/*
* Copyright (c) 2020, Matthew Olsson <mattco@serenityos.org>
* Copyright (c) 2022, Bruno Conde <brunompconde@gmail.com>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <AK/BuiltinWrappers.h>
#include <AK/ByteString.h>
#include <AK/Debug.h>
#include <AK/Error.h>
#include <AK/Function.h>
#include <AK/Try.h>
#include <AK/Vector.h>
#include <LibGfx/ImageFormats/BMPLoader.h>
namespace Gfx {
u8 const bmp_header_size = 14;
u32 const color_palette_limit = 1024;
// Compression flags
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/4e588f70-bd92-4a6f-b77f-35d0feaf7a57
struct Compression {
enum : u32 {
RGB = 0,
RLE8,
RLE4,
BITFIELDS,
RLE24, // doubles as JPEG for V4+, but that is unsupported
PNG,
ALPHABITFIELDS,
CMYK = 11,
CMYKRLE8,
CMYKRLE4,
};
};
struct DIBCore {
// u16 for BITMAPHEADERCORE, but i32 for everything else. If the dib type is
// BITMAPHEADERCORE, this is range checked.
i32 width;
i32 height;
u16 bpp;
};
struct DIBInfo {
u32 compression { Compression::RGB };
u32 image_size { 0 };
i32 horizontal_resolution { 0 };
i32 vertical_resolution { 0 };
u32 number_of_palette_colors { 0 };
u32 number_of_important_palette_colors { number_of_palette_colors };
// Introduced in the BITMAPV2INFOHEADER and would ideally be stored in the
// DIBV2 struct, however with a compression value of BI_BITFIELDS or
// BI_ALPHABITFIELDS, these can be specified with the Info header.
Vector<u32> masks;
Vector<i8> mask_shifts;
Vector<u8> mask_sizes;
};
struct DIBOSV2 {
u16 recording;
u16 halftoning;
u16 size1;
u16 size2;
};
template<typename T>
struct Endpoint {
T x;
T y;
T z;
};
}
namespace AK {
template<typename T>
struct Formatter<Gfx::Endpoint<T>> : Formatter<StringView> {
ErrorOr<void> format(FormatBuilder& builder, Gfx::Endpoint<T> const& value)
{
return Formatter<StringView>::format(builder, ByteString::formatted("({}, {}, {})", value.x, value.y, value.z));
}
};
}
namespace Gfx {
// CALIBRATED_RGB, sRGB, WINDOWS_COLOR_SPACE values are from
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/eb4bbd50-b3ce-4917-895c-be31f214797f
// PROFILE_LINKED, PROFILE_EMBEDDED values are from
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/3c289fe1-c42e-42f6-b125-4b5fc49a2b20
struct ColorSpace {
enum : u32 {
// "This value implies that endpoints and gamma values are given in the appropriate fields" in DIBV4.
// The only valid value in v4 bmps.
CALIBRATED_RGB = 0,
// "Specifies that the bitmap is in sRGB color space."
sRGB = 0x73524742, // 'sRGB'
// "This value indicates that the bitmap is in the system default color space, sRGB."
WINDOWS_COLOR_SPACE = 0x57696E20, // 'Win '
// "This value indicates that bV5ProfileData points to the file name of the profile to use
// (gamma and endpoints values are ignored)."
LINKED = 0x4C494E4B, // 'LINK'
// "This value indicates that bV5ProfileData points to a memory buffer that contains the profile to be used
// (gamma and endpoints values are ignored)."
EMBEDDED = 0x4D424544, // 'MBED'
};
};
// https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapv4header
struct DIBV4 {
u32 color_space { 0 };
Endpoint<i32> red_endpoint { 0, 0, 0 };
Endpoint<i32> green_endpoint { 0, 0, 0 };
Endpoint<i32> blue_endpoint { 0, 0, 0 };
Endpoint<u32> gamma_endpoint { 0, 0, 0 };
};
// https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-wmf/9fec0834-607d-427d-abd5-ab240fb0db38
struct GamutMappingIntent {
enum : u32 {
// "Specifies that the white point SHOULD be maintained.
// Typically used when logical colors MUST be matched to their nearest physical color in the destination color gamut.
//
// Intent: Match
//
// ICC name: Absolute Colorimetric"
ABS_COLORIMETRIC = 8,
// "Specifies that saturation SHOULD be maintained.
// Typically used for business charts and other situations in which dithering is not required.
//
// Intent: Graphic
//
// ICC name: Saturation"
BUSINESS = 1,
// "Specifies that a colorimetric match SHOULD be maintained.
// Typically used for graphic designs and named colors.
//
// Intent: Proof
//
// ICC name: Relative Colorimetric"
GRAPHICS = 2,
// "Specifies that contrast SHOULD be maintained.
// Typically used for photographs and natural images.
