[refactor] extract paint code from Ui/Context to new struct Painter

Author: emilk

egui/src/containers/collapsing_header.rs

@@ -87,7 +87,7 @@ impl State {
             *p = rect.center() + v;
         }
 
-        ui.add_paint_cmd(PaintCmd::Path {
+        ui.painter().add(PaintCmd::Path {
             path: Path::from_point_loop(&points),
             closed: true,
             fill: None,
@@ -219,7 +219,7 @@ impl CollapsingHeader {
             state.toggle(ui);
         }
 
-        let where_to_put_background = ui.paint_list_len();
+        let bg_index = ui.painter().add(PaintCmd::Noop);
 
         {
             let (mut icon_rect, _) = ui.style().icon_rectangles(interact.rect);
@@ -234,15 +234,16 @@ impl CollapsingHeader {
             state.paint_icon(ui, &icon_interact);
         }
 
-        ui.add_galley(
+        let painter = ui.painter();
+        painter.add_galley(
             text_pos,
             galley,
             label.text_style,
-            Some(ui.style().interact(&interact).stroke_color),
+            ui.style().interact(&interact).stroke_color,
         );
 
-        ui.insert_paint_cmd(
-            where_to_put_background,
+        painter.set(
+            bg_index,
             PaintCmd::Rect {
                 corner_radius: ui.style().interact(&interact).corner_radius,
                 fill: ui.style().interact(&interact).bg_fill,

egui/src/containers/frame.rs

@@ -1,6 +1,6 @@
 //! Frame container
 
-use crate::{paint::*, *};
+use crate::{layers::PaintCmdIdx, paint::*, *};
 
 #[derive(Clone, Debug, Default)]
 pub struct Frame {
@@ -62,15 +62,15 @@ impl Frame {
 pub struct Prepared {
     pub frame: Frame,
     outer_rect_bounds: Rect,
-    where_to_put_background: usize,
+    where_to_put_background: PaintCmdIdx,
     pub content_ui: Ui,
 }
 
 impl Frame {
     pub fn begin(self, ui: &mut Ui) -> Prepared {
         let outer_rect_bounds = ui.available();
         let inner_rect = outer_rect_bounds.shrink2(self.margin);
-        let where_to_put_background = ui.paint_list_len();
+        let where_to_put_background = ui.painter().add(PaintCmd::Noop);
         let content_ui = ui.child_ui(inner_rect);
         Prepared {
             frame: self,
@@ -105,7 +105,7 @@ impl Prepared {
             ..
         } = self;
 
-        ui.insert_paint_cmd(
+        ui.painter().set(
             where_to_put_background,
             PaintCmd::Rect {
                 corner_radius: frame.corner_radius,

egui/src/containers/resize.rs

@@ -226,7 +226,7 @@ impl Resize {
             // so we must follow the contents:
 
             state.desired_size = state.desired_size.max(state.last_content_size);
-            state.desired_size = ui.round_vec_to_pixels(state.desired_size);
+            state.desired_size = ui.painter().round_vec_to_pixels(state.desired_size);
 
             // We are as large as we look
             ui.allocate_space(state.desired_size);
@@ -240,7 +240,7 @@ impl Resize {
         if self.outline && corner_interact.is_some() {
             let rect = Rect::from_min_size(content_ui.top_left(), state.desired_size);
             let rect = rect.expand(2.0); // breathing room for content
-            ui.add_paint_cmd(paint::PaintCmd::Rect {
+            ui.painter().add(paint::PaintCmd::Rect {
                 rect,
                 corner_radius: 3.0,
                 fill: None,
@@ -259,12 +259,12 @@ impl Resize {
         ui.memory().resize.insert(id, state);
 
         if ui.ctx().style().debug_resize {
-            ui.ctx().debug_rect(
+            ui.ctx().debug_painter().debug_rect(
                 Rect::from_min_size(content_ui.top_left(), state.desired_size),
                 color::GREEN,
                 "desired_size",
             );
-            ui.ctx().debug_rect(
+            ui.ctx().debug_painter().debug_rect(
                 Rect::from_min_size(content_ui.top_left(), state.last_content_size),
                 color::LIGHT_BLUE,
                 "last_content_size",
@@ -277,11 +277,13 @@ fn paint_resize_corner(ui: &mut Ui, interact: &InteractInfo) {
     let color = ui.style().interact(interact).stroke_color;
     let width = ui.style().interact(interact).stroke_width;
 
