Redesign `iced_wgpu` layering architecture

1 files changed, 409 insertions, 219 deletions

diff --git a/wgpu/src/text.rs b/wgpu/src/text.rs
index 97ff77f5..016ac92a 100644
--- a/wgpu/src/text.rs
+++ b/wgpu/src/text.rs
@@ -1,20 +1,67 @@
 use crate::core::alignment;
 use crate::core::{Rectangle, Size, Transformation};
 use crate::graphics::color;
-use crate::graphics::text::cache::{self, Cache};
+use crate::graphics::text::cache::{self, Cache as BufferCache};
 use crate::graphics::text::{font_system, to_color, Editor, Paragraph};
-use crate::layer::Text;
 
-use std::borrow::Cow;
-use std::cell::RefCell;
 use std::sync::Arc;
 
+pub use crate::graphics::Text;
+
+pub type Batch = Vec<Text>;
+
 #[allow(missing_debug_implementations)]
 pub struct Pipeline {
-    renderers: Vec<glyphon::TextRenderer>,
+    format: wgpu::TextureFormat,
     atlas: glyphon::TextAtlas,
+    renderers: Vec<glyphon::TextRenderer>,
     prepare_layer: usize,
-    cache: RefCell<Cache>,
+    cache: BufferCache,
+}
+
+pub enum Cache {
+    Staged(Batch),
+    Uploaded {
+        batch: Batch,
+        renderer: glyphon::TextRenderer,
+        atlas: Option<glyphon::TextAtlas>,
+        buffer_cache: Option<BufferCache>,
+        scale_factor: f32,
+        target_size: Size<u32>,
+        needs_reupload: bool,
+    },
+}
+
+impl Cache {
+    pub fn is_empty(&self) -> bool {
+        match self {
+            Cache::Staged(batch) | Cache::Uploaded { batch, .. } => {
+                batch.is_empty()
+            }
+        }
+    }
+
+    pub fn update(&mut self, new_batch: Batch) {
+        match self {
+            Self::Staged(batch) => {
+                *batch = new_batch;
+            }
+            Self::Uploaded {
+                batch,
+                needs_reupload,
+                ..
+            } => {
+                *batch = new_batch;
+                *needs_reupload = true;
+            }
+        }
+    }
+}
+
+impl Default for Cache {
+    fn default() -> Self {
+        Self::Staged(Batch::default())
+    }
 }
 
 impl Pipeline {
@@ -24,6 +71,7 @@ impl Pipeline {
         format: wgpu::TextureFormat,
     ) -> Self {
         Pipeline {
+            format,
             renderers: Vec::new(),
             atlas: glyphon::TextAtlas::with_color_mode(
                 device,
@@ -36,25 +84,16 @@ impl Pipeline {
                 },
             ),
             prepare_layer: 0,
-            cache: RefCell::new(Cache::new()),
+            cache: BufferCache::new(),
         }
     }
 
-    pub fn load_font(&mut self, bytes: Cow<'static, [u8]>) {
-        font_system()
-            .write()
-            .expect("Write font system")
-            .load_font(bytes);
-
-        self.cache = RefCell::new(Cache::new());
-    }
-
-    pub fn prepare(
+    pub fn prepare_batch(
         &mut self,
         device: &wgpu::Device,
         queue: &wgpu::Queue,
         encoder: &mut wgpu::CommandEncoder,
-        sections: &[Text<'_>],
+        sections: &Batch,
         layer_bounds: Rectangle,
         scale_factor: f32,
         target_size: Size<u32>,
@@ -68,210 +107,18 @@ impl Pipeline {
             ));
         }
 