//
// Intent: Picture
//
// ICC name: Perceptual"
IMAGES = 4,
};
};
// https://learn.microsoft.com/en-us/windows/win32/api/wingdi/ns-wingdi-bitmapv5header
struct DIBV5 {
u32 intent { 0 };
u32 profile_data { 0 };
u32 profile_size { 0 };
};
struct DIB {
DIBCore core;
DIBInfo info;
DIBOSV2 osv2;
DIBV4 v4;
DIBV5 v5;
};
enum class DIBType {
Core = 0,
OSV2Short,
OSV2,
Info,
V2,
V3,
V4,
V5,
};
struct BMPLoadingContext {
enum class State {
NotDecoded = 0,
DIBDecoded,
ColorTableDecoded,
PixelDataDecoded,
Error,
};
State state { State::NotDecoded };
u8 const* file_bytes { nullptr };
size_t file_size { 0 };
u32 data_offset { 0 };
bool is_included_in_ico { false };
DIB dib;
DIBType dib_type;
Vector<u32> color_table;
RefPtr<Gfx::Bitmap> bitmap;
u32 dib_size() const
{
switch (dib_type) {
case DIBType::Core:
return 12;
case DIBType::OSV2Short:
return 16;
case DIBType::OSV2:
return 64;
case DIBType::Info:
return 40;
case DIBType::V2:
return 52;
case DIBType::V3:
return 56;
case DIBType::V4:
return 108;
case DIBType::V5:
return 124;
}
VERIFY_NOT_REACHED();
}
};
class InputStreamer {
public:
InputStreamer(u8 const* data, size_t size)
: m_data_ptr(data)
, m_size_remaining(size)
{
}
u8 read_u8()
{
VERIFY(m_size_remaining >= 1);
m_size_remaining--;
return *(m_data_ptr++);
}
u16 read_u16()
{
return read_u8() | (read_u8() << 8);
}
u32 read_u24()
{
return read_u8() | (read_u8() << 8) | (read_u8() << 16);
}
i32 read_i32()
{
return static_cast<i32>(read_u16() | (read_u16() << 16));
}
u32 read_u32()
{
return read_u16() | (read_u16() << 16);
}
void drop_bytes(u8 num_bytes)
{
VERIFY(m_size_remaining >= num_bytes);
m_size_remaining -= num_bytes;
m_data_ptr += num_bytes;
}
bool at_end() const { return !m_size_remaining; }
bool has_u8() const { return m_size_remaining >= 1; }
bool has_u16() const { return m_size_remaining >= 2; }
bool has_u24() const { return m_size_remaining >= 3; }
bool has_u32() const { return m_size_remaining >= 4; }
size_t remaining() const { return m_size_remaining; }
private:
u8 const* m_data_ptr { nullptr };
size_t m_size_remaining { 0 };
};
// Lookup table for distributing all possible 2-bit numbers evenly into 8-bit numbers
static u8 scaling_factors_2bit[4] = {
0x00,
0x55,
0xaa,
0xff,
};
// Lookup table for distributing all possible 3-bit numbers evenly into 8-bit numbers
static u8 scaling_factors_3bit[8] = {
0x00,
0x24,
0x48,
0x6d,
0x91,
0xb6,
0xdb,
0xff,
};
static u8 scale_masked_8bit_number(u8 number, u8 bits_set)
{
// If there are more than 4 bit set, an easy way to scale the number is to
// just copy the most significant bits into the least significant bits
if (bits_set >= 4)
return number | (number >> bits_set);
if (!bits_set)
return 0;
if (bits_set == 1)
return number ? 0xff : 0;
if (bits_set == 2)
return scaling_factors_2bit[number >> 6];
return scaling_factors_3bit[number >> 5];
}
static u8 get_scaled_color(u32 data, u8 mask_size, i8 mask_shift)
{
// A negative mask_shift indicates we actually need to left shift
// the result in order to get out a valid 8-bit color (for example, the blue
// value in an RGB555 encoding is XXXBBBBB, which needs to be shifted to the
// left by 3, hence it would have a "mask_shift" value of -3).
if (mask_shift < 0)
return scale_masked_8bit_number(data << -mask_shift, mask_size);
return scale_masked_8bit_number(data >> mask_shift, mask_size);
}
// Scales an 8-bit number with "mask_size" bits set (and "8 - mask_size" bits
// ignored). This function scales the number appropriately over the entire
// 256 value color spectrum.
// Note that a much simpler scaling can be done by simple bit shifting. If you
// just ignore the bottom 8-mask_size bits, then you get *close*. However,
// consider, as an example, a 5 bit number (so the bottom 3 bits are ignored).
// The purest white you could get is 0xf8, which is 248 in RGB-land. We need
// to scale the values in order to reach the proper value of 255.
static u32 int_to_scaled_rgb(BMPLoadingContext& context, u32 data)
{
dbgln_if(BMP_DEBUG, "DIB info sizes before access: #masks={}, #mask_sizes={}, #mask_shifts={}",
context.dib.info.masks.size(),
context.dib.info.mask_sizes.size(),
context.dib.info.mask_shifts.size());
u8 r = get_scaled_color(data & context.dib.info.masks[0], context.dib.info.mask_sizes[0], context.dib.info.mask_shifts[0]);
u8 g = get_scaled_color(data & context.dib.info.masks[1], context.dib.info.mask_sizes[1], context.dib.info.mask_shifts[1]);
u8 b = get_scaled_color(data & context.dib.info.masks[2], context.dib.info.mask_sizes[2], context.dib.info.mask_shifts[2]);
u32 color = (r << 16) | (g << 8) | b;
if (context.dib.info.masks.size() == 4) {
// The bitmap has an alpha mask
u8 a = get_scaled_color(data & context.dib.info.masks[3], context.dib.info.mask_sizes[3], context.dib.info.mask_shifts[3]);
color |= (a << 24);
} else {
color |= 0xff000000;
}
return color;
}
static void populate_dib_mask_info_if_needed(BMPLoadingContext& context)
{
if (context.dib.info.masks.is_empty())
return;
// Mask shift is the number of right shifts needed to align the MSb of the
// mask to the MSb of the LSB. Note that this can be a negative number.
// Mask size is the number of set bits in the mask. This is required for
// color scaling (for example, ensuring that a 4-bit color value spans the
// entire 256 value color spectrum.
auto& masks = context.dib.info.masks;
auto& mask_shifts = context.dib.info.mask_shifts;
auto& mask_sizes = context.dib.info.mask_sizes;
if (!mask_shifts.is_empty() && !mask_sizes.is_empty())
return;
VERIFY(mask_shifts.is_empty() && mask_sizes.is_empty());
mask_shifts.ensure_capacity(masks.size());
mask_sizes.ensure_capacity(masks.size());
for (size_t i = 0; i < masks.size(); ++i) {
u32 mask = masks[i];
if (!mask) {
mask_shifts.append(0);
mask_sizes.append(0);
continue;
}
int trailing_zeros = count_trailing_zeroes(mask);
// If mask is exactly `0xFFFFFFFF`, then we might try to count the trailing zeros of 0x00000000 here, so we need the safe version:
int size = count_trailing_zeroes_safe(~(mask >> trailing_zeros));
if (size > 8) {
// Drop lowest bits if mask is longer than 8 bits.
