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png: Move metadata.
This commit is contained in:
Jeroen van Rijn
+17
-107
@@ -51,95 +51,6 @@ Signature :: enum u64be {
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PNG = 0x89 << 56 | 'P' << 48 | 'N' << 40 | 'G' << 32 | '\r' << 24 | '\n' << 16 | 0x1a << 8 | '\n',
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}
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Info :: struct {
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header: IHDR,
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chunks: [dynamic]Chunk,
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}
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Chunk_Header :: struct #packed {
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length: u32be,
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type: Chunk_Type,
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}
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Chunk :: struct #packed {
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header: Chunk_Header,
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data: []byte,
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crc: u32be,
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}
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Chunk_Type :: enum u32be {
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// IHDR must come first in a file
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IHDR = 'I' << 24 | 'H' << 16 | 'D' << 8 | 'R',
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// PLTE must precede the first IDAT chunk
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PLTE = 'P' << 24 | 'L' << 16 | 'T' << 8 | 'E',
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bKGD = 'b' << 24 | 'K' << 16 | 'G' << 8 | 'D',
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tRNS = 't' << 24 | 'R' << 16 | 'N' << 8 | 'S',
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IDAT = 'I' << 24 | 'D' << 16 | 'A' << 8 | 'T',
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iTXt = 'i' << 24 | 'T' << 16 | 'X' << 8 | 't',
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tEXt = 't' << 24 | 'E' << 16 | 'X' << 8 | 't',
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zTXt = 'z' << 24 | 'T' << 16 | 'X' << 8 | 't',
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iCCP = 'i' << 24 | 'C' << 16 | 'C' << 8 | 'P',
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pHYs = 'p' << 24 | 'H' << 16 | 'Y' << 8 | 's',
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gAMA = 'g' << 24 | 'A' << 16 | 'M' << 8 | 'A',
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tIME = 't' << 24 | 'I' << 16 | 'M' << 8 | 'E',
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sPLT = 's' << 24 | 'P' << 16 | 'L' << 8 | 'T',
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sRGB = 's' << 24 | 'R' << 16 | 'G' << 8 | 'B',
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hIST = 'h' << 24 | 'I' << 16 | 'S' << 8 | 'T',
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cHRM = 'c' << 24 | 'H' << 16 | 'R' << 8 | 'M',
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sBIT = 's' << 24 | 'B' << 16 | 'I' << 8 | 'T',
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/*
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eXIf tags are not part of the core spec, but have been ratified
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in v1.5.0 of the PNG Ext register.
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We will provide unprocessed chunks to the caller if `.return_metadata` is set.
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Applications are free to implement an Exif decoder.
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*/
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eXIf = 'e' << 24 | 'X' << 16 | 'I' << 8 | 'f',
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// PNG files must end with IEND
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IEND = 'I' << 24 | 'E' << 16 | 'N' << 8 | 'D',
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/*
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XCode sometimes produces "PNG" files that don't adhere to the PNG spec.
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We recognize them only in order to avoid doing further work on them.
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Some tools like PNG Defry may be able to repair them, but we're not
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going to reward Apple for producing proprietary broken files purporting
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to be PNGs by supporting them.
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*/
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iDOT = 'i' << 24 | 'D' << 16 | 'O' << 8 | 'T',
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CbGI = 'C' << 24 | 'b' << 16 | 'H' << 8 | 'I',
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}
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IHDR :: struct #packed {
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width: u32be,
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height: u32be,
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bit_depth: u8,
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color_type: Color_Type,
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compression_method: u8,
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filter_method: u8,
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interlace_method: Interlace_Method,
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}
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IHDR_SIZE :: size_of(IHDR)
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#assert (IHDR_SIZE == 13)
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Color_Value :: enum u8 {
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Paletted = 0, // 1 << 0 = 1
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Color = 1, // 1 << 1 = 2
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Alpha = 2, // 1 << 2 = 4
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}
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Color_Type :: distinct bit_set[Color_Value; u8]
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Interlace_Method :: enum u8 {
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None = 0,
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Adam7 = 1,
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}
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Row_Filter :: enum u8 {
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None = 0,
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Sub = 1,
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@@ -262,8 +173,8 @@ ADAM7_Y_SPACING := []int{ 8,8,8,4,4,2,2 }
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// Implementation starts here
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read_chunk :: proc(ctx: ^$C) -> (chunk: Chunk, err: Error) {
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ch, e := compress.read_data(ctx, Chunk_Header)
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read_chunk :: proc(ctx: ^$C) -> (chunk: image.PNG_Chunk, err: Error) {
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ch, e := compress.read_data(ctx, image.PNG_Chunk_Header)
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if e != .None {
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return {}, compress.General_Error.Stream_Too_Short
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}
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@@ -305,7 +216,7 @@ read_chunk :: proc(ctx: ^$C) -> (chunk: Chunk, err: Error) {
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return chunk, nil
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}
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copy_chunk :: proc(src: Chunk, allocator := context.allocator) -> (dest: Chunk, err: Error) {
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copy_chunk :: proc(src: image.PNG_Chunk, allocator := context.allocator) -> (dest: image.PNG_Chunk, err: Error) {
