1 files changed, 240 insertions, 0 deletions
diff --git a/gfx/wr/webrender_build/src/shader_features.rs b/gfx/wr/webrender_build/src/shader_features.rs
new file mode 100644
index 0000000000..db16cdf703
--- /dev/null
+++ b/gfx/wr/webrender_build/src/shader_features.rs
@@ -0,0 +1,240 @@
+/* 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
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+use std::collections::HashMap;
+
+bitflags! {
+    #[derive(Default)]
+    pub struct ShaderFeatureFlags: u32 {
+        const GL = 1 << 0;
+        const GLES = 1 << 1;
+
+        const ADVANCED_BLEND_EQUATION = 1 << 8;
+        const DUAL_SOURCE_BLENDING = 1 << 9;
+        const DITHERING = 1 << 10;
+        const TEXTURE_EXTERNAL = 1 << 11;
+        const TEXTURE_EXTERNAL_ESSL1 = 1 << 12;
+        const DEBUG = 1 << 13;
+    }
+}
+
+pub type ShaderFeatures = HashMap<&'static str, Vec<String>>;
+
+/// Builder for a list of features.
+#[derive(Clone)]
+struct FeatureList<'a> {
+    list: Vec<&'a str>,
+}
+
+impl<'a> FeatureList<'a> {
+    fn new() -> Self {
+        FeatureList {
+            list: Vec::new(),
+        }
+    }
+
+    fn add(&mut self, feature: &'a str) {
+        assert!(!feature.contains(','));
+        self.list.push(feature);
+    }
+
+    fn with(&self, feature: &'a str) -> Self {
+        let mut other = self.clone();
+        other.add(feature);
+        other
+    }
+
+    fn concat(&self, other: &Self) -> Self {
+        let mut list = self.list.clone();
+        list.extend_from_slice(&other.list);
+        FeatureList {
+            list
+        }
+    }
+
+    fn finish(&mut self) -> String {
+        self.list.sort_unstable();
+        self.list.join(",")
+    }
+}
+
+/// Computes available shaders and their features for the given feature flags.
+pub fn get_shader_features(flags: ShaderFeatureFlags) -> ShaderFeatures {
+    let mut shaders = ShaderFeatures::new();
+
+    // Clip shaders
+    shaders.insert("cs_clip_rectangle", vec![String::new(), "FAST_PATH".to_string()]);
+    shaders.insert("cs_clip_image", vec!["TEXTURE_2D".to_string()]);
+    shaders.insert("cs_clip_box_shadow", vec!["TEXTURE_2D".to_string()]);
+
+    // Cache shaders
+    shaders.insert("cs_blur", vec!["ALPHA_TARGET".to_string(), "COLOR_TARGET".to_string()]);
+
+    shaders.insert("ps_quad_mask", vec![String::new(), "FAST_PATH".to_string()]);
+
+    for name in &[
+        "cs_line_decoration",
+        "cs_fast_linear_gradient",
+        "cs_border_segment",
+        "cs_border_solid",
+        "cs_svg_filter",
+    ] {
+        shaders.insert(name, vec![String::new()]);
+    }
+
+    for name in &[
+        "cs_linear_gradient",
+        "cs_radial_gradient",
+        "cs_conic_gradient",
+    ] {
+        let mut features = Vec::new();
+        features.push(String::new());
+        if flags.contains(ShaderFeatureFlags::DITHERING) {
+            features.push("DITHERING".to_string());
+        }
+        shaders.insert(name, features);
+    }
+
+    let mut base_prim_features = FeatureList::new();
+
+    // Brush shaders
+    let mut brush_alpha_features = base_prim_features.with("ALPHA_PASS");
+    for name in &["brush_solid", "brush_blend", "brush_mix_blend"] {
+        let mut features: Vec<String> = Vec::new();
+        features.push(base_prim_features.finish());
+        features.push(brush_alpha_features.finish());
+        features.push("DEBUG_OVERDRAW".to_string());
+        shaders.insert(name, features);
+    }
+    for name in &["brush_linear_gradient"] {
+        let mut features: Vec<String> = Vec::new();
+        let mut list = FeatureList::new();
+        if flags.contains(ShaderFeatureFlags::DITHERING) {
+            list.add("DITHERING");
+        }
+        features.push(list.concat(&base_prim_features).finish());
+        features.push(list.concat(&brush_alpha_features).finish());
+        features.push(list.with("DEBUG_OVERDRAW").finish());
+        shaders.insert(name, features);
+    }
+
+    {
+        let mut features: Vec<String> = Vec::new();
+        features.push(base_prim_features.finish());
+        features.push(brush_alpha_features.finish());
+        features.push(base_prim_features.with("ANTIALIASING").finish());
+        features.push(brush_alpha_features.with("ANTIALIASING").finish());
+        features.push("ANTIALIASING,DEBUG_OVERDRAW".to_string());
+        features.push("DEBUG_OVERDRAW".to_string());
+        shaders.insert("brush_opacity", features);