trailing_zeros += size - 8;
size = 8;
}
mask_shifts.append(size + trailing_zeros - 8);
mask_sizes.append(size);
}
}
static bool check_for_invalid_bitmask_combinations(BMPLoadingContext& context)
{
auto& bpp = context.dib.core.bpp;
auto& compression = context.dib.info.compression;
if (compression == Compression::ALPHABITFIELDS && context.dib_type != DIBType::Info)
return false;
switch (context.dib_type) {
case DIBType::Core:
if (bpp == 2 || bpp == 16 || bpp == 32)
return false;
break;
case DIBType::Info:
switch (compression) {
case Compression::BITFIELDS:
case Compression::ALPHABITFIELDS:
if (bpp != 16 && bpp != 32)
return false;
break;
case Compression::RGB:
break;
case Compression::RLE8:
if (bpp > 8)
return false;
break;
case Compression::RLE4:
if (bpp > 4)
return false;
break;
default:
// Other compressions are not officially supported.
// Technically, we could even drop ALPHABITFIELDS.
return false;
}
break;
case DIBType::OSV2Short:
case DIBType::OSV2:
case DIBType::V2:
case DIBType::V3:
case DIBType::V4:
case DIBType::V5:
if (compression == Compression::BITFIELDS && bpp != 16 && bpp != 32)
return false;
break;
}
return true;
}
static bool set_dib_bitmasks(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!check_for_invalid_bitmask_combinations(context))
return false;
auto& bpp = context.dib.core.bpp;
if (bpp <= 8 || bpp == 24)
return true;
auto& compression = context.dib.info.compression;
auto& type = context.dib_type;
if (type > DIBType::OSV2 && bpp == 16 && compression == Compression::RGB) {
context.dib.info.masks.extend({ 0x7c00, 0x03e0, 0x001f });
context.dib.info.mask_shifts.extend({ 7, 2, -3 });
context.dib.info.mask_sizes.extend({ 5, 5, 5 });
} else if (type == DIBType::Info && (compression == Compression::BITFIELDS || compression == Compression::ALPHABITFIELDS)) {
// Consume the extra BITFIELDS bytes
auto number_of_mask_fields = compression == Compression::ALPHABITFIELDS ? 4 : 3;
for (auto i = 0; i < number_of_mask_fields; i++) {
if (!streamer.has_u32())
return false;
context.dib.info.masks.append(streamer.read_u32());
}
}
populate_dib_mask_info_if_needed(context);
return true;
}
static ErrorOr<void> decode_bmp_header(BMPLoadingContext& context)
{
if (!context.file_bytes || context.file_size < bmp_header_size) {
dbgln_if(BMP_DEBUG, "Missing BMP header");
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("Missing BMP header");
}
InputStreamer streamer(context.file_bytes, bmp_header_size);
u16 header = streamer.read_u16();
if (header != 0x4d42) {
dbgln_if(BMP_DEBUG, "BMP has invalid magic header number: {:#04x}", header);
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP has invalid magic header number");
}
// The reported size of the file in the header is actually not important
// for decoding the file. Some specifications say that this value should
// be the size of the header instead, so we just rely on the known file
// size, instead of a possibly-correct-but-also-possibly-incorrect reported
// value of the file size.
streamer.drop_bytes(4);
// Ignore reserved bytes
streamer.drop_bytes(4);
context.data_offset = streamer.read_u32();
if (context.data_offset >= context.file_size) {
dbgln_if(BMP_DEBUG, "BMP has invalid data offset: {}", context.data_offset);
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP has invalid data offset");
}
if constexpr (BMP_DEBUG) {
dbgln("BMP file size: {}", context.file_size);
dbgln("BMP data offset: {}", context.data_offset);
}
if (context.data_offset >= context.file_size) {
dbgln_if(BMP_DEBUG, "BMP data offset is beyond file end?!");
return Error::from_string_literal("BMP data offset is beyond file end");
}
return {};
}
static bool decode_bmp_core_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
auto& core = context.dib.core;
// The width and height are u16 fields in the actual BITMAPCOREHEADER format.
if (context.dib_type == DIBType::Core) {
core.width = streamer.read_u16();
core.height = streamer.read_u16();
} else {
core.width = streamer.read_i32();
core.height = streamer.read_i32();
}
if (core.width < 0) {
dbgln("BMP has a negative width: {}", core.width);
return false;
}
auto color_planes = streamer.read_u16();
if (color_planes != 1) {
dbgln("BMP has an invalid number of color planes: {}", color_planes);
return false;
}
core.bpp = streamer.read_u16();
switch (core.bpp) {
case 1:
case 2:
case 4:
case 8:
case 16:
case 24:
case 32:
break;
default:
dbgln("BMP has an invalid bpp: {}", core.bpp);
context.state = BMPLoadingContext::State::Error;
return false;
}
if constexpr (BMP_DEBUG) {
dbgln("BMP width: {}", core.width);
dbgln("BMP height: {}", core.height);
dbgln("BMP bits_per_pixel: {}", core.bpp);
}
return true;
}
ALWAYS_INLINE static bool is_supported_compression_format(BMPLoadingContext& context, u32 compression)
{
return compression == Compression::RGB || compression == Compression::BITFIELDS
|| compression == Compression::ALPHABITFIELDS || compression == Compression::RLE8
|| compression == Compression::RLE4 || (compression == Compression::RLE24 && context.dib_type <= DIBType::OSV2);
}
static bool decode_bmp_osv2_dib(BMPLoadingContext& context, InputStreamer& streamer, bool short_variant = false)
{
auto& core = context.dib.core;
core.width = streamer.read_u32();
core.height = streamer.read_u32();
if (core.width < 0) {
dbgln("BMP has a negative width: {}", core.width);
return false;
}
auto color_planes = streamer.read_u16();
if (color_planes != 1) {
dbgln("BMP has an invalid number of color planes: {}", color_planes);
return false;
}
core.bpp = streamer.read_u16();
switch (core.bpp) {
case 1:
case 2:
case 4:
case 8:
case 24:
break;
default:
// OS/2 didn't expect 16- or 32-bpp to be popular.