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if int(src.header.length) != len(src.data) {
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return {}, .Invalid_Chunk_Length
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}
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@@ -318,7 +229,7 @@ copy_chunk :: proc(src: Chunk, allocator := context.allocator) -> (dest: Chunk,
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return
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}
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append_chunk :: proc(list: ^[dynamic]Chunk, src: Chunk, allocator := context.allocator) -> (err: Error) {
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append_chunk :: proc(list: ^[dynamic]image.PNG_Chunk, src: image.PNG_Chunk, allocator := context.allocator) -> (err: Error) {
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if int(src.header.length) != len(src.data) {
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return .Invalid_Chunk_Length
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}
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@@ -334,13 +245,13 @@ append_chunk :: proc(list: ^[dynamic]Chunk, src: Chunk, allocator := context.all
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return
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}
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read_header :: proc(ctx: ^$C) -> (IHDR, Error) {
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read_header :: proc(ctx: ^$C) -> (image.PNG_IHDR, Error) {
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c, e := read_chunk(ctx)
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if e != nil {
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return {}, e
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}
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header := (^IHDR)(raw_data(c.data))^
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header := (^image.PNG_IHDR)(raw_data(c.data))^
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// Validate IHDR
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using header
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if width == 0 || height == 0 || u128(width) * u128(height) > MAX_DIMENSIONS {
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@@ -407,7 +318,7 @@ read_header :: proc(ctx: ^$C) -> (IHDR, Error) {
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return header, nil
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}
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chunk_type_to_name :: proc(type: ^Chunk_Type) -> string {
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chunk_type_to_name :: proc(type: ^image.PNG_Chunk_Type) -> string {
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t := transmute(^u8)type
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return strings.string_from_ptr(t, 4)
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}
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@@ -462,9 +373,8 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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img = new(Image)
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}
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info := new(Info)
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img.metadata_ptr = info
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img.metadata_type = typeid_of(Info)
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info := new(image.PNG_Info)
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img.metadata = info
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signature, io_error := compress.read_data(ctx, Signature)
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if io_error != .None || signature != .PNG {
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@@ -477,11 +387,11 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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idat_length := u64(0)
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c: Chunk
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ch: Chunk_Header
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c: image.PNG_Chunk
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ch: image.PNG_Chunk_Header
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e: io.Error
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header: IHDR
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header: image.PNG_IHDR
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// State to ensure correct chunk ordering.
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seen_ihdr := false; first := true
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@@ -492,7 +402,7 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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seen_iend := false
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_plte := PLTE{}
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trns := Chunk{}
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trns := image.PNG_Chunk{}
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final_image_channels := 0
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@@ -502,7 +412,7 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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// Peek at next chunk's length and type.
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// TODO: Some streams may not provide seek/read_at
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ch, e = compress.peek_data(ctx, Chunk_Header)
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ch, e = compress.peek_data(ctx, image.PNG_Chunk_Header)
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if e != .None {
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return img, compress.General_Error.Stream_Too_Short
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}
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@@ -547,7 +457,7 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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img.height = int(header.height)
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using header
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h := IHDR{
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h := image.PNG_IHDR{
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width = width,
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height = height,
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bit_depth = bit_depth,
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@@ -607,7 +517,7 @@ load_from_context :: proc(ctx: ^$C, options := Options{}, allocator := context.a
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return {}, image.PNG_Error.IDAT_Size_Too_Large
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}
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ch, e = compress.peek_data(ctx, Chunk_Header)
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ch, e = compress.peek_data(ctx, image.PNG_Chunk_Header)
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if e != .None {
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return img, compress.General_Error.Stream_Too_Short
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}
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@@ -1599,7 +1509,7 @@ defilter_16 :: proc(params: ^Filter_Params) -> (ok: bool) {
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return
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}
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defilter :: proc(img: ^Image, filter_bytes: ^bytes.Buffer, header: ^IHDR, options: Options) -> (err: Error) {
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defilter :: proc(img: ^Image, filter_bytes: ^bytes.Buffer, header: ^image.PNG_IHDR, options: Options) -> (err: Error) {
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input := bytes.buffer_to_bytes(filter_bytes)
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width := int(header.width)
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height := int(header.height)
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