Fix layout edge cases and gradient generation

Improves Block.SetRect to handle cases where padding exceeds block size, preventing invalid rectangles. Refactors Grid.Draw to correctly calculate item boundaries and prevent overflow. Adds a guard in GenerateGradient to return an empty slice for non-positive lengths.

Author: metaspartan

block.go

@@ -285,12 +285,23 @@ func (b *Block) drawTitles(buf *Buffer) {
 // SetRect implements the Drawable interface.
 func (b *Block) SetRect(x1, y1, x2, y2 int) {
 	b.Rectangle = image.Rect(x1, y1, x2, y2)
-	b.Inner = image.Rect(
-		b.Min.X+1+b.PaddingLeft,
-		b.Min.Y+1+b.PaddingTop,
-		b.Max.X-1-b.PaddingRight,
-		b.Max.Y-1-b.PaddingBottom,
-	)
+	innerMinX := b.Min.X + 1 + b.PaddingLeft
+	innerMinY := b.Min.Y + 1 + b.PaddingTop
+	innerMaxX := b.Max.X - 1 - b.PaddingRight
+	innerMaxY := b.Max.Y - 1 - b.PaddingBottom
+
+	if innerMinX > innerMaxX {
+		mid := b.Min.X + (b.Max.X-b.Min.X)/2
+		innerMinX = mid
+		innerMaxX = mid
+	}
+	if innerMinY > innerMaxY {
+		mid := b.Min.Y + (b.Max.Y-b.Min.Y)/2
+		innerMinY = mid
+		innerMaxY = mid
+	}
+
+	b.Inner = image.Rect(innerMinX, innerMinY, innerMaxX, innerMaxY)
 }
 
 // GetRect implements the Drawable interface.

grid.go

@@ -100,25 +100,24 @@ func (g *Grid) setHelper(item GridItem, parentWidthRatio, parentHeightRatio floa
 }
 
 func (g *Grid) Draw(buf *Buffer) {
-	width := float64(g.Dx()) + 1
-	height := float64(g.Dy()) + 1
 
 	for _, item := range g.Items {
 		entry, _ := item.Entry.(Drawable)
 
-		x := int(width*item.XRatio) + g.Min.X
-		y := int(height*item.YRatio) + g.Min.Y
-		w := int(width * item.WidthRatio)
-		h := int(height * item.HeightRatio)
+		xStart := int(float64(g.Dx())*item.XRatio) + g.Min.X
+		yStart := int(float64(g.Dy())*item.YRatio) + g.Min.Y
 
-		if x+w > g.Dx() {
-			w--
+		xEnd := int(float64(g.Dx())*(item.XRatio+item.WidthRatio)) + g.Min.X
+		yEnd := int(float64(g.Dy())*(item.YRatio+item.HeightRatio)) + g.Min.Y
+
+		if xEnd > g.Max.X {
+			xEnd = g.Max.X
 		}
-		if y+h > g.Dy() {
-			h--
+		if yEnd > g.Max.Y {
+			yEnd = g.Max.Y
 		}
 
-		entry.SetRect(x, y, x+w, y+h)
+		entry.SetRect(xStart, yStart, xEnd, yEnd)
 
 		entry.Lock()
 		entry.Draw(buf)

style_gradient.go

@@ -25,6 +25,9 @@ func InterpolateColor(c1, c2 Color, step, steps int) Color {
 }
 
 func GenerateGradient(start, end Color, length int) []Color {
+	if length <= 0 {
+		return []Color{}
+	}
 	colors := make([]Color, length)
 	for i := 0; i < length; i++ {
 		colors[i] = InterpolateColor(start, end, i, length)