From f2e64e17527f16966a37c788ca65e1e88bf44907 Mon Sep 17 00:00:00 2001
From: Kae <80987908+Novaenia@users.noreply.github.com>
Date: Wed, 21 Jun 2023 18:59:15 +1000
Subject: [PATCH] Font improvements

?border and ?outline blend nicer when applied to font glyphs
---
 source/core/StarColor.hpp                 |  3 +--
 source/core/StarFont.cpp                  |  4 ++--
 source/core/StarImageProcessing.cpp       | 20 ++++++++++++++++++--
 source/core/StarImageProcessing.hpp       |  1 +
 source/rendering/StarFontTextureGroup.cpp |  7 ++++++-
 5 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/source/core/StarColor.hpp b/source/core/StarColor.hpp
index 33f3374..e2fe2b5 100644
--- a/source/core/StarColor.hpp
+++ b/source/core/StarColor.hpp
@@ -141,10 +141,9 @@ public:
   Color& operator+=(Color const& c);
   Color& operator*=(Color const& c);
 
-private:
   static float toLinear(float in);
   static float fromLinear(float in);
-
+private:
   Vec4F m_data;
 };
 
diff --git a/source/core/StarFont.cpp b/source/core/StarFont.cpp
index 66767aa..59a094b 100644
--- a/source/core/StarFont.cpp
+++ b/source/core/StarFont.cpp
@@ -87,10 +87,10 @@ unsigned Font::width(String::Char c) {
 
 Image Font::render(String::Char c) {
   if (!m_fontImpl)
-    throw FontException("Font::render called on uninitialzed font.");
+    throw FontException("Font::render called on uninitialized font.");
 
   FT_UInt glyph_index = FT_Get_Char_Index(m_fontImpl->face, c);
-  if (FT_Load_Glyph(m_fontImpl->face, glyph_index, FT_LOAD_DEFAULT) != 0)
+  if (FT_Load_Glyph(m_fontImpl->face, glyph_index, FT_LOAD_FORCE_AUTOHINT) != 0)
     return {};
 
   /* convert to an anti-aliased bitmap */
diff --git a/source/core/StarImageProcessing.cpp b/source/core/StarImageProcessing.cpp
index 3e1db89..ebb0947 100644
--- a/source/core/StarImageProcessing.cpp
+++ b/source/core/StarImageProcessing.cpp
@@ -224,6 +224,7 @@ ImageOperation imageOperationFromString(String const& string) {
       else
         operation.endColor = operation.startColor;
       operation.outlineOnly = type == "outline";
+      operation.includeTransparent = false; // Currently just here for anti-aliased fonts
 
       return operation;
 
@@ -476,7 +477,8 @@ Image processImageOperations(List<ImageOperation> const& operations, Image image
 
       borderImage.forEachPixel([&op, &image, &borderImageSize](int x, int y, Vec4B& pixel) {
         int pixels = op->pixels;
-        if (pixel[3] == 0) {
+        bool includeTransparent = op->includeTransparent;
+        if (pixel[3] == 0 || (includeTransparent && pixel[3] != 255)) {
           int dist = std::numeric_limits<int>::max();
           for (int j = -pixels; j < pixels + 1; j++) {
             for (int i = -pixels; i < pixels + 1; i++) {
@@ -493,7 +495,21 @@ Image processImageOperations(List<ImageOperation> const& operations, Image image
 
           if (dist < std::numeric_limits<int>::max()) {
             float percent = (dist - 1) / (2.0f * pixels - 1);
-            pixel = Vec4B(Vec4F(op->startColor) * (1 - percent) + Vec4F(op->endColor) * percent);
+            Vec4F color = (Vec4F(op->startColor) * ((1.0f - percent) / 255.0f)) + (Vec4F(op->endColor) * (percent / 255.0f));
+            color.clamp(0.0f, 1.0f);
+            if (pixel[3] != 0) {
+              float pixelA = byteToFloat(pixel[3]);
+              if (op->outlineOnly)
+                color[3] *= (1.0f - pixelA);
+              else {
+                float colorA = pixelA * (1.0f - color[3]);
+                color[0] = Color::fromLinear((Color::toLinear(color[0]) * colorA) + (Color::toLinear(byteToFloat(pixel[0])) * pixelA));
+                color[1] = Color::fromLinear((Color::toLinear(color[1]) * colorA) + (Color::toLinear(byteToFloat(pixel[1])) * pixelA));
+                color[2] = Color::fromLinear((Color::toLinear(color[2]) * colorA) + (Color::toLinear(byteToFloat(pixel[2])) * pixelA));
+                color[3] += colorA;
+              }
+            }
+            pixel = Vec4B(color.piecewiseMultiply(Vec4F::filled(255.0f)));
           }
         } else if (op->outlineOnly) {
           pixel = Vec4B(0, 0, 0, 0);
diff --git a/source/core/StarImageProcessing.hpp b/source/core/StarImageProcessing.hpp
index e2008b8..bcb5936 100644
--- a/source/core/StarImageProcessing.hpp
+++ b/source/core/StarImageProcessing.hpp
@@ -102,6 +102,7 @@ struct BorderImageOperation {
   Vec4B startColor;
   Vec4B endColor;
   bool outlineOnly;
+  bool includeTransparent;
 };
 
 struct ScaleImageOperation {
diff --git a/source/rendering/StarFontTextureGroup.cpp b/source/rendering/StarFontTextureGroup.cpp
index 7517c8b..340a389 100644
--- a/source/rendering/StarFontTextureGroup.cpp
+++ b/source/rendering/StarFontTextureGroup.cpp
@@ -21,7 +21,12 @@ const FontTextureGroup::GlyphTexture& FontTextureGroup::glyphTexture(String::Cha
     Image image = m_font->render(c);
     if (!processingDirectives.empty()) {
       Vec2F preSize = Vec2F(image.size());
-      image = processImageOperations(parseImageOperations(processingDirectives), image);
+      auto imageOperations = parseImageOperations(processingDirectives);
+      for (auto& imageOp : imageOperations) {
+        if (auto border = imageOp.ptr<BorderImageOperation>())
+          border->includeTransparent = true;
+      }
+      image = processImageOperations(imageOperations, image);
       res.first->second.processingOffset = preSize - Vec2F(image.size());
     }
     else