1 files changed, 70 insertions, 0 deletions
diff --git a/engine/UI/FlexElement.go b/engine/UI/FlexElement.go
new file mode 100644
index 0000000..233b89f
--- /dev/null
+++ b/engine/UI/FlexElement.go
@@ -0,0 +1,70 @@
+package ui
+
+import rl "github.com/gen2brain/raylib-go/raylib"
+
+// A dynamically shrinking element that contains other elements
+type flexElement interface {
+	GetElements() []UIElement
+	GetSpacing() float32
+	RecalculateCache(*rl.Rectangle)
+}
+
+// Calculates the element weight to pixel ratio
+func getWeightToPixelsRatio(base flexElement, totalSpace float32) float32 { 
+	var elements = base.GetElements()
+	var totalWeights float32 = 0
+	for _, v := range elements {
+		totalWeights += v.GetOccupationWeight()
+	}
+	var spacingPx = totalSpace * base.GetSpacing()
+	var totalSpacing = float32(len(elements) - 1) * spacingPx
+	if totalSpace < 0 {
+		totalSpace = 0
+	}
+	return (totalSpace - totalSpacing) / totalWeights
+}
+
+
+type layoutCache struct {
+	// The screen resolution the cache was calculated for
+	ScreenResolution rl.Vector2
+	// The resolution the cache was calculated for
+	SpanResolution rl.Vector2
+	// Horizontal offset in pixels
+	OffsetX float32
+	// Vertical offset in pixels
+	OffsetY float32
+	// The X size of a row
+	Width float32
+	// The Y size of a row
+	Height float32
+	// The horizontal start and end of each row. 
+	// Index of an array is representive with row index
+	RowLocations []rl.Vector2
+}
+
+func (base layoutCache) IsValid() bool {
+	return base.ScreenResolution.X == float32(rl.GetScreenWidth()) && 
+		base.ScreenResolution.Y == float32(rl.GetScreenHeight())
+}
+
+func (base *layoutCache) CalculateOffsets(X float32, Y float32, paddingX float32, paddingY float32) {
+	base.OffsetX = (X * paddingX)
+	base.OffsetY = (Y * paddingY)
+	base.Width = X - base.OffsetX * 2
+	base.Height = Y - base.OffsetY * 2
+}
+
+func (base *layoutCache) CalculateRowsLocations (rows []UIElement, WeightToPixels float32, spacing float32, baseOffset float32) {
+	base.RowLocations = make([]rl.Vector2, len(rows))
+	var ptr float32 = baseOffset
+	for i, v := range rows {
+		// The spacing should be accounted for in the WeightToPixels param
+		var elemSpace = (WeightToPixels * v.GetOccupationWeight())
+		base.RowLocations[i] = rl.Vector2 {
+			X: ptr,
+			Y: elemSpace,
+		}
+		ptr += elemSpace + spacing
+	}
+}