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Hand Android's develop frame to the compositor as a texture again

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With Skia drawing pre-rotated on wgpu's Vulkan swapchain, Android no
longer needs to draw with Skia over OpenGL, which was the only reason
the develop view read its frame back through memory (TD-1).

So `unstable-wgpu-29` moves back to the common slint dependency. The
android-activity backend then builds `SkiaRenderer::default_wgpu_29`,
and `shared_gpu` loses its Android arm. The one wgpu device is handed to
Slint through `BackendSelector::require_wgpu_29` on both platforms.
`slint::android::init_with_event_listener` runs before `dr_ui::run`, so
the selector reaches the Android adapter before its window exists.
`renderer-femtovg-wgpu` stays desktop-only, since Android has no FemtoVG.

The two `#[cfg(target_os = "android")]` readbacks in `develop::render`
(the frame through `export_pixels` and the focus overlay through
`read_overlay`) are gone. `read_overlay` stays for the tests that check
what the overlay marks.

Built for arm64 and release-signed. Not yet run on the tablet.
This commit is contained in:
dtourolle
2026-09-25 04:20:19 -04:00
parent 4b4c9e2e6d
commit a8043e6827
6 changed files with 72 additions and 159 deletions
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ui/dr-ui/src/develop/render.rs
+8 -50
View File
@@ -278,29 +278,8 @@ impl DevelopSession {
// in `AdjustPass`'s texture descriptor — so a failure here is a
// descriptor that drifted, not anything the caller did. Say that,
// rather than surfacing "InvalidUsage" to a photographer.
#[cfg(not(target_os = "android"))]
{
slint::Image::try_from(texture.clone())
.map_err(|e| format!("the render target is not importable by the compositor: {e}"))
}
// Android draws with Skia over OpenGL and cannot sample a
// `wgpu::Texture`, so the frame comes back through memory. See
// `crate::shared_gpu`'s Android arm for why that is the trade on this
// platform. The pass still runs on the GPU; only this last hop does not.
#[cfg(target_os = "android")]
{
let _ = texture;
let (rgba, w, h) = self
.adjust
.export_pixels()
.map_err(|e| format!("reading the rendered frame back: {e}"))?;
let mut buf = slint::SharedPixelBuffer::<slint::Rgba8Pixel>::new(w, h);
let wanted = (w as usize) * (h as usize) * 4;
let src = &rgba[..wanted.min(rgba.len())];
buf.make_mut_bytes()[..src.len()].copy_from_slice(src);
Ok(slint::Image::from_rgba8(buf))
}
slint::Image::try_from(texture.clone())
.map_err(|e| format!("the render target is not importable by the compositor: {e}"))
}
/// TRACES: FR-DSP-7
@@ -463,33 +442,12 @@ impl DevelopSession {
.ok()?
.clone();
#[cfg(not(target_os = "android"))]
{
// A layer over the canvas rather than a tint in it, so nothing
// here reaches the histogram or an export — see `FocusPeakPass`
// for the whole of that argument.
slint::Image::try_from(overlay)
.inspect_err(|e| log::warn!("the focus overlay is not importable: {e}"))
.ok()
}
// Android draws with Skia over OpenGL and cannot sample a
// `wgpu::Texture`, so the overlay follows the frame it belongs to back
// through memory (technical-debt.md TD-1). The measurement still
// happens on the GPU; only this last hop does not.
#[cfg(target_os = "android")]
{
let _ = overlay;
let (rgba, w, h) = pass
.read_overlay()
.inspect_err(|e| log::warn!("reading the focus overlay back: {e}"))
.ok()?;
let mut buf = slint::SharedPixelBuffer::<slint::Rgba8Pixel>::new(w, h);
let wanted = (w as usize) * (h as usize) * 4;
let src = &rgba[..wanted.min(rgba.len())];
buf.make_mut_bytes()[..src.len()].copy_from_slice(src);
Some(slint::Image::from_rgba8(buf))
}
// A layer over the canvas rather than a tint in it, so nothing
// here reaches the histogram or an export — see `FocusPeakPass`
// for the whole of that argument.
slint::Image::try_from(overlay)
.inspect_err(|e| log::warn!("the focus overlay is not importable: {e}"))
.ok()
}
/// Render the *whole* frame for the crop overlay to be drawn over.