158 lines
3.7 KiB
C++
158 lines
3.7 KiB
C++
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#include "precompiled.h"
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#include "lib/byte_order.h"
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#include "tex_codec.h"
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#pragma pack(push, 1)
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enum TgaImgType
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{
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TGA_TRUE_COLOUR = 2, // uncompressed 24 or 32 bit direct RGB
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TGA_GREY = 3 // uncompressed 8 bit direct greyscale
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};
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enum TgaImgDesc
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{
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TGA_RIGHT_TO_LEFT = BIT(4),
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TGA_TOP_DOWN = BIT(5),
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TGA_BOTTOM_UP = 0 // opposite of TGA_TOP_DOWN
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};
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typedef struct
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{
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u8 img_id_len; // 0 - no image identifier present
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u8 colour_map_type; // 0 - no colour map present
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u8 img_type; // see TgaImgType
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u8 colour_map[5]; // unused
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u16 x_origin; // unused
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u16 y_origin; // unused
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u16 w;
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u16 h;
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u8 bpp; // bits per pixel
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u8 img_desc;
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}
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TgaHeader;
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// TGA file: header [img id] [colour map] image data
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#pragma pack(pop)
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static int tga_transform(Tex* t, int new_flags)
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{
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return TEX_CODEC_CANNOT_HANDLE;
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}
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// requirements: uncompressed, direct colour, bottom up
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static int tga_decode(u8* file, size_t file_size, Tex* t, const char** perr_msg)
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{
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TgaHeader* hdr = (TgaHeader*)file;
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// the first TGA header doesn't have a magic field;
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// we can only check if the first 4 bytes are valid
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// .. not direct colour
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if(hdr->colour_map_type != 0)
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return TEX_CODEC_CANNOT_HANDLE;
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// .. wrong colour type (not uncompressed greyscale or RGB)
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if(hdr->img_type != TGA_TRUE_COLOUR && hdr->img_type != TGA_GREY)
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return TEX_CODEC_CANNOT_HANDLE;
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// make sure we can access all header fields
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const size_t hdr_size = sizeof(TgaHeader) + hdr->img_id_len;
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if(file_size < hdr_size)
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{
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*perr_msg = "header not completely read";
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fail:
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return ERR_CORRUPTED;
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}
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const u8 type = hdr->img_type;
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const uint w = read_le16(&hdr->w);
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const uint h = read_le16(&hdr->h);
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const uint bpp = hdr->bpp;
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const u8 desc = hdr->img_desc;
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const u8 alpha_bits = desc & 0x0f;
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const int orientation = (desc & TGA_TOP_DOWN)? TEX_TOP_DOWN : TEX_BOTTOM_UP;
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u8* const img = file + hdr_size;
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const size_t img_size = w * h * bpp/8;
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int flags = 0;
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if(alpha_bits != 0)
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flags |= TEX_ALPHA;
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if(bpp == 8)
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flags |= TEX_GREY;
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if(type == TGA_TRUE_COLOUR)
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flags |= TEX_BGR;
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// sanity checks
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const char* err = 0;
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// .. storing right-to-left is just stupid;
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// we're not going to bother converting it.
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if(desc & TGA_RIGHT_TO_LEFT)
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err = "image is stored right-to-left";
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if(bpp != 8 && bpp != 16 && bpp != 24 && bpp != 32)
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err = "invalid bpp";
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if(file_size < hdr_size + img_size)
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err = "size < image size";
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if(err)
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{
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*perr_msg = err;
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goto fail;
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}
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t->ofs = hdr_size;
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t->w = w;
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t->h = h;
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t->bpp = bpp;
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t->flags = flags;
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tex_codec_set_orientation(t, orientation);
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return 0;
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}
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static int tga_encode(const char* ext, Tex* t, u8** out, size_t* out_size, const char** perr_msg)
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{
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if(stricmp(ext, "tga"))
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return TEX_CODEC_CANNOT_HANDLE;
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/*
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CHECK_ERR(tex_codec_validate_format(t->bpp, t->flags));
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u8 img_desc = (t->flags & TEX_TOP_DOWN)? TGA_TOP_DOWN : TGA_BOTTOM_UP;
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if(t->bpp == 32)
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img_desc |= 8; // size of alpha channel
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TgaImgType img_type = (t->flags & TEX_GREY)? TGA_GREY : TGA_TRUE_COLOUR;
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// transform
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int transforms = t->flags;
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transforms &= ~TEX_ORIENTATION; // no flip needed - we can set top-down bit.
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transforms ^= TEX_BGR; // TGA is native BGR.
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transform(t, transforms);
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TgaHeader hdr =
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{
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0, // no image identifier present
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0, // no colour map present
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(u8)img_type,
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{0,0,0,0,0}, // unused (colour map)
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0, 0, // unused (origin)
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t->w,
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t->h,
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t->bpp,
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img_desc
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};
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return write_img(fn, &hdr, sizeof(hdr), img, img_size);
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*/
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return 0;
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}
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TEX_CODEC_REGISTER(tga);
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