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      1 /* Copyright (c) 2013 The Chromium OS Authors. All rights reserved.
      2  * Use of this source code is governed by a BSD-style license that can be
      3  * found in the LICENSE file.
      4  *
      5  * This describes the internal format used to pack a set of character glpyhs so
      6  * we can render strings by drawing one character at a time.
      7  *
      8  * The format is this:
      9  *
     10  *   +-------------------------+
     11  *   | FontArrayHeader         |
     12  *   +-------------------------+
     13  *   | FontArrayEntryHeader[0] |
     14  *   +-------------------------+
     15  *   | raw image data[0]       |
     16  *   +-------------------------+
     17  *   | FontArrayEntryHeader[1] |
     18  *   +-------------------------+
     19  *   | raw image data[1]       |
     20  *   +-------------------------+
     21  *   | FontArrayEntryHeader[2] |
     22  *   +-------------------------+
     23  *   | raw image data[2]       |
     24  *   +-------------------------+
     25  *      ...
     26  *   +-------------------------+
     27  *   | FontArrayEntryHeader[n] |
     28  *   +-------------------------+
     29  *   | raw image data[n]       |
     30  *   +-------------------------+
     31  *
     32  * The FontArrayHeader describes how many characters will be encoded.
     33  * Each character encoding consists of a FontArrayEntryHeader followed
     34  * immediately by the raw image data for that character.
     35  */
     36 
     37 #ifndef VBOOT_REFERENCE_BMPBLK_FONT_H_
     38 #define VBOOT_REFERENCE_BMPBLK_FONT_H_
     39 
     40 #include "bmpblk_header.h"
     41 
     42 #define FONT_SIGNATURE      "FONT"
     43 #define FONT_SIGNATURE_SIZE 4
     44 
     45 typedef struct FontArrayHeader {
     46 	uint8_t  signature[FONT_SIGNATURE_SIZE];
     47 	uint32_t num_entries;  /* Number of chars encoded here. */
     48 } __attribute__((packed)) FontArrayHeader;
     49 
     50 typedef struct FontArrayEntryHeader {
     51 	uint32_t ascii;  /* What to show. Could even be UTF? */
     52 	ImageInfo info;  /* Describes the bitmap. */
     53 
     54 	/*
     55 	 * The image to use follows immediately, NOT compressed. It's
     56 	 * uncompressed because each glyph is only a few hundred bytes, but
     57 	 * they have much in common (colormaps, for example). When we add the
     58 	 * whole font blob to the bmpblk, it will be compressed as a single
     59 	 * item there.
     60 	 */
     61 } __attribute__((packed)) FontArrayEntryHeader;
     62 
     63 #endif  /* VBOOT_REFERENCE_BMPBLK_FONT_H_ */
     64