Merge pull request #343 from gucio321/alignment-row-bug

alignment consider a case when *RowWidget is a part of Layout

Alignment.go

@@ -24,10 +24,9 @@ type AlignmentSetter struct {
 // Align sets widgets alignment.
 // usage: see examples/align
 //
-// FIXME: DONOT put giu widgets inside of CustomWidget function in
-// Align setter. CustomWidgets will be skip in alignment process
-//
-// BUG: DatePickerWidget doesn't work properly
+// - BUG: DatePickerWidget doesn't work properly
+// - BUG: there is some bug with SelectableWidget
+// - BUG: ComboWidget and ComboCustomWidgets doesn't work properly
 func Align(at AlignmentType) *AlignmentSetter {
 	return &AlignmentSetter{
 		alignType: at,
@@ -53,34 +52,28 @@ func (a *AlignmentSetter) Build() {
 		return
 	}
 
-	// WORKAROUND: get widgets widths rendering them with 100% transparency
-	// to align them later
 	a.layout.Range(func(item Widget) {
 		// if item is inil, just skip it
 		if item == nil {
 			return
 		}
 
-		// exclude some widgets from alignment process
-		// nolint:gocritic // could have more cases later
 		switch item.(type) {
+		// ok, it doesn't make sense to align again :-)
+		case *AlignmentSetter:
+			item.Build()
+			return
 		case *CustomWidget:
 			item.Build()
 			return
+		// there is a bug with selectables and combos, so skip them for now
+		case *SelectableWidget, *ComboWidget, *ComboCustomWidget:
+			item.Build()
+			return
 		}
 
-		// save cursor position before rendering
 		currentPos := GetCursorPos()
-
-		// render widget in `dry` mode
-		imgui.PushStyleVarFloat(imgui.StyleVarAlpha, 0)
-		item.Build()
-		imgui.PopStyleVar()
-
-		// save widget's width
-		size := imgui.GetItemRectSize()
-		w := size.X
-
+		w := GetWidgetWidth(item)
 		availableW, _ := GetAvailableRegion()
 
 		// set cursor position to align the widget
@@ -99,3 +92,61 @@ func (a *AlignmentSetter) Build() {
 		item.Build()
 	})
 }
+
+// GetWidgetWidth returns a width of widget
+// NOTE: THIS IS A BETA SOLUTION and may contain bugs
+// in most cases, you may want to use supported by imgui GetItemRectSize.
+// There is an upstream issue for this problem:
+// https://github.com/ocornut/imgui/issues/3714
+//
+// This function is just a workaround used in giu.
+//
+// NOTE: user-definied widgets, which contains more than one
+// giu widget will be processed incorrectly (only width of the last built
+// widget will be processed)
+//
+// here is a list of known bugs:
+// - BUG: Custom widgets are skipped, so if user put some widgets
+// inside of CustomWidget, its sizes will not be returned
+//
+// if you find anything else, please report it on
+// https://github.com/AllenDang/giu Any contribution is appreciated!
+func GetWidgetWidth(w Widget) (result float32) {
+	// save cursor position before rendering
+	currentPos := GetCursorPos()
+	// enumerate some special cases
+	switch typed := w.(type) {
+	// Don't process custom widgets
+	case *CustomWidget:
+		return 0
+	// when row, sum all widget's sizes (adding spacing)
+	case *RowWidget:
+		isFirst := true
+		typed.widgets.Range(func(r Widget) {
+			result += GetWidgetWidth(r)
+			if !isFirst {
+				spacing, _ := GetItemSpacing()
+				result += spacing
+			} else {
+				isFirst = false
+			}
+		})
+		return result
+	// panic if layout - cannot calculate width of multiple widgets
+	case Layout, *Layout:
+		panic("GetWidgetWidth: requires Widget argument, but []Widget (Layout) got")
+	default:
+		// render widget in `dry` mode
+		imgui.PushStyleVarFloat(imgui.StyleVarAlpha, 0)
+		w.Build()
+		imgui.PopStyleVar()
+
+		// save widget's width
+		size := imgui.GetItemRectSize()
+		result = size.X
+	}
+
+	SetCursorPos(currentPos)
+
+	return result
+}

examples/align/align.go

@@ -24,6 +24,13 @@ func loop() {
 			},
 			giu.Label("I'm the last label"),
 		),
+		giu.Label("Buttons in row:"),
+		giu.Align(giu.AlignCenter).To(
+			giu.Row(
+				giu.Button("button 1"),
+				giu.Button("button 2"),
+			),
+		),
 	)
 }