Rebased.

core/image/common.odin

@@ -12,6 +12,7 @@ package image
 
 import "core:bytes"
 import "core:mem"
+import "core:io"
 import "core:compress"
 import "base:runtime"
 
@@ -62,6 +63,7 @@ Image_Metadata :: union #shared_nil {
 	^PNG_Info,
 	^QOI_Info,
 	^TGA_Info,
+	^BMP_Info,
 }
 
 
@@ -159,11 +161,13 @@ Error :: union #shared_nil {
 	Netpbm_Error,
 	PNG_Error,
 	QOI_Error,
+	BMP_Error,
 
 	compress.Error,
 	compress.General_Error,
 	compress.Deflate_Error,
 	compress.ZLIB_Error,
+	io.Error,
 	runtime.Allocator_Error,
 }
 
@@ -196,6 +200,128 @@ General_Image_Error :: enum {
 	Unable_To_Allocate_Or_Resize,
 }
 
+/*
+	BMP-specific
+*/
+BMP_Error :: enum {
+	None = 0,
+	Invalid_File_Size,
+	Unsupported_BMP_Version,
+	Unsupported_OS2_File,
+	Unsupported_Compression,
+	Unsupported_BPP,
+	Invalid_Stride,
+	Invalid_Color_Count,
+	Implausible_File_Size,
+	Bitfield_Version_Unhandled, // We don't (yet) handle bit fields for this BMP version.
+	Bitfield_Sum_Exceeds_BPP,   // Total mask bit count > bpp
+	Bitfield_Overlapped,        // Channel masks overlap
+}
+
+// img.metadata is wrapped in a struct in case we need to add to it later
+// without putting it in BMP_Header
+BMP_Info :: struct {
+	info: BMP_Header,
+}
+
+BMP_Magic :: enum u16le {
+	Bitmap            = 0x4d42, // 'BM'
+	OS2_Bitmap_Array  = 0x4142, // 'BA'
+	OS2_Icon          = 0x4349, // 'IC',
+	OS2_Color_Icon    = 0x4943, // 'CI'
+	OS2_Pointer       = 0x5450, // 'PT'
+	OS2_Color_Pointer = 0x5043, // 'CP'
+}
+
+// See: http://justsolve.archiveteam.org/wiki/BMP#Well-known_versions
+BMP_Version :: enum u32le {
+	OS2_v1    = 12,  // BITMAPCOREHEADER  (Windows V2 / OS/2 version 1.0)
+	OS2_v2    = 64,  // BITMAPCOREHEADER2 (OS/2 version 2.x)
+	V3        = 40,  // BITMAPINFOHEADER
+	V4        = 108, // BITMAPV4HEADER
+	V5        = 124, // BITMAPV5HEADER
+
+	ABBR_16   = 16,  // Abbreviated
+	ABBR_24   = 24,  // ..
+	ABBR_48   = 48,  // ..
+	ABBR_52   = 52,  // ..
+	ABBR_56   = 56,  // ..
+}
+
+BMP_Header :: struct #packed {
+	// File header
+	magic:            BMP_Magic,
+	size:             u32le,
+	_res1:            u16le, // Reserved; must be zero
+	_res2:            u16le, // Reserved; must be zero
+	pixel_offset:     u32le, // Offset in bytes, from the beginning of BMP_Header to the pixel data
+	// V3
+	info_size:        BMP_Version,
+	width:            i32le,
+	height:           i32le,
+	planes:           u16le,
+	bpp:              u16le,
+	compression:      BMP_Compression,
+	image_size:       u32le,
+	pels_per_meter:   [2]u32le,
+	colors_used:      u32le,
+	colors_important: u32le, // OS2_v2 is equal up to here
+	// V4
+	masks:            [4]u32le `fmt:"32b"`,
+	colorspace:       BMP_Logical_Color_Space,
+	endpoints:        BMP_CIEXYZTRIPLE,
+	gamma:            [3]BMP_GAMMA16_16,
+	// V5
+	intent:           BMP_Gamut_Mapping_Intent,
+	profile_data:     u32le,
+	profile_size:     u32le,
+	reserved:         u32le,
+}
+#assert(size_of(BMP_Header) == 138)
+
+OS2_Header :: struct #packed {
+	// BITMAPCOREHEADER minus info_size field
+	width:            i16le,
+	height:           i16le,
+	planes:           u16le,
+	bpp:              u16le,
+}
+#assert(size_of(OS2_Header) == 8)
+
+BMP_Compression :: enum u32le {
+	RGB              = 0x0000,
+	RLE8             = 0x0001,
+	RLE4             = 0x0002,
+	Bit_Fields       = 0x0003, // If Windows
+	Huffman1D        = 0x0003, // If OS2v2
+	JPEG             = 0x0004, // If Windows
+	RLE24            = 0x0004, // If OS2v2
+	PNG              = 0x0005,
+	Alpha_Bit_Fields = 0x0006,
+	CMYK             = 0x000B,
+	CMYK_RLE8        = 0x000C,
+	CMYK_RLE4        = 0x000D,
+}
+
+BMP_Logical_Color_Space :: enum u32le {
+	CALIBRATED_RGB      = 0x00000000,
+	sRGB                = 0x73524742, // 'sRGB'
+	WINDOWS_COLOR_SPACE = 0x57696E20, // 'Win '
+}
+
+BMP_FXPT2DOT30   :: u32le
+BMP_CIEXYZ       :: [3]BMP_FXPT2DOT30
+BMP_CIEXYZTRIPLE :: [3]BMP_CIEXYZ
+BMP_GAMMA16_16   :: [2]u16le
+
+BMP_Gamut_Mapping_Intent :: enum u32le {
+	INVALID          = 0x00000000, // If not V5, this field will just be zero-initialized and not valid.
+	ABS_COLORIMETRIC = 0x00000008,
+	BUSINESS         = 0x00000001,
+	GRAPHICS         = 0x00000002,
+	IMAGES           = 0x00000004,
+}
+
 /*
 	Netpbm-specific definitions
 */