// Write the spritesheet image to a file.
func WriteSpriteSheet(img image.Image, folder string, name string, log *golog.Logger) (err error) {
dir, err := os.Open(folder)
if err != nil {
err = os.MkdirAll(folder, 0775)
if err != nil {
log.Errorf("Unable to create sprite-sheet output folder '%s'", folder)
return err
} else {
log.Infof("Created sprite-sheet output folder '%s'", folder)
}
} else {
defer dir.Close()
}
fullname := filepath.Join(folder, name+".png")
os.Remove(fullname)
outFile, err := os.Create(fullname)
if err != nil {
log.Errorf("Couldn't create sprite-sheet output file '%s'", fullname)
return err
} else {
defer outFile.Close()
}
err = png.Encode(outFile, img)
if err != nil {
log.Warningf("Problem writing sprite-sheet to '%s'", fullname)
return err
}
return nil
}
// Compose the spritesheet image and return an array of individual sprite data.
func GenerateSpriteSheet(images []Image, log *golog.Logger) (sheet draw.Image, sprites []Sprite) {
var (
sheetHeight int = 0
sheetWidth int = 0
)
sprites = make([]Sprite, 0)
// calculate the size of the spritesheet and accumulate position and padding
// data for the individual sprites within the sheet
for _, img := range images {
bounds := img.Bounds()
_, name, factor := IsMagnified(img.Name)
thisTopPadding := math.Ceil(factor)
thisBottomPadding := thisTopPadding
// see if the image dimensions are a multiple of the magnification factor
fudge := 0
if math.Mod(float64(bounds.Dy()), factor) != 0 {
fudge = 1
log.Warningf("Height of sprite `%s` (%dpx) is not a multiple of its magnification factor (%vx); rounding up to avoid truncated pixels.", name, bounds.Dy(), factor)
}
var prevBottomPadding float64
if len(sprites) == 0 {
prevBottomPadding = 0
thisTopPadding = 0
} else {
prevBottomPadding = float64(sprites[len(sprites)-1].BottomPadding)
}
thisTopPadding = math.Max(thisTopPadding, prevBottomPadding)
thisTopPaddingInt := int(thisTopPadding)
thisBottomPaddingInt := int(thisBottomPadding)
newSprite := Sprite{
name,
factor,
thisTopPaddingInt,
thisBottomPaddingInt,
image.Rect(0, sheetHeight+thisTopPaddingInt-fudge, bounds.Dx(), sheetHeight+thisTopPaddingInt+bounds.Dy()),
}
sprites = append(sprites, newSprite)
sheetHeight += bounds.Dy() + thisTopPaddingInt
if bounds.Dx() > sheetWidth {
sheetWidth = bounds.Dx()
}
}
// create the sheet image
sheet = image.NewRGBA(image.Rect(0, 0, sheetWidth, sheetHeight))
// compose the sheet
for i, img := range images {
draw.Draw(sheet, sprites[i].Rectangle, img, image.Pt(0, 0), draw.Src)
}
return sheet, sprites
}
// Take a folder name, read all the images within, and return them in an array.
func ReadImageFolder(path string, log *golog.Logger) (images []Image, err error) {
dir, err := os.Open(path)
if err != nil {
log.Errorf("Couldn't open folder '%s'", path)
return nil, err
} else {
defer dir.Close()
}
dirInfo, err := dir.Stat()
if err != nil {
log.Errorf("Couldn't gather information for folder '%s'", path)
return nil, err
}
if !dirInfo.IsDir() {
// just ignore the request if it isn't a folder
return nil, nil
}
names, err := dir.Readdirnames(0)
if err != nil {
log.Errorf("Problem gathering names of image files in '%s'", path)
return nil, err
}
// put these in a canonical order, otherwise it'll be platform-specific
sort.Strings(names)
images = make([]Image, 0)
for _, name := range names {
fullName := filepath.Join(path, name)
imgFile, err := os.Open(fullName)
if err != nil {
log.Errorf("Couldn't open image file '%s'", fullName)
continue
} else {
defer imgFile.Close()
}
imgInfo, err := imgFile.Stat()
if err != nil {
log.Errorf("Couldn't gather information for image file '%s'", fullName)
}
if imgInfo.IsDir() {
// skip non-files
continue
}
ext := strings.ToLower(filepath.Ext(name))
if ext == ".png" {
img, err := png.Decode(imgFile)
if err != nil {
log.Errorf("Problem decoding png image in '%s'", fullName)
continue
}
name = name[0 : len(name)-len(ext)]
images = append(images, Image{name, img})
} else if ext == ".jpg" || ext == ".jpeg" {
img, err := jpeg.Decode(imgFile)
if err != nil {
log.Errorf("Problem decoding jpeg image in '%s'", fullName)
continue
}
name = name[0 : len(name)-len(ext)]
images = append(images, Image{name, img})
} else {
log.Debugf("Ignoring unrecognized file '%s'", fullName)
}
}
if len(images) == 0 {
log.Warningf("Folder '%s' contains no images; no sprite-sheet will be generated", path)
}
return images, nil
}
