287 lines
8.6 KiB
C++
287 lines
8.6 KiB
C++
/*
|
||
* Copyright © 2018 Ebrahim Byagowi
|
||
*
|
||
* This is part of HarfBuzz, a text shaping library.
|
||
*
|
||
* Permission is hereby granted, without written agreement and without
|
||
* license or royalty fees, to use, copy, modify, and distribute this
|
||
* software and its documentation for any purpose, provided that the
|
||
* above copyright notice and the following two paragraphs appear in
|
||
* all copies of this software.
|
||
*
|
||
* IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE TO ANY PARTY FOR
|
||
* DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
|
||
* ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN
|
||
* IF THE COPYRIGHT HOLDER HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH
|
||
* DAMAGE.
|
||
*
|
||
* THE COPYRIGHT HOLDER SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
|
||
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
|
||
* FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE PROVIDED HEREUNDER IS
|
||
* ON AN "AS IS" BASIS, AND THE COPYRIGHT HOLDER HAS NO OBLIGATION TO
|
||
* PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
|
||
*/
|
||
|
||
#ifndef HB_OT_COLOR_SBIX_TABLE_HH
|
||
#define HB_OT_COLOR_SBIX_TABLE_HH
|
||
|
||
#include "hb-open-type.hh"
|
||
|
||
/*
|
||
* sbix -- Standard Bitmap Graphics
|
||
* https://docs.microsoft.com/en-us/typography/opentype/spec/sbix
|
||
* https://developer.apple.com/fonts/TrueType-Reference-Manual/RM06/Chap6sbix.html
|
||
*/
|
||
#define HB_OT_TAG_sbix HB_TAG('s','b','i','x')
|
||
|
||
|
||
namespace OT {
|
||
|
||
|
||
struct SBIXGlyph
|
||
{
|
||
HBINT16 xOffset; /* The horizontal (x-axis) offset from the left
|
||
* edge of the graphic to the glyph’s origin.
|
||
* That is, the x-coordinate of the point on the
|
||
* baseline at the left edge of the glyph. */
|
||
HBINT16 yOffset; /* The vertical (y-axis) offset from the bottom
|
||
* edge of the graphic to the glyph’s origin.
|
||
* That is, the y-coordinate of the point on the
|
||
* baseline at the left edge of the glyph. */
|
||
Tag graphicType; /* Indicates the format of the embedded graphic
|
||
* data: one of 'jpg ', 'png ' or 'tiff', or the
|
||
* special format 'dupe'. */
|
||
UnsizedArrayOf<HBUINT8>
|
||
data; /* The actual embedded graphic data. The total
|
||
* length is inferred from sequential entries in
|
||
* the glyphDataOffsets array and the fixed size
|
||
* (8 bytes) of the preceding fields. */
|
||
public:
|
||
DEFINE_SIZE_ARRAY (8, data);
|
||
};
|
||
|
||
struct SBIXStrike
|
||
{
|
||
bool sanitize (hb_sanitize_context_t *c) const
|
||
{
|
||
TRACE_SANITIZE (this);
|
||
return_trace (c->check_struct (this) &&
|
||
imageOffsetsZ.sanitize_shallow (c, c->get_num_glyphs () + 1));
|
||
}
|
||
|
||
hb_blob_t *get_glyph_blob (unsigned int glyph_id,
|
||
hb_blob_t *sbix_blob,
|
||
hb_tag_t file_type,
|
||
int *x_offset,
|
||
int *y_offset,
|
||
unsigned int num_glyphs,
|
||
unsigned int *strike_ppem) const
|
||
{
|
||
if (unlikely (!ppem)) return hb_blob_get_empty (); /* To get Null() object out of the way. */
