114 lines
2.9 KiB
Go
114 lines
2.9 KiB
Go
package layouts
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import "image"
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import "golang.org/x/image/math/fixed"
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import "git.tebibyte.media/sashakoshka/tomo"
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import "git.tebibyte.media/sashakoshka/tomo/artist"
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import "git.tebibyte.media/sashakoshka/tomo/fixedutil"
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// Vertical arranges elements vertically. Elements at the start of the entry
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// list will be positioned at the top, and elements at the end of the entry list
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// will positioned at the bottom. All elements have the same width.
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type Vertical struct {
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// If Gap is true, a gap will be placed between each element.
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Gap bool
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// If Pad is true, there will be padding running along the inside of the
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// layout's border.
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Pad bool
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}
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// Arrange arranges a list of entries vertically.
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func (layout Vertical) Arrange (
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entries []tomo.LayoutEntry,
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margin image.Point,
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padding artist.Inset,
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bounds image.Rectangle,
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) {
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if layout.Pad { bounds = padding.Apply(bounds) }
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// get height of expanding elements
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expandingElementHeight, minimumHeights := layout.expandingElementHeight (
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entries, margin, padding, bounds.Dy())
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// set the size and position of each element
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dot := fixedutil.Pt(bounds.Min)
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for index, entry := range entries {
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if index > 0 && layout.Gap { dot.Y += fixed.I(margin.Y) }
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entry.Bounds.Min = fixedutil.FloorPt(dot)
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entryHeight := fixed.Int26_6(0)
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if entry.Expand {
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entryHeight = expandingElementHeight
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} else {
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entryHeight = fixed.I(minimumHeights[index])
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}
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dot.Y += entryHeight
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entryBounds := entry.Bounds
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entry.Bounds.Max = entryBounds.Min.Add (
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image.Pt(bounds.Dx(),
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entryHeight.Floor()))
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entries[index] = entry
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}
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}
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// MinimumSize returns the minimum width and height that will be needed to
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// arrange the given list of entries.
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func (layout Vertical) MinimumSize (
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entries []tomo.LayoutEntry,
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margin image.Point,
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padding artist.Inset,
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) (
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width, height int,
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) {
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for index, entry := range entries {
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entryWidth, entryHeight := entry.MinimumSize()
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if entryWidth > width {
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width = entryWidth
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}
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height += entryHeight
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if layout.Gap && index > 0 {
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height += margin.Y
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}
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}
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if layout.Pad {
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width += padding.Horizontal()
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height += padding.Vertical()
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}
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return
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}
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func (layout Vertical) expandingElementHeight (
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entries []tomo.LayoutEntry,
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margin image.Point,
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padding artist.Inset,
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freeSpace int,
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) (
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height fixed.Int26_6,
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minimumHeights []int,
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) {
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// count the number of expanding elements and the amount of free space
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// for them to collectively occupy, while gathering minimum heights.
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minimumHeights = make([]int, len(entries))
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expandingElements := 0
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for index, entry := range entries {
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_, entryMinHeight := entry.MinimumSize()
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minimumHeights[index] = entryMinHeight
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if entry.Expand {
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expandingElements ++
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} else {
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freeSpace -= entryMinHeight
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}
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if index > 0 && layout.Gap {
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freeSpace -= margin.Y
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}
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}
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if expandingElements > 0 {
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height = fixed.I(freeSpace) / fixed.Int26_6(expandingElements)
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}
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return
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}
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