Commit 80e0504b authored by Luis Penaranda's avatar Luis Penaranda
Browse files

improved support for PNG images

parent 4c79db4c

image_read.cpp

+47 −19
Original line number Diff line number Diff line
@@ -116,9 +116,9 @@ unsigned char *FileRead::pngRead(const char *texturePath, 
    }

    // initialize

    png_structp png_ptr=png_create_read_struct(PNG_LIBPNG_VER_STRING,

                                               NULL,//(png_voidp)user_error_ptr,

                                               NULL,//user_error_fn,

                                               NULL);//user_warning_fn);

                                               NULL,

                                               NULL,

                                               NULL);

    if(!png_ptr){

        fprintf(stderr,"error reading %s\n",texturePath);

        exit(-1);
@@ -139,40 +139,68 @@ unsigned char *FileRead::pngRead(const char *texturePath, 
    *outImageWidth=png_get_image_width(png_ptr,info_ptr);

    *outImageHeight=png_get_image_height(png_ptr,info_ptr);

    png_byte color_type=png_get_color_type(png_ptr,info_ptr);

    if(color_type!=PNG_COLOR_TYPE_RGB){

            fprintf(stderr,"color type of %s must be RGB\n",texturePath);

            // TODO: at this moment, it is only implemented reading RGB images

            exit(-1);

    png_byte bit_depth=png_get_bit_depth(png_ptr,info_ptr);

    if(bit_depth==16)

        png_set_strip_16(png_ptr);

    if(bit_depth<8)

        png_set_expand_gray_1_2_4_to_8(png_ptr);

    if(color_type==PNG_COLOR_TYPE_GRAY||color_type==PNG_COLOR_TYPE_GRAY_ALPHA)

        png_set_gray_to_rgb(png_ptr);

    if(color_type==PNG_COLOR_TYPE_PALETTE){

        png_set_palette_to_rgb(png_ptr);

        // TODO: Read the transparency values for indexed images;

        // currently, they are ignored by stripping the alpha information.

        png_set_strip_alpha(png_ptr);

    }

    // TODO: set the value of depth according to the color type

    int depth=3;        // RGB

    //png_byte bit_depth=png_get_bit_depth(png_ptr,info_ptr);

    //int number_of_passes=png_set_interlace_handling(png_ptr);

    png_read_update_info(png_ptr,info_ptr);

    // allocate memory to store the texture

    unsigned char *textureBytes=

            (unsigned char*)malloc((*outImageWidth)*

                                   (*outImageHeight)*

                                   depth*

                                   3* // RGB

                                   sizeof(unsigned char));

    // read the contents of the file

    if(setjmp(png_jmpbuf(png_ptr))){

        fprintf(stderr,"error reading %s\n",texturePath);

        exit(-1);

    }

    // TODO: we can avoid writing in row_pointers[] and later copying to

    // the texture.

    png_bytep *row_pointers=

            (png_bytep*)malloc(sizeof(png_bytep)*(*outImageHeight));

    for(int y=0;y<(*outImageHeight);++y)

        row_pointers[y]=(png_byte*)malloc(png_get_rowbytes(png_ptr,info_ptr));

    png_read_image(png_ptr,row_pointers);

    for(int row=0;row<(*outImageHeight);++row){

        for(int j=0;j<(*outImageWidth);++j){

            for(int k=0;k<depth;++k){

                textureBytes[row*(*outImageWidth)*depth+j*depth+k]=

                    row_pointers[(*outImageHeight)-row-1][j*depth+k];

            }

        }

    switch(color_type){

    case PNG_COLOR_TYPE_GRAY:

    case PNG_COLOR_TYPE_PALETTE:

    case PNG_COLOR_TYPE_RGB:

        // RGB: copy directly RGB bits to the texture.

        for(int row=0;row<(*outImageHeight);++row)

            for(int j=0;j<(*outImageWidth);++j)

                for(int k=0;k<3;++k)

                        textureBytes[row*(*outImageWidth)*3+j*3+k]=

                            row_pointers[(*outImageHeight)-row-1][j*3+k];

        break;

    case PNG_COLOR_TYPE_GRAY_ALPHA:

    case PNG_COLOR_TYPE_RGB_ALPHA:

        // RGBA: multiply each one of the three first bytes (channels R, G

        // and B), by the alpha (the fourth byte).

        for(int row=0;row<(*outImageHeight);++row)

            for(int j=0;j<(*outImageWidth);++j)

                for(int k=0;k<3;++k)

                        textureBytes[row*(*outImageWidth)*3+j*3+k]=

                            (double)

                            row_pointers[(*outImageHeight)-row-1][j*4+k]*

                            row_pointers[(*outImageHeight)-row-1][j*4+3]/

                            255;

        break;

    default:

        fprintf(stderr,"%s: unrecognized PNG type\n",texturePath);

        exit(-1);

    }

    png_read_end(png_ptr,NULL);

    png_destroy_read_struct(&png_ptr,&info_ptr,NULL);

    for(int row=0;row<(*outImageHeight);++row)

            free(row_pointers[row]);

    free(row_pointers);

input_images/grid.png

0 → 100644
+1.47 KiB
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input_images/grid.pnm

deleted100644 → 0
−5.72 MiB

File deleted.

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