|
||
|
||
unsigned int retry_count = 8;
|
||
unsigned int sbix_len = sbix_blob->length;
|
||
unsigned int strike_offset = (const char *) this - (const char *) sbix_blob->data;
|
||
assert (strike_offset < sbix_len);
|
||
|
||
retry:
|
||
if (unlikely (glyph_id >= num_glyphs ||
|
||
imageOffsetsZ[glyph_id + 1] <= imageOffsetsZ[glyph_id] ||
|
||
imageOffsetsZ[glyph_id + 1] - imageOffsetsZ[glyph_id] <= SBIXGlyph::min_size ||
|
||
(unsigned int) imageOffsetsZ[glyph_id + 1] > sbix_len - strike_offset))
|
||
return hb_blob_get_empty ();
|
||
|
||
unsigned int glyph_offset = strike_offset + (unsigned int) imageOffsetsZ[glyph_id] + SBIXGlyph::min_size;
|
||
unsigned int glyph_length = imageOffsetsZ[glyph_id + 1] - imageOffsetsZ[glyph_id] - SBIXGlyph::min_size;
|
||
|
||
const SBIXGlyph *glyph = &(this+imageOffsetsZ[glyph_id]);
|
||
|
||
if (glyph->graphicType == HB_TAG ('d','u','p','e'))
|
||
{
|
||
if (glyph_length >= 2)
|
||
{
|
||
glyph_id = *((HBUINT16 *) &glyph->data);
|
||
if (retry_count--)
|
||
goto retry;
|
||
}
|
||
return hb_blob_get_empty ();
|
||
}
|
||
|
||
if (unlikely (file_type != glyph->graphicType))
|
||
return hb_blob_get_empty ();
|
||
|
||
if (strike_ppem) *strike_ppem = ppem;
|
||
if (x_offset) *x_offset = glyph->xOffset;
|
||
if (y_offset) *y_offset = glyph->yOffset;
|
||
return hb_blob_create_sub_blob (sbix_blob, glyph_offset, glyph_length);
|
||
}
|
||
|
||
public:
|
||
HBUINT16 ppem; /* The PPEM size for which this strike was designed. */
|
||
HBUINT16 resolution; /* The device pixel density (in PPI) for which this
|
||
* strike was designed. (E.g., 96 PPI, 192 PPI.) */
|
||
protected:
|
||
UnsizedArrayOf<LOffsetTo<SBIXGlyph> >
|
||
imageOffsetsZ; /* Offset from the beginning of the strike data header
|
||
* to bitmap data for an individual glyph ID. */
|
||
public:
|
||
DEFINE_SIZE_STATIC (8);
|
||
};
|
||
|
||
struct sbix
|
||
{
|
||
static constexpr hb_tag_t tableTag = HB_OT_TAG_sbix;
|
||
|
||
bool has_data () const { return version; }
|
||
|
||
const SBIXStrike &get_strike (unsigned int i) const { return this+strikes[i]; }
|
||
|
||
struct accelerator_t
|
||
{
|
||
void init (hb_face_t *face)
|
||
{
|
||
table = hb_sanitize_context_t().reference_table<sbix> (face);
|
||
num_glyphs = face->get_num_glyphs ();
|
||
}
|
||
void fini () { table.destroy (); }
|
||
|
||
bool has_data () const { return table->has_data (); }
|
||
|
||
bool get_extents (hb_font_t *font,
|
||
hb_codepoint_t glyph,
|
||
hb_glyph_extents_t *extents) const
|
||
{
|
||
/* We only support PNG right now, and following function checks type. */
|
||
return get_png_extents (font, glyph, extents);
|
||
}
|
||
|
||
hb_blob_t *reference_png (hb_font_t *font,
|
||
hb_codepoint_t glyph_id,
|
||
int *x_offset,
|
||
int *y_offset,
|
||
unsigned int *available_ppem) const
|
||
{
|
||
return choose_strike (font).get_glyph_blob (glyph_id, table.get_blob (),
|
||
HB_TAG ('p','n','g',' '),
|
||
x_offset, y_offset,
|
||
num_glyphs, available_ppem);
|
||
}
|
||
|
||
private:
|
||
|
||
const SBIXStrike &choose_strike (hb_font_t *font) const
