go-opengl-pixel/picture.go

72 lines
2.0 KiB
Go

package pixel
import (
"image"
"image/draw"
"github.com/faiface/mainthread"
"github.com/faiface/pixel/pixelgl"
)
// Picture is a raster picture. It is usually used with sprites.
//
// A picture is created from an image.Image, that can be either loaded from a file, or
// generated. After the creation a picture can be sliced (slicing creates a "sub-picture"
// from a picture) into smaller pictures.
type Picture struct {
texture *pixelgl.Texture
bounds Rect
}
// NewPicture creates a new picture from an image.Image.
func NewPicture(img image.Image, smooth bool) *Picture {
// convert the image to NRGBA format
var nrgba *image.NRGBA
if nrgbaImg, ok := img.(*image.NRGBA); ok {
nrgba = nrgbaImg
} else {
nrgba = image.NewNRGBA(image.Rect(0, 0, img.Bounds().Dx(), img.Bounds().Dy()))
draw.Draw(nrgba, nrgba.Bounds(), img, img.Bounds().Min, draw.Src)
}
var texture *pixelgl.Texture
mainthread.Call(func() {
texture = pixelgl.NewTexture(
img.Bounds().Dx(),
img.Bounds().Dy(),
smooth,
nrgba.Pix,
)
})
return &Picture{
texture: texture,
bounds: R(0, 0, float64(texture.Width()), float64(texture.Height())),
}
}
// Texture returns a pointer to the underlying OpenGL texture of a picture.
func (p *Picture) Texture() *pixelgl.Texture {
return p.texture
}
// Slice returns a picture within the supplied rectangle of the original picture. The original
// and the sliced picture share the same texture.
//
// For example, suppose we have a 100x200 pixels picture. If we slice it with rectangle (50,
// 100, 50, 100), we get the upper-right quadrant of the original picture.
func (p *Picture) Slice(slice Rect) *Picture {
return &Picture{
texture: p.texture,
bounds: Rect{p.bounds.Pos + slice.Pos, slice.Size},
}
}
// Bounds returns the bounding rectangle of this picture relative to the most original picture.
//
// If the original picture gets sliced with the return value of this method, this picture will
// be obtained.
func (p *Picture) Bounds() Rect {
return p.bounds
}