add layout from Keitio

1 files changed, 115 insertions, 0 deletions

diff --git a/gui/layout/grid.go b/gui/layout/grid.go
new file mode 100644
index 0000000..324353c
--- /dev/null
+++ b/gui/layout/grid.go
@@ -0,0 +1,115 @@
+package layout
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"log"
+
+	"volute/gui"
+)
+
+var _ Layout = Grid{}
+
+// Grid represents a grid with rows and columns in each row.
+// Each row can be a different length.
+type Grid struct {
+	// Rows represents the number of childs of each row.
+	Rows []int
+	// Background represents the background of the grid as a uniform color.
+	Background color.Color
+	// Gap represents the grid gap, equal on all sides.
+	Gap int
+	// Split represents the way the space is divided among the columns in each row.
+	Split SplitFunc
+	// SplitRows represents the way the space is divided among the rows.
+	SplitRows SplitFunc
+
+	Margin      int
+	Border      int
+	BorderColor color.Color
+
+	// Flip represents the orientation of the grid.
+	// When false, rows are spread in the Y axis and columns in the X axis.
+	// When true, rows are spread in the X axis and columns in the Y axis.
+	Flip bool
+}
+
+func (g Grid) redraw(drw draw.Image, bounds image.Rectangle) {
+	col := g.Background
+	if col == nil {
+		col = color.Black
+	}
+	if g.Border > 0 {
+		bcol := g.BorderColor
+		if bcol == nil {
+			bcol = color.Black
+		}
+		draw.Draw(drw, bounds, image.NewUniform(bcol), image.ZP, draw.Src)
+	}
+	draw.Draw(drw, bounds.Inset(g.Border), image.NewUniform(col), image.ZP, draw.Src)
+}
+
+func (g Grid) Intercept(env gui.Env) gui.Env {
+	return RedrawIntercepter{g.redraw}.Intercept(env)
+}
+
+func (g Grid) Lay(bounds image.Rectangle) []image.Rectangle {
+	gap := g.Gap
+	rows := g.Rows
+	splitMain := g.Split
+	if splitMain == nil {
+		splitMain = EvenSplit
+	}
+	splitSec := g.SplitRows
+	if splitSec == nil {
+		splitSec = EvenSplit
+	}
+	margin := g.Margin
+	flip := g.Flip
+	if margin+gap < 0 {
+		log.Println("Grid goes out of bounds")
+	}
+	if margin+gap < g.Border {
+		log.Println("Grid border will not be shown properly")
+	}
+
+	ret := make([]image.Rectangle, 0)
+
+	// Sorry it's not very understandable
+	var H, W int
+	var mX, mY int
+	if flip {
+		H = bounds.Dx()
+		W = bounds.Dy()
+		mX = bounds.Min.Y
+		mY = bounds.Min.X
+	} else {
+		H = bounds.Dy()
+		W = bounds.Dx()
+		mX = bounds.Min.X
+		mY = bounds.Min.Y
+	}
+	rowsH := splitSec(len(rows), H-(gap*(len(rows)+1))-margin*2)
+	var X int
+	var Y int
+	Y = gap + mY + margin
+	for y, cols := range rows {
+		h := rowsH[y]
+		colsW := splitMain(cols, W-(gap*(cols+1))-margin*2)
+		X = gap + mX + margin
+		for _, w := range colsW {
+			var r image.Rectangle
+			if flip {
+				r = image.Rect(Y, X, Y+h, X+w)
+			} else {
+				r = image.Rect(X, Y, X+w, Y+h)
+			}
+			ret = append(ret, r)
+			X += gap + w
+		}
+		Y += gap + h
+	}
+
+	return ret
+}