|
||
{
|
||
unsigned count = table->strikes.len;
|
||
if (unlikely (!count))
|
||
return Null(SBIXStrike);
|
||
|
||
unsigned int requested_ppem = MAX (font->x_ppem, font->y_ppem);
|
||
if (!requested_ppem)
|
||
requested_ppem = 1<<30; /* Choose largest strike. */
|
||
/* TODO Add DPI sensitivity as well? */
|
||
unsigned int best_i = 0;
|
||
unsigned int best_ppem = table->get_strike (0).ppem;
|
||
|
||
for (unsigned int i = 1; i < count; i++)
|
||
{
|
||
unsigned int ppem = (table->get_strike (i)).ppem;
|
||
if ((requested_ppem <= ppem && ppem < best_ppem) ||
|
||
(requested_ppem > best_ppem && ppem > best_ppem))
|
||
{
|
||
best_i = i;
|
||
best_ppem = ppem;
|
||
}
|
||
}
|
||
|
||
return table->get_strike (best_i);
|
||
}
|
||
|
||
struct PNGHeader
|
||
{
|
||
HBUINT8 signature[8];
|
||
struct
|
||
{
|
||
struct
|
||
{
|
||
HBUINT32 length;
|
||
Tag type;
|
||
} header;
|
||
HBUINT32 width;
|
||
HBUINT32 height;
|
||
HBUINT8 bitDepth;
|
||
HBUINT8 colorType;
|
||
HBUINT8 compressionMethod;
|
||
HBUINT8 filterMethod;
|
||
HBUINT8 interlaceMethod;
|
||
} IHDR;
|
||
|
||
public:
|
||
DEFINE_SIZE_STATIC (29);
|
||
};
|
||
|
||
bool get_png_extents (hb_font_t *font,
|
||
hb_codepoint_t glyph,
|
||
hb_glyph_extents_t *extents) const
|
||
{
|
||
/* Following code is safe to call even without data.
|
||
* But faster to short-circuit. */
|
||
if (!has_data ())
|
||
return false;
|
||
|
||
int x_offset = 0, y_offset = 0;
|
||
unsigned int strike_ppem = 0;
|
||
hb_blob_t *blob = reference_png (font, glyph, &x_offset, &y_offset, &strike_ppem);
|
||
|
||
const PNGHeader &png = *blob->as<PNGHeader>();
|
||
|
||
extents->x_bearing = x_offset;
|
||
extents->y_bearing = y_offset;
|
||
extents->width = png.IHDR.width;
|
||
extents->height = png.IHDR.height;
|
||
|
||
/* Convert to font units. */
|
||
if (strike_ppem)
|
||
{
|
||
double scale = font->face->get_upem () / (double) strike_ppem;
|
||
extents->x_bearing = round (extents->x_bearing * scale);
|
||
extents->y_bearing = round (extents->y_bearing * scale);
|
||
extents->width = round (extents->width * scale);
|
||
extents->height = round (extents->height * scale);
|
||
}
|
||
|
||
hb_blob_destroy (blob);
|
||
|
||
return strike_ppem;
|
||
}
|
||
|
||
private:
|
||
hb_blob_ptr_t<sbix> table;
|
||
|
||
unsigned int num_glyphs;
|
||
};
|
||
|
||
bool sanitize (hb_sanitize_context_t *c) const
|
||
{
|
||
TRACE_SANITIZE (this);
|
||
return_trace (likely (c->check_struct (this) &&
|
||
version >= 1 &&
|
||
strikes.sanitize (c, this)));
|
||
}
|
||
|
||
protected:
|
||
HBUINT16 version; /* Table version number — set to 1 */
|
||
HBUINT16 flags; /* Bit 0: Set to 1. Bit 1: Draw outlines.
|
||
* Bits 2 to 15: reserved (set to 0). */
|
||
LOffsetLArrayOf<SBIXStrike>
|
||
strikes; /* Offsets from the beginning of the 'sbix'
|
||
* table to data for each individual bitmap strike. */
|
||
public:
|
||
DEFINE_SIZE_ARRAY (8, strikes);
|
||
};
|
||
|
||
struct sbix_accelerator_t : sbix::accelerator_t {};
|
||
|
||
} /* namespace OT */
|
||
|
||
#endif /* HB_OT_COLOR_SBIX_TABLE_HH */
|