From 368f18016c96a1516e9e72bc151e523ec94622a8 Mon Sep 17 00:00:00 2001
From: ManoloFLTK <41016272+ManoloFLTK@users.noreply.github.com>
Date: Sat, 13 Mar 2021 19:21:25 +0100
Subject: Fast pango (#201)

* Cache single unicode character widths under Xft+Pango
---
 .../Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx      | 49 +++++++++++++++++++---
 1 file changed, 43 insertions(+), 6 deletions(-)

(limited to 'src/drivers/Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx')

diff --git a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx
index a8039df46..a755d881f 100644
--- a/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx
+++ b/src/drivers/Xlib/Fl_Xlib_Graphics_Driver_font_xft.cxx
@@ -1012,6 +1012,10 @@ float Fl_Xlib_Graphics_Driver::scale_bitmap_for_PostScript() {
 Fl_Xlib_Font_Descriptor::~Fl_Xlib_Font_Descriptor() {
   if (this == fl_graphics_driver->font_descriptor()) fl_graphics_driver->font_descriptor(NULL);
   //  XftFontClose(fl_display, font);
+#if USE_PANGO
+  if (width) for (int i = 0; i < 64; i++) delete[] width[i];
+  delete[] width;
+#endif
 }
 
 
@@ -1347,7 +1351,45 @@ void Fl_Xlib_Graphics_Driver::do_draw(int from_right, const char *str, int n, in
                           (y - y_correction  - lheight + desc) * PANGO_SCALE ); // 1.8
   }
 
+// cache the widths of single Unicode characters
+double Fl_Xlib_Graphics_Driver::width_unscaled(unsigned int utf32) {
+  unsigned r=0;
+  Fl_Xlib_Font_Descriptor *desc = NULL;
+  if (utf32 <= 0xFFFF) {
+    desc = (Fl_Xlib_Font_Descriptor*)font_descriptor();
+    r = (utf32 & 0xFC00) >> 10;
+    if (!desc->width) {
+      desc->width = (int**)new int*[64];
+      memset(desc->width, 0, 64*sizeof(int*));
+    }
+    if (!desc->width[r]) {
+      desc->width[r] = (int*)new int[0x0400];
+      for (int i = 0; i < 0x0400; i++) desc->width[r][i] = -1;
+    } else {
+      if ( desc->width[r][utf32&0x03FF] >= 0 ) { // already cached
+        return double(desc->width[r][utf32 & 0x03FF]);
+      }
+    }
+  }
+  char buf4[4];
+  int n = fl_utf8encode(utf32, buf4);
+  double width = do_width_unscaled_(buf4, n);
+  if (utf32 <= 0xFFFF) {
+    desc->width[r][utf32 & 0x03FF] = (int)width;
+  }
+  return width;
+}
+
 double Fl_Xlib_Graphics_Driver::width_unscaled(const char* str, int n) {
+  if (n == fl_utf8len(*str)) { // str contains a single unicode character
+    int l;
+    unsigned c = fl_utf8decode(str, str+n, &l);
+    return width_unscaled(c); // that character's width may have been cached
+  }
+  return do_width_unscaled_(str, n); // full width computation for multi-char strings
+}
+
+double Fl_Xlib_Graphics_Driver::do_width_unscaled_(const char* str, int n) {
   if (!n) return 0;
   if (!fl_display || size_ == 0) return -1;
   if (!playout_) context();
@@ -1373,12 +1415,6 @@ int Fl_Xlib_Graphics_Driver::height_unscaled() {
   else return -1;
 }
 
-double Fl_Xlib_Graphics_Driver::width_unscaled(unsigned int c) {
-  char buf4[4];
-  int n = fl_utf8encode(c, buf4);
-  return width_unscaled(buf4, n);
-}
-
 int Fl_Xlib_Graphics_Driver::descent_unscaled() {
   if (font_descriptor()) return ((Fl_Xlib_Font_Descriptor*)font_descriptor())->descent_;
   else return -1;
@@ -1458,6 +1494,7 @@ Fl_Xlib_Font_Descriptor::Fl_Xlib_Font_Descriptor(const char* name, Fl_Fontsize f
   angle = fangle;
   height_ = 0;
   descent_ = 0;
+  width = NULL;
 }
 
 #endif // USE_PANGO
-- 
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