added layout basics

1 files changed, 64 insertions, 0 deletions

diff --git a/examples/layout/button.go b/examples/layout/button.go
new file mode 100644
index 0000000..6c907e3
--- /dev/null
+++ b/examples/layout/button.go
@@ -0,0 +1,64 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"log"
+
+	"github.com/faiface/gui"
+	"github.com/faiface/gui/win"
+)
+
+func Button(env gui.Env, theme *Theme, text string, action func()) {
+	textImg := MakeTextImage(text, theme.Face, theme.Text)
+
+	redraw := func(r image.Rectangle, over, pressed bool) func(draw.Image) image.Rectangle {
+		return func(drw draw.Image) image.Rectangle {
+			var clr color.Color
+			if pressed {
+				clr = theme.ButtonDown
+			} else if over {
+				clr = theme.ButtonOver
+			} else {
+				clr = theme.ButtonUp
+			}
+			draw.Draw(drw, r, &image.Uniform{clr}, image.ZP, draw.Src)
+			DrawCentered(drw, r, textImg, draw.Over)
+			return r
+		}
+	}
+
+	var (
+		r       image.Rectangle
+		over    bool
+		pressed bool
+	)
+
+	for e := range env.Events() {
+		switch e := e.(type) {
+		case gui.Resize:
+			r = e.Rectangle
+			log.Print("button ", e)
+			env.Draw() <- redraw(r, over, pressed)
+
+		case win.MoDown:
+			newPressed := e.Point.In(r)
+			if newPressed != pressed {
+				pressed = newPressed
+				env.Draw() <- redraw(r, over, pressed)
+			}
+
+		case win.MoUp:
+			if pressed {
+				if e.Point.In(r) {
+					action()
+				}
+				pressed = false
+				env.Draw() <- redraw(r, over, pressed)
+			}
+		}
+	}
+
+	close(env.Draw())
+}