check for overlaps to validate top left

d2graph/d2graph.go

@@ -52,6 +52,8 @@ type Graph struct {
 	Steps     []*Graph `json:"steps,omitempty"`
 
 	Theme *d2themes.Theme `json:"theme,omitempty"`
+
+	err LayoutError
 }
 
 func NewGraph() *Graph {
@@ -1545,9 +1547,64 @@ func (g *Graph) SetDimensions(mtexts []*d2target.MText, ruler *textmeasure.Ruler
 
 		edge.LabelDimensions = *dims
 	}
+
+	g.validateTopLeft()
+	if len(g.err.Errors) > 0 {
+		return g.err
+	}
+
 	return nil
 }
 
+func (g *Graph) validateTopLeft() {
+	g.Root.validateTopLeft()
+	g.Root.IterDescendants(func(_, obj *Object) {
+		if !obj.IsContainer() {
+			return
+		}
+		obj.validateTopLeft()
+	})
+}
+
+func (obj *Object) validateTopLeft() {
+	var fixedChildren []*Object
+	for _, child := range obj.ChildrenArray {
+		if child.Top == nil || child.Left == nil {
+			continue
+		}
+		fixedChildren = append(fixedChildren, child)
+	}
+	if len(fixedChildren) < 2 {
+		return
+	}
+
+	for i, childI := range fixedChildren {
+		iTop, _ := strconv.Atoi(childI.Top.Value)
+		iLeft, _ := strconv.Atoi(childI.Left.Value)
+		iRight := iLeft + int(math.Ceil(childI.Width))
+		iBottom := iTop + int(math.Ceil(childI.Height))
+
+		for j := i + 1; j < len(fixedChildren); j++ {
+			childJ := fixedChildren[j]
+			jTop, _ := strconv.Atoi(childJ.Top.Value)
+			jLeft, _ := strconv.Atoi(childJ.Left.Value)
+			jRight := jLeft + int(math.Ceil(childJ.Width))
+			jBottom := jTop + int(math.Ceil(childJ.Height))
+
+			overlapsHorizontally := (iLeft <= jLeft && jLeft <= iRight) ||
+				(iLeft <= jRight && jRight <= iRight)
+			overlapsVertically := (iTop <= jTop && jTop <= iBottom) ||
+				(iTop <= jBottom && jBottom <= iBottom)
+
+			if overlapsHorizontally && overlapsVertically {
+				obj.Graph.errorf(childI.Top.MapKey, "invalid top/left overlapping with %#v", childJ.ID)
+				obj.Graph.errorf(childJ.Top.MapKey, "invalid top/left overlapping with %#v", childI.ID)
+				continue
+			}
+		}
+	}
+}
+
 func (g *Graph) Texts() []*d2target.MText {
 	var texts []*d2target.MText
 

d2graph/layout.go

@@ -3,6 +3,8 @@ package d2graph
 import (
 	"strings"
 
+	"oss.terrastruct.com/d2/d2ast"
+	"oss.terrastruct.com/d2/d2parser"
 	"oss.terrastruct.com/d2/d2target"
 	"oss.terrastruct.com/d2/lib/geo"
 	"oss.terrastruct.com/d2/lib/label"
@@ -189,3 +191,26 @@ func (obj *Object) GetLabelTopLeft() *geo.Point {
 	)
 	return labelTL
 }
+
+type LayoutError struct {
+	Errors []d2ast.Error `json:"errs"`
+}
+
+func (le LayoutError) Empty() bool {
+	return len(le.Errors) == 0
+}
+
+func (le LayoutError) Error() string {
+	var sb strings.Builder
+	for i, err := range le.Errors {
+		if i > 0 {
+			sb.WriteByte('\n')
+		}
+		sb.WriteString(err.Error())
+	}
+	return sb.String()
+}
+
+func (g *Graph) errorf(n d2ast.Node, f string, v ...interface{}) {
+	g.err.Errors = append(g.err.Errors, d2parser.Errorf(n, f, v...).(d2ast.Error))
+}

d2lib/d2lib_test.go

@@ -0,0 +1,89 @@
+package d2lib_test
+
+import (
+	"context"
+	"testing"
+
+	"oss.terrastruct.com/d2/d2graph"
+	"oss.terrastruct.com/d2/d2layouts/d2dagrelayout"
+	"oss.terrastruct.com/d2/d2lib"
+	"oss.terrastruct.com/d2/lib/textmeasure"
+	"oss.terrastruct.com/util-go/assert"
+)
+
+func TestValidateTopLeft(t *testing.T) {
+	assertCompile(t, `
+container: {
+	a: {
+		top: 100
+		left: 100
+	}
+	b: {
+		top: 100
+		left: 100
+	}
+}
+`,
+		`4:3: invalid top/left overlapping with "b"
+8:3: invalid top/left overlapping with "a"`,
+	)
+
+	assertCompile(t, `
+container: {
+	a: {
+		top: 100
+		left: 100
+	}
+	b: {
+		top: 100
+		left: 200
+	}
+}
+`,
+		``,
+	)
+
+	assertCompile(t, `
+a: {
+	top: 100
+	left: 100
+}
+b: {
+	top: 101
+	left: 101
+}
+`,
+		`3:2: invalid top/left overlapping with "b"
+7:2: invalid top/left overlapping with "a"`,
+	)
+
+	assertCompile(t, `
+a: {
+	top: 100
+	left: 100
+}
+b: {
+	top: 99
+	left: 99
+}
+`,
+		`3:2: invalid top/left overlapping with "b"
+7:2: invalid top/left overlapping with "a"`,
+	)
+}
+
+func assertCompile(t *testing.T, text string, expErr string) {
+	ruler, _ := textmeasure.NewRuler()
+	defaultLayout := func(ctx context.Context, g *d2graph.Graph) error {
+		return d2dagrelayout.Layout(ctx, g, nil)
+	}
+	_, _, err := d2lib.Compile(context.Background(), text, &d2lib.CompileOptions{
+		Layout: defaultLayout,
+		Ruler:  ruler,
+	})
+	if expErr != "" {
+		assert.ErrorString(t, err, expErr)
+	} else {
+		assert.Success(t, err)
+	}
+}