-        let mut font_system = font_system().write().expect("Write font system");
-        let font_system = font_system.raw();
-
         let renderer = &mut self.renderers[self.prepare_layer];
-        let cache = self.cache.get_mut();
-
-        enum Allocation {
-            Paragraph(Paragraph),
-            Editor(Editor),
-            Cache(cache::KeyHash),
-            Raw(Arc<glyphon::Buffer>),
-        }
-
-        let allocations: Vec<_> = sections
-            .iter()
-            .map(|section| match section {
-                Text::Paragraph { paragraph, .. } => {
-                    paragraph.upgrade().map(Allocation::Paragraph)
-                }
-                Text::Editor { editor, .. } => {
-                    editor.upgrade().map(Allocation::Editor)
-                }
-                Text::Cached(text) => {
-                    let (key, _) = cache.allocate(
-                        font_system,
-                        cache::Key {
-                            content: text.content,
-                            size: text.size.into(),
-                            line_height: f32::from(
-                                text.line_height.to_absolute(text.size),
-                            ),
-                            font: text.font,
-                            bounds: Size {
-                                width: text.bounds.width,
-                                height: text.bounds.height,
-                            },
-                            shaping: text.shaping,
-                        },
-                    );
-
-                    Some(Allocation::Cache(key))
-                }
-                Text::Raw { raw, .. } => {
-                    raw.buffer.upgrade().map(Allocation::Raw)
-                }
-            })
-            .collect();
-
-        let layer_bounds = layer_bounds * scale_factor;
-
-        let text_areas = sections.iter().zip(allocations.iter()).filter_map(
-            |(section, allocation)| {
-                let (
-                    buffer,
-                    bounds,
-                    horizontal_alignment,
-                    vertical_alignment,
-                    color,
-                    clip_bounds,
-                    transformation,
-                ) = match section {
-                    Text::Paragraph {
-                        position,
-                        color,
-                        clip_bounds,
-                        transformation,
-                        ..
-                    } => {
-                        use crate::core::text::Paragraph as _;
-
-                        let Some(Allocation::Paragraph(paragraph)) = allocation
-                        else {
-                            return None;
-                        };
-
-                        (
-                            paragraph.buffer(),
-                            Rectangle::new(*position, paragraph.min_bounds()),
-                            paragraph.horizontal_alignment(),
-                            paragraph.vertical_alignment(),
-                            *color,
-                            *clip_bounds,
-                            *transformation,
-                        )
-                    }
-                    Text::Editor {
-                        position,
-                        color,
-                        clip_bounds,
-                        transformation,
-                        ..
-                    } => {
-                        use crate::core::text::Editor as _;
-
-                        let Some(Allocation::Editor(editor)) = allocation
-                        else {
-                            return None;
-                        };
-
-                        (
-                            editor.buffer(),
-                            Rectangle::new(*position, editor.bounds()),
-                            alignment::Horizontal::Left,
-                            alignment::Vertical::Top,
-                            *color,
-                            *clip_bounds,
-                            *transformation,
-                        )
-                    }
-                    Text::Cached(text) => {
-                        let Some(Allocation::Cache(key)) = allocation else {
-                            return None;
-                        };
-
-                        let entry = cache.get(key).expect("Get cached buffer");
-
-                        (
-                            &entry.buffer,
-                            Rectangle::new(
-                                text.bounds.position(),
-                                entry.min_bounds,
-                            ),
-                            text.horizontal_alignment,
-                            text.vertical_alignment,
-                            text.color,
-                            text.clip_bounds,
-                            Transformation::IDENTITY,
-                        )
-                    }
-                    Text::Raw {
-                        raw,
-                        transformation,
-                    } => {
-                        let Some(Allocation::Raw(buffer)) = allocation else {
-                            return None;
-                        };
-
-                        let (width, height) = buffer.size();
-
-                        (
-                            buffer.as_ref(),
-                            Rectangle::new(
-                                raw.position,
-                                Size::new(width, height),
-                            ),
-                            alignment::Horizontal::Left,
-                            alignment::Vertical::Top,
-                            raw.color,
-                            raw.clip_bounds,
-                            *transformation,
-                        )
-                    }
-                };
-
-                let bounds = bounds * transformation * scale_factor;
-
-                let left = match horizontal_alignment {
-                    alignment::Horizontal::Left => bounds.x,
-                    alignment::Horizontal::Center => {
-                        bounds.x - bounds.width / 2.0
-                    }
-                    alignment::Horizontal::Right => bounds.x - bounds.width,
-                };
-
-                let top = match vertical_alignment {
-                    alignment::Vertical::Top => bounds.y,
-                    alignment::Vertical::Center => {
-                        bounds.y - bounds.height / 2.0
-                    }
-                    alignment::Vertical::Bottom => bounds.y - bounds.height,
-                };
-
-                let clip_bounds = layer_bounds.intersection(
-                    &(clip_bounds * transformation * scale_factor),
-                )?;
-
-                Some(glyphon::TextArea {
-                    buffer,
-                    left,
-                    top,
-                    scale: scale_factor * transformation.scale_factor(),
-                    bounds: glyphon::TextBounds {
-                        left: clip_bounds.x as i32,
-                        top: clip_bounds.y as i32,
-                        right: (clip_bounds.x + clip_bounds.width) as i32,
-                        bottom: (clip_bounds.y + clip_bounds.height) as i32,
-                    },
-                    default_color: to_color(color),
-                })
-            },
-        );
-
-        let result = renderer.prepare(
+        let result = prepare(
             device,
             queue,
             encoder,
-            font_system,
+            renderer,
             &mut self.atlas,
-            glyphon::Resolution {
-                width: target_size.width,
-                height: target_size.height,
-            },
-            text_areas,
-            &mut glyphon::SwashCache::new(),
+            &mut self.cache,
+            sections,
+            layer_bounds,
+            scale_factor,
+            target_size,
         );
 
