/
header.go
134 lines (128 loc) · 3.77 KB
/
header.go
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package aseprite
import (
"encoding/binary"
"fmt"
"io"
)
type header struct {
size uint32
magic uint16
frameCount uint16
width uint16
height uint16
depth uint16
flags uint32
speed uint16 // Deprecated, use "duration" of AsepriteFrameHeader
next uint32
frit uint32
transparentIndex uint8
ignore [3]uint8 //3 bytes to ignore uint8
ncolors uint16
pixelWidth uint8
pixelHeight uint8
gridX int16
gridY int16
gridWidth int16
gridHeight int16
}
func (h *header) String() string {
return fmt.Sprintf("header &{size: %d, frameCount: %d, dimensions: %dx%d, depth: %d, flags: %d, speed: %d, next: %d, frit: %d, transparentIndex: %d, ncolors: %d, pixelDimensions: %dx%d, gridPos: %dx%d, gridDimensions: %dx%d}", h.size, h.frameCount, h.width, h.height, h.depth, h.flags, h.speed, h.next, h.frit, h.transparentIndex, h.ncolors, h.pixelWidth, h.pixelHeight, h.gridX, h.gridY, h.gridWidth, h.gridHeight)
}
func readHeader(f io.ReadSeeker) (*header, error) {
var err error
h := &header{}
if f == nil {
return nil, fmt.Errorf("file must not be nil")
}
err = binary.Read(f, binary.LittleEndian, &h.size)
if err != nil {
return nil, fmt.Errorf("size: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.magic)
if err != nil {
return nil, fmt.Errorf("magic: %w", err)
}
if h.magic != 0xA5E0 {
return nil, fmt.Errorf("magic should be %x, got %x", 0xA5E0, h.magic)
}
err = binary.Read(f, binary.LittleEndian, &h.frameCount)
if err != nil {
return nil, fmt.Errorf("frameCount: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.width)
if err != nil {
return nil, fmt.Errorf("width: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.height)
if err != nil {
return nil, fmt.Errorf("height: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.depth)
if err != nil {
return nil, fmt.Errorf("depth: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.flags)
if err != nil {
return nil, fmt.Errorf("flags: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.speed)
if err != nil {
return nil, fmt.Errorf("speed: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.next)
if err != nil {
return nil, fmt.Errorf("next: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.frit)
if err != nil {
return nil, fmt.Errorf("frit: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.transparentIndex)
if err != nil {
return nil, fmt.Errorf("transparentIndex: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.ignore)
if err != nil {
return nil, fmt.Errorf("ignore: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.ncolors)
if err != nil {
return nil, fmt.Errorf("ncolors: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.pixelWidth)
if err != nil {
return nil, fmt.Errorf("pixelWidth: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.pixelHeight)
if err != nil {
return nil, fmt.Errorf("pixelHeight: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.gridX)
if err != nil {
return nil, fmt.Errorf("gridX: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.gridY)
if err != nil {
return nil, fmt.Errorf("gridY: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.gridWidth)
if err != nil {
return nil, fmt.Errorf("gridWidth: %w", err)
}
err = binary.Read(f, binary.LittleEndian, &h.gridHeight)
if err != nil {
return nil, fmt.Errorf("gridHeight: %w", err)
}
if h.ncolors == 0 {
h.ncolors = 256
}
if h.pixelWidth == 0 || h.pixelHeight == 0 {
h.pixelHeight = 1
h.pixelWidth = 1
}
_, err = f.Seek(128, 0)
if err != nil {
return nil, fmt.Errorf("header offset: %w", err)
}
return h, nil
}