+    }
+
+    // Image brush shaders
+    let mut texture_types = vec!["TEXTURE_2D"];
+    if flags.contains(ShaderFeatureFlags::GL) {
+        texture_types.push("TEXTURE_RECT");
+    }
+    if flags.contains(ShaderFeatureFlags::TEXTURE_EXTERNAL) {
+        texture_types.push("TEXTURE_EXTERNAL");
+    }
+    let mut image_features: Vec<String> = Vec::new();
+    for texture_type in &texture_types {
+        let mut fast = FeatureList::new();
+        if !texture_type.is_empty() {
+            fast.add(texture_type);
+        }
+        image_features.push(fast.concat(&base_prim_features).finish());
+        image_features.push(fast.concat(&brush_alpha_features).finish());
+        image_features.push(fast.with("DEBUG_OVERDRAW").finish());
+        let mut slow = fast.clone();
+        slow.add("REPETITION");
+        slow.add("ANTIALIASING");
+        image_features.push(slow.concat(&base_prim_features).finish());
+        image_features.push(slow.concat(&brush_alpha_features).finish());
+        image_features.push(slow.with("DEBUG_OVERDRAW").finish());
+        if flags.contains(ShaderFeatureFlags::ADVANCED_BLEND_EQUATION) {
+            let advanced_blend_features = brush_alpha_features.with("ADVANCED_BLEND");
+            image_features.push(fast.concat(&advanced_blend_features).finish());
+            image_features.push(slow.concat(&advanced_blend_features).finish());
+        }
+        if flags.contains(ShaderFeatureFlags::DUAL_SOURCE_BLENDING) {
+            let dual_source_features = brush_alpha_features.with("DUAL_SOURCE_BLENDING");
+            image_features.push(fast.concat(&dual_source_features).finish());
+            image_features.push(slow.concat(&dual_source_features).finish());
+        }
+    }
+    shaders.insert("brush_image", image_features);
+
+    let mut composite_texture_types = texture_types.clone();
+    if flags.contains(ShaderFeatureFlags::TEXTURE_EXTERNAL_ESSL1) {
+        composite_texture_types.push("TEXTURE_EXTERNAL_ESSL1");
+    }
+    let mut composite_features: Vec<String> = Vec::new();
+    for texture_type in &composite_texture_types {
+        let base = texture_type.to_string();
+        composite_features.push(base);
+    }
+    shaders.insert("cs_scale", composite_features.clone());
+
+    // YUV image brush and composite shaders
+    let mut yuv_features: Vec<String> = Vec::new();
+    for texture_type in &texture_types {
+        let mut list = FeatureList::new();
+        if !texture_type.is_empty() {
+            list.add(texture_type);
+        }
+        list.add("YUV");
+        composite_features.push(list.finish());
+        yuv_features.push(list.concat(&base_prim_features).finish());
+        yuv_features.push(list.concat(&brush_alpha_features).finish());
+        yuv_features.push(list.with("DEBUG_OVERDRAW").finish());
+    }
+    shaders.insert("brush_yuv_image", yuv_features);
+
+    // Fast path composite shaders
+    for texture_type in &composite_texture_types {
+        let mut list = FeatureList::new();
+        if !texture_type.is_empty() {
+            list.add(texture_type);
+        }
+        list.add("FAST_PATH");
+        composite_features.push(list.finish());
+    }
+    shaders.insert("composite", composite_features);
+
+    // Prim shaders
+    let mut text_types = vec![""];
+    if flags.contains(ShaderFeatureFlags::DUAL_SOURCE_BLENDING) {
+        text_types.push("DUAL_SOURCE_BLENDING");
+    }
+    let mut text_features: Vec<String> = Vec::new();
+    for text_type in &text_types {
+        let mut list = base_prim_features.with("TEXTURE_2D");
+        if !text_type.is_empty() {
+            list.add(text_type);
+        }
+        let mut alpha_list = list.with("ALPHA_PASS");
+        text_features.push(alpha_list.finish());
+        text_features.push(alpha_list.with("GLYPH_TRANSFORM").finish());
+        text_features.push(list.with("DEBUG_OVERDRAW").finish());
+    }
+    shaders.insert("ps_text_run", text_features);
+
+    shaders.insert("ps_split_composite", vec![base_prim_features.finish()]);
+
+    shaders.insert("ps_quad_textured", vec![base_prim_features.finish()]);
+
+    shaders.insert("ps_clear", vec![base_prim_features.finish()]);
+
+    shaders.insert("ps_copy", vec![base_prim_features.finish()]);
+
+    if flags.contains(ShaderFeatureFlags::DEBUG) {
+        for name in &["debug_color", "debug_font"] {
+            shaders.insert(name, vec![String::new()]);
+        }
+    }
+
+    shaders
+}
+