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| 1 /***************************************************************************/ |
| 2 /* */ |
| 3 /* pngshim.c */ |
| 4 /* */ |
| 5 /* PNG Bitmap glyph support. */ |
| 6 /* */ |
| 7 /* Copyright 2013 by Google, Inc. */ |
| 8 /* Written by Stuart Gill and Behdad Esfahbod. */ |
| 9 /* */ |
| 10 /* This file is part of the FreeType project, and may only be used, */ |
| 11 /* modified, and distributed under the terms of the FreeType project */ |
| 12 /* license, LICENSE.TXT. By continuing to use, modify, or distribute */ |
| 13 /* this file you indicate that you have read the license and */ |
| 14 /* understand and accept it fully. */ |
| 15 /* */ |
| 16 /***************************************************************************/ |
| 17 |
| 18 |
| 19 #include <ft2build.h> |
| 20 #include FT_INTERNAL_DEBUG_H |
| 21 #include FT_INTERNAL_STREAM_H |
| 22 #include FT_TRUETYPE_TAGS_H |
| 23 #include FT_CONFIG_STANDARD_LIBRARY_H |
| 24 |
| 25 |
| 26 #ifdef FT_CONFIG_OPTION_USE_PNG |
| 27 |
| 28 /* We always include <stjmp.h>, so make libpng shut up! */ |
| 29 #define PNG_SKIP_SETJMP_CHECK 1 |
| 30 #include <png.h> |
| 31 #include "pngshim.h" |
| 32 |
| 33 #include "sferrors.h" |
| 34 |
| 35 |
| 36 /* This code is freely based on cairo-png.c. There's so many ways */ |
| 37 /* to call libpng, and the way cairo does it is defacto standard. */ |
| 38 |
| 39 static int |
| 40 multiply_alpha( int alpha, |
| 41 int color ) |
| 42 { |
| 43 int temp = ( alpha * color ) + 0x80; |
| 44 |
| 45 |
| 46 return ( temp + ( temp >> 8 ) ) >> 8; |
| 47 } |
| 48 |
| 49 |
| 50 /* Premultiplies data and converts RGBA bytes => native endian. */ |
| 51 static void |
| 52 premultiply_data( png_structp png, |
| 53 png_row_infop row_info, |
| 54 png_bytep data ) |
| 55 { |
| 56 unsigned int i; |
| 57 |
| 58 FT_UNUSED( png ); |
| 59 |
| 60 |
| 61 for ( i = 0; i < row_info->rowbytes; i += 4 ) |
| 62 { |
| 63 unsigned char* base = &data[i]; |
| 64 unsigned int alpha = base[3]; |
| 65 |
| 66 |
| 67 if ( alpha == 0 ) |
| 68 base[0] = base[1] = base[2] = base[3] = 0; |
| 69 |
| 70 else |
| 71 { |
| 72 unsigned int red = base[0]; |
| 73 unsigned int green = base[1]; |
| 74 unsigned int blue = base[2]; |
| 75 |
| 76 |
| 77 if ( alpha != 0xFF ) |
| 78 { |
| 79 red = multiply_alpha( alpha, red ); |
| 80 green = multiply_alpha( alpha, green ); |
| 81 blue = multiply_alpha( alpha, blue ); |
| 82 } |
| 83 |
| 84 base[0] = blue; |
| 85 base[1] = green; |
| 86 base[2] = red; |
| 87 base[3] = alpha; |
| 88 } |
| 89 } |
| 90 } |
| 91 |
| 92 |
| 93 /* Converts RGBx bytes to BGRA. */ |
| 94 static void |
| 95 convert_bytes_to_data( png_structp png, |
| 96 png_row_infop row_info, |
| 97 png_bytep data ) |
| 98 { |
| 99 unsigned int i; |
| 100 |
| 101 FT_UNUSED( png ); |
| 102 |
| 103 |
| 104 for ( i = 0; i < row_info->rowbytes; i += 4 ) |
| 105 { |
| 106 unsigned char* base = &data[i]; |
| 107 unsigned int red = base[0]; |
| 108 unsigned int green = base[1]; |
| 109 unsigned int blue = base[2]; |
| 110 |