         match result {
@@ -286,7 +133,109 @@ impl Pipeline {
         }
     }
 
-    pub fn render<'a>(
+    pub fn prepare_cache(
+        &mut self,
+        device: &wgpu::Device,
+        queue: &wgpu::Queue,
+        encoder: &mut wgpu::CommandEncoder,
+        cache: &mut Cache,
+        layer_bounds: Rectangle,
+        new_scale_factor: f32,
+        new_target_size: Size<u32>,
+    ) {
+        match cache {
+            Cache::Staged(_) => {
+                let Cache::Staged(batch) =
+                    std::mem::replace(cache, Cache::Staged(Batch::default()))
+                else {
+                    unreachable!()
+                };
+
+                // TODO: Find a better heuristic (?)
+                let (mut atlas, mut buffer_cache) = if batch.len() > 10 {
+                    (
+                        Some(glyphon::TextAtlas::with_color_mode(
+                            device,
+                            queue,
+                            self.format,
+                            if color::GAMMA_CORRECTION {
+                                glyphon::ColorMode::Accurate
+                            } else {
+                                glyphon::ColorMode::Web
+                            },
+                        )),
+                        Some(BufferCache::new()),
+                    )
+                } else {
+                    (None, None)
+                };
+
+                let mut renderer = glyphon::TextRenderer::new(
+                    atlas.as_mut().unwrap_or(&mut self.atlas),
+                    device,
+                    wgpu::MultisampleState::default(),
+                    None,
+                );
+
+                let _ = prepare(
+                    device,
+                    queue,
+                    encoder,
+                    &mut renderer,
+                    atlas.as_mut().unwrap_or(&mut self.atlas),
+                    buffer_cache.as_mut().unwrap_or(&mut self.cache),
+                    &batch,
+                    layer_bounds,
+                    new_scale_factor,
+                    new_target_size,
+                );
+
+                *cache = Cache::Uploaded {
+                    batch,
+                    needs_reupload: false,
+                    renderer,
+                    atlas,
+                    buffer_cache,
+                    scale_factor: new_scale_factor,
+                    target_size: new_target_size,
+                }
+            }
+            Cache::Uploaded {
+                batch,
+                needs_reupload,
+                renderer,
+                atlas,
+                buffer_cache,
+                scale_factor,
+                target_size,
+            } => {
+                if *needs_reupload
+                    || atlas.is_none()
+                    || buffer_cache.is_none()
+                    || new_scale_factor != *scale_factor
+                    || new_target_size != *target_size
+                {
+                    let _ = prepare(
+                        device,
+                        queue,
+                        encoder,
+                        renderer,
+                        atlas.as_mut().unwrap_or(&mut self.atlas),
+                        buffer_cache.as_mut().unwrap_or(&mut self.cache),
+                        batch,
+                        layer_bounds,
+                        *scale_factor,
+                        *target_size,
+                    );
+
+                    *scale_factor = new_scale_factor;
+                    *target_size = new_target_size;
+                }
+            }
+        }
+    }
+
+    pub fn render_batch<'a>(
         &'a self,
         layer: usize,
         bounds: Rectangle<u32>,
@@ -306,10 +255,251 @@ impl Pipeline {
             .expect("Render text");
     }
 
