/* * 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 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> imageOffsetsZ; /* Offset from the beginning of the strike data header * to bitmap data for an individual glyph ID. */ public: DEFINE_SIZE_ARRAY (4, imageOffsetsZ); }; 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 (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 = hb_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(); extents->x_bearing = x_offset; extents->y_bearing = png.IHDR.height + y_offset; extents->width = png.IHDR.width; extents->height = -png.IHDR.height; /* Convert to font units. */ if (strike_ppem) { float scale = font->face->get_upem () / (float) strike_ppem; extents->x_bearing = roundf (extents->x_bearing * scale); extents->y_bearing = roundf (extents->y_bearing * scale); extents->width = roundf (extents->width * scale); extents->height = roundf (extents->height * scale); } hb_blob_destroy (blob); return strike_ppem; } private: hb_blob_ptr_t 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 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 */