| 111 |
| 112 base[0] = blue; |
| 113 base[1] = green; |
| 114 base[2] = red; |
| 115 base[3] = 0xFF; |
| 116 } |
| 117 } |
| 118 |
| 119 |
| 120 /* Use error callback to avoid png writing to stderr. */ |
| 121 static void |
| 122 error_callback( png_structp png, |
| 123 png_const_charp error_msg ) |
| 124 { |
| 125 FT_Error* error = png_get_error_ptr( png ); |
| 126 |
| 127 FT_UNUSED( error_msg ); |
| 128 |
| 129 |
| 130 *error = FT_THROW( Out_Of_Memory ); |
| 131 #ifdef PNG_SETJMP_SUPPORTED |
| 132 longjmp( png_jmpbuf( png ), 1 ); |
| 133 #endif |
| 134 /* if we get here, then we have no choice but to abort ... */ |
| 135 } |
| 136 |
| 137 |
| 138 /* Use warning callback to avoid png writing to stderr. */ |
| 139 static void |
| 140 warning_callback( png_structp png, |
| 141 png_const_charp error_msg ) |
| 142 { |
| 143 FT_UNUSED( png ); |
| 144 FT_UNUSED( error_msg ); |
| 145 |
| 146 /* Just ignore warnings. */ |
| 147 } |
| 148 |
| 149 |
| 150 static void |
| 151 read_data_from_FT_Stream( png_structp png, |
| 152 png_bytep data, |
| 153 png_size_t length ) |
| 154 { |
| 155 FT_Error error; |
| 156 png_voidp p = png_get_io_ptr( png ); |
| 157 FT_Stream stream = (FT_Stream)p; |
| 158 |
| 159 |
| 160 if ( FT_FRAME_ENTER( length ) ) |
| 161 { |
| 162 FT_Error* e = png_get_error_ptr( png ); |
| 163 |
| 164 |
| 165 *e = FT_THROW( Invalid_Stream_Read ); |
| 166 png_error( png, NULL ); |
| 167 |
| 168 return; |
| 169 } |
| 170 |
| 171 memcpy( data, stream->cursor, length ); |
| 172 |
| 173 FT_FRAME_EXIT(); |
| 174 } |
| 175 |
| 176 |
| 177 static FT_Error |
| 178 Load_SBit_Png( FT_Bitmap* map, |
| 179 FT_Int x_offset, |
| 180 FT_Int y_offset, |
| 181 FT_Int pix_bits, |
| 182 TT_SBit_Metrics metrics, |
| 183 FT_Memory memory, |
| 184 FT_Byte* data, |
| 185 FT_UInt png_len ) |
| 186 { |
| 187 FT_Error error = FT_Err_Ok; |
| 188 FT_StreamRec stream; |
| 189 |
| 190 png_structp png; |
| 191 png_infop info; |
| 192 png_uint_32 imgWidth, imgHeight; |
| 193 |
| 194 int bitdepth, color_type, interlace; |
| 195 FT_Int i; |
| 196 png_byte* *rows; |
| 197 |
| 198 |
| 199 if ( x_offset < 0 || x_offset + metrics->width > map->width || |
| 200 y_offset < 0 || y_offset + metrics->height > map->rows || |
| 201 pix_bits != 32 || map->pixel_mode != FT_PIXEL_MODE_BGRA ) |
| 202 { |
| 203 error = FT_THROW( Invalid_Argument ); |
| 204 goto Exit; |
| 205 } |
| 206 |
| 207 FT_Stream_OpenMemory( &stream, data, png_len ); |
| 208 |
| 209 png = png_create_read_struct( PNG_LIBPNG_VER_STRING, |
| 210 &error, |
| 211 error_callback, |
| 212 warning_callback ); |
| 213 if ( !png ) |
| 214 { |
| 215 error = FT_THROW( Out_Of_Memory ); |
| 216 goto Exit; |
| 217 } |
| 218 |
| 219 info = png_create_info_struct( png ); |
| 220 if ( !info ) |
| 221 { |
| 222 error = FT_THROW( Out_Of_Memory ); |
| 223 png_destroy_read_struct( &png, NULL, NULL ); |
| 224 goto Exit; |
| 225 } |
| 226 |
| 227 if ( ft_setjmp( png_jmpbuf( png ) ) ) |
| 228 { |
| 229 error = FT_THROW( Invalid_File_Format ); |
| 230 goto DestroyExit; |
| 231 } |
| 232 |