+    pub fn render_cache<'a>(
+        &'a self,
+        cache: &'a Cache,
+        bounds: Rectangle<u32>,
+        render_pass: &mut wgpu::RenderPass<'a>,
+    ) {
+        let Cache::Uploaded {
+            renderer, atlas, ..
+        } = cache
+        else {
+            return;
+        };
+
+        render_pass.set_scissor_rect(
+            bounds.x,
+            bounds.y,
+            bounds.width,
+            bounds.height,
+        );
+
+        renderer
+            .render(atlas.as_ref().unwrap_or(&self.atlas), render_pass)
+            .expect("Render text");
+    }
+
     pub fn end_frame(&mut self) {
         self.atlas.trim();
-        self.cache.get_mut().trim();
+        self.cache.trim();
 
         self.prepare_layer = 0;
     }
 }
+
+fn prepare(
+    device: &wgpu::Device,
+    queue: &wgpu::Queue,
+    encoder: &mut wgpu::CommandEncoder,
+    renderer: &mut glyphon::TextRenderer,
+    atlas: &mut glyphon::TextAtlas,
+    buffer_cache: &mut BufferCache,
+    sections: &Batch,
+    layer_bounds: Rectangle,
+    scale_factor: f32,
+    target_size: Size<u32>,
+) -> Result<(), glyphon::PrepareError> {
+    let mut font_system = font_system().write().expect("Write font system");
+    let font_system = font_system.raw();
+
+    enum Allocation {
+        Paragraph(Paragraph),
+        Editor(Editor),
+        Cache(cache::KeyHash),
+        Raw(Arc<glyphon::Buffer>),
+    }
+
+    let allocations: Vec<_> = sections
+        .iter()
+        .map(|section| match section {
+            Text::Paragraph { paragraph, .. } => {
+                paragraph.upgrade().map(Allocation::Paragraph)
+            }
+            Text::Editor { editor, .. } => {
+                editor.upgrade().map(Allocation::Editor)
+            }
+            Text::Cached {
+                content,
+                bounds,
+                size,
+                line_height,
+                font,
+                shaping,
+                ..
+            } => {
+                let (key, _) = buffer_cache.allocate(
+                    font_system,
+                    cache::Key {
+                        content,
+                        size: (*size).into(),
+                        line_height: f32::from(line_height.to_absolute(*size)),
+                        font: *font,
+                        bounds: Size {
+                            width: bounds.width,
+                            height: bounds.height,
+                        },
+                        shaping: *shaping,
+                    },
+                );
+
+                Some(Allocation::Cache(key))
+            }
+            Text::Raw { raw, .. } => raw.buffer.upgrade().map(Allocation::Raw),
+        })
+        .collect();
+
+    let layer_bounds = layer_bounds * scale_factor;
+
+    let text_areas = sections.iter().zip(allocations.iter()).filter_map(
+        |(section, allocation)| {
+            let (
+                buffer,
+                bounds,
+                horizontal_alignment,
+                vertical_alignment,
+                color,
+                clip_bounds,
+                transformation,
+            ) = match section {
+                Text::Paragraph {
+                    position,
+                    color,
+                    clip_bounds,
+                    transformation,
+                    ..
+                } => {
+                    use crate::core::text::Paragraph as _;
+
+                    let Some(Allocation::Paragraph(paragraph)) = allocation
+                    else {
+                        return None;
+                    };
+
+                    (
+                        paragraph.buffer(),
+                        Rectangle::new(*position, paragraph.min_bounds()),
+                        paragraph.horizontal_alignment(),
+                        paragraph.vertical_alignment(),
+                        *color,
+                        *clip_bounds,
+                        *transformation,
+                    )
+                }
+                Text::Editor {
