all: rename the gioui.org/ui module to gioui.org

The "ui" is redundant and stutters.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/gpu/pack.go

@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package gpu
+
+import (
+	"image"
+)
+
+// packer packs a set of many smaller rectangles into
+// much fewer larger atlases.
+type packer struct {
+	maxDim int
+	spaces []image.Rectangle
+
+	sizes []image.Point
+	pos   image.Point
+}
+
+type placement struct {
+	Idx int
+	Pos image.Point
+}
+
+// add adds the given rectangle to the atlases and
+// return the allocated position.
+func (p *packer) add(s image.Point) (placement, bool) {
+	if place, ok := p.tryAdd(s); ok {
+		return place, true
+	}
+	p.newPage()
+	return p.tryAdd(s)
+}
+
+func (p *packer) clear() {
+	p.sizes = p.sizes[:0]
+	p.spaces = p.spaces[:0]
+}
+
+func (p *packer) newPage() {
+	p.pos = image.Point{}
+	p.sizes = append(p.sizes, image.Point{})
+	p.spaces = p.spaces[:0]
+	p.spaces = append(p.spaces, image.Rectangle{
+		Max: image.Point{X: p.maxDim, Y: p.maxDim},
+	})
+}
+
+func (p *packer) tryAdd(s image.Point) (placement, bool) {
+	// Go backwards to prioritize smaller spaces first.
+	for i := len(p.spaces) - 1; i >= 0; i-- {
+		space := p.spaces[i]
+		rightSpace := space.Dx() - s.X
+		bottomSpace := space.Dy() - s.Y
+		if rightSpace >= 0 && bottomSpace >= 0 {
+			// Remove space.
+			p.spaces[i] = p.spaces[len(p.spaces)-1]
+			p.spaces = p.spaces[:len(p.spaces)-1]
+			// Put s in the top left corner and add the (at most)
+			// two smaller spaces.
+			pos := space.Min
+			if bottomSpace > 0 {
+				p.spaces = append(p.spaces, image.Rectangle{
+					Min: image.Point{X: pos.X, Y: pos.Y + s.Y},
+					Max: image.Point{X: space.Max.X, Y: space.Max.Y},
+				})
+			}
+			if rightSpace > 0 {
+				p.spaces = append(p.spaces, image.Rectangle{
+					Min: image.Point{X: pos.X + s.X, Y: pos.Y},
+					Max: image.Point{X: space.Max.X, Y: pos.Y + s.Y},
+				})
+			}
+			idx := len(p.sizes) - 1
+			size := &p.sizes[idx]
+			if x := pos.X + s.X; x > size.X {
+				size.X = x
+			}
+			if y := pos.Y + s.Y; y > size.Y {
+				size.Y = y
+			}
+			return placement{Idx: idx, Pos: pos}, true
+		}
+	}
+	return placement{}, false
+}