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/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
use api::{ColorF, MixBlendMode};
use api::units::*;
use crate::pattern::{
Pattern, PatternBuilder, PatternBuilderContext, PatternBuilderState, PatternKind,
PatternShaderInput, PatternTextureInput,
};
use crate::render_task_graph::RenderTaskId;
use crate::renderer::BlendMode;
/// A mix-blend-mode pattern that can't be expressed with a GPU blend equation.
/// Drawn via the ps_quad_mix_blend shader.
///
/// The backdrop (a readback render task) is sampled from slot 0 (sColor0).
/// The source (the picture's own content) is sampled from slot 1 (sColor1), its
/// texture-cache rect is written to the pattern's gpu block.
pub struct MixBlendPattern {
pub backdrop_task_id: RenderTaskId,
pub src_task_id: RenderTaskId,
pub mode: MixBlendMode,
}
impl PatternBuilder for MixBlendPattern {
fn build(
&self,
_sub_rect: Option<DeviceRect>,
_offset: LayoutVector2D,
_ctx: &PatternBuilderContext,
state: &mut PatternBuilderState,
) -> Pattern {
// See fetch in ps_quad_mix_blend.glsl: the source texture-cache rect,
// resolved from its render task.
let mut writer = state.frame_gpu_data.f32.write_blocks(1);
writer.push_render_task(self.src_task_id);
let addr = writer.finish();
Pattern {
kind: PatternKind::MixBlend,
shader_input: PatternShaderInput(addr.as_int(), self.mode as u32 as i32),
texture_input: PatternTextureInput {
task_ids: [self.backdrop_task_id, self.src_task_id, RenderTaskId::INVALID],
},
base_color: ColorF::WHITE,
is_opaque: false,
blend_mode: BlendMode::PremultipliedAlpha,
}
}
}
/// A mix-blend-mode patterns that maps to a GPU blend state (potentially using
/// an advanced blend equation).
/// The source is drawn as a normal premultiplied image with ps_quad_textured
/// and the blend mode is applied by the blend stage against the destination.
pub struct FixedFunctionMixBlendPattern {
pub src_task_id: RenderTaskId,
pub blend_mode: BlendMode,
}
impl PatternBuilder for FixedFunctionMixBlendPattern {
fn build(
&self,
_sub_rect: Option<DeviceRect>,
_offset: LayoutVector2D,
_ctx: &PatternBuilderContext,
_state: &mut PatternBuilderState,
) -> Pattern {
Pattern::texture(self.src_task_id, false).with_blend_mode(self.blend_mode)
}
}