+                    position,
+                    color,
+                    clip_bounds,
+                    transformation,
+                    ..
+                } => {
+                    use crate::core::text::Editor as _;
+
+                    let Some(Allocation::Editor(editor)) = allocation else {
+                        return None;
+                    };
+
+                    (
+                        editor.buffer(),
+                        Rectangle::new(*position, editor.bounds()),
+                        alignment::Horizontal::Left,
+                        alignment::Vertical::Top,
+                        *color,
+                        *clip_bounds,
+                        *transformation,
+                    )
+                }
+                Text::Cached {
+                    bounds,
+                    horizontal_alignment,
+                    vertical_alignment,
+                    color,
+                    clip_bounds,
+                    ..
+                } => {
+                    let Some(Allocation::Cache(key)) = allocation else {
+                        return None;
+                    };
+
+                    let entry =
+                        buffer_cache.get(key).expect("Get cached buffer");
+
+                    (
+                        &entry.buffer,
+                        Rectangle::new(bounds.position(), entry.min_bounds),
+                        *horizontal_alignment,
+                        *vertical_alignment,
+                        *color,
+                        *clip_bounds,
+                        Transformation::IDENTITY,
+                    )
+                }
+                Text::Raw {
+                    raw,
+                    transformation,
+                } => {
+                    let Some(Allocation::Raw(buffer)) = allocation else {
+                        return None;
+                    };
+
+                    let (width, height) = buffer.size();
+
+                    (
+                        buffer.as_ref(),
+                        Rectangle::new(raw.position, Size::new(width, height)),
+                        alignment::Horizontal::Left,
+                        alignment::Vertical::Top,
+                        raw.color,
+                        raw.clip_bounds,
+                        *transformation,
+                    )
+                }
+            };
+
+            let bounds = bounds * transformation * scale_factor;
+
+            let left = match horizontal_alignment {
+                alignment::Horizontal::Left => bounds.x,
+                alignment::Horizontal::Center => bounds.x - bounds.width / 2.0,
+                alignment::Horizontal::Right => bounds.x - bounds.width,
+            };
+
+            let top = match vertical_alignment {
+                alignment::Vertical::Top => bounds.y,
+                alignment::Vertical::Center => bounds.y - bounds.height / 2.0,
+                alignment::Vertical::Bottom => bounds.y - bounds.height,
+            };
+
+            let clip_bounds = layer_bounds
+                .intersection(&(clip_bounds * transformation * scale_factor))?;
+
+            Some(glyphon::TextArea {
+                buffer,
+                left,
+                top,
+                scale: scale_factor * transformation.scale_factor(),
+                bounds: glyphon::TextBounds {
+                    left: clip_bounds.x as i32,
+                    top: clip_bounds.y as i32,
+                    right: (clip_bounds.x + clip_bounds.width) as i32,
+                    bottom: (clip_bounds.y + clip_bounds.height) as i32,
+                },
+                default_color: to_color(color),
+            })
+        },
+    );
+
+    renderer.prepare(
+        device,
+        queue,
+        encoder,
+        font_system,
+        atlas,
+        glyphon::Resolution {
+            width: target_size.width,
+            height: target_size.height,
+        },
+        text_areas,
+        &mut glyphon::SwashCache::new(),
+    )
+}