dbgln("BMP has an invalid bpp: {}", core.bpp);
context.state = BMPLoadingContext::State::Error;
return false;
}
if constexpr (BMP_DEBUG) {
dbgln("BMP width: {}", core.width);
dbgln("BMP height: {}", core.height);
dbgln("BMP bits_per_pixel: {}", core.bpp);
}
if (short_variant)
return true;
auto& info = context.dib.info;
auto& osv2 = context.dib.osv2;
info.compression = streamer.read_u32();
info.image_size = streamer.read_u32();
info.horizontal_resolution = streamer.read_u32();
info.vertical_resolution = streamer.read_u32();
info.number_of_palette_colors = streamer.read_u32();
info.number_of_important_palette_colors = streamer.read_u32();
if (!is_supported_compression_format(context, info.compression)) {
dbgln("BMP has unsupported compression value: {}", info.compression);
return false;
}
if (info.number_of_palette_colors > color_palette_limit || info.number_of_important_palette_colors > color_palette_limit) {
dbgln("BMP header indicates too many palette colors: {}", info.number_of_palette_colors);
return false;
}
// Units (2) + reserved (2)
streamer.drop_bytes(4);
osv2.recording = streamer.read_u16();
osv2.halftoning = streamer.read_u16();
osv2.size1 = streamer.read_u32();
osv2.size2 = streamer.read_u32();
// ColorEncoding (4) + Identifier (4)
streamer.drop_bytes(8);
if constexpr (BMP_DEBUG) {
dbgln("BMP compression: {}", info.compression);
dbgln("BMP image size: {}", info.image_size);
dbgln("BMP horizontal res: {}", info.horizontal_resolution);
dbgln("BMP vertical res: {}", info.vertical_resolution);
dbgln("BMP colors: {}", info.number_of_palette_colors);
dbgln("BMP important colors: {}", info.number_of_important_palette_colors);
}
return true;
}
static bool decode_bmp_info_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!decode_bmp_core_dib(context, streamer))
return false;
auto& info = context.dib.info;
auto compression = streamer.read_u32();
info.compression = compression;
if (!is_supported_compression_format(context, compression)) {
dbgln("BMP has unsupported compression value: {}", compression);
return false;
}
info.image_size = streamer.read_u32();
info.horizontal_resolution = streamer.read_i32();
info.vertical_resolution = streamer.read_i32();
info.number_of_palette_colors = streamer.read_u32();
info.number_of_important_palette_colors = streamer.read_u32();
if (info.number_of_palette_colors > color_palette_limit || info.number_of_important_palette_colors > color_palette_limit) {
dbgln("BMP header indicates too many palette colors: {}", info.number_of_palette_colors);
return false;
}
if (info.number_of_important_palette_colors == 0)
info.number_of_important_palette_colors = info.number_of_palette_colors;
if constexpr (BMP_DEBUG) {
dbgln("BMP compression: {}", info.compression);
dbgln("BMP image size: {}", info.image_size);
dbgln("BMP horizontal res: {}", info.horizontal_resolution);
dbgln("BMP vertical res: {}", info.vertical_resolution);
dbgln("BMP colors: {}", info.number_of_palette_colors);
dbgln("BMP important colors: {}", info.number_of_important_palette_colors);
}
return true;
}
static bool decode_bmp_v2_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!decode_bmp_info_dib(context, streamer))
return false;
context.dib.info.masks.append(streamer.read_u32());
context.dib.info.masks.append(streamer.read_u32());
context.dib.info.masks.append(streamer.read_u32());
if constexpr (BMP_DEBUG) {
dbgln("BMP red mask: {:#08x}", context.dib.info.masks[0]);
dbgln("BMP green mask: {:#08x}", context.dib.info.masks[1]);
dbgln("BMP blue mask: {:#08x}", context.dib.info.masks[2]);
}
return true;
}
static bool decode_bmp_v3_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!decode_bmp_v2_dib(context, streamer))
return false;
// There is zero documentation about when alpha masks actually get applied.
// Well, there's some, but it's not even close to comprehensive. So, this is
// in no way based off of any spec, it's simply based off of the BMP test
// suite results.
if (context.dib.info.compression == Compression::ALPHABITFIELDS) {
context.dib.info.masks.append(streamer.read_u32());
dbgln_if(BMP_DEBUG, "BMP alpha mask: {:#08x}", context.dib.info.masks[3]);
} else if (context.dib_size() >= 56 && context.dib.core.bpp >= 16) {
auto mask = streamer.read_u32();
if ((context.dib.core.bpp == 32 && mask != 0) || context.dib.core.bpp == 16) {
context.dib.info.masks.append(mask);
dbgln_if(BMP_DEBUG, "BMP alpha mask: {:#08x}", mask);
} else {
dbgln_if(BMP_DEBUG, "BMP alpha mask (ignored): {:#08x}", mask);
}
} else {
streamer.drop_bytes(4);
dbgln_if(BMP_DEBUG, "BMP alpha mask skipped");
}
return true;
}
static bool decode_bmp_v4_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!decode_bmp_v3_dib(context, streamer))
return false;
auto& v4 = context.dib.v4;
v4.color_space = streamer.read_u32();
v4.red_endpoint = { streamer.read_i32(), streamer.read_i32(), streamer.read_i32() };
v4.green_endpoint = { streamer.read_i32(), streamer.read_i32(), streamer.read_i32() };
v4.blue_endpoint = { streamer.read_i32(), streamer.read_i32(), streamer.read_i32() };
v4.gamma_endpoint = { streamer.read_u32(), streamer.read_u32(), streamer.read_u32() };
if constexpr (BMP_DEBUG) {
dbgln("BMP color space: {}", v4.color_space);
dbgln("BMP red endpoint: {}", v4.red_endpoint);
dbgln("BMP green endpoint: {}", v4.green_endpoint);
dbgln("BMP blue endpoint: {}", v4.blue_endpoint);
dbgln("BMP gamma endpoint: {}", v4.gamma_endpoint);
}
return true;
}
static bool decode_bmp_v5_dib(BMPLoadingContext& context, InputStreamer& streamer)
{
if (!decode_bmp_v4_dib(context, streamer))
return false;
auto& v5 = context.dib.v5;
v5.intent = streamer.read_u32();
v5.profile_data = streamer.read_u32();
v5.profile_size = streamer.read_u32();
streamer.drop_bytes(4); // Ignore reserved field.
