19513f2604
-Codechange: store the SpriteID in the spritecache too -Add: add a PNG loader for graphical files -Documentation: added a document to explain the PNG format
105 lines
2.8 KiB
C++
105 lines
2.8 KiB
C++
/* $Id$ */
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/** @file grf.cpp */
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#include "../stdafx.h"
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#include "../gfx.h"
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#include "../fileio.h"
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#include "../debug.h"
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#include "grf.hpp"
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bool SpriteLoaderGrf::LoadSprite(SpriteLoader::Sprite *sprite, const char *filename, uint32 file_pos)
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{
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/* Open the right file and go to the correct position */
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FioSeekToFile(file_pos);
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/* Read the size and type */
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int num = FioReadWord();
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byte type = FioReadByte();
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/* Type 0xFF indicates either a colormap or some other non-sprite info; we do not handle them here */
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if (type == 0xFF) return false;
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sprite->height = FioReadByte();
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sprite->width = FioReadWord();
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sprite->x_offs = FioReadWord();
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sprite->y_offs = FioReadWord();
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/* 0x02 indicates it is a compressed sprite, so we can't rely on 'num' to be valid.
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* In case it is uncompressed, the size is 'num' - 8 (header-size). */
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num = (type & 0x02) ? sprite->width * sprite->height : num - 8;
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/* XXX -- We should use a pre-located memory segment for this, malloc/free is pretty expensive */
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byte *dest_orig = MallocT<byte>(num);
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byte *dest = dest_orig;
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/* Read the file, which has some kind of compression */
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while (num > 0) {
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int8 code = FioReadByte();
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if (code >= 0) {
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/* Plain bytes to read */
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int size = (code == 0) ? 0x80 : code;
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num -= size;
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for (; size > 0; size--) {
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*dest = FioReadByte();
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dest++;
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}
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} else {
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/* Copy bytes from earlier in the sprite */
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const uint data_offset = ((code & 7) << 8) | FioReadByte();
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int size = -(code >> 3);
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num -= size;
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for (; size > 0; size--) {
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*dest = *(dest - data_offset);
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dest++;
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}
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}
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}
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assert(num == 0);
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sprite->data = CallocT<SpriteLoader::CommonPixel>(sprite->width * sprite->height);
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/* When there are transparency pixels, this format has an other trick.. decode it */
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if (type & 0x08) {
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for (int y = 0; y < sprite->height; y++) {
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bool last_item = false;
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/* Look up in the header-table where the real data is stored for this row */
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int offset = (dest_orig[y * 2 + 1] << 8) | dest_orig[y * 2];
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/* Go to that row */
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dest = &dest_orig[offset];
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do {
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SpriteLoader::CommonPixel *data;
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/* Read the header:
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* 0 .. 14 - length
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* 15 - last_item
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* 16 .. 31 - transparency bytes */
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last_item = ((*dest) & 0x80) != 0;
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int length = (*dest++) & 0x7F;
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int skip = *dest++;
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data = &sprite->data[y * sprite->width + skip];
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for (int x = 0; x < length; x++) {
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data->m = *dest;
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dest++;
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data++;
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}
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} while (!last_item);
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}
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} else {
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dest = dest_orig;
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for (int i = 0; i < sprite->width * sprite->height; i++)
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sprite->data[i].m = dest[i];
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}
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/* Make sure to mark all transparent pixels transparent on the alpha channel too */
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for (int i = 0; i < sprite->width * sprite->height; i++)
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if (sprite->data[i].m != 0) sprite->data[i].a = 0xFF;
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free(dest_orig);
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return true;
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}
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