minecraft - maps/encode.go

     1  package maps
     2  
     3  import (
     4  	"errors"
     5  	"image"
     6  	"io"
     7  
     8  	"vimagination.zapto.org/minecraft/nbt"
     9  )
    10  
    11  // Encode writes an image an as uncompressed Minecraft map.
    12  //
    13  // As Minecraft expects the map to be gzip compressed, the Writer sohuld be the
    14  // wrapped in gzip.NewWriter
    15  func Encode(w io.Writer, i image.Image) error {
    16  	e := Encoder{
    17  		Dimension: -128,
    18  		Scale:     3,
    19  	}
    20  	return e.Encode(w, i)
    21  }
    22  
    23  // Encoder lets you specify options for the Minecraft map
    24  type Encoder struct {
    25  	Scale, Dimension int8
    26  	CenterX, CenterZ int32
    27  }
    28  
    29  // Encode writes an image an as uncompressed Minecraft map.
    30  //
    31  // As Minecraft expects the map to be gzip compressed, the Writer sohuld be the
    32  // wrapped in gzip.NewWriter
    33  func (e *Encoder) Encode(w io.Writer, im image.Image) error {
    34  	width := im.Bounds().Dx()
    35  	height := im.Bounds().Dy()
    36  	if width > 0xffff || height > 0xffff || width < 0 || height < 0 {
    37  		return ErrInvalidDimensions
    38  	}
    39  
    40  	colours := make(nbt.ByteArray, 0, width*height)
    41  	for j := im.Bounds().Min.Y; j < im.Bounds().Max.Y; j++ {
    42  		for i := im.Bounds().Min.X; i < im.Bounds().Max.X; i++ {
    43  			colours = append(colours, int8(palette.Index(im.At(i, j))))
    44  		}
    45  	}
    46  
    47  	return nbt.Encode(w, nbt.NewTag("", nbt.Compound{
    48  		nbt.NewTag("data", nbt.Compound{
    49  			nbt.NewTag("scale", nbt.Byte(e.Scale)),
    50  			nbt.NewTag("dimension", nbt.Byte(e.Dimension)),
    51  			nbt.NewTag("height", nbt.Short(height)),
    52  			nbt.NewTag("width", nbt.Short(width)),
    53  			nbt.NewTag("xCenter", nbt.Int(e.CenterX)),
    54  			nbt.NewTag("zCenter", nbt.Int(e.CenterZ)),
    55  			nbt.NewTag("colors", colours),
    56  		}),
    57  	}))
    58  }
    59  
    60  // Errors
    61  var (
    62  	ErrInvalidDimensions = errors.New("cannot encode an image with the given dimensions")
    63  )
    64