if constexpr (BMP_DEBUG) {
dbgln("BMP intent: {}", v5.intent);
dbgln("BMP profile data: {}", v5.profile_data);
dbgln("BMP profile size: {}", v5.profile_size);
}
return true;
}
static ErrorOr<void> decode_bmp_dib(BMPLoadingContext& context)
{
if (context.state == BMPLoadingContext::State::Error)
return Error::from_string_literal("Error before starting decode_bmp_dib");
if (context.state >= BMPLoadingContext::State::DIBDecoded)
return {};
if (!context.is_included_in_ico)
TRY(decode_bmp_header(context));
u8 header_size = context.is_included_in_ico ? 0 : bmp_header_size;
if (context.file_size < header_size + 4u)
return Error::from_string_literal("File size too short");
InputStreamer streamer(context.file_bytes + header_size, 4);
u64 dib_size = streamer.read_u32();
if (context.file_size < header_size + dib_size)
return Error::from_string_literal("File size too short");
if (!context.is_included_in_ico && (context.data_offset < header_size + dib_size)) {
dbgln("Shenanigans! BMP pixel data and header usually don't overlap.");
return Error::from_string_literal("BMP pixel data and header usually don't overlap");
}
// NOTE: If this is a headless BMP (embedded on ICO files), then we can only infer the data_offset after we know the data table size.
// We are also assuming that no Extra bit masks are present
u64 dib_offset = dib_size;
if (!context.is_included_in_ico) {
if (context.data_offset < header_size + 4u)
return Error::from_string_literal("Data offset too small");
dib_offset = context.data_offset - header_size - 4;
}
if (dib_offset + header_size + 4 >= context.file_size)
return Error::from_string_literal("DIB too large");
streamer = InputStreamer(context.file_bytes + header_size + 4, dib_offset);
dbgln_if(BMP_DEBUG, "BMP dib size: {}", dib_size);
bool error = false;
if (dib_size == 12) {
context.dib_type = DIBType::Core;
if (!decode_bmp_core_dib(context, streamer))
error = true;
} else if (dib_size == 64) {
context.dib_type = DIBType::OSV2;
if (!decode_bmp_osv2_dib(context, streamer))
error = true;
} else if (dib_size == 16) {
context.dib_type = DIBType::OSV2Short;
if (!decode_bmp_osv2_dib(context, streamer, true))
error = true;
} else if (dib_size == 40) {
context.dib_type = DIBType::Info;
if (!decode_bmp_info_dib(context, streamer))
error = true;
} else if (dib_size == 52) {
context.dib_type = DIBType::V2;
if (!decode_bmp_v2_dib(context, streamer))
error = true;
} else if (dib_size == 56) {
context.dib_type = DIBType::V3;
if (!decode_bmp_v3_dib(context, streamer))
error = true;
} else if (dib_size == 108) {
context.dib_type = DIBType::V4;
if (!decode_bmp_v4_dib(context, streamer))
error = true;
} else if (dib_size == 124) {
context.dib_type = DIBType::V5;
if (!decode_bmp_v5_dib(context, streamer))
error = true;
} else {
dbgln("Unsupported BMP DIB size: {}", dib_size);
error = true;
}
switch (context.dib.info.compression) {
case Compression::RGB:
case Compression::RLE8:
case Compression::RLE4:
case Compression::BITFIELDS:
case Compression::RLE24:
case Compression::PNG:
case Compression::ALPHABITFIELDS:
case Compression::CMYK:
case Compression::CMYKRLE8:
case Compression::CMYKRLE4:
break;
default:
error = true;
}
if (!error && !set_dib_bitmasks(context, streamer))
error = true;
if (error) {
dbgln("BMP has an invalid DIB");
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP has an invalid DIB");
}
// NOTE: If this is a headless BMP (included on ICOns), the data_offset is set based on the number_of_palette_colors found on the DIB header
if (context.is_included_in_ico) {
if (context.dib.core.bpp > 8)
context.data_offset = dib_size;
else {
auto bytes_per_color = context.dib_type == DIBType::Core ? 3 : 4;
u32 max_colors = 1 << context.dib.core.bpp;
auto size_of_color_table = (context.dib.info.number_of_palette_colors > 0 ? context.dib.info.number_of_palette_colors : max_colors) * bytes_per_color;
context.data_offset = dib_size + size_of_color_table;
}
}
if (context.data_offset >= context.file_size) {
dbgln_if(BMP_DEBUG, "BMP has invalid data offset: {}", context.data_offset);
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP has invalid data offset");
}
context.state = BMPLoadingContext::State::DIBDecoded;
return {};
}
static ErrorOr<void> decode_bmp_color_table(BMPLoadingContext& context)
{
if (context.state == BMPLoadingContext::State::Error)
return Error::from_string_literal("Error before starting decode_bmp_color_table");
if (context.state >= BMPLoadingContext::State::ColorTableDecoded)
return {};
if (context.dib.core.bpp > 8) {
context.state = BMPLoadingContext::State::ColorTableDecoded;
return {};
}
auto bytes_per_color = context.dib_type == DIBType::Core ? 3 : 4;
u32 max_colors = 1 << context.dib.core.bpp;
u8 header_size = !context.is_included_in_ico ? bmp_header_size : 0;
VERIFY(context.data_offset >= header_size + context.dib_size());
u32 size_of_color_table;
if (!context.is_included_in_ico) {
size_of_color_table = context.data_offset - header_size - context.dib_size();
} else {
size_of_color_table = (context.dib.info.number_of_palette_colors > 0 ? context.dib.info.number_of_palette_colors : max_colors) * bytes_per_color;
}
if (context.dib_type <= DIBType::OSV2) {
// Partial color tables are not supported, so the space of the color
// table must be at least enough for the maximum amount of colors
