Problem: You want to create an image from scratch.
Solution: Create one of the Image implementation structs (e.g., NRGBA ) and populate it with the appropriate data.
As you remember from earlier, NRGBA has three attributes:
Pix
• A slice of bytes that contains the pixels in the image (it’s just a slice of color.Color )
Stride
• The distance between the two vertically adjacent pixels
Rect
• The dimensions of the image
func main () { rect := image . Rect ( 0 , 0 , 100 , 100 ) img := createRandomImage ( rect ) save ( "random.png" , img ) } func createRandomImage ( rect image . Rectangle ) ( created * image . NRGBA ) { pix := make ([] uint8 , rect . Dx () * rect . Dy () * 4 ) rand . Read ( pix ) created = & image . NRGBA { Pix : pix , Stride : rect . Dx () * 4 , Rect : rect , } return }
Say you want to create an image that is 100 × 100 pixels. First, you need to create a Rect with the correct dimensions. Next, the Pix should be a slice of bytes of size 100 × 100 × 4 = 40,000 because each pixel is represented by 4 bytes (R, G, B, and A). Lastly, the Stride is the distance between two vertical pixels, which is the width of the image, multiplied by 4, which is 100 × 4 = 400.
The example code created a random image with each pixel a random color by populating the Pix slice of bytes with random bytes using rand.Read . You can fill it up with anything else, of course.