-    let corner = ui.round_pos_to_pixels(interact.rect.right_bottom());
+    let painter = ui.painter();
+
+    let corner = painter.round_pos_to_pixels(interact.rect.right_bottom());
     let mut w = 2.0;
 
     while w < 12.0 {
-        ui.add_paint_cmd(paint::PaintCmd::line_segment(
+        painter.add(paint::PaintCmd::line_segment(
             [pos2(corner.x - w, corner.y), pos2(corner.x, corner.y - w)],
             color,
             width,

egui/src/containers/scroll_area.rs

@@ -268,14 +268,14 @@ impl Prepared {
             let handle_fill = style.interact(&interact).fill;
             let handle_outline = style.interact(&interact).rect_outline;
 
-            ui.add_paint_cmd(paint::PaintCmd::Rect {
+            ui.painter().add(paint::PaintCmd::Rect {
                 rect: outer_scroll_rect,
                 corner_radius,
                 fill: Some(ui.style().dark_bg_color),
                 outline: None,
             });
 
-            ui.add_paint_cmd(paint::PaintCmd::Rect {
+            ui.painter().add(paint::PaintCmd::Rect {
                 rect: handle_rect.expand(-2.0),
                 corner_radius,
                 fill: Some(handle_fill),

egui/src/containers/window.rs

@@ -511,7 +511,7 @@ fn paint_frame_interaction(
         path.add_circle_quadrant(pos2(max.x - cr, min.y + cr), cr, 3.0);
         path.add_line_segment([pos2(max.x, min.y + cr), pos2(max.x, max.y - cr)]);
     }
-    ui.add_paint_cmd(PaintCmd::Path {
+    ui.painter().add(PaintCmd::Path {
         path,
         closed: false,
         fill: None,
@@ -614,7 +614,7 @@ impl TitleBar {
             let left = outer_rect.left();
             let right = outer_rect.right();
             let y = content_rect.top() + ui.style().item_spacing.y * 0.5;
-            ui.add_paint_cmd(PaintCmd::LineSegment {
+            ui.painter().add(PaintCmd::LineSegment {
                 points: [pos2(left, y), pos2(right, y)],
                 style: ui.style().interact.inactive.rect_outline.unwrap(),
             });
@@ -650,12 +650,12 @@ fn close_button(ui: &mut Ui, rect: Rect) -> InteractInfo {
 
     let stroke_color = ui.style().interact(&interact).stroke_color;
     let stroke_width = ui.style().interact(&interact).stroke_width;
-    ui.add_paint_cmd(PaintCmd::line_segment(
+    ui.painter().add(PaintCmd::line_segment(
         [rect.left_top(), rect.right_bottom()],
         stroke_color,
         stroke_width,
     ));
-    ui.add_paint_cmd(PaintCmd::line_segment(
+    ui.painter().add(PaintCmd::line_segment(
         [rect.right_top(), rect.left_bottom()],
         stroke_color,
         stroke_width,

egui/src/context.rs

@@ -2,7 +2,7 @@ use std::sync::Arc;
 
 use {ahash::AHashMap, parking_lot::Mutex};
 
-use crate::{layout::align_rect, paint::*, *};
+use crate::{paint::*, *};
 
 #[derive(Clone, Copy, Default)]
 struct PaintStats {
@@ -234,7 +234,7 @@ impl Context {
 
     /// Generate a id from the given source.
     /// If it is not unique, an error will be printed at the given position.
-    pub fn make_unique_id<IdSource>(&self, source: IdSource, pos: Pos2) -> Id
+    pub fn make_unique_id<IdSource>(self: &Arc<Self>, source: IdSource, pos: Pos2) -> Id
     where
         IdSource: std::hash::Hash + std::fmt::Debug + Copy,
     {
@@ -246,19 +246,25 @@ impl Context {
     }
 
     /// If the given Id is not unique, an error will be printed at the given position.
-    pub fn register_unique_id(&self, id: Id, source_name: impl std::fmt::Debug, pos: Pos2) -> Id {
+    pub fn register_unique_id(
+        self: &Arc<Self>,
+        id: Id,
+        source_name: impl std::fmt::Debug,
+        pos: Pos2,
+    ) -> Id {
         if let Some(clash_pos) = self.used_ids.lock().insert(id, pos) {
+            let painter = self.debug_painter();
             if clash_pos.distance(pos) < 4.0 {
-                self.show_error(
+                painter.error(
                     pos,
                     &format!("use of non-unique ID {:?} (name clash?)", source_name),
                 );
             } else {
-                self.show_error(
+                painter.error(
                     clash_pos,
                     &format!("first use of non-unique ID {:?} (name clash?)", source_name),
                 );
-                self.show_error(
+                painter.error(
                     pos,
                     &format!(
                         "second use of non-unique ID {:?} (name clash?)",
@@ -422,103 +428,12 @@ impl Context {
             }
         }
     }
+}
 
