render: make widget trees JSON serializable

render/animation.go

@@ -1,6 +1,7 @@
 package render
 
 import (
+	"encoding/json"
 	"image"
 
 	"github.com/tidbyt/gg"
@@ -26,7 +27,8 @@ import (
 // )
 // EXAMPLE END
 type Animation struct {
-	Widget
+	Type string `starlark:"-"`
+
 	Children []Widget
 }
 
@@ -63,3 +65,26 @@ func (a Animation) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int) {
 
 	a.Children[ModInt(frameIdx, len(a.Children))].Paint(dc, bounds, frameIdx)
 }
+
+func (a *Animation) UnmarshalJSON(data []byte) error {
+	type Alias Animation
+	aux := &struct {
+		Children []json.RawMessage
+		*Alias
+	}{
+		Alias: (*Alias)(a),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+	children := []Widget{}
+	for _, childData := range aux.Children {
+		child, err := UnmarshalWidgetJSON(childData)
+		if err != nil {
+			return err
+		}
+		children = append(children, child)
+	}
+	a.Children = children
+	return nil
+}

render/animation/positioned.go

@@ -24,7 +24,8 @@ import (
 // DOC(Hold): Delay after animation in frames
 //
 type AnimatedPositioned struct {
-	render.Widget
+	Type string `starlark:"-"`
+
 	Child    render.Widget `starlark:"child,required"`
 	XStart   int           `starlark:"x_start"`
 	XEnd     int           `starlark:"x_end"`

render/animation/transformation.go

@@ -162,7 +162,7 @@ func findKeyframes(arr []Keyframe, p float64) (Keyframe, Keyframe, error) {
 // ),
 // EXAMPLE END
 type Transformation struct {
-	render.Widget
+	Type string `starlark:"-"`
 
 	Child        render.Widget `starlark:"child,required"`
 	Keyframes    []Keyframe    `starlark:"keyframes,required"`

render/box.go

@@ -1,6 +1,8 @@
 package render
 
 import (
+	"encoding/json"
+	"fmt"
 	"image"
 	"image/color"
 
@@ -31,11 +33,12 @@ import (
 // )
 // EXAMPLE END
 type Box struct {
-	Widget
+	Type string `starlark:"-"`
+
 	Child         Widget
 	Width, Height int
 	Padding       int
-	Color         color.Color
+	Color         color.RGBA
 }
 
 func (b Box) PaintBounds(bounds image.Rectangle, frameIdx int) image.Rectangle {
@@ -58,7 +61,7 @@ func (b Box) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int) {
 		h = bounds.Dy()
 	}
 
-	if b.Color != nil {
+	if b.Color != (color.RGBA{}) {
 		dc.SetColor(b.Color)
 		dc.DrawRectangle(0, 0, float64(w), float64(h))
 		dc.Fill()
@@ -103,3 +106,53 @@ func (b Box) FrameCount() int {
 	}
 	return 1
 }
+
+func (b *Box) UnmarshalJSON(data []byte) error {
+	type Alias Box
+	aux := &struct {
+		Child json.RawMessage
+		Color string
+		*Alias
+	}{
+		Alias: (*Alias)(b),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+
+	if aux.Child != nil {
+		child, err := UnmarshalWidgetJSON(aux.Child)
+		if err != nil {
+			return err
+		}
+		b.Child = child
+	}
+
+	if aux.Color != "" {
+		col, err := ParseColor(aux.Color)
+		if err != nil {
+			return err
+		}
+		b.Color = col
+	}
+
+	return nil
+}
+
+func (b *Box) MarshalJSON() ([]byte, error) {
+	col := ""
+	if b.Color != (color.RGBA{}) {
+		r, g, b, a := b.Color.RGBA()
+		col = fmt.Sprintf("#%02x%02x%02x%02x", r>>8, g>>8, b>>8, a>>8)
+	}
+	type Alias Box
+	aux := &struct {
+		*Alias
+		Color string
+	}{
+		Alias: (*Alias)(b),
+		Color: col,
+	}
+
+	return json.Marshal(aux)
+}

render/circle.go

@@ -1,6 +1,8 @@
 package render
 
 import (
+	"encoding/json"
+	"fmt"
 	"image"
 	"image/color"
 	"math"
@@ -24,11 +26,11 @@ import (
 // )
 // EXAMPLE END
 type Circle struct {
-	Widget
+	Type string `starlark:"-"`
 
 	Child    Widget
-	Color    color.Color `starlark:"color, required"`
-	Diameter int         `starlark:"diameter,required"`
+	Color    color.RGBA `starlark:"color, required"`
+	Diameter int        `starlark:"diameter,required"`
 }
 
 func (c Circle) PaintBounds(bounds image.Rectangle, frameIdx int) image.Rectangle {
@@ -69,3 +71,43 @@ func (c Circle) FrameCount() int {
 	}
 	return 1
 }
+
+func (c *Circle) UnmarshalJSON(data []byte) error {
+	type Alias Circle
+	aux := &struct {
+		Child json.RawMessage
+		*Alias
+	}{
+		Alias: (*Alias)(c),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+
+	if aux.Child != nil {
+		child, err := UnmarshalWidgetJSON(aux.Child)
+		if err != nil {
+			return err
+		}
+		c.Child = child
+	}
+	return nil
+}
+
+func (c *Circle) MarshalJSON() ([]byte, error) {
+	col := ""
+	if c.Color != (color.RGBA{}) {
+		r, g, b, a := c.Color.RGBA()
+		col = fmt.Sprintf("#%02x%02x%02x%02x", r>>8, g>>8, b>>8, a>>8)
+	}
+	type Alias Circle
+	aux := &struct {
+		*Alias
+		Color string
+	}{
+		Alias: (*Alias)(c),
+		Color: col,
+	}
+
+	return json.Marshal(aux)
+}

render/colors.go

@@ -6,7 +6,7 @@ import (
 	"strings"
 )
 
