149 lines
3.6 KiB
Go
149 lines
3.6 KiB
Go
package layout
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import (
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"fyne.io/fyne/v2"
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"fyne.io/fyne/v2/theme"
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)
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// Declare conformity with Layout interface
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var _ fyne.Layout = (*boxLayout)(nil)
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type boxLayout struct {
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horizontal bool
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}
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// NewHBoxLayout returns a horizontal box layout for stacking a number of child
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// canvas objects or widgets left to right. The objects are always displayed
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// at their horizontal MinSize. Use a different layout if the objects are intended
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// to be larger then their horizontal MinSize.
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func NewHBoxLayout() fyne.Layout {
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return &boxLayout{true}
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}
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// NewVBoxLayout returns a vertical box layout for stacking a number of child
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// canvas objects or widgets top to bottom. The objects are always displayed
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// at their vertical MinSize. Use a different layout if the objects are intended
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// to be larger then their vertical MinSize.
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func NewVBoxLayout() fyne.Layout {
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return &boxLayout{false}
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}
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func (g *boxLayout) isSpacer(obj fyne.CanvasObject) bool {
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if !obj.Visible() {
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return false // invisible spacers don't impact layout
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}
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spacer, ok := obj.(SpacerObject)
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if !ok {
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return false
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}
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if g.horizontal {
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return spacer.ExpandHorizontal()
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}
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return spacer.ExpandVertical()
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}
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// Layout is called to pack all child objects into a specified size.
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// For a VBoxLayout this will pack objects into a single column where each item
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// is full width but the height is the minimum required.
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// Any spacers added will pad the view, sharing the space if there are two or more.
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func (g *boxLayout) Layout(objects []fyne.CanvasObject, size fyne.Size) {
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spacers := 0
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visibleObjects := 0
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// Size taken up by visible objects
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total := float32(0)
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for _, child := range objects {
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if !child.Visible() {
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continue
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}
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if g.isSpacer(child) {
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spacers++
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continue
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}
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visibleObjects++
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if g.horizontal {
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total += child.MinSize().Width
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} else {
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total += child.MinSize().Height
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}
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}
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padding := theme.Padding()
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// Amount of space not taken up by visible objects and inter-object padding
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var extra float32
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if g.horizontal {
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extra = size.Width - total - (padding * float32(visibleObjects-1))
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} else {
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extra = size.Height - total - (padding * float32(visibleObjects-1))
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}
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// Spacers split extra space equally
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spacerSize := float32(0)
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if spacers > 0 {
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spacerSize = extra / float32(spacers)
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}
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x, y := float32(0), float32(0)
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for _, child := range objects {
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if !child.Visible() {
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continue
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}
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if g.isSpacer(child) {
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if g.horizontal {
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x += spacerSize
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} else {
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y += spacerSize
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}
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continue
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}
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child.Move(fyne.NewPos(x, y))
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if g.horizontal {
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width := child.MinSize().Width
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x += padding + width
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child.Resize(fyne.NewSize(width, size.Height))
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} else {
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height := child.MinSize().Height
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y += padding + height
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child.Resize(fyne.NewSize(size.Width, height))
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}
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}
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}
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// MinSize finds the smallest size that satisfies all the child objects.
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// For a BoxLayout this is the width of the widest item and the height is
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// the sum of of all children combined with padding between each.
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func (g *boxLayout) MinSize(objects []fyne.CanvasObject) fyne.Size {
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minSize := fyne.NewSize(0, 0)
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addPadding := false
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padding := theme.Padding()
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for _, child := range objects {
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if !child.Visible() || g.isSpacer(child) {
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continue
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}
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childMin := child.MinSize()
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if g.horizontal {
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minSize.Height = fyne.Max(childMin.Height, minSize.Height)
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minSize.Width += childMin.Width
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if addPadding {
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minSize.Width += padding
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}
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} else {
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minSize.Width = fyne.Max(childMin.Width, minSize.Width)
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minSize.Height += childMin.Height
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if addPadding {
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minSize.Height += padding
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}
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}
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addPadding = true
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}
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return minSize
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}
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