146 lines
3.2 KiB
C++
146 lines
3.2 KiB
C++
/**
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* =========================================================================
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* File : tex_bmp.cpp
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* Project : 0 A.D.
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* Description : Windows BMP codec
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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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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struct BmpHeader
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{
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// BITMAPFILEHEADER
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u16 bfType; // "BM"
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u32 bfSize; // of file
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u16 bfReserved1;
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u16 bfReserved2;
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u32 bfOffBits; // offset to image data
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// BITMAPINFOHEADER
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u32 biSize;
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long biWidth;
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long biHeight;
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u16 biPlanes;
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u16 biBitCount;
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u32 biCompression;
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u32 biSizeImage;
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// the following are unused and zeroed when writing:
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long biXPelsPerMeter;
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long biYPelsPerMeter;
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u32 biClrUsed;
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u32 biClrImportant;
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};
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#pragma pack(pop)
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#define BI_RGB 0 // biCompression
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static LibError bmp_transform(Tex* UNUSED(t), uint UNUSED(transforms))
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{
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return INFO::TEX_CODEC_CANNOT_HANDLE;
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}
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static bool bmp_is_hdr(const u8* file)
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{
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// check header signature (bfType == "BM"?).
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// we compare single bytes to be endian-safe.
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return (file[0] == 'B' && file[1] == 'M');
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}
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static bool bmp_is_ext(const std::string& extension)
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{
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return !strcasecmp(extension.c_str(), ".bmp");
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}
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static size_t bmp_hdr_size(const u8* file)
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{
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const size_t hdr_size = sizeof(BmpHeader);
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if(file)
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{
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BmpHeader* hdr = (BmpHeader*)file;
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const u32 ofs = read_le32(&hdr->bfOffBits);
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debug_assert(ofs >= hdr_size && "bmp_hdr_size invalid");
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return ofs;
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}
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return hdr_size;
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}
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// requirements: uncompressed, direct colour, bottom up
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static LibError bmp_decode(DynArray* RESTRICT da, Tex* RESTRICT t)
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{
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u8* file = da->base;
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const BmpHeader* hdr = (const BmpHeader*)file;
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const long w = (long)read_le32(&hdr->biWidth);
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const long h_ = (long)read_le32(&hdr->biHeight);
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const u16 bpp = read_le16(&hdr->biBitCount);
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const u32 compress = read_le32(&hdr->biCompression);
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const long h = abs(h_);
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uint flags = 0;
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flags |= (h_ < 0)? TEX_TOP_DOWN : TEX_BOTTOM_UP;
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if(bpp > 16)
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flags |= TEX_BGR;
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if(bpp == 32)
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flags |= TEX_ALPHA;
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// sanity checks
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if(compress != BI_RGB)
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WARN_RETURN(ERR::TEX_COMPRESSED);
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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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return INFO::OK;
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}
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static LibError bmp_encode(Tex* RESTRICT t, DynArray* RESTRICT da)
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{
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const size_t hdr_size = sizeof(BmpHeader); // needed for BITMAPFILEHEADER
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const size_t img_size = tex_img_size(t);
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const size_t file_size = hdr_size + img_size;
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const long h = (t->flags & TEX_TOP_DOWN)? -(long)t->h : t->h;
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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; // BMP is native BGR.
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const BmpHeader hdr =
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{
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// BITMAPFILEHEADER
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0x4D42, // bfType = 'B','M'
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(u32)file_size, // bfSize
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0, 0, // bfReserved1,2
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hdr_size, // bfOffBits
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// BITMAPINFOHEADER
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40, // biSize = sizeof(BITMAPINFOHEADER)
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t->w,
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h,
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1, // biPlanes
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t->bpp,
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BI_RGB, // biCompression
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(u32)img_size, // biSizeImage
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0, 0, 0, 0 // unused (bi?PelsPerMeter, biClr*)
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};
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return tex_codec_write(t, transforms, &hdr, hdr_size, da);
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}
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TEX_CODEC_REGISTER(bmp);
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