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tomo-old/artist/line.go
Sasha Koshka 34bf3038ac Replaced tomo.Image with tomo.Canvas and tomo.Pattern
This is the first step in transitioning the API over to the new
design. The new tomo.Canvas interface gives drawing functions
direct access to data buffers and eliminates overhead associated
with calling functions for every pixel.

The entire artist package will be remade around this.
2023-01-14 01:54:57 -05:00

115 lines
1.8 KiB
Go

package artist
import "image"
import "git.tebibyte.media/sashakoshka/tomo"
func Line (
destination tomo.Canvas,
source Pattern,
weight int,
min image.Point,
max image.Point,
) (
updatedRegion image.Rectangle,
) {
// TODO: respect weight
updatedRegion = image.Rectangle { Min: min, Max: max }.Canon()
updatedRegion.Max.X ++
updatedRegion.Max.Y ++
width := updatedRegion.Dx()
height := updatedRegion.Dy()
if abs(max.Y - min.Y) <
abs(max.X - min.X) {
if max.X < min.X {
temp := min
min = max
max = temp
}
lineLow(destination, source, weight, min, max, width, height)
} else {
if max.Y < min.Y {
temp := min
min = max
max = temp
}
lineHigh(destination, source, weight, min, max, width, height)
}
return
}
func lineLow (
destination tomo.Canvas,
source Pattern,
weight int,
min image.Point,
max image.Point,
width, height int,
) {
data, stride := destination.Buffer()
deltaX := max.X - min.X
deltaY := max.Y - min.Y
yi := 1
if deltaY < 0 {
yi = -1
deltaY *= -1
}
D := (2 * deltaY) - deltaX
y := min.Y
for x := min.X; x < max.X; x ++ {
data[x + y * stride] = source.AtWhen(x, y, width, height)
if D > 0 {
y += yi
D += 2 * (deltaY - deltaX)
} else {
D += 2 * deltaY
}
}
}
func lineHigh (
destination tomo.Canvas,
source Pattern,
weight int,
min image.Point,
max image.Point,
width, height int,
) {
data, stride := destination.Buffer()
deltaX := max.X - min.X
deltaY := max.Y - min.Y
xi := 1
if deltaX < 0 {
xi = -1
deltaX *= -1
}
D := (2 * deltaX) - deltaY
x := min.X
for y := min.Y; y < max.Y; y ++ {
data[x + y * stride] = source.AtWhen(x, y, width, height)
if D > 0 {
x += xi
D += 2 * (deltaX - deltaY)
} else {
D += 2 * deltaX
}
}
}
func abs (in int) (out int) {
if in < 0 { in *= -1}
out = in
return
}