zntg/ui/examples/03_dragdrop/dragdrop.go

123 lines
2.6 KiB
Go

package main
import (
"image/color"
"log"
"strings"
"time"
"opslag.de/schobers/geom"
_ "opslag.de/schobers/zntg/addons/dragdrop" // import drag & drop functionality
_ "opslag.de/schobers/zntg/sdlui" // import the renderer for the UI
"opslag.de/schobers/zntg/ui"
)
type dropFiles struct {
ui.StackPanel
ctx ui.Context
files *ui.Paragraph
ping *ping
}
type ping struct {
ui.OverlayBase
circle ui.Texture
position geom.PointF32
over bool
tick time.Time
}
func (p *ping) Render(ctx ui.Context) {
elapsed := time.Since(p.tick)
const animationDuration = 500 * time.Millisecond
if elapsed > animationDuration {
return
}
tint := color.Gray{Y: uint8(elapsed * 255 / animationDuration)}
center := geom.PtF32(float32(p.circle.Width()), float32(p.circle.Height())).Mul(.5)
ctx.Renderer().DrawTexturePointOptions(p.circle, p.position.Sub(center), ui.DrawOptions{Tint: tint})
ctx.Animate()
}
func (d *dropFiles) Handle(ctx ui.Context, e ui.Event) bool {
switch e := e.(type) {
case *ui.DisplayDragMoveEvent:
d.ping.tick = time.Now()
d.ping.position = geom.PtF32(e.X, e.Y)
d.ping.over = true
d.ctx.Animate()
return true
case *ui.DisplayDropEvent:
d.files.Text = "Files dropped:\n" + strings.Join(e.Files, "\n")
d.ping.tick = time.Now()
d.ping.position = geom.PtF32(e.X, e.Y)
d.ping.over = false
d.ctx.Animate()
return true
}
return d.StackPanel.Handle(ctx, e)
}
func newCircle() ui.ImageSource {
const side = 16
center := geom.PtF32(.5*side, .5*side)
return &ui.AlphaPixelImageSource{
ImageAlphaPixelTestFn: func(p geom.PointF32) uint8 {
dist := p.Distance(center)
if dist < 7 {
return 255
} else if dist > 8 {
return 0
}
return uint8((8 - dist) * 255 * 0.5)
},
Size: geom.Pt(side, side),
}
}
func (d *dropFiles) Init(ctx ui.Context) error {
d.ctx = ctx
_, err := ctx.Fonts().CreateFontPath("default", "../resources/font/OpenSans-Regular.ttf", 14)
if err != nil {
return err
}
d.files = ui.BuildParagraph("", nil)
pingCircle, err := ctx.Renderer().CreateTexture(newCircle())
if err != nil {
return err
}
d.ping = &ping{circle: pingCircle}
ctx.Overlays().AddOnTop("ping", d.ping, true)
d.Background = color.White
d.Children = []ui.Control{
&ui.Label{Text: "Drop files on this window!"},
d.files,
}
return nil
}
func run() error {
var render, err = ui.NewRendererDefault("Files Drop Example", 800, 600)
if err != nil {
return err
}
defer render.Destroy()
return ui.RunWait(render, ui.DefaultStyle(), &dropFiles{}, true)
}
func main() {
var err = run()
if err != nil {
log.Fatal(err)
}
}