scroll
Scroll the pixels in an image up, down, right, or left.
image.create(0, 0).scroll(0, 0)Images are scrolled by a number of pixel rows or columns (the scroll distance). An image can even be scrolled by both rows and columns at the same time. The scroll direction depends on the sign (-) of the scroll distance value. Scrolling up will use a negative scroll value. Scrolling to the left also uses a negative scroll value. Scrolling down or to the right use positive scroll values.
Scrolling is a destructive operation. This means that the pixels scrolled outside the image are lost and can’t be scrolled back inside again. As scrolling happens, the pixels that are scrolled have their original locations replaced by transparent pixels.
Parameters
- dx: the number of pixels to scroll the image to the left or right Use a negative value to scroll to the left.
- dy: the number of pixels to scroll the image up or down. Use a negative value to scroll up.
Examples
Color bands
Scroll an image of 15 color bands up until it disappears.
let showBands: Sprite = null
let colorBands: Image = null
let scrollCount = 0
scrollCount = 16
colorBands = img`
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4
5 5 5 5 5 5 5 5 5 5 5 5 5 5 5 5
6 6 6 6 6 6 6 6 6 6 6 6 6 6 6 6
7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7
8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9
a a a a a a a a a a a a a a a a
b b b b b b b b b b b b b b b b
c c c c c c c c c c c c c c c c
d d d d d d d d d d d d d d d d
e e e e e e e e e e e e e e e e
f f f f f f f f f f f f f f f f
`
showBands = sprites.create(colorBands)
game.onUpdateInterval(500, function () {
if (scrollCount > 0) {
colorBands.scroll(0, -1)
scrollCount += -1
}
})Diagonal scroll
Scroll a green square diagonally down and to the right.
let showSquare: Sprite = null
let greenSquare: Image = null
greenSquare = image.create(32, 32)
greenSquare.fill(6)
showSquare = sprites.create(greenSquare)
game.onUpdateInterval(500, function () {
greenSquare.scroll(1, 1)
})