doodle/pkg/sprites/sprites.go

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/*
Package sprites manages miscellaneous in-game sprites.
The sprites are relatively few for UI purposes. Their textures are
loaded ONE time and cached in this package for performance.
*/
package sprites
import (
"bytes"
"errors"
"image/png"
"io/ioutil"
"os"
"runtime"
"git.kirsle.net/apps/doodle/assets"
"git.kirsle.net/apps/doodle/pkg/log"
"git.kirsle.net/apps/doodle/pkg/wasm"
"git.kirsle.net/go/render"
"git.kirsle.net/go/ui"
)
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// Cache of loaded sprites.
var cache = map[string]*ui.Image{}
// FlushCache clears the sprites cache.
func FlushCache() {
panic("TODO: free textures")
}
// LoadImage loads a sprite as a ui.Image object. It checks Doodle's embedded
// bindata, then the filesystem before erroring out.
//
// NOTE: only .png images supported as of now. TODO
func LoadImage(e render.Engine, filename string) (*ui.Image, error) {
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if cached, ok := cache[filename]; ok {
return cached, nil
}
// Try the bindata first.
if data, err := assets.Asset(filename); err == nil {
log.Debug("sprites.LoadImage: %s from bindata", filename)
img, err := png.Decode(bytes.NewBuffer(data))
if err != nil {
return nil, err
}
return ui.ImageFromImage(img)
}
// WASM: try the file over HTTP ajax request.
if runtime.GOOS == "js" {
data, err := wasm.HTTPGet(filename)
if err != nil {
return nil, err
}
img, err := png.Decode(bytes.NewBuffer(data))
if err != nil {
return nil, err
}
return ui.ImageFromImage(img)
}
// Then try the file system.
if _, err := os.Stat(filename); !os.IsNotExist(err) {
log.Debug("sprites.LoadImage: %s from filesystem", filename)
data, err := ioutil.ReadFile(filename)
if err != nil {
return nil, err
}
img, err := png.Decode(bytes.NewBuffer(data))
if err != nil {
return nil, err
}
return ui.ImageFromImage(img)
}
return nil, errors.New("no such sprite found")
}