debugui: add Context.Loop

Updates #43

Author: hajimehoshi

dropdown.go

@@ -5,7 +5,6 @@ package debugui
 
 import (
 	"image"
-	"strconv"
 
 	"github.com/hajimehoshi/ebiten/v2"
 )
@@ -58,17 +57,16 @@ func (c *Context) dropdown(selectedIndex *int, options []string, id widgetID) (E
 			}
 			c.SetGridLayout([]int{-1}, nil)
 
-			for i, option := range options {
-				c.IDScope(strconv.Itoa(i), func() {
-					c.Button(option).On(func() {
-						*selectedIndex = i
-						if cnt := c.container(dropdownID, 0); cnt != nil {
-							// Start the close delay timer (0.1 seconds at TPS rate)
-							cnt.dropdownCloseDelay = ebiten.TPS() / 10
-						}
-					})
+			c.Loop(len(options), func(i int) {
+				option := options[i]
+				c.Button(option).On(func() {
+					*selectedIndex = i
+					if cnt := c.container(dropdownID, 0); cnt != nil {
+						// Start the close delay timer (0.1 seconds at TPS rate)
+						cnt.dropdownCloseDelay = ebiten.TPS() / 10
+					}
 				})
-			}
+			})
 		}); err != nil {
 			return nil, err
 		}

example/gallery/ui.go

@@ -216,12 +216,10 @@ func (g *Game) logWindow(ctx *debugui.Context) {
 func (g *Game) buttonWindows(ctx *debugui.Context) {
 	ctx.Window("Button Windows", image.Rect(350, 300, 650, 500), func(layout debugui.ContainerLayout) {
 		ctx.SetGridLayout([]int{-1, -1, -1, -1}, nil)
-		for i := 0; i < 100; i++ {
-			ctx.IDScope(fmt.Sprintf("%d", i), func() {
-				ctx.Button("Button").On(func() {
-					g.writeLog(fmt.Sprintf("Pressed button %d in Button Window", i))
-				})
+		ctx.Loop(100, func(i int) {
+			ctx.Button("Button").On(func() {
+				g.writeLog(fmt.Sprintf("Pressed button %d in Button Window", i))
 			})
-		}
+		})
 	})
 }

id.go

@@ -18,10 +18,27 @@ func caller() uintptr {
 	return pc
 }
 
+// Loop creates a loop to iterate by the given count.
+// Loop creates a unique ID scope for each iteration.
+func (c *Context) Loop(count int, f func(i int)) {
+	pc := caller()
+	c.idStack = append(c.idStack, widgetID(fmt.Sprintf("caller:%d", pc)))
+	defer func() {
+		c.idStack = slices.Delete(c.idStack, len(c.idStack)-1, len(c.idStack))
+	}()
+	for i := range count {
+		c.idStack = append(c.idStack, widgetID(fmt.Sprintf("string:%d", i)))
+		f(i)
+		c.idStack = slices.Delete(c.idStack, len(c.idStack)-1, len(c.idStack))
+	}
+}
+
 // IDScope creates a new scope for widget IDs.
 // IDScope creates a unique scope based on the caller's position and the given name string.
 //
 // IDScope is useful when you want to create multiple widgets at the same position e.g. in a for loop.
+//
+// IDScope is a low level API. For a simple loop, use [Loop] instead.
 func (c *Context) IDScope(name string, f func()) {
 	pc := caller()
 	c.idStack = append(c.idStack, widgetID(fmt.Sprintf("caller:%d", pc)))