rom/graphics/textextent.c

   1 /*
   2     Copyright © 1995-2012, 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 that a text string
  31         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.
  44                                       Often zero.
  45                      te_Extent.MinY - same as -tf_Baseline.  The offset
  46                                       from the baseline to the top of the
  47                                       rectangle this would render into.
  48                      te_Extent.MaxX - the offset of the left side of the
  49                                       rectangle this would render into.
  50                                       Often the same as te_Width-1.
  51                      te_Extent.MaxY - same as tf_YSize-tf_Baseline-1.
  52                                       The offset from the baseline to the
  53                                       bottom of the rectangle this would
  54                                       render into.
  55
  56     RESULT
  57
  58     NOTES
  59
  60     EXAMPLE
  61
  62     BUGS
  63
  64     SEE ALSO
  65
  66     INTERNALS
  67
  68 *****************************************************************************/
  69 {
  70     AROS_LIBFUNC_INIT
  71
  72     struct TextFont *tf = rp->Font;
  73
  74     textExtent->te_Width = TextLength(rp, string, count);
  75     textExtent->te_Height = tf->tf_YSize;
  76     textExtent->te_Extent.MinY = -tf->tf_Baseline;
  77     textExtent->te_Extent.MaxY = textExtent->te_Height - 1 - tf->tf_Baseline;
  78
  79     /* MinX/MaxX can be a bit more complicated if there are kerning/space
  80      * tables */
  81
  82     if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern
  83         || tf->tf_CharSpace)
  84     {
  85         WORD  idx;
  86         WORD  defaultidx = NUMCHARS(tf) - 1; /* Last glyph is 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) \
 111                         textExtent->te_Extent.MinX = (x); \
 112                     if ((x) > textExtent->te_Extent.MaxX) \
 113                         textExtent->te_Extent.MaxX = (x);
 114
 115                 x += ((WORD *)tf->tf_CharKern)[idx];
 116                 CHECK_MINMAX(x);
 117
 118                 x2 = x + ( ( ((ULONG *)tf->tf_CharLoc)[idx] ) & 0xFFFF);
 119                 CHECK_MINMAX(x2);
 120
 121                 x += ((WORD *)tf->tf_CharSpace)[idx];
 122                 CHECK_MINMAX(x);
 123
 124                 x += rp->TxSpacing;
 125                 CHECK_MINMAX(x);
 126
 127             } /* while(count--) */
 128
 129             textExtent->te_Extent.MaxX--;
 130
 131         } /* if (count) */
 132
 133     } /* if ((tf->tf_Flags & FPF_PROPORTIONAL) || tf->tf_CharKern
 134        * || tf->tf_CharSpace) */
 135     else
 136     {
 137         /* Normal non-proportional Font */
 138         textExtent->te_Extent.MinX = 0;
 139         textExtent->te_Extent.MaxX = textExtent->te_Width - 1;
 140     }
 141
 142     if (rp->AlgoStyle & FSF_BOLD)
 143     {
 144         textExtent->te_Extent.MaxX += tf->tf_BoldSmear;
 145     }
 146
 147     if (rp->AlgoStyle & FSF_ITALIC)
 148     {
 149         /*  ######            ######
 150         **  ##  ##            ##  ##
 151         **  ##  ##           ##  ##
 152         **  ##  ##  ===>     ##  ##
 153         **  ##  ##          ##  ##
 154         **..##..##..      ..##..##..
 155         **  ##  ##         ##  ##
 156         **  ######         ######
 157         */
 158
 159         textExtent->te_Extent.MaxX += tf->tf_Baseline / 2;
 160         textExtent->te_Extent.MinX -= (tf->tf_YSize - tf->tf_Baseline) / 2;
 161     }
 162
 163     AROS_LIBFUNC_EXIT
 164
 165 } /* TextExtent */