From 219e23855fee17d08acc19432ed53a054a59899d Mon Sep 17 00:00:00 2001
From: Mira Grudzinska <veleveta@gmail.com>
Date: Sun, 16 Apr 2023 12:22:18 +0200
Subject: [PATCH] svg_loader: paint-order attrib handled

@Issue: https://github.com/thorvg/thorvg/issues/1340
---
 src/loaders/svg/tvgSvgLoader.cpp       | 48 +++++++++++++++++++++++++-
 src/loaders/svg/tvgSvgLoaderCommon.h   |  4 ++-
 src/loaders/svg/tvgSvgSceneBuilder.cpp |  2 ++
 3 files changed, 52 insertions(+), 2 deletions(-)

diff --git a/src/loaders/svg/tvgSvgLoader.cpp b/src/loaders/svg/tvgSvgLoader.cpp
index ee938f96..d6b635c0 100644
--- a/src/loaders/svg/tvgSvgLoader.cpp
+++ b/src/loaders/svg/tvgSvgLoader.cpp
@@ -252,6 +252,36 @@ static SvgMaskType _toMaskType(const char* str)
 }
 
 
+//The default rendering order: fill, stroke, markers
+//If any is omitted, will be rendered in its default order after the specified ones.
+static bool _toPaintOrder(const char* str)
+{
+    uint8_t position = 1;
+    uint8_t strokePosition = 0;
+    uint8_t fillPosition = 0;
+
+    while (*str != '\0') {
+        str = _skipSpace(str, nullptr);
+        if (!strncmp(str, "fill", 4)) {
+            fillPosition = position++;
+            str += 4;
+        } else if (!strncmp(str, "stroke", 6)) {
+            strokePosition = position++;
+            str += 6;
+        } else if (!strncmp(str, "markers", 7)) {
+            str += 7;
+        } else {
+            return _toPaintOrder("fill stroke");
+        }
+    }
+
+    if (fillPosition == 0) fillPosition = position++;
+    if (strokePosition == 0) strokePosition = position++;
+
+    return fillPosition < strokePosition;
+}
+
+
 #define _PARSE_TAG(Type, Name, Name1, Tags_Array, Default)                        \
     static Type _to##Name1(const char* str)                                       \
     {                                                                             \
@@ -1011,6 +1041,13 @@ static void _handleDisplayAttr(TVG_UNUSED SvgLoaderData* loader, SvgNode* node,
 }
 
 
+static void _handlePaintOrderAttr(TVG_UNUSED SvgLoaderData* loader, SvgNode* node, const char* value)
+{
+    node->style->flags = (SvgStyleFlags)((int)node->style->flags | (int)SvgStyleFlags::PaintOrder);
+    node->style->paintOrder = _toPaintOrder(value);
+}
+
+
 static void _handleCssClassAttr(SvgLoaderData* loader, SvgNode* node, const char* value)
 {
     auto cssClass = &node->style->cssClass;
@@ -1061,7 +1098,8 @@ static constexpr struct
     STYLE_DEF(clip-path, ClipPath, SvgStyleFlags::ClipPath),
     STYLE_DEF(mask, Mask, SvgStyleFlags::Mask),
     STYLE_DEF(mask-type, MaskType, SvgStyleFlags::MaskType),
-    STYLE_DEF(display, Display, SvgStyleFlags::Display)
+    STYLE_DEF(display, Display, SvgStyleFlags::Display),
+    STYLE_DEF(paint-order, PaintOrder, SvgStyleFlags::PaintOrder)
 };
 
 
@@ -1263,6 +1301,8 @@ static SvgNode* _createNode(SvgNode* parent, SvgNodeType type)
     node->style->stroke.join = StrokeJoin::Miter;
     node->style->stroke.scale = 1.0;
 
+    node->style->paintOrder = _toPaintOrder("fill stroke");
+
     //Default display is true("inline").
     node->display = true;
 
@@ -2688,6 +2728,9 @@ static void _styleInherit(SvgStyleProperty* child, const SvgStyleProperty* paren
         child->color = parent->color;
         child->curColorSet = parent->curColorSet;
     }
+    if (!((int)child->flags & (int)SvgStyleFlags::PaintOrder)) {
+        child->paintOrder = parent->paintOrder;
+    }
     //Fill
     if (!((int)child->fill.flags & (int)SvgFillFlags::Paint)) {
         child->fill.paint.color = parent->fill.paint.color;
@@ -2746,6 +2789,9 @@ static void _styleCopy(SvgStyleProperty* to, const SvgStyleProperty* from)
         to->color = from->color;
         to->curColorSet = true;
     }
+    if (((int)from->flags & (int)SvgStyleFlags::PaintOrder)) {
+        to->paintOrder = from->paintOrder;
+    }
     //Fill
     to->fill.flags = (SvgFillFlags)((int)to->fill.flags | (int)from->fill.flags);
     if (((int)from->fill.flags & (int)SvgFillFlags::Paint)) {
diff --git a/src/loaders/svg/tvgSvgLoaderCommon.h b/src/loaders/svg/tvgSvgLoaderCommon.h
index 3bcc031b..c19086fe 100644
--- a/src/loaders/svg/tvgSvgLoaderCommon.h
+++ b/src/loaders/svg/tvgSvgLoaderCommon.h
@@ -115,7 +115,8 @@ enum class SvgStyleFlags
     ClipPath = 0x1000,
     Mask = 0x2000,
     MaskType = 0x4000,
-    Display = 0x8000
+    Display = 0x8000,
+    PaintOrder = 0x10000
 };
 
 enum class SvgStopStyleFlags
@@ -411,6 +412,7 @@ struct SvgStyleProperty
     SvgColor color;
     bool curColorSet;
     char* cssClass;
+    bool paintOrder; //true if default (fill, stroke), false otherwise
     SvgStyleFlags flags;
 };
 
diff --git a/src/loaders/svg/tvgSvgSceneBuilder.cpp b/src/loaders/svg/tvgSvgSceneBuilder.cpp
index 900dfbf8..e83844ff 100644
--- a/src/loaders/svg/tvgSvgSceneBuilder.cpp
+++ b/src/loaders/svg/tvgSvgSceneBuilder.cpp
@@ -330,6 +330,8 @@ static void _applyProperty(SvgNode* node, Shape* vg, const Box& vBox, const stri
 
     //Apply the fill rule
     vg->fill((tvg::FillRule)style->fill.fillRule);
+    //Rendering order
+    vg->order(!style->paintOrder);
 
     //Apply node opacity
     if (style->opacity < 255) vg->opacity(style->opacity);