package ui import ( "git.kirsle.net/go/render" ) // Place provides configuration fields for Frame.Place(). type Place struct { // X and Y coordinates for explicit location of widget within its parent. // This placement option trumps all others. Point render.Point // Place relative to an edge of the window. The widget will stick to the // edge of the window even as it resizes. Options are ignored if Point // is set. Top int Left int Right int Bottom int Center bool Middle bool } // Strategy returns the placement strategy for a Place config struct. // Returns 'Point' if a render.Point is used (even if zero, zero) // Returns 'Side' if the side values are set. func (p Place) Strategy() string { if p.Top != 0 || p.Left != 0 || p.Right != 0 || p.Bottom != 0 || p.Center || p.Middle { return "Side" } return "Point" } // placedWidget holds the data for a widget placed in a frame. type placedWidget struct { widget Widget place Place } // Place a widget into the frame. func (w *Frame) Place(child Widget, config Place) { w.placed = append(w.placed, placedWidget{ widget: child, place: config, }) w.Add(child) // Adopt the child widget so it can access the Frame. child.SetParent(w) } // computePlaced processes all the Place layout widgets in the Frame, // determining their X,Y location and whether they need to change. func (w *Frame) computePlaced(e render.Engine) { var ( frameSize = w.BoxSize() ) for _, row := range w.placed { // X,Y placement takes priority. switch row.place.Strategy() { case "Point": row.widget.MoveTo(row.place.Point) row.widget.Compute(e) case "Side": var moveTo render.Point // Compute the initial X,Y based on Top, Left, Right, Bottom. if row.place.Left > 0 { moveTo.X = row.place.Left } if row.place.Top > 0 { moveTo.Y = row.place.Top } if row.place.Right > 0 { moveTo.X = frameSize.W - row.widget.Size().W - row.place.Right } if row.place.Bottom > 0 { moveTo.Y = frameSize.H - row.widget.Size().H - row.place.Bottom } // Center and Middle aligned values override Left/Right, Top/Bottom // settings respectively. if row.place.Center { moveTo.X = frameSize.W - (w.Size().W / 2) - (row.widget.Size().W / 2) } if row.place.Middle { moveTo.Y = frameSize.H - (w.Size().H / 2) - (row.widget.Size().H / 2) } row.widget.MoveTo(moveTo) row.widget.Compute(e) } // If this widget itself has placed widgets, call its function too. if frame, ok := row.widget.(*Frame); ok { frame.computePlaced(e) } } }