From 3c3662b3ba9ae8cd36a42aa0bcf43016fc21e9fb Mon Sep 17 00:00:00 2001
From: Francesco Abbate <francesco.bbt@gmail.com>
Date: Fri, 12 Jun 2020 16:06:39 +0200
Subject: [PATCH] Add option to disable X axis font's pre-scaling

If used pre-scaling along X null the effect of the font's hinting.
---
 lib/font_renderer/font_renderer.cpp     | 13 +++++++------
 lib/font_renderer/font_renderer.h       |  7 ++++---
 lib/font_renderer/font_renderer_alpha.h | 10 ++++++----
 src/renderer.c                          |  2 +-
 4 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/lib/font_renderer/font_renderer.cpp b/lib/font_renderer/font_renderer.cpp
index 1db68600..de08313d 100644
--- a/lib/font_renderer/font_renderer.cpp
+++ b/lib/font_renderer/font_renderer.cpp
@@ -20,8 +20,8 @@ public:
     // Conventional LUT values: (1./3., 2./9., 1./9.)
     // The values below are fine tuned as in the Elementary Plot library.
 
-    FR_Impl(bool hinting, bool kerning, bool subpixel, float gamma_value) :
-        m_renderer(hinting, kerning, subpixel),
+    FR_Impl(bool hinting, bool kerning, bool subpixel, bool prescale_x, float gamma_value) :
+        m_renderer(hinting, kerning, subpixel, prescale_x),
         m_gamma_lut(double(gamma_value)),
         m_lcd_lut(0.448, 0.184, 0.092),
         m_subpixel(subpixel)
@@ -40,10 +40,11 @@ private:
 };
 
 FR_Renderer *FR_Renderer_New(unsigned int flags, float gamma) {
-    bool hinting  = ((flags & FR_HINTING) != 0);
-    bool kerning  = ((flags & FR_KERNING) != 0);
-    bool subpixel = ((flags & FR_SUBPIXEL) != 0);
-    return new FR_Impl(hinting, kerning, subpixel, gamma);
+    bool hinting    = ((flags & FR_HINTING)    != 0);
+    bool kerning    = ((flags & FR_KERNING)    != 0);
+    bool subpixel   = ((flags & FR_SUBPIXEL)   != 0);
+    bool prescale_x = ((flags & FR_PRESCALE_X) != 0);
+    return new FR_Impl(hinting, kerning, subpixel, prescale_x, gamma);
 }
 
 FR_Bitmap* FR_Bitmap_New(FR_Renderer *font_renderer, int width, int height) {
diff --git a/lib/font_renderer/font_renderer.h b/lib/font_renderer/font_renderer.h
index 8f05ee97..a72911de 100644
--- a/lib/font_renderer/font_renderer.h
+++ b/lib/font_renderer/font_renderer.h
@@ -18,9 +18,10 @@ struct FR_Impl;
 typedef struct FR_Impl FR_Renderer;
 
 enum {
-    FR_HINTING   = 1 << 0,
-    FR_KERNING   = 1 << 2,
-    FR_SUBPIXEL  = 1 << 3,
+    FR_HINTING    = 1 << 0,
+    FR_KERNING    = 1 << 1,
+    FR_SUBPIXEL   = 1 << 2,
+    FR_PRESCALE_X = 1 << 3,
 };
 
 typedef struct {
diff --git a/lib/font_renderer/font_renderer_alpha.h b/lib/font_renderer/font_renderer_alpha.h
index c61b5990..5dcf5e37 100644
--- a/lib/font_renderer/font_renderer_alpha.h
+++ b/lib/font_renderer/font_renderer_alpha.h
@@ -27,6 +27,7 @@ class font_renderer_alpha
     bool m_hinting;
     bool m_kerning;
     bool m_subpixel;
+    bool m_prescale_x;
 
     bool m_font_loaded;
 
@@ -37,12 +38,13 @@ class font_renderer_alpha
 public:
     typedef agg::pixfmt_alpha8::color_type color_type;
 
-    font_renderer_alpha(bool hinting, bool kerning, bool subpixel):
+    font_renderer_alpha(bool hinting, bool kerning, bool subpixel, bool prescale_x):
         m_feng(),
         m_fman(m_feng),
         m_hinting(hinting),
         m_kerning(kerning),
         m_subpixel(subpixel),
+        m_prescale_x(prescale_x),
         m_font_loaded(false),
         m_curves(m_fman.path_adaptor()),
         m_trans(m_curves, m_mtx)
@@ -77,7 +79,7 @@ public:
     }
 
     void set_font_height(double height) {
-        const double scale_x = 100.0;
+        const double scale_x = (m_prescale_x ? 100.0 : 1.0);
         m_feng.height(height);
         if (m_subpixel) {
             const int subpixel_scale = 3;
@@ -88,11 +90,11 @@ public:
     }
 
     template<class Rasterizer, class Scanline, class RenSolid>
-    void draw_codepoint(Rasterizer& ras, Scanline& sl, 
+    void draw_codepoint(Rasterizer& ras, Scanline& sl,
         RenSolid& ren_solid, const color_type color,
         int codepoint, double& x, double& y, int subpixel_scale)
     {
-        const double scale_x = 100;
+        const double scale_x = (m_prescale_x ? 100.0 : 1.0);
 
         // Represent the delta in x scaled by scale_x.
         double x_delta = 0;
diff --git a/src/renderer.c b/src/renderer.c
index f34d782d..f5f5854d 100644
--- a/src/renderer.c
+++ b/src/renderer.c
@@ -149,7 +149,7 @@ RenFont* ren_load_font(const char *filename, float size) {
   font->size = size;
 
   const float gamma = 1.5;
-  font->renderer = FR_Renderer_New(FR_HINTING | FR_SUBPIXEL, gamma);
+  font->renderer = FR_Renderer_New(FR_HINTING | FR_SUBPIXEL | FR_PRESCALE_X, gamma);
   if (FR_Load_Font(font->renderer, filename)) {
     free(font);
     return NULL;