[freetype2-demos] master 3659e83 1/2: Teach `FT_String_Draw' to recycle glyphs.

[Alexei Podtelezhnikov]

branch: master
commit 3659e839ed0594d9379d14e86e03af46f8954ab1
Author: Alexei Podtelezhnikov <address@hidden>
Commit: Alexei Podtelezhnikov <address@hidden>

    Teach `FT_String_Draw' to recycle glyphs.
    
    * src/ftcommon.h (FTDemo_String_Context): New fields for offset glyph
    and extent to fill.
    (FTDemo_String_Draw): Return the number of glyphs drawn.
    * src/ftcommon.c (FTDemo_String_Draw): Implement glyph recycling until
    the extent is full.
---
 ChangeLog      | 10 ++++++++++
 src/ftcommon.c | 35 ++++++++++++++++++++++++-----------
 src/ftcommon.h |  7 ++++++-
 3 files changed, 40 insertions(+), 12 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index 82f35ce..0b52588 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2018-09-13  Alexei Podtelezhnikov  <address@hidden>
+
+       Teach `FT_String_Draw' to recycle glyphs.
+
+       * src/ftcommon.h (FTDemo_String_Context): New fields for offset glyph
+       and extent to fill.
+       (FTDemo_String_Draw): Return the number of glyphs drawn.
+       * src/ftcommon.c (FTDemo_String_Draw): Implement glyph recycling until 
+       the extent is full.
+
 2018-09-12  Alexei Podtelezhnikov  <address@hidden>
 
        [ftstring] Load glyphs and advances explicitly.
diff --git a/src/ftcommon.c b/src/ftcommon.c
index c0149bd..b803d70 100644
--- a/src/ftcommon.c
+++ b/src/ftcommon.c
@@ -1423,37 +1423,50 @@
   }
 
 
-  FT_Error
+  int
   FTDemo_String_Draw( FTDemo_Handle*          handle,
                       FTDemo_Display*         display,
                       FTDemo_String_Context*  sc,
                       int                     x,
                       int                     y )
   {
-    int        n;
+    int        first = sc->offset;
+    int        last  = handle->string_length;
+    int        m, n;
     FT_Vector  pen = { 0, 0};
     FT_Vector  advance;
 
 
-    if ( !sc                        ||
-         x < 0                      ||
+    if ( x < 0                      ||
          y < 0                      ||
          x > display->bitmap->width ||
          y > display->bitmap->rows  )
-      return FT_Err_Invalid_Argument;
+      return 0;
 
     /* change to Cartesian coordinates */
     y = display->bitmap->rows - y;
 
     /* calculate the extent */
-    if ( sc->vertical )
-      for ( n = 0; n < handle->string_length; n++ )
+    if ( sc->extent )
+      for( n = first; ; n++ )
+      {
+        m = n % handle->string_length;  /* recycling */
+        if ( pen.x + handle->string[m].hadvance.x > sc->extent )
+        {
+          last = n;
+          break;
+        }
+        pen.x += handle->string[m].hadvance.x;
+        pen.y += handle->string[m].hadvance.y;
+      }
+    else if ( sc->vertical )
+      for ( n = first; n < last; n++ )
       {
         pen.x += handle->string[n].vadvance.x;
         pen.y += handle->string[n].vadvance.y;
       }
     else
-      for ( n = 0; n < handle->string_length; n++ )
+      for ( n = first; n < last; n++ )
       {
         pen.x += handle->string[n].hadvance.x;
         pen.y += handle->string[n].hadvance.y;
@@ -1469,9 +1482,9 @@
     pen.x = ( x << 6 ) - pen.x;
     pen.y = ( y << 6 ) - pen.y;
 
-    for ( n = 0; n < handle->string_length; n++ )
+    for ( n = first; n < last; n++ )
     {
-      PGlyph    glyph = handle->string + n;
+      PGlyph    glyph = handle->string + n % handle->string_length;
       FT_Glyph  image;
       FT_BBox   bbox;
 
@@ -1564,7 +1577,7 @@
       FT_Done_Glyph( image );
     }
 
-    return error;
+    return last - first;
   }
 
 
diff --git a/src/ftcommon.h b/src/ftcommon.h
index 3a3b04c..3e8f5b5 100644
--- a/src/ftcommon.h
+++ b/src/ftcommon.h
@@ -168,10 +168,14 @@
   {
     int         kerning_mode;
     int         kerning_degree;
+
     FT_Fixed    center;            /* 0..1 */
     int         vertical;          /* displayed vertically? */
     FT_Matrix*  matrix;            /* string transformation */
 
+    FT_Pos      extent;            /* extent to fill, glyphs recycled */
+    int         offset;            /* initial glyph */
+
   } FTDemo_String_Context;
 
   typedef struct
@@ -345,8 +349,9 @@
 
 
   /* draw a string centered at (center_x, center_y) --  */
+  /* returns the number of rendered glyphs              */
   /* note that handle->use_sbits_cache is not supported */
-  FT_Error
+  int
   FTDemo_String_Draw( FTDemo_Handle*          handle,
                       FTDemo_Display*         display,
                       FTDemo_String_Context*  sc,