rom/graphics/textextent.c

   1 /*
   2     Copyright © 1995-2001, 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     AROS_LIBBASE_EXT_DECL(struct GfxBase *,GfxBase)
  74
  75     struct TextFont *tf = rp->Font;
  76
  77     textExtent->te_Width = TextLength(rp, string, count);
  78     textExtent->te_Height = tf->tf_YSize;
  79     textExtent->te_Extent.MinY = -tf->tf_Baseline;
  80     textExtent->te_Extent.MaxY = textExtent->te_Height - 1 - tf->tf_Baseline;
  81
  82     /* MinX/MaxX can be a bit more complicated if there are kerning/space tables */
  83
  84     if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern || tf->tf_CharSpace)
  85     {
  86         WORD  idx;
  87         WORD  defaultidx = NUMCHARS(tf) - 1; /* Last glyph is the default glyph */
  88         WORD  x, x2;
  89         UBYTE c;
  90
  91         textExtent->te_Extent.MinX = 0;
  92         textExtent->te_Extent.MaxX = 0;
  93         x = 0;
  94
  95         if (count)
  96         {
  97             while(count--)
  98             {
  99                 c = *string++;
 100
 101                 if ( c < tf->tf_LoChar || c > tf->tf_HiChar)
 102                 {
 103                     idx = defaultidx;
 104                 }
 105                 else
 106                 {
 107                     idx = c - tf->tf_LoChar;
 108                 }
 109
 110                 #define CHECK_MINMAX(x) \
 111                     if ((x) < textExtent->te_Extent.MinX) textExtent->te_Extent.MinX = (x); \
 112                     if ((x) > textExtent->te_Extent.MaxX) textExtent->te_Extent.MaxX = (x);
 113
 114                 x += ((WORD *)tf->tf_CharKern)[idx];
 115                 CHECK_MINMAX(x);
 116
 117                 x2 = x + ( ( ((ULONG *)tf->tf_CharLoc)[idx] ) & 0xFFFF);
 118                 CHECK_MINMAX(x2);
 119
 120                 x += ((WORD *)tf->tf_CharSpace)[idx];
 121                 CHECK_MINMAX(x);
 122
 123                 x += rp->TxSpacing;
 124                 CHECK_MINMAX(x);
 125
 126             } /* while(count--) */
 127
 128             textExtent->te_Extent.MaxX--;
 129
 130         } /* if (count) */
 131
 132     } /* if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern || tf->tf_CharSpace) */
 133     else
 134     {
 135         /* Normal non-proportional Font */
 136         textExtent->te_Extent.MinX = 0;
 137         textExtent->te_Extent.MaxX = textExtent->te_Width - 1;
 138     }
 139
 140     if (rp->AlgoStyle & FSF_BOLD)
 141     {
 142         textExtent->te_Extent.MaxX += tf->tf_BoldSmear;
 143     }
 144
 145     if (rp->AlgoStyle & FSF_ITALIC)
 146     {
 147         /*  ######            ######
 148         **  ##  ##            ##  ##
 149         **  ##  ##           ##  ##
 150         **  ##  ##  ===>     ##  ##
 151         **  ##  ##          ##  ##
 152         **..##..##..      ..##..##..
 153         **  ##  ##         ##  ##
 154         **  ######         ######
 155         */
 156
 157         textExtent->te_Extent.MaxX += tf->tf_Baseline / 2;
 158         textExtent->te_Extent.MinX -= (tf->tf_YSize - tf->tf_Baseline) / 2;
 159     }
 160
 161     AROS_LIBFUNC_EXIT
 162
 163 } /* TextExtent */