-    // ---------------------------------------------------------------------
-
-    pub fn show_error(&self, pos: Pos2, text: impl Into<String>) {
-        let text = text.into();
-        let align = (Align::Min, Align::Min);
-        let layer = Layer::debug();
-        let text_style = TextStyle::Monospace;
-        let font = &self.fonts()[text_style];
-        let galley = font.layout_multiline(text, f32::INFINITY);
-        let rect = align_rect(Rect::from_min_size(pos, galley.size), align);
-        self.add_paint_cmd(
-            layer,
-            PaintCmd::Rect {
-                corner_radius: 0.0,
-                fill: Some(color::gray(0, 240)),
-                outline: Some(LineStyle::new(1.0, color::RED)),
-                rect: rect.expand(2.0),
-            },
-        );
-        self.add_galley(layer, rect.min, galley, text_style, Some(color::RED));
-    }
-
-    pub fn debug_text(&self, pos: Pos2, text: impl Into<String>) {
-        let text = text.into();
-        let layer = Layer::debug();
-        let align = (Align::Min, Align::Min);
-        self.floating_text(
-            layer,
-            pos,
-            text,
-            TextStyle::Monospace,
-            align,
-            Some(color::YELLOW),
-        );
-    }
-
-    pub fn debug_rect(&self, rect: Rect, color: Color, name: impl Into<String>) {
-        let text = format!("{} {:?}", name.into(), rect);
-        let layer = Layer::debug();
-        self.add_paint_cmd(
-            layer,
-            PaintCmd::Rect {
-                corner_radius: 0.0,
-                fill: None,
-                outline: Some(LineStyle::new(2.0, color)),
-                rect,
-            },
-        );
-        let align = (Align::Min, Align::Min);
-        let text_style = TextStyle::Monospace;
-        self.floating_text(layer, rect.min, text, text_style, align, Some(color));
-    }
-
-    /// Show some text anywhere on screen.
-    /// To center the text at the given position, use `align: (Center, Center)`.
-    pub fn floating_text(
-        &self,
-        layer: Layer,
-        pos: Pos2,
-        text: String,
-        text_style: TextStyle,
-        align: (Align, Align),
-        text_color: Option<Color>,
-    ) -> Rect {
-        let font = &self.fonts()[text_style];
-        let galley = font.layout_multiline(text, f32::INFINITY);
-        let rect = align_rect(Rect::from_min_size(pos, galley.size), align);
-        self.add_galley(layer, rect.min, galley, text_style, text_color);
-        rect
-    }
-
-    /// Already layed out text.
-    pub fn add_galley(
-        &self,
-        layer: Layer,
-        pos: Pos2,
-        galley: font::Galley,
-        text_style: TextStyle,
-        color: Option<Color>,
-    ) {
-        let color = color.unwrap_or_else(|| self.style().text_color);
-        self.add_paint_cmd(
-            layer,
-            PaintCmd::Text {
-                pos,
-                galley,
-                text_style,
-                color,
-            },
-        );
-    }
-
-    pub fn add_paint_cmd(&self, layer: Layer, paint_cmd: PaintCmd) {
-        self.graphics()
-            .layer(layer)
-            .push((Rect::everything(), paint_cmd))
+/// ## Painting
+impl Context {
+    pub fn debug_painter(self: &Arc<Self>) -> Painter {
+        Painter::new(self.clone(), Layer::debug(), self.rect())
     }
 }
 

egui/src/demos/app.rs

@@ -469,7 +469,7 @@ impl BoxPainting {
                 outline: Some(LineStyle::new(self.stroke_width, gray(255, 255))),
             });
         }
-        ui.add_paint_cmds(cmds);
+        ui.painter().extend(cmds);
     }
 }
 
@@ -498,7 +498,8 @@ impl Painting {
         let rect = ui.allocate_space(ui.available_finite().size());
         let interact = ui.interact(rect, ui.id(), Sense::drag());
         let rect = interact.rect;
-        ui.set_clip_rect(ui.clip_rect().intersect(rect)); // Make sure we don't paint out of bounds
+        let clip_rect = ui.clip_rect().intersect(rect); // Make sure we don't paint out of bounds
+        let painter = Painter::new(ui.ctx().clone(), ui.layer(), clip_rect);
 
         if self.lines.is_empty() {
             self.lines.push(vec![]);
@@ -520,7 +521,7 @@ impl Painting {
         for line in &self.lines {
             if line.len() >= 2 {
                 let points: Vec<Pos2> = line.iter().map(|p| rect.min + *p).collect();
-                ui.add_paint_cmd(PaintCmd::Path {
+                painter.add(PaintCmd::Path {
                     path: Path::from_open_points(&points),
                     closed: false,
                     outline: Some(LineStyle::new(2.0, LIGHT_GRAY)),