layout: move examples to example_test.go

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

layout/example_test.go

@@ -0,0 +1,127 @@
+package layout_test
+
+import (
+	"fmt"
+	"image"
+
+	"gioui.org/layout"
+	"gioui.org/unit"
+)
+
+func ExampleInset() {
+	gtx := new(layout.Context)
+	gtx.Reset(nil, image.Point{X: 100, Y: 100})
+	// Loose constraints with no minimal size.
+	gtx.Constraints.Width.Min = 0
+	gtx.Constraints.Height.Min = 0
+
+	// Inset all edges by 10.
+	inset := layout.UniformInset(unit.Dp(10))
+	inset.Layout(gtx, func() {
+		// Lay out a 50x50 sized widget.
+		layoutWidget(gtx, 50, 50)
+		fmt.Println(gtx.Dimensions.Size)
+	})
+
+	fmt.Println(gtx.Dimensions.Size)
+
+	// Output:
+	// (50,50)
+	// (70,70)
+}
+
+func ExampleAlign() {
+	gtx := new(layout.Context)
+	// Rigid constraints with both minimum and maximum set.
+	gtx.Reset(nil, image.Point{X: 100, Y: 100})
+
+	align := layout.Align(layout.Center)
+	align.Layout(gtx, func() {
+		// Lay out a 50x50 sized widget.
+		layoutWidget(gtx, 50, 50)
+		fmt.Println(gtx.Dimensions.Size)
+	})
+
+	fmt.Println(gtx.Dimensions.Size)
+
+	// Output:
+	// (50,50)
+	// (100,100)
+}
+
+func ExampleFlex() {
+	gtx := new(layout.Context)
+	gtx.Reset(nil, image.Point{X: 100, Y: 100})
+
+	flex := layout.Flex{}
+
+	// Rigid 10x10 widget.
+	child1 := flex.Rigid(gtx, func() {
+		fmt.Printf("Rigid: %v\n", gtx.Constraints.Width)
+		layoutWidget(gtx, 10, 10)
+	})
+
+	// Child with 50% space allowance.
+	child2 := flex.Flex(gtx, 0.5, func() {
+		fmt.Printf("50%%: %v\n", gtx.Constraints.Width)
+		layoutWidget(gtx, 10, 10)
+	})
+
+	flex.Layout(gtx, child1, child2)
+
+	// Output:
+	// Rigid: {0 100}
+	// 50%: {45 45}
+}
+
+func ExampleStack() {
+	gtx := new(layout.Context)
+	gtx.Reset(nil, image.Point{X: 100, Y: 100})
+
+	stack := layout.Stack{}
+
+	// Rigid 50x50 widget.
+	child1 := stack.Rigid(gtx, func() {
+		layoutWidget(gtx, 50, 50)
+	})
+
+	// Force widget to the same size as the first.
+	child2 := stack.Expand(gtx, func() {
+		fmt.Printf("Expand: %v\n", gtx.Constraints)
+		layoutWidget(gtx, 10, 10)
+	})
+
+	stack.Layout(gtx, child1, child2)
+
+	// Output:
+	// Expand: {{50 100} {50 100}}
+}
+
+func ExampleList() {
+	gtx := new(layout.Context)
+	gtx.Reset(nil, image.Point{X: 100, Y: 100})
+
+	// The list is 1e6 elements, but only 5 fit the constraints.
+	const listLen = 1e6
+
+	var list layout.List
+	count := 0
+	list.Layout(gtx, listLen, func(i int) {
+		count++
+		layoutWidget(gtx, 20, 20)
+	})
+
+	fmt.Println(count)
+
+	// Output:
+	// 5
+}
+
+func layoutWidget(ctx *layout.Context, width, height int) {
+	ctx.Dimensions = layout.Dimensions{
+		Size: image.Point{
+			X: width,
+			Y: height,
+		},
+	}
+}