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Codechange: simplify BMP header creation

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Rubidium
2026-07-11 20:54:07 +02:00
committed by rubidium42
parent 1d1c603494
commit 121df5b461
2 changed files with 24 additions and 40 deletions
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src/screenshot_bmp.cpp
+24 -39
View File
@@ -8,30 +8,15 @@
/** @file screenshot_bmp.cpp BMP screenshot provider. */
#include "stdafx.h"
#include "core/endian_func.hpp"
#include "core/math_func.hpp"
#include "core/string_builder.hpp"
#include "fileio_func.h"
#include "screenshot_type.h"
#include "safeguards.h"
/** BMP File Header (stored in little endian) */
PACK(struct BitmapFileHeader {
uint16_t type;
uint32_t size;
uint32_t reserved;
uint32_t off_bits;
});
static_assert(sizeof(BitmapFileHeader) == 14);
/** BMP Info Header (stored in little endian) */
struct BitmapInfoHeader {
uint32_t size;
int32_t width, height;
uint16_t planes, bitcount;
uint32_t compression, sizeimage, xpels, ypels, clrused, clrimp;
};
static_assert(sizeof(BitmapInfoHeader) == 40);
constexpr size_t BITMAP_FILE_HEADER_SIZE = 14; ///< The size of a bitmap file header.
constexpr size_t BITMAP_INFO_HEADER_SIZE = 40; ///< The size of a bitmap info header.
/** Format of palette data in BMP header */
struct RgbQuad {
@@ -64,29 +49,29 @@ public:
/* Size of palette. Only present for 8bpp mode */
uint pal_size = pixelformat == 8 ? sizeof(RgbQuad) * 256 : 0;
/* Setup the file header */
BitmapFileHeader bfh;
bfh.type = TO_LE16('MB');
bfh.size = TO_LE32(sizeof(BitmapFileHeader) + sizeof(BitmapInfoHeader) + pal_size + static_cast<size_t>(bytewidth) * h);
bfh.reserved = 0;
bfh.off_bits = TO_LE32(sizeof(BitmapFileHeader) + sizeof(BitmapInfoHeader) + pal_size);
std::string header;
StringBuilder sb(header);
sb.Put("BM"); // header field
sb.PutUint32LE(BITMAP_FILE_HEADER_SIZE + BITMAP_INFO_HEADER_SIZE + pal_size + static_cast<size_t>(bytewidth) * h); // full image size
sb.PutUint16LE(0); // reserved 1
sb.PutUint16LE(0); // reserved 2
sb.PutUint32LE(BITMAP_FILE_HEADER_SIZE + BITMAP_INFO_HEADER_SIZE + pal_size); // offset of bitmap image data
/* Setup the info header */
BitmapInfoHeader bih;
bih.size = TO_LE32(sizeof(BitmapInfoHeader));
bih.width = TO_LE32(w);
bih.height = TO_LE32(h);
bih.planes = TO_LE16(1);
bih.bitcount = TO_LE16(bpp * 8);
bih.compression = 0;
bih.sizeimage = 0;
bih.xpels = 0;
bih.ypels = 0;
bih.clrused = 0;
bih.clrimp = 0;
sb.PutUint32LE(BITMAP_INFO_HEADER_SIZE); // size of info header
sb.PutUint32LE(w); // width of the image
sb.PutUint32LE(h); // height of the image
sb.PutUint16LE(1); // number of planes
sb.PutUint16LE(bpp * 8); // bits per pixel
sb.PutUint32LE(0); // compression
sb.PutUint32LE(0); // size of raw image data, dummy of 0 is allowed
sb.PutUint32LE(0); // vertical resolution in pixels per meter
sb.PutUint32LE(0); // horizontal resolution in pixels per meter
sb.PutUint32LE(0); // number of colours in the palette, 0 is allowed
sb.PutUint32LE(0); // number of important colours, 0 is all colours are important
assert(header.size() == BITMAP_FILE_HEADER_SIZE + BITMAP_INFO_HEADER_SIZE);
/* Write file header and info header */
if (fwrite(&bfh, sizeof(bfh), 1, f) != 1 || fwrite(&bih, sizeof(bih), 1, f) != 1) {
/* Write headers */
if (fwrite(header.data(), header.size(), 1, f) != 1) {
return false;
}
src/stdafx.h
-1
View File
@@ -184,7 +184,6 @@ using namespace std::literals::string_view_literals;
#else
# define PACK_N(type_dec, n) type_dec __attribute__((__packed__, aligned(n)))
#endif
#define PACK(type_dec) PACK_N(type_dec, 1)
/** @def debug_inline
* When making a (pure) debug build, the compiler will by default disable