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 */ 337
