders black
• an error in the webgpu_cube sample
• gamepad tested only with no controller attached