if (size_of_color_table < 3 * max_colors) {
// This is against the spec, but most viewers process it anyways
dbgln("BMP with CORE header does not have enough colors. Has: {}, expected: {}", size_of_color_table, (3 * max_colors));
}
}
InputStreamer streamer(context.file_bytes + header_size + context.dib_size(), size_of_color_table);
for (u32 i = 0; !streamer.at_end() && i < max_colors; ++i) {
if (bytes_per_color == 4) {
if (!streamer.has_u32())
return Error::from_string_literal("Cannot read 32 bits");
context.color_table.append(streamer.read_u32() | 0xff'00'00'00);
} else {
if (!streamer.has_u24())
return Error::from_string_literal("Cannot read 24 bits");
context.color_table.append(streamer.read_u24() | 0xff'00'00'00);
}
}
context.state = BMPLoadingContext::State::ColorTableDecoded;
return {};
}
struct RLEState {
enum : u8 {
PixelCount = 0,
PixelValue,
Meta, // Represents just consuming a null byte, which indicates something special
};
};
static ErrorOr<void> uncompress_bmp_rle_data(BMPLoadingContext& context, ByteBuffer& buffer)
{
// RLE-compressed images cannot be stored top-down
if (context.dib.core.height < 0) {
dbgln_if(BMP_DEBUG, "BMP is top-down and RLE compressed");
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP is top-down and RLE compressed");
}
InputStreamer streamer(context.file_bytes + context.data_offset, context.file_size - context.data_offset);
auto compression = context.dib.info.compression;
u32 total_rows = static_cast<u32>(context.dib.core.height);
u32 total_columns = round_up_to_power_of_two(static_cast<u32>(context.dib.core.width), 4);
u32 column = 0;
u32 row = 0;
auto currently_consuming = RLEState::PixelCount;
i16 pixel_count = 0;
// ByteBuffer asserts that allocating the memory never fails.
// FIXME: ByteBuffer should return either RefPtr<> or Optional<>.
// Decoding the RLE data on-the-fly might actually be faster, and avoids this topic entirely.
u32 buffer_size;
if (compression == Compression::RLE24) {
buffer_size = total_rows * round_up_to_power_of_two(total_columns, 4) * 4;
} else {
buffer_size = total_rows * round_up_to_power_of_two(total_columns, 4);
}
if (buffer_size > 300 * MiB) {
dbgln("Suspiciously large amount of RLE data");
return Error::from_string_literal("Suspiciously large amount of RLE data");
}
auto buffer_result = ByteBuffer::create_zeroed(buffer_size);
if (buffer_result.is_error()) {
dbgln("Not enough memory for buffer allocation");
return buffer_result.release_error();
}
buffer = buffer_result.release_value();
// Avoid as many if statements as possible by pulling out
// compression-dependent actions into separate lambdas
Function<u32()> get_buffer_index;
Function<ErrorOr<void>(u32, bool)> set_byte;
Function<ErrorOr<u32>()> read_byte;
if (compression == Compression::RLE8) {
get_buffer_index = [&]() -> u32 { return row * total_columns + column; };
} else if (compression == Compression::RLE4) {
get_buffer_index = [&]() -> u32 { return (row * total_columns + column) / 2; };
} else {
get_buffer_index = [&]() -> u32 { return (row * total_columns + column) * 3; };
}
if (compression == Compression::RLE8) {
set_byte = [&](u32 color, bool) -> ErrorOr<void> {
if (column >= total_columns) {
column = 0;
row++;
}
auto index = get_buffer_index();
if (index >= buffer.size()) {
dbgln("BMP has badly-formatted RLE data");
return Error::from_string_literal("BMP has badly-formatted RLE data");
}
buffer[index] = color;
column++;
return {};
};
} else if (compression == Compression::RLE24) {
set_byte = [&](u32 color, bool) -> ErrorOr<void> {
if (column >= total_columns) {
column = 0;
row++;
}
auto index = get_buffer_index();
if (index + 3 >= buffer.size()) {
dbgln("BMP has badly-formatted RLE data");
return Error::from_string_literal("BMP has badly-formatted RLE data");
}
((u32&)buffer[index]) = color;
column++;
return {};
};
} else {
set_byte = [&](u32 byte, bool rle4_set_second_nibble) -> ErrorOr<void> {
if (column >= total_columns) {
column = 0;
row++;
}
u32 index = get_buffer_index();
if (index >= buffer.size() || (rle4_set_second_nibble && index + 1 >= buffer.size())) {
dbgln("BMP has badly-formatted RLE data");
return Error::from_string_literal("BMP has badly-formatted RLE data");
}
if (column % 2) {
buffer[index] |= byte >> 4;
if (rle4_set_second_nibble) {
buffer[index + 1] |= byte << 4;
column++;
}
} else {
if (rle4_set_second_nibble) {
buffer[index] = byte;
column++;
} else {
buffer[index] |= byte & 0xf0;
}
}
column++;
return {};
};
}
if (compression == Compression::RLE24) {
read_byte = [&]() -> ErrorOr<u32> {
if (!streamer.has_u24()) {
dbgln("BMP has badly-formatted RLE data");
return Error::from_string_literal("BMP has badly-formatted RLE data");
}
return streamer.read_u24();
};
} else {
read_byte = [&]() -> ErrorOr<u32> {
if (!streamer.has_u8()) {
dbgln("BMP has badly-formatted RLE data");
return Error::from_string_literal("BMP has badly-formatted RLE data");
}
return streamer.read_u8();
};
}
while (true) {
u32 byte;
switch (currently_consuming) {
case RLEState::PixelCount:
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
byte = streamer.read_u8();
if (!byte) {
currently_consuming = RLEState::Meta;
} else {
pixel_count = byte;
currently_consuming = RLEState::PixelValue;
}
break;
case RLEState::PixelValue:
byte = TRY(read_byte());
for (u16 i = 0; i < pixel_count; ++i) {
