Add retained paints and shared text selection

core/src/ui/painter.rs

@@ -1,5 +1,5 @@
 use crate::{
-    Axis, Color, Len, MoveOffset, RegionAlign, RenderedText, Size, StrongWidget, TextAttrs,
+    Axis, Len, MoveOffset, PaintId, RegionAlign, RenderedText, Size, StrongWidget, TextAttrs,
     TextBuffer, TextData, TextureHandle, UiRegion, UiRenderState, UiRsc, UiScalar, UiVec2,
     WidgetId,
     render::{
@@ -20,6 +20,7 @@ pub struct Painter<'a> {
     pub(super) child_move_slot: Option<MoveIdx>,
     pub(super) own_mask: MaskIdx,
     pub(super) textures: Vec<TextureHandle>,
+    pub(super) paints: Vec<PaintId>,
     pub(super) primitives: Vec<PrimitiveHandle>,
     pub(super) recycle: std::iter::Peekable<std::vec::IntoIter<PrimitiveHandle>>,
     pub(super) children: Vec<WidgetId>,
@@ -118,6 +119,20 @@ impl<'a> Painter<'a> {
         self.primitive_at(primitive, self.region)
     }
 
+    /// Resolves a public paint handle to the compact index stored by a GPU
+    /// primitive and retains the handle for exactly as long as that draw.
+    pub fn paint(&mut self, paint: &PaintId) -> u32 {
+        if !self.paints.contains(paint) {
+            self.paints.push(paint.clone());
+        }
+        paint.slot()
+    }
+
+    pub fn paint_value(&mut self, paint: &mut crate::PaintValue) -> u32 {
+        let paint = paint.resolve(&mut self.rsc.ui_mut().paints).clone();
+        self.paint(&paint)
+    }
+
     pub fn primitive_within<P: Primitive>(&mut self, primitive: P, region: UiRegion) {
         self.primitive_at(primitive, region.within(&self.region));
     }
@@ -128,7 +143,8 @@ impl<'a> Painter<'a> {
     /// so keeps pointing at whichever slot it was drawn under. See
     /// `ActiveData::own_mask` for what pushing a fresh one cost.
     pub fn set_mask(&mut self, region: UiRegion) {
-        let shape = self.write_primitive(RectPrimitive::color(Color::NONE), region, Drawn::No);
+        let paint = self.paint(&PaintId::NONE);
+        let shape = self.write_primitive(RectPrimitive::color(paint), region, Drawn::No);
         self.set_mask_to(shape);
     }
 
@@ -433,6 +449,9 @@ impl<'a> Painter<'a> {
                 0
             }
         };
+        for paint in text.paints.iter() {
+            self.paint(paint);
+        }
         for glyph in text.glyphs.iter() {
             let mut region = origin;
             region.x.end = region.x.start;
@@ -445,7 +464,7 @@ impl<'a> Painter<'a> {
                     glyph.entry.uv_min,
                     glyph.entry.uv_max,
                     glyph.entry.layer,
-                    glyph.color,
+                    glyph.paint,
                     flags_for(glyph.entry.is_color),
                 ),
                 region,