From 02ca997488c0b89d86636552071ab2961b6d590a Mon Sep 17 00:00:00 2001
From: faiface <faiface2202@gmail.com>
Date: Thu, 2 May 2019 17:42:59 +0200
Subject: examples: add paint example

---
 examples/paint/main.go | 131 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 131 insertions(+)
 create mode 100644 examples/paint/main.go

diff --git a/examples/paint/main.go b/examples/paint/main.go
new file mode 100644
index 0000000..57adeb4
--- /dev/null
+++ b/examples/paint/main.go
@@ -0,0 +1,131 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+
+	"github.com/faiface/gui"
+	"github.com/faiface/gui/win"
+	"github.com/faiface/mainthread"
+	"github.com/fogleman/gg"
+)
+
+func ColorPicker(env gui.Env, pick chan<- color.Color, r image.Rectangle, clr color.Color) {
+	env.Draw() <- func(drw draw.Image) image.Rectangle {
+		draw.Draw(drw, r, &image.Uniform{clr}, r.Min, draw.Src)
+		return r
+	}
+
+	for event := range env.Events() {
+		var x, y int
+		switch {
+		case event.Matches("mo/down/%d/%d", &x, &y):
+			if image.Pt(x, y).In(r) {
+				pick <- clr
+			}
+		}
+	}
+
+	close(env.Draw())
+}
+
+func Canvas(env gui.Env, pick <-chan color.Color, r image.Rectangle) {
+	canvas := image.NewRGBA(r)
+	draw.Draw(canvas, r, image.White, r.Min, draw.Src)
+	dc := gg.NewContextForRGBA(canvas)
+
+	env.Draw() <- func(drw draw.Image) image.Rectangle {
+		draw.Draw(drw, r, canvas, r.Min, draw.Src)
+		return r
+	}
+
+	var (
+		clr     = color.Color(color.Black)
+		pressed = false
+		px, py  = 0, 0
+	)
+
+	for {
+		select {
+		case clr = <-pick:
+
+		case event, ok := <-env.Events():
+			if !ok {
+				close(env.Draw())
+				return
+			}
+
+			var x, y int
+			switch {
+			case event.Matches("mo/down/%d/%d", &x, &y):
+				if image.Pt(x, y).In(r) {
+					pressed = true
+					px, py = x, y
+				}
+
+			case event.Matches("mo/up/%d/%d", &x, &y):
+				pressed = false
+
+			case event.Matches("mo/move/%d/%d", &x, &y):
+				if pressed {
+					x0, y0, x1, y1 := px, py, x, y
+					px, py = x, y
+
+					env.Draw() <- func(drw draw.Image) image.Rectangle {
+						dc.SetColor(clr)
+						dc.SetLineCapRound()
+						dc.SetLineWidth(5)
+						dc.DrawLine(float64(x0), float64(y0), float64(x1), float64(y1))
+						dc.Stroke()
+						rect := image.Rect(x0, y0, x1, y1)
+						rect.Min.X -= 5
+						rect.Min.Y -= 5
+						rect.Max.X += 5
+						rect.Max.Y += 5
+						draw.Draw(drw, rect, canvas, rect.Min, draw.Src)
+						return rect
+					}
+				}
+			}
+		}
+	}
+}
+
+func run() {
+	w, err := win.New(win.Title("Paint"), win.Size(800, 600))
+	if err != nil {
+		panic(err)
+	}
+
+	mux, env := gui.NewMux(w)
+
+	pick := make(chan color.Color)
+
+	for i, clr := range []color.Color{
+		color.RGBA{255, 0, 0, 255},
+		color.RGBA{255, 255, 0, 255},
+		color.RGBA{0, 255, 0, 255},
+		color.RGBA{0, 255, 255, 255},
+		color.RGBA{0, 0, 255, 255},
+		color.RGBA{255, 0, 255, 255},
+		color.RGBA{255, 255, 255, 255},
+		color.RGBA{0, 0, 0, 255},
+	} {
+		go ColorPicker(mux.MakeEnv(), pick, image.Rect(750, i*75, 800, (i+1)*75), clr)
+	}
+
+	go Canvas(mux.MakeEnv(), pick, image.Rect(0, 0, 750, 600))
+
+	for event := range env.Events() {
+		switch {
+		case event.Matches("wi/close"):
+			close(env.Draw())
+			return
+		}
+	}
+}
+
+func main() {
+	mainthread.Run(run)
+}
-- 
cgit v1.2.3