all: initial import

Signed-off-by: Elias Naur <mail@eliasnaur.com>
2019-03-30 13:18:49 +01:00
commit 0f05231c35
102 changed files with 17926 additions and 0 deletions
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package layout
+
+import (
+	"image"
+
+	"gioui.org/ui/draw"
+	"gioui.org/ui/gesture"
+	"gioui.org/ui/pointer"
+	"gioui.org/ui"
+)
+
+type scrollChild struct {
+	op   ui.Op
+	size image.Point
+}
+
+type List struct {
+	Axis Axis
+
+	CrossAxisAlignment CrossAxisAlignment
+
+	// The distance scrolled since last call to Init.
+	Distance int
+
+	scroll    gesture.Scroll
+	scrollDir int
+
+	offset int
+	first  int
+
+	cs  Constraints
+	len int
+
+	maxSize  int
+	children []scrollChild
+	elem     func(w Widget)
+
+	size image.Point
+	ops  ui.Ops
+}
+
+type Interface interface {
+	Len() int
+	At(i int) Widget
+}
+
+func (l *List) Init(cs Constraints, len int) (int, bool) {
+	l.maxSize = 0
+	l.children = l.children[:0]
+	l.cs = cs
+	l.len = len
+	l.elem = nil
+	if l.first > len {
+		l.first = len
+	}
+	l.ops = l.ops[:0]
+	if len == 0 {
+		return 0, false
+	}
+	return l.Index()
+}
+
+func (l *List) Dragging() bool {
+	return l.scroll.Dragging()
+}
+
+func (l *List) Scroll(c *ui.Config, q pointer.Events) {
+	l.Distance = 0
+	d := l.scroll.Scroll(c, q, gesture.Axis(l.Axis))
+	l.scrollDir = d
+	l.Distance += d
+	l.offset += d
+}
+
+func (l *List) Index() (int, bool) {
+	i, ok := l.next()
+	if !ok {
+		l.draw()
+	}
+	return i, ok
+}
+
+func (l *List) Layout() (ui.Op, Dimens) {
+	ops := append(ui.Ops{l.scroll.Op(gesture.Rect(l.size))}, l.ops...)
+	return ops, Dimens{Size: l.size}
+}
+
+func (l *List) next() (int, bool) {
+	mainc := axisMainConstraint(l.Axis, l.cs)
+	if l.offset <= 0 {
+		if l.first > 0 {
+			l.elem = l.backward
+			return l.first - 1, true
+		}
+		l.offset = 0
+	}
+	if l.maxSize-l.offset < mainc.Max {
+		i := l.first + len(l.children)
+		if i < l.len {
+			l.elem = l.forward
+			return i, true
+		}
+		missing := mainc.Max - (l.maxSize - l.offset)
+		if missing > l.offset {
+			missing = l.offset
+		}
+		l.offset -= missing
+	}
+	return 0, false
+}
+
+func (l *List) Elem(w Widget) {
+	l.elem(w)
+}
+
+func (l *List) backward(w Widget) {
+	subcs := axisConstraints(l.Axis, Constraint{Max: ui.Inf}, l.crossConstraintChild(l.cs))
+	l.first--
+	op, dims := w.Layout(subcs)
+	mainSize := axisMain(l.Axis, dims.Size)
+	l.offset += mainSize
+	l.maxSize += mainSize
+	l.children = append([]scrollChild{{op, dims.Size}}, l.children...)
+}
+
+func (l *List) forward(w Widget) {
+	subcs := axisConstraints(l.Axis, Constraint{Max: ui.Inf}, l.crossConstraintChild(l.cs))
+	op, dims := w.Layout(subcs)
+	mainSize := axisMain(l.Axis, dims.Size)
+	l.maxSize += mainSize
+	l.children = append(l.children, scrollChild{op, dims.Size})
+}
+
+func (l *List) draw() {
+	mainc := axisMainConstraint(l.Axis, l.cs)
+	for len(l.children) > 0 {
+		sz := l.children[0].size
+		mainSize := axisMain(l.Axis, sz)
+		if l.offset <= mainSize {
+			break
+		}
+		l.first++
+		l.offset -= mainSize
+		l.children = l.children[1:]
+	}
+	size := -l.offset
+	var maxCross int
+	for i, child := range l.children {
+		sz := child.size
+		if c := axisCross(l.Axis, sz); c > maxCross {
+			maxCross = c
+		}
+		size += axisMain(l.Axis, sz)
+		if size >= mainc.Max {
+			l.children = l.children[:i+1]
+			break
+		}
+	}
+	pos := -l.offset
+	for _, child := range l.children {
+		sz := child.size
+		var cross int
+		switch l.CrossAxisAlignment {
+		case End:
+			cross = maxCross - axisCross(l.Axis, sz)
+		case Center:
+			cross = (maxCross - axisCross(l.Axis, sz)) / 2
+		}
+		max := axisMain(l.Axis, sz) + pos
+		if max > mainc.Max {
+			max = mainc.Max
+		}
+		min := pos
+		if min < 0 {
+			min = 0
+		}
+		op := draw.ClipRect(
+			image.Rectangle{
+				Min: axisPoint(l.Axis, min, -ui.Inf),
+				Max: axisPoint(l.Axis, max, ui.Inf),
+			},
+			ui.OpTransform{Transform: ui.Offset(toPointF(axisPoint(l.Axis, pos, cross))), Op: child.op},
+		)
+		l.ops = append(l.ops, ui.OpLayer{Op: op})
+		pos += axisMain(l.Axis, sz)
+	}
+	atStart := l.first == 0 && l.offset <= 0
+	atEnd := l.first+len(l.children) == l.len && mainc.Max >= pos
+	if atStart && l.scrollDir < 0 || atEnd && l.scrollDir > 0 {
+		l.scroll.Stop()
+	}
+	l.size = axisPoint(l.Axis, mainc.Constrain(pos), maxCross)
+}
+
+func (l *List) crossConstraintChild(cs Constraints) Constraint {
+	c := axisCrossConstraint(l.Axis, cs)
+	switch l.CrossAxisAlignment {
+	case Stretch:
+		c.Min = c.Max
+	default:
+		c.Min = 0
+	}
+	return c
+}