if (compression != Compression::RLE4) {
TRY(set_byte(byte, true));
} else {
TRY(set_byte(byte, i != pixel_count - 1));
i++;
}
}
currently_consuming = RLEState::PixelCount;
break;
case RLEState::Meta:
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
byte = streamer.read_u8();
if (!byte) {
column = 0;
row++;
currently_consuming = RLEState::PixelCount;
continue;
}
if (byte == 1)
return {};
if (byte == 2) {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 offset_x = streamer.read_u8();
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 offset_y = streamer.read_u8();
column += offset_x;
if (column >= total_columns) {
column -= total_columns;
row++;
}
row += offset_y;
currently_consuming = RLEState::PixelCount;
continue;
}
// Consume literal bytes
pixel_count = byte;
i16 i = byte;
while (i >= 1) {
byte = TRY(read_byte());
TRY(set_byte(byte, i != 1));
i--;
if (compression == Compression::RLE4)
i--;
}
// Optionally consume a padding byte
if (compression != Compression::RLE4) {
if (pixel_count % 2) {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
byte = streamer.read_u8();
}
} else {
if (((pixel_count + 1) / 2) % 2) {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
byte = streamer.read_u8();
}
}
currently_consuming = RLEState::PixelCount;
break;
}
}
VERIFY_NOT_REACHED();
}
static ErrorOr<void> decode_bmp_pixel_data(BMPLoadingContext& context)
{
if (context.state == BMPLoadingContext::State::Error)
return Error::from_string_literal("Error before starting decode_bmp_pixel_data");
if (context.state <= BMPLoadingContext::State::ColorTableDecoded)
TRY(decode_bmp_color_table(context));
u16 const bits_per_pixel = context.dib.core.bpp;
BitmapFormat format = [&]() -> BitmapFormat {
// NOTE: If this is an BMP included in an ICO, the bitmap format will be converted to BGRA8888.
// This is because images with less than 32 bits of color depth follow a particular format:
// the image is encoded with a color mask (the "XOR mask") together with an opacity mask (the "AND mask") of 1 bit per pixel.
// The height of the encoded image must be exactly twice the real height, before both masks are combined.
// Bitmaps have no knowledge of this format as they do not store extra rows for the AND mask.
if (context.is_included_in_ico)
return BitmapFormat::BGRA8888;
switch (bits_per_pixel) {
case 1:
case 2:
case 4:
case 8:
return BitmapFormat::BGRx8888;
case 16:
if (context.dib.info.masks.size() == 4)
return BitmapFormat::BGRA8888;
return BitmapFormat::BGRx8888;
case 24:
return BitmapFormat::BGRx8888;
case 32:
return BitmapFormat::BGRA8888;
default:
return BitmapFormat::Invalid;
}
}();
if (format == BitmapFormat::Invalid) {
dbgln("BMP has invalid bpp of {}", bits_per_pixel);
context.state = BMPLoadingContext::State::Error;
return Error::from_string_literal("BMP has invalid bpp");
}
u32 const width = abs(context.dib.core.width);
u32 const height = !context.is_included_in_ico ? abs(context.dib.core.height) : (abs(context.dib.core.height) / 2);
context.bitmap = TRY(Bitmap::create(format, { static_cast<int>(width), static_cast<int>(height) }));
ByteBuffer rle_buffer;
ReadonlyBytes bytes { context.file_bytes + context.data_offset, context.file_size - context.data_offset };
if (context.dib.info.compression == Compression::RLE4 || context.dib.info.compression == Compression::RLE8
|| context.dib.info.compression == Compression::RLE24) {
TRY(uncompress_bmp_rle_data(context, rle_buffer));
bytes = rle_buffer.bytes();
}
InputStreamer streamer(bytes.data(), bytes.size());
auto process_row_padding = [&](u8 const consumed) -> ErrorOr<void> {
// Calculate padding
u8 remaining = consumed % 4;
u8 bytes_to_drop = remaining == 0 ? 0 : 4 - remaining;
if (streamer.remaining() < bytes_to_drop)
return Error::from_string_literal("Not enough bytes available to drop");
streamer.drop_bytes(bytes_to_drop);
return {};
};
auto process_row = [&](u32 row) -> ErrorOr<void> {
u32 space_remaining_before_consuming_row = streamer.remaining();
for (u32 column = 0; column < width;) {
switch (bits_per_pixel) {
case 1: {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 byte = streamer.read_u8();
u8 mask = 8;
while (column < width && mask > 0) {
mask -= 1;
size_t color_idx = (byte >> mask) & 0x1;
if (color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[color_idx];
context.bitmap->scanline(row)[column++] = color;
}
break;
}
case 2: {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 byte = streamer.read_u8();
u8 mask = 8;
while (column < width && mask > 0) {
mask -= 2;
size_t color_idx = (byte >> mask) & 0x3;
if (color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[color_idx];
context.bitmap->scanline(row)[column++] = color;
}
break;
}
case 4: {
if (!streamer.has_u8()) {
return Error::from_string_literal("Cannot read 8 bits");
}
u8 byte = streamer.read_u8();
u32 high_color_idx = (byte >> 4) & 0xf;
u32 low_color_idx = byte & 0xf;
if (high_color_idx >= context.color_table.size() || low_color_idx >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto high_color = context.color_table[high_color_idx];
auto low_color = context.color_table[low_color_idx];
context.bitmap->scanline(row)[column++] = high_color;
if (column < width) {
context.bitmap->scanline(row)[column++] = low_color;
}
break;
}
