add linear progress bar

Sources/CoffeeCraft/LinearProgressBar.swift

@@ -0,0 +1,54 @@
+import SwiftUI
+
+public struct LinearProgressBar: View {
+    let value: CGFloat
+    let width: CGFloat
+    let height: CGFloat
+    let cornerRadius: CGFloat
+    let foreground: Color
+    let background: Color
+    
+    /// Creates a linear progress bar view
+    /// - Parameters:
+    ///   - value: the amount of progress ranging from `0.0` to `1.0`
+    ///   - width: the width of the progress bar
+    ///   - height: the height of the progress bar, defaults to `4`
+    ///   - cornerRadius: the corner radius of the progress bar, defaults to `height/2`
+    ///   - foreground: progress bar foreground color, defaults to `accentColor`
+    ///   - background: progress bar background color, defaults to `gray`
+    public init(value: CGFloat, width: CGFloat, height: CGFloat = 4, cornerRadius: CGFloat? = nil, foreground: Color = Color.accentColor, background: Color = Color.gray) {
+        
+        self.value = value
+        self.width = width
+        self.height = height
+        self.foreground = foreground
+        self.background = background
+        
+        if let cornerRadius = cornerRadius {
+            self.cornerRadius = cornerRadius
+        } else {
+            self.cornerRadius = height / 2
+        }
+    }
+    
+    public var body: some View {
+        ZStack {
+            RoundedRectangle(cornerRadius: cornerRadius)
+                .fill(background)
+                .frame(height: height)
+            HStack {
+                RoundedRectangle(cornerRadius: 2)
+                    .fill(foreground)
+                    .frame(width: width * value, height: height)
+                Spacer()
+            }
+        }
+        .frame(width: width)
+    }
+}
+
+struct LinearProgressBar_Previews: PreviewProvider {
+    static var previews: some View {
+        LinearProgressBar(value: 0.5, width: 200)
+    }
+}