131 lines
3.2 KiB
Go
131 lines
3.2 KiB
Go
package basicLayouts
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import "image"
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import "git.tebibyte.media/sashakoshka/tomo/layouts"
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import "git.tebibyte.media/sashakoshka/tomo/elements"
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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 []layouts.LayoutEntry,
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margin int,
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bounds image.Rectangle,
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) {
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if layout.Pad { bounds = bounds.Inset(margin) }
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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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freeSpace := bounds.Dy()
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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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var entryMinHeight int
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if child, flexible := entry.Element.(elements.Flexible); flexible {
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entryMinHeight = child.FlexibleHeightFor(bounds.Dx())
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} else {
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_, entryMinHeight = entry.MinimumSize()
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}
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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
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}
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}
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expandingElementHeight := 0
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if expandingElements > 0 {
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expandingElementHeight = freeSpace / expandingElements
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}
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// set the size and position of each element
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dot := bounds.Min
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for index, entry := range entries {
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if index > 0 && layout.Gap { dot.Y += margin }
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entry.Bounds.Min = dot
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entryHeight := 0
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if entry.Expand {
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entryHeight = expandingElementHeight
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} else {
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entryHeight = 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(image.Pt(bounds.Dx(), entryHeight))
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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 []layouts.LayoutEntry,
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margin int,
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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
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}
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}
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if layout.Pad {
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width += margin * 2
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height += margin * 2
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}
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return
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}
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// FlexibleHeightFor Returns the minimum height the layout needs to lay out the
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// specified elements at the given width, taking into account flexible elements.
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func (layout Vertical) FlexibleHeightFor (
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entries []layouts.LayoutEntry,
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margin int,
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width int,
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) (
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height int,
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) {
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if layout.Pad {
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width -= margin * 2
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height += margin * 2
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}
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for index, entry := range entries {
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child, flexible := entry.Element.(elements.Flexible)
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if flexible {
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height += child.FlexibleHeightFor(width)
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} else {
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_, entryHeight := entry.MinimumSize()
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height += entryHeight
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}
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if layout.Gap && index > 0 {
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height += margin
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}
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}
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return
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}
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