From f2028f687500873246e69a41ec0f7c0ab99a6da8 Mon Sep 17 00:00:00 2001
From: Myriad-Dreamin <35292584+Myriad-Dreamin@users.noreply.github.com>
Date: Tue, 31 Oct 2023 19:49:36 +0800
Subject: [PATCH] fix(exporter::svg): partially disable incr rendering  (#387)

* fix(exporter): partially disable incr rendering
+ on elements that contains gradient fill
---
 exporter/svg/src/backend/mod.rs      | 14 +++++++----
 exporter/svg/src/frontend/context.rs | 35 +++++++++++++++++++++++++++-
 exporter/svg/src/frontend/mod.rs     |  4 ++++
 exporter/svg/src/utils.rs            | 15 ++++++++++++
 4 files changed, 63 insertions(+), 5 deletions(-)

diff --git a/exporter/svg/src/backend/mod.rs b/exporter/svg/src/backend/mod.rs
index 6a04ea13..af105540 100644
--- a/exporter/svg/src/backend/mod.rs
+++ b/exporter/svg/src/backend/mod.rs
@@ -20,7 +20,7 @@ use typst_ts_core::{
 mod escape;
 use escape::{PcDataEscapes, TextContentDataEscapes};
 
-use crate::utils::ToCssExt;
+use crate::{frontend::HasGradient, utils::ToCssExt};
 
 pub trait BuildClipPath {
     fn build_clip_path(&mut self, path: &ir::PathItem) -> Fingerprint;
@@ -586,8 +586,10 @@ impl<
 }
 
 /// See [`FlatGroupContext`].
-impl<'m, C: FlatIncrRenderVm<'m, Resultant = Arc<SvgTextNode>, Group = SvgTextBuilder>>
-    FlatIncrGroupContext<C> for SvgTextBuilder
+impl<
+        'm,
+        C: FlatIncrRenderVm<'m, Resultant = Arc<SvgTextNode>, Group = SvgTextBuilder> + HasGradient,
+    > FlatIncrGroupContext<C> for SvgTextBuilder
 {
     fn render_diff_item_ref_at(
         &mut self,
@@ -597,7 +599,8 @@ impl<'m, C: FlatIncrRenderVm<'m, Resultant = Arc<SvgTextNode>, Group = SvgTextBu
         item: &Fingerprint,
         prev_item: &Fingerprint,
     ) {
-        let content = if item == prev_item {
+        let has_gradient = ctx.has_gradient(item);
+        let content = if item == prev_item && !has_gradient {
             // todo: update transform
             vec![]
         } else {
@@ -612,6 +615,9 @@ impl<'m, C: FlatIncrRenderVm<'m, Resultant = Arc<SvgTextNode>, Group = SvgTextBu
         };
         attributes.push(("data-tid", item.as_svg_id("p")));
         attributes.push(("data-reuse-from", prev_item.as_svg_id("p")));
+        if has_gradient {
+            attributes.push(("data-bad-equality", "1".to_owned()));
+        }
 
         self.content.push(SvgText::Content(Arc::new(SvgTextNode {
             attributes,
diff --git a/exporter/svg/src/frontend/context.rs b/exporter/svg/src/frontend/context.rs
index 97bfee0d..8b94aa34 100644
--- a/exporter/svg/src/frontend/context.rs
+++ b/exporter/svg/src/frontend/context.rs
@@ -8,7 +8,7 @@ use typst_ts_core::{
         flat_vm::{FlatGroupContext, FlatIncrRenderVm, FlatRenderVm},
         ir::{
             self, BuildGlyph, FontIndice, FontRef, GlyphHashStablizer, GlyphIndice, GlyphItem,
-            GlyphPackBuilder, GlyphRef, ImmutStr, PathItem, Scalar, StyleNs,
+            GlyphPackBuilder, GlyphRef, ImmutStr, PathItem, PathStyle, Scalar, StyleNs,
         },
         vm::GroupContext,
         vm::{RenderState, RenderVm},
@@ -21,9 +21,12 @@ use crate::{
         BuildClipPath, BuildFillStyleClass, DynExportFeature, NotifyPaint, SvgText, SvgTextBuilder,
         SvgTextNode,
     },
+    utils::MemorizeFree,
     ExportFeature, GlyphProvider, SvgGlyphBuilder,
 };
 
+use super::HasGradient;
+
 /// Maps the style name to the style definition.
 /// See [`StyleNs`].
 pub(crate) type StyleDefMap = HashMap<(StyleNs, ImmutStr), String>;
@@ -146,6 +149,36 @@ impl<'m, 't, Feat: ExportFeature> BuildClipPath for RenderContext<'m, 't, Feat>
     }
 }
 
+#[comemo::memoize]
+fn has_gradient<'m, 't, Feat: ExportFeature>(
+    ctx: &MemorizeFree<RenderContext<'m, 't, Feat>>,
+    x: &Fingerprint,
+) -> bool {
+    let Some(item) = ctx.0.get_item(x) else {
+        // overestimated
+        return true;
+    };
+
+    use FlatSvgItem::*;
+    match item {
+        Gradient(..) => true,
+        Image(..) | Link(..) | None => false,
+        Item(t) => has_gradient(ctx, &t.1),
+        Group(g, ..) => g.0.iter().any(|(_, x)| has_gradient(ctx, x)),
+        Path(p) => p.styles.iter().any(|s| match s {
+            PathStyle::Fill(color) | PathStyle::Stroke(color) => color.starts_with('@'),
+            _ => false,
+        }),
+        Text(p) => p.shape.fill.starts_with('@'),
+    }
+}
+
+impl<'m, 't, Feat: ExportFeature> HasGradient for RenderContext<'m, 't, Feat> {
+    fn has_gradient(&self, a: &Fingerprint) -> bool {
+        has_gradient(&MemorizeFree(self), a)
+    }
+}
+
 impl<'m, 't, Feat: ExportFeature> NotifyPaint for RenderContext<'m, 't, Feat> {
     fn notify_paint(&mut self, url_ref: ImmutStr) -> (u8, Fingerprint, Option<bool>) {
         if let Some(f) = self.gradients.get(&url_ref) {
diff --git a/exporter/svg/src/frontend/mod.rs b/exporter/svg/src/frontend/mod.rs
index 3763f6b1..66e68460 100644
--- a/exporter/svg/src/frontend/mod.rs
+++ b/exporter/svg/src/frontend/mod.rs
@@ -752,3 +752,7 @@ impl std::fmt::Display for RatioRepr {
         write!(f, "{:.3}%", self.0 * 100.0)
     }
 }
+
+pub trait HasGradient {
+    fn has_gradient(&self, f: &Fingerprint) -> bool;
+}
diff --git a/exporter/svg/src/utils.rs b/exporter/svg/src/utils.rs
index 059ac6d1..0f104664 100644
--- a/exporter/svg/src/utils.rs
+++ b/exporter/svg/src/utils.rs
@@ -60,3 +60,18 @@ impl ToCssExt for ir::Transform {
         )
     }
 }
+
+#[derive(Clone, Copy)]
+pub(crate) struct MemorizeFree<'a, T>(pub &'a T);
+
+impl<'a, T> std::hash::Hash for MemorizeFree<'a, T> {
+    fn hash<H: std::hash::Hasher>(&self, _state: &mut H) {}
+}
+
+impl<'a, T> std::cmp::PartialEq for MemorizeFree<'a, T> {
+    fn eq(&self, _other: &Self) -> bool {
+        true
+    }
+}
+
+impl<'a, T> std::cmp::Eq for MemorizeFree<'a, T> {}