43 lines
1.2 KiB
Go
43 lines
1.2 KiB
Go
package theme
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import "image"
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// Inset represents an inset amount for all four sides of a rectangle. The top
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// side is at index zero, the right at index one, the bottom at index two, and
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// the left at index three. These values may be negative.
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type Inset [4]int
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// Apply returns the given rectangle, shrunk on all four sides by the given
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// inset. If a measurment of the inset is negative, that side will instead be
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// expanded outward. If the rectangle's dimensions cannot be reduced any
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// further, an empty rectangle near its center will be returned.
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func (inset Inset) Apply (bigger image.Rectangle) (smaller image.Rectangle) {
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smaller = bigger
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if smaller.Dx() < inset[3] + inset[1] {
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smaller.Min.X = (smaller.Min.X + smaller.Max.X) / 2
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smaller.Max.X = smaller.Min.X
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} else {
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smaller.Min.X += inset[3]
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smaller.Max.X -= inset[1]
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}
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if smaller.Dy() < inset[0] + inset[2] {
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smaller.Min.Y = (smaller.Min.Y + smaller.Max.Y) / 2
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smaller.Max.Y = smaller.Min.Y
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} else {
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smaller.Min.Y += inset[0]
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smaller.Max.Y -= inset[2]
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}
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return
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}
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// Inverse returns a negated version of the inset.
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func (inset Inset) Inverse () (prime Inset) {
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return Inset {
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inset[0] * -1,
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inset[1] * -1,
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inset[2] * -1,
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inset[3] * -1,
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}
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}
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