1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137

// Copyright 2006 The Android Open Source Project
// Copyright 2020 Yevhenii Reizner
//
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

mod gradient;
mod linear_gradient;
mod radial_gradient;
mod pattern;

pub use gradient::GradientStop;
pub use linear_gradient::LinearGradient;
pub use radial_gradient::RadialGradient;
pub use pattern::{Pattern, FilterQuality, PixmapPaint};

use crate::{Color, Transform};

use crate::floating_point::NormalizedF32;
use crate::pipeline::RasterPipelineBuilder;
use crate::scalar::Scalar;


/// A shader spreading mode.
#[derive(Copy, Clone, PartialEq, Debug)]
pub enum SpreadMode {
    /// Replicate the edge color if the shader draws outside of its
    /// original bounds.
    Pad,

    /// Repeat the shader's image horizontally and vertically, alternating
    /// mirror images so that adjacent images always seam.
    Reflect,

    /// Repeat the shader's image horizontally and vertically.
    Repeat,
}

impl Default for SpreadMode {
    fn default() -> Self {
        SpreadMode::Pad
    }
}


/// A shader specifies the source color(s) for what is being drawn.
///
/// If a paint has no shader, then the paint's color is used. If the paint has a
/// shader, then the shader's color(s) are use instead, but they are
/// modulated by the paint's alpha. This makes it easy to create a shader
/// once (e.g. bitmap tiling or gradient) and then change its transparency
/// without having to modify the original shader. Only the paint's alpha needs
/// to be modified.
#[derive(Clone, Debug)]
pub enum Shader<'a> {
    /// A solid color shader.
    SolidColor(Color),
    /// A linear gradient shader.
    LinearGradient(LinearGradient),
    /// A radial gradient shader.
    RadialGradient(RadialGradient),
    /// A pattern shader.
    Pattern(Pattern<'a>),
}

impl<'a> Shader<'a> {
    /// Checks if the shader is guaranteed to produce only opaque colors.
    pub fn is_opaque(&self) -> bool {
        match self {
            Shader::SolidColor(ref c) => c.is_opaque(),
            Shader::LinearGradient(ref g) => g.is_opaque(),
            Shader::RadialGradient(_) => false,
            Shader::Pattern(_) => false,
        }
    }

    // Unlike Skia, we do not have is_constant, because we don't have Color shaders.

    /// If this returns false, then we draw nothing (do not fall back to shader context)
    pub(crate) fn push_stages(&self, p: &mut RasterPipelineBuilder) -> Option<()> {
        match self {
            Shader::SolidColor(color) => {
                p.push_uniform_color(color.premultiply());
                Some(())
            }
            Shader::LinearGradient(ref g) => g.push_stages(p),
            Shader::RadialGradient(ref g) => g.push_stages(p),
            Shader::Pattern(ref patt) => patt.push_stages(p),
        }
    }

    /// Transforms the shader.
    pub fn transform(&mut self, ts: Transform) {
        match self {
            Shader::SolidColor(_) => {}
            Shader::LinearGradient(g) => {
                g.base.transform = g.base.transform.post_concat(ts);
            }
            Shader::RadialGradient(g) => {
                g.base.transform = g.base.transform.post_concat(ts);
            }
            Shader::Pattern(p) => {
                p.transform = p.transform.post_concat(ts);
            }
        }
    }

    /// Shifts shader's opacity.
    ///
    /// `opacity` will be clamped to the 0..=1 range.
    ///
    /// This is roughly the same as Skia's `SkPaint::setAlpha`.
    ///
    /// Unlike Skia, we do not support global alpha/opacity, which is in Skia
    /// is set via the alpha channel of the `SkPaint::fColor4f`.
    /// Instead, you can shift the opacity of the shader to whatever value you need.
    ///
    /// - For `SolidColor` this function will multiply `color.alpha` by `opacity`.
    /// - For gradients this function will multiply all colors by `opacity`.
    /// - For `Pattern` this function will multiply `Patter::opacity` by `opacity`.
    pub fn apply_opacity(&mut self, opacity: f32) {
        match self {
            Shader::SolidColor(ref mut c) => {
                c.apply_opacity(opacity);
            }
            Shader::LinearGradient(g) => {
                g.base.apply_opacity(opacity);
            }
            Shader::RadialGradient(g) => {
                g.base.apply_opacity(opacity);
            }
            Shader::Pattern(ref mut p) => {
                p.opacity = NormalizedF32::new(p.opacity.get() * opacity.bound(0.0, 1.0)).unwrap();
            }
        }
    }
}