| 233 png_set_read_fn( png, &stream, read_data_from_FT_Stream ); |
| 234 |
| 235 png_read_info( png, info ); |
| 236 png_get_IHDR( png, info, |
| 237 &imgWidth, &imgHeight, |
| 238 &bitdepth, &color_type, &interlace, |
| 239 NULL, NULL ); |
| 240 |
| 241 if ( error != FT_Err_Ok || |
| 242 (FT_Int)imgWidth != metrics->width || |
| 243 (FT_Int)imgHeight != metrics->height ) |
| 244 goto DestroyExit; |
| 245 |
| 246 /* convert palette/gray image to rgb */ |
| 247 if ( color_type == PNG_COLOR_TYPE_PALETTE ) |
| 248 png_set_palette_to_rgb( png ); |
| 249 |
| 250 /* expand gray bit depth if needed */ |
| 251 if ( color_type == PNG_COLOR_TYPE_GRAY ) |
| 252 { |
| 253 #if PNG_LIBPNG_VER >= 10209 |
| 254 png_set_expand_gray_1_2_4_to_8( png ); |
| 255 #else |
| 256 png_set_gray_1_2_4_to_8( png ); |
| 257 #endif |
| 258 } |
| 259 |
| 260 /* transform transparency to alpha */ |
| 261 if ( png_get_valid(png, info, PNG_INFO_tRNS ) ) |
| 262 png_set_tRNS_to_alpha( png ); |
| 263 |
| 264 if ( bitdepth == 16 ) |
| 265 png_set_strip_16( png ); |
| 266 |
| 267 if ( bitdepth < 8 ) |
| 268 png_set_packing( png ); |
| 269 |
| 270 /* convert grayscale to RGB */ |
| 271 if ( color_type == PNG_COLOR_TYPE_GRAY || |
| 272 color_type == PNG_COLOR_TYPE_GRAY_ALPHA ) |
| 273 png_set_gray_to_rgb( png ); |
| 274 |
| 275 if ( interlace != PNG_INTERLACE_NONE ) |
| 276 png_set_interlace_handling( png ); |
| 277 |
| 278 png_set_filler( png, 0xFF, PNG_FILLER_AFTER ); |
| 279 |
| 280 /* recheck header after setting EXPAND options */ |
| 281 png_read_update_info(png, info ); |
| 282 png_get_IHDR( png, info, |
| 283 &imgWidth, &imgHeight, |
| 284 &bitdepth, &color_type, &interlace, |
| 285 NULL, NULL ); |
| 286 |
| 287 if ( bitdepth != 8 || |
| 288 !( color_type == PNG_COLOR_TYPE_RGB || |
| 289 color_type == PNG_COLOR_TYPE_RGB_ALPHA ) ) |
| 290 { |
| 291 error = FT_THROW( Invalid_File_Format ); |
| 292 goto DestroyExit; |
| 293 } |
| 294 |
| 295 switch ( color_type ) |
| 296 { |
| 297 default: |
| 298 /* Shouldn't happen, but fall through. */ |
| 299 |
| 300 case PNG_COLOR_TYPE_RGB_ALPHA: |
| 301 png_set_read_user_transform_fn( png, premultiply_data ); |
| 302 break; |
| 303 |
| 304 case PNG_COLOR_TYPE_RGB: |
| 305 /* Humm, this smells. Carry on though. */ |
| 306 png_set_read_user_transform_fn( png, convert_bytes_to_data ); |
| 307 break; |
| 308 } |
| 309 |
| 310 if ( FT_NEW_ARRAY( rows, imgHeight ) ) |
| 311 { |
| 312 error = FT_THROW( Out_Of_Memory ); |
| 313 goto DestroyExit; |
| 314 } |
| 315 |
| 316 for ( i = 0; i < (FT_Int)imgHeight; i++ ) |
| 317 rows[i] = map->buffer + ( y_offset + i ) * map->pitch + x_offset * 4; |
| 318 |
| 319 png_read_image( png, rows ); |
| 320 |
| 321 FT_FREE( rows ); |
| 322 |
| 323 png_read_end( png, info ); |
| 324 |
| 325 DestroyExit: |
| 326 png_destroy_read_struct( &png, &info, NULL ); |
| 327 FT_Stream_Close( &stream ); |
| 328 |
| 329 Exit: |
| 330 return error; |
| 331 } |
| 332 |
| 333 #endif /* FT_CONFIG_OPTION_USE_PNG */ |
| 334 |
| 335 |
| 336 /* END */ |
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