rom/graphics/textextent.c

   1 /*
   2     Copyright © 1995-2007, The AROS Development Team. All rights reserved.
   3     $Id$
   4
   5     Desc: Calculate the size a text needs in a specific rastport.
   6     Lang: english
   7 */
   8 #include "graphics_intern.h"
   9 #include <graphics/rastport.h>
  10
  11 /*****************************************************************************
  12
  13     NAME */
  14 #include <graphics/rastport.h>
  15 #include <graphics/text.h>
  16 #include <proto/graphics.h>
  17
  18         AROS_LH4(void, TextExtent,
  19
  20 /*  SYNOPSIS */
  21         AROS_LHA(struct RastPort   *, rp, A1),
  22         AROS_LHA(CONST_STRPTR       , string, A0),
  23         AROS_LHA(ULONG              , count, D0),
  24         AROS_LHA(struct TextExtent *, textExtent, A2),
  25
  26 /*  LOCATION */
  27         struct GfxBase *, GfxBase, 115, Graphics)
  28
  29 /*  FUNCTION
  30         This function determines the metric of the space
  31         that a text string would render into.
  32
  33     INPUTS
  34         rp -     RastPort
  35         string - address of string
  36         count -  number of characters
  37         textExtent - storing place for the result
  38                      te_Width  - same as TextLength() result: the rp_cp_x
  39                                  advance that rendering this text would cause.
  40                      te_Height - same as tf_YSize.  The height of the
  41                                  font.
  42                      te_Extent.MinX - the offset to the left side of the
  43                                       rectangle this would render into.  Often zero.
  44                      te_Extent.MinY - same as -tf_Baseline.  The offset
  45                                       from the baseline to the top of the rectangle
  46                                       this would render into.
  47                      te_Extent.MaxX - the offset of the left side of the
  48                                       rectangle this would render into.  Often the
  49                                       same as te_Width-1.
  50                      te_Extent.MaxY - same as tf_YSize-tf_Baseline-1.
  51                                       The offset from the baseline to the bottom of
  52                                       the rectangle this would render into.
  53
  54     RESULT
  55
  56     NOTES
  57
  58     EXAMPLE
  59
  60     BUGS
  61
  62     SEE ALSO
  63
  64     INTERNALS
  65
  66     HISTORY
  67         29-10-95    digulla automatically created from
  68                             graphics_lib.fd and clib/graphics_protos.h
  69
  70 *****************************************************************************/
  71 {
  72     AROS_LIBFUNC_INIT
  73
  74     struct TextFont *tf = rp->Font;
  75
  76     textExtent->te_Width = TextLength(rp, string, count);
  77     textExtent->te_Height = tf->tf_YSize;
  78     textExtent->te_Extent.MinY = -tf->tf_Baseline;
  79     textExtent->te_Extent.MaxY = textExtent->te_Height - 1 - tf->tf_Baseline;
  80
  81     /* MinX/MaxX can be a bit more complicated if there are kerning/space tables */
  82
  83     if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern || tf->tf_CharSpace)
  84     {
  85         WORD  idx;
  86         WORD  defaultidx = NUMCHARS(tf) - 1; /* Last glyph is the default glyph */
  87         WORD  x, x2;
  88         UBYTE c;
  89
  90         textExtent->te_Extent.MinX = 0;
  91         textExtent->te_Extent.MaxX = 0;
  92         x = 0;
  93
  94         if (count)
  95         {
  96             while(count--)
  97             {
  98                 c = *string++;
  99
 100                 if ( c < tf->tf_LoChar || c > tf->tf_HiChar)
 101                 {
 102                     idx = defaultidx;
 103                 }
 104                 else
 105                 {
 106                     idx = c - tf->tf_LoChar;
 107                 }
 108
 109                 #define CHECK_MINMAX(x) \
 110                     if ((x) < textExtent->te_Extent.MinX) textExtent->te_Extent.MinX = (x); \
 111                     if ((x) > textExtent->te_Extent.MaxX) textExtent->te_Extent.MaxX = (x);
 112
 113                 x += ((WORD *)tf->tf_CharKern)[idx];
 114                 CHECK_MINMAX(x);
 115
 116                 x2 = x + ( ( ((ULONG *)tf->tf_CharLoc)[idx] ) & 0xFFFF);
 117                 CHECK_MINMAX(x2);
 118
 119                 x += ((WORD *)tf->tf_CharSpace)[idx];
 120                 CHECK_MINMAX(x);
 121
 122                 x += rp->TxSpacing;
 123                 CHECK_MINMAX(x);
 124
 125             } /* while(count--) */
 126
 127             textExtent->te_Extent.MaxX--;
 128
 129         } /* if (count) */
 130
 131     } /* if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern || tf->tf_CharSpace) */
 132     else
 133     {
 134         /* Normal non-proportional Font */
 135         textExtent->te_Extent.MinX = 0;
 136         textExtent->te_Extent.MaxX = textExtent->te_Width - 1;
 137     }
 138
 139     if (rp->AlgoStyle & FSF_BOLD)
 140     {
 141         textExtent->te_Extent.MaxX += tf->tf_BoldSmear;
 142     }
 143
 144     if (rp->AlgoStyle & FSF_ITALIC)
 145     {
 146         /*  ######            ######
 147         **  ##  ##            ##  ##
 148         **  ##  ##           ##  ##
 149         **  ##  ##  ===>     ##  ##
 150         **  ##  ##          ##  ##
 151         **..##..##..      ..##..##..
 152         **  ##  ##         ##  ##
 153         **  ######         ######
 154         */
 155
 156         textExtent->te_Extent.MaxX += tf->tf_Baseline / 2;
 157         textExtent->te_Extent.MinX -= (tf->tf_YSize - tf->tf_Baseline) / 2;
 158     }
 159
 160     AROS_LIBFUNC_EXIT
 161
 162 } /* TextExtent */