case 8: {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 byte = streamer.read_u8();
if (byte >= context.color_table.size())
return Error::from_string_literal("Invalid color table index");
auto color = context.color_table[byte];
context.bitmap->scanline(row)[column++] = color;
break;
}
case 16: {
if (!streamer.has_u16())
return Error::from_string_literal("Cannot read 16 bits");
context.bitmap->scanline(row)[column++] = int_to_scaled_rgb(context, streamer.read_u16());
break;
}
case 24: {
if (!streamer.has_u24())
return Error::from_string_literal("Cannot read 24 bits");
context.bitmap->scanline(row)[column++] = streamer.read_u24();
break;
}
case 32:
if (!streamer.has_u32())
return Error::from_string_literal("Cannot read 32 bits");
if (context.dib.info.masks.is_empty()) {
context.bitmap->scanline(row)[column++] = streamer.read_u32();
} else {
context.bitmap->scanline(row)[column++] = int_to_scaled_rgb(context, streamer.read_u32());
}
break;
}
}
auto consumed = space_remaining_before_consuming_row - streamer.remaining();
return process_row_padding(consumed);
};
auto process_mask_row = [&](u32 row) -> ErrorOr<void> {
u32 space_remaining_before_consuming_row = streamer.remaining();
for (u32 column = 0; column < width;) {
if (!streamer.has_u8())
return Error::from_string_literal("Cannot read 8 bits");
u8 byte = streamer.read_u8();
u8 mask = 8;
while (column < width && mask > 0) {
mask -= 1;
// apply transparency mask
// AND mask = 0 -> fully opaque
// AND mask = 1 -> fully transparent
u8 and_byte = (byte >> (mask)) & 0x1;
auto pixel = context.bitmap->scanline(row)[column];
if (and_byte) {
pixel &= 0x00ffffff;
} else if (context.dib.core.bpp < 32) {
pixel |= 0xff000000;
}
context.bitmap->scanline(row)[column++] = pixel;
}
}
auto consumed = space_remaining_before_consuming_row - streamer.remaining();
return process_row_padding(consumed);
};
if (context.dib.core.height < 0) {
// BMP is stored top-down
for (u32 row = 0; row < height; ++row) {
TRY(process_row(row));
}
if (context.is_included_in_ico && !streamer.at_end()) {
for (u32 row = 0; row < height; ++row) {
TRY(process_mask_row(row));
}
}
} else {
// BMP is stored bottom-up
for (i32 row = height - 1; row >= 0; --row) {
TRY(process_row(row));
}
if (context.is_included_in_ico && !streamer.at_end()) {
for (i32 row = height - 1; row >= 0; --row) {
TRY(process_mask_row(row));
}
}
}
context.state = BMPLoadingContext::State::PixelDataDecoded;
return {};
}
BMPImageDecoderPlugin::BMPImageDecoderPlugin(u8 const* data, size_t data_size, IncludedInICO is_included_in_ico)
{
m_context = make<BMPLoadingContext>();
m_context->file_bytes = data;
m_context->file_size = data_size;
m_context->is_included_in_ico = (is_included_in_ico == IncludedInICO::Yes);
}
BMPImageDecoderPlugin::~BMPImageDecoderPlugin() = default;
IntSize BMPImageDecoderPlugin::size()
{
return { m_context->dib.core.width, abs(m_context->dib.core.height) };
}
bool BMPImageDecoderPlugin::sniff(ReadonlyBytes data)
{
BMPLoadingContext context;
context.file_bytes = data.data();
context.file_size = data.size();
return !decode_bmp_header(context).is_error();
}
ErrorOr<NonnullOwnPtr<BMPImageDecoderPlugin>> BMPImageDecoderPlugin::create_impl(ReadonlyBytes data, IncludedInICO included_in_ico)
{
auto plugin = TRY(adopt_nonnull_own_or_enomem(new (nothrow) BMPImageDecoderPlugin(data.data(), data.size(), included_in_ico)));
TRY(decode_bmp_dib(*plugin->m_context));
return plugin;
}
ErrorOr<NonnullOwnPtr<ImageDecoderPlugin>> BMPImageDecoderPlugin::create(ReadonlyBytes data)
{
return create_impl(data, IncludedInICO::No);
}
ErrorOr<NonnullOwnPtr<BMPImageDecoderPlugin>> BMPImageDecoderPlugin::create_as_included_in_ico(Badge<ICOImageDecoderPlugin>, ReadonlyBytes data)
{
return create_impl(data, IncludedInICO::Yes);
}
bool BMPImageDecoderPlugin::sniff_dib()
{
return !decode_bmp_dib(*m_context).is_error();
}
ErrorOr<ImageFrameDescriptor> BMPImageDecoderPlugin::frame(size_t index, Optional<IntSize>)
{
if (index > 0)
return Error::from_string_literal("BMPImageDecoderPlugin: Invalid frame index");
if (m_context->state == BMPLoadingContext::State::Error)
return Error::from_string_literal("BMPImageDecoderPlugin: Decoding failed");
if (m_context->state < BMPLoadingContext::State::PixelDataDecoded)
TRY(decode_bmp_pixel_data(*m_context));
VERIFY(m_context->bitmap);
return ImageFrameDescriptor { m_context->bitmap, 0 };
}
ErrorOr<Optional<ReadonlyBytes>> BMPImageDecoderPlugin::icc_data()
{
if (m_context->dib_type != DIBType::V5)
return OptionalNone {};
// FIXME: For LINKED, return data from the linked file?
// FIXME: For sRGB and WINDOWS_COLOR_SPACE, return an sRGB profile somehow.
// FIXME: For CALIBRATED_RGB, do something with v4.{red_endpoint,green_endpoint,blue_endpoint,gamma_endpoint}
if (m_context->dib.v4.color_space != ColorSpace::EMBEDDED)
return OptionalNone {};
auto const& v5 = m_context->dib.v5;
if (!v5.profile_data || !v5.profile_size)
return OptionalNone {};
// FIXME: Do something with v5.intent (which has a GamutMappingIntent value).
u8 header_size = m_context->is_included_in_ico ? 0 : bmp_header_size;
if (v5.profile_data + header_size + v5.profile_size > m_context->file_size)
return Error::from_string_literal("BMPImageDecoderPlugin: ICC profile data out of bounds");
return ReadonlyBytes { m_context->file_bytes + header_size + v5.profile_data, v5.profile_size };
}
}