-func ParseColor(scol string) (color.Color, error) {
+func ParseColor(scol string) (color.RGBA, error) {
 	var format string
 	var fourBits bool
 	var hasAlpha bool
@@ -31,26 +31,26 @@ func ParseColor(scol string) (color.Color, error) {
 		fourBits = false
 		hasAlpha = true
 	default:
-		return color.Gray{0}, fmt.Errorf("color: %v is not a hex-color", scol)
+		return color.RGBA{}, fmt.Errorf("color: %v is not a hex-color", scol)
 	}
 
 	var r, g, b, a uint8
 
 	if hasAlpha {
 		n, err := fmt.Sscanf(scol, format, &r, &g, &b, &a)
 		if err != nil {
-			return color.Gray{0}, err
+			return color.RGBA{}, err
 		}
 		if n != 4 {
-			return color.Gray{0}, fmt.Errorf("color: %v is not a hex-color", scol)
+			return color.RGBA{}, fmt.Errorf("color: %v is not a hex-color", scol)
 		}
 	} else {
 		n, err := fmt.Sscanf(scol, format, &r, &g, &b)
 		if err != nil {
-			return color.Gray{0}, err
+			return color.RGBA{}, err
 		}
 		if n != 3 {
-			return color.Gray{0}, fmt.Errorf("color: %v is not a hex-color", scol)
+			return color.RGBA{}, fmt.Errorf("color: %v is not a hex-color", scol)
 		}
 		if fourBits {
 			a = 15
@@ -66,5 +66,5 @@ func ParseColor(scol string) (color.Color, error) {
 		a |= a << 4
 	}
 
-	return color.NRGBA{r, g, b, a}, nil
+	return color.RGBA{r, g, b, a}, nil
 }

render/colors_test.go

@@ -1,7 +1,6 @@
 package render
 
 import (
-	"image/color"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -15,12 +14,9 @@ func ParseAndAssertColor(
 	expectedB uint8,
 	expectedA uint8,
 ) {
-	col, err := ParseColor(scol)
+	c, err := ParseColor(scol)
 	assert.Nil(t, err)
 
-	c, ok := col.(color.NRGBA)
-	assert.True(t, ok)
-
 	assert.Equal(t, expectedR, c.R)
 	assert.Equal(t, expectedG, c.G)
 	assert.Equal(t, expectedB, c.B)

render/column.go

@@ -1,6 +1,7 @@
 package render
 
 import (
+	"encoding/json"
 	"image"
 
 	"github.com/tidbyt/gg"
@@ -56,7 +57,7 @@ import (
 // )
 // EXAMPLE END
 type Column struct {
-	Widget
+	Type string `starlark:"-"`
 
 	Children   []Widget `starlark:"children,required"`
 	MainAlign  string   `starlark:"main_align"`
@@ -89,3 +90,26 @@ func (c Column) Paint(dc *gg.Context, bounds image.Rectangle, frameIdx int) {
 func (c Column) FrameCount() int {
 	return MaxFrameCount(c.Children)
 }
+
+func (c *Column) UnmarshalJSON(data []byte) error {
+	type Alias Column
+	aux := &struct {
+		Children []json.RawMessage
+		*Alias
+	}{
+		Alias: (*Alias)(c),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+	children := []Widget{}
+	for _, childData := range aux.Children {
+		child, err := UnmarshalWidgetJSON(childData)
+		if err != nil {
+			return err
+		}
+		children = append(children, child)
+	}
+	c.Children = children
+	return nil
+}

render/image.go

@@ -2,6 +2,8 @@ package render
 
 import (
 	"bytes"
+	"encoding/base64"
+	"encoding/json"
 	"errors"
 	"fmt"
 	"image"
@@ -36,7 +38,8 @@ import (
 // DOC(Height): Scale image to this height
 // DOC(Delay): (Read-only) Frame delay in ms, for animated GIFs
 type Image struct {
-	Widget
+	Type string `starlark:"-"`
+
 	Src           string `starlark:"src,required"`
 	Width, Height int
 	Delay         int `starlark:"delay,readonly"`
@@ -195,3 +198,37 @@ func (p *Image) Init() error {
 
 	return nil
 }
+
+func (p *Image) UnmarshalJSON(data []byte) error {
+	type Alias Image
+	aux := &struct {
+		*Alias
+	}{
+		Alias: (*Alias)(p),
+	}
+
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+
+	src, err := base64.StdEncoding.DecodeString(aux.Src)
+	if err != nil {
+		return err
+	}
+	p.Src = string(src)
+
+	return p.Init()
+}
+
+func (p *Image) MarshalJSON() ([]byte, error) {
+	type Alias Image
+	aux := &struct {
+		*Alias
+	}{
+		Alias: (*Alias)(p),
+	}
+
+	aux.Src = base64.StdEncoding.EncodeToString([]byte(p.Src))
+
+	return json.Marshal(aux)
+}