pulp::canvas::GpuBloomEffect Struct Reference

GPU bloom/glow — a real bright-pass + blur + additive composite. More...

#include <view_effect.hpp>

Public Member Functions
void	configure_layer (Canvas &canvas, float x, float y, float w, float h) override
	Push the compositing layer(s) this effect needs, configured with its opacity, image filters, blend mode, etc.
virtual int	layer_count () const
	How many layers configure_layer() pushes.
virtual bool	needs_layer () const
	Whether this effect requires a compositing layer (most do).
virtual void	paint_overlay (Canvas &canvas, float x, float y, float w, float h)
	Paint an overlay on TOP of the already-painted subtree, but still INSIDE the effect's compositing layer(s) (called by View::paint_all just before the layers are popped).

Public Attributes
float	threshold = 0.8f
	Brightness cutoff in [0,1]; below it, no glow.
float	intensity = 0.5f
	Glow gain applied to the thresholded highlights.
float	radius = 8.0f
	Blur radius (px) of the glow.

Detailed Description

GPU bloom/glow — a real bright-pass + blur + additive composite.

SkiaCanvas thresholds the subtree (only pixels brighter than threshold contribute), blurs the survivors by radius, and composites them back additively (kPlus) so bright regions bleed a glow past their edges. Backends without offscreen post-processing degrade to a plain blurred layer (the base save_layer_with_bloom default); RecordingCanvas records the bloom intent so headless tests can assert it.

threshold is a brightness cutoff WITHIN the 8-bit [0,1] range — Pulp surfaces are 8-bit unorm + sRGB (see core/render/), so this is a low-dynamic-range bloom, not HDR headroom above 1.0. That is enough for the light-on-dark glow it exists for; a true HDR bloom would need a float color pipeline Pulp does not have.

Member Function Documentation

configure_layer()

void pulp::canvas::GpuBloomEffect::configure_layer ( Canvas & canvas, float x, float y, float w, float h )

inlineoverridevirtual

Push the compositing layer(s) this effect needs, configured with its opacity, image filters, blend mode, etc.

The subtree paints into the layer(s); the caller pops them once the subtree is done.

An implementation MUST push exactly layer_count() layers. The caller (View::paint_all) pops that many, so an effect that saves a different number than it reports unbalances the canvas save stack for the rest of the frame.

Implements pulp::canvas::ViewEffect.

layer_count()

virtual int pulp::canvas::ViewEffect::layer_count ( ) const

inlinevirtualinherited

How many layers configure_layer() pushes.

One for a simple effect; EffectChain reports the sum across its children.

Reimplemented in pulp::canvas::EffectChain.

needs_layer()

virtual bool pulp::canvas::ViewEffect::needs_layer ( ) const

inlinevirtualinherited

Whether this effect requires a compositing layer (most do).

Reimplemented in pulp::canvas::EffectChain.

paint_overlay()

virtual void pulp::canvas::ViewEffect::paint_overlay ( Canvas & canvas, float x, float y, float w, float h )

inlinevirtualinherited

Paint an overlay on TOP of the already-painted subtree, but still INSIDE the effect's compositing layer(s) (called by View::paint_all just before the layers are popped).

This is how an effect that darkens or tints the finished content — a vignette drawing a radial gradient — is implemented, instead of the wrong "reduce the whole layer's opacity" approximation. Default: nothing.

Limitation: the overlay draws into the innermost still-open layer. That is correct for a single effect (the only non-chain path today), but in a multi-effect EffectChain (e.g. [vignette, blur]) an earlier effect's overlay lands in a later effect's layer and is filtered by it. See the View::paint_all call site — revisit if overlays-in-chains are needed.

Reimplemented in pulp::canvas::EffectChain, and pulp::canvas::VignetteEffect.

Member Data Documentation

intensity

float pulp::canvas::GpuBloomEffect::intensity = 0.5f

Glow gain applied to the thresholded highlights.

radius

float pulp::canvas::GpuBloomEffect::radius = 8.0f

Blur radius (px) of the glow.

threshold

float pulp::canvas::GpuBloomEffect::threshold = 0.8f

Brightness cutoff in [0,1]; below it, no glow.

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The documentation for this struct was generated from the following file:

• /home/runner/work/pulp/pulp/core/canvas/include/pulp/canvas/view_effect.hpp