Add about dialog and window for helping apps make a pretty about scre…

…en (#87)

Co-authored-by: Jacob Alzén <jacalz@tutanota.com>

README.md

@@ -216,6 +216,23 @@ m := NewMap()
 
 ![](img/map.png)
 
+## Dialogs
+
+### About
+
+A cool parallax about dialog that pulls data from the app metadata and includes
+some markup content and links at the bottom of the window/dialog.
+
+```go
+	docURL, _ := url.Parse("https://docs.fyne.io")
+	links := []*widget.Hyperlink{
+		widget.NewHyperlink("Docs", docURL),
+	}
+	dialog.ShowAboutWindow("Some **cool** stuff", links, a)
+```
+
+![](img/about.png)
+
 ## Data Binding
 
 Community contributed data sources for binding.

cmd/fyne-x/FyneApp.toml

@@ -0,0 +1,4 @@
+[Details]
+  Icon = "Icon.png"
+  Version = "0.1.0"
+  Build = 5

cmd/fyne-x/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"net/url"
+
+	"fyne.io/fyne/v2/app"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/widget"
+	"fyne.io/x/fyne/dialog"
+)
+
+func main() {
+	a := app.New()
+	w := a.NewWindow("Fyne-x demo")
+
+	docURL, _ := url.Parse("https://docs.fyne.io")
+	links := []*widget.Hyperlink{
+		widget.NewHyperlink("Docs", docURL),
+	}
+	w.SetContent(container.NewGridWithColumns(1,
+		widget.NewButton("About", func() {
+			dialog.ShowAbout("Some **cool** stuff", links, a, w)
+		}),
+		widget.NewButton("About window", func() {
+			dialog.ShowAboutWindow("Some **cool** stuff", links, a)
+		}),
+	))
+
+	w.ShowAndRun()
+}

dialog/about.go

@@ -0,0 +1,175 @@
+package dialog
+
+import (
+	"image/color"
+
+	"fyne.io/fyne/v2"
+	"fyne.io/fyne/v2/canvas"
+	"fyne.io/fyne/v2/container"
+	"fyne.io/fyne/v2/dialog"
+	"fyne.io/fyne/v2/layout"
+	"fyne.io/fyne/v2/theme"
+	"fyne.io/fyne/v2/widget"
+)
+
+// NewAbout creates a parallax about dialog using the app metadata along with the
+// markdown content and links passed into this method.
+// You should call Show on the returned dialog to display it.
+func NewAbout(content string, links []*widget.Hyperlink, a fyne.App, w fyne.Window) dialog.Dialog {
+	d := dialog.NewCustom("About", "OK", aboutContent(content, links, a), w)
+	d.Resize(fyne.NewSize(400, 360))
+
+	return d
+}
+
+// NewAboutWindow creates a parallax about window using the app metadata along with the
+// markdown content and links passed into this method.
+// You should call Show on the returned window to display it.
+func NewAboutWindow(content string, links []*widget.Hyperlink, a fyne.App) fyne.Window {
+	w := a.NewWindow("About")
+	w.SetContent(aboutContent(content, links, a))
+	w.Resize(fyne.NewSize(360, 300))
+
+	return w
+}
+
+// ShowAbout opens a parallax about dialog using the app metadata along with the
+// markdown content and links passed into this method.
+func ShowAbout(content string, links []*widget.Hyperlink, a fyne.App, w fyne.Window) {
+	d := NewAbout(content, links, a, w)
+	d.Show()
+}
+
+// ShowAboutWindow opens a parallax about window using the app metadata along with the
+// markdown content and links passed into this method.
+func ShowAboutWindow(content string, links []*widget.Hyperlink, a fyne.App) {
+	w := NewAboutWindow(content, links, a)
+	w.Show()
+}
+
+func aboutContent(content string, links []*widget.Hyperlink, a fyne.App) fyne.CanvasObject {
+	rich := widget.NewRichTextFromMarkdown(content)
+	footer := aboutFooter(links)
+
+	logo := canvas.NewImageFromResource(a.Metadata().Icon)
+	logo.FillMode = canvas.ImageFillContain
+	logo.SetMinSize(fyne.NewSize(128, 128))
+
+	appData := widget.NewRichTextFromMarkdown(
+		"## " + a.Metadata().Name + "\n**Version:** " + a.Metadata().Version)
+	centerText(appData)
+	space := canvas.NewRectangle(color.Transparent)
+	space.SetMinSize(fyne.NewSquareSize(theme.Padding() * 4))
+	body := container.NewVBox(
+		space,
+		logo,
+		appData,
+		container.NewCenter(rich))
+	scroll := container.NewScroll(body)
+
+	bgColor := withAlpha(theme.BackgroundColor(), 0xe0)
+	shadowColor := withAlpha(theme.BackgroundColor(), 0x33)
+
+	underlay := canvas.NewImageFromResource(a.Metadata().Icon)
+	bg := canvas.NewRectangle(bgColor)
+	underlayer := underLayout{}
+	slideBG := container.New(underlayer, underlay)
+	footerBG := canvas.NewRectangle(shadowColor)
+	watchTheme(bg, footerBG, a)
+
+	underlay.Resize(fyne.NewSize(512, 512))
+	scroll.OnScrolled = func(p fyne.Position) {
+		underlayer.offset = -p.Y / 3
+		underlayer.Layout(slideBG.Objects, slideBG.Size())
+	}
+
+	bgClip := container.NewScroll(slideBG)
+	bgClip.Direction = container.ScrollNone
+	return container.NewStack(container.New(unpad{top: true}, bgClip, bg),
+		container.NewBorder(nil,
+			container.NewStack(footerBG, footer), nil, nil,
+			container.New(unpad{top: true, bottom: true}, scroll)))
+}
+
+func aboutFooter(links []*widget.Hyperlink) fyne.CanvasObject {
+	footer := container.NewHBox(layout.NewSpacer())
+	for i, a := range links {
+		footer.Add(a)
+		if i < len(links)-1 {
+			footer.Add(widget.NewLabel("-"))
+		}
+	}
+	footer.Add(layout.NewSpacer())
+
+	return footer
+}
+
+func centerText(rich *widget.RichText) {
+	for _, s := range rich.Segments {
+		if text, ok := s.(*widget.TextSegment); ok {
+			text.Style.Alignment = fyne.TextAlignCenter
+		}
+	}
+}
+
+func watchTheme(bg, footer *canvas.Rectangle, a fyne.App) {
+	listen := make(chan fyne.Settings)
+	fyne.CurrentApp().Settings().AddChangeListener(listen)
+	go func() {
+		for range listen {
+			bgColor := withAlpha(theme.BackgroundColor(), 0xe0)
+			bg.FillColor = bgColor
+			bg.Refresh()
+
+			shadowColor := withAlpha(theme.BackgroundColor(), 0x33)
+			footer.FillColor = shadowColor
+			footer.Refresh()
+		}
+	}()
+}
+
+func withAlpha(c color.Color, alpha uint8) color.Color {
+	r, g, b, _ := c.RGBA()
+	return color.NRGBA{R: uint8(r >> 8), G: uint8(g >> 8), B: uint8(b >> 8), A: alpha}
+}
+
+type underLayout struct {
+	offset float32
+}
+
+func (u underLayout) Layout(objs []fyne.CanvasObject, size fyne.Size) {
+	under := objs[0]
+	left := size.Width/2 - under.Size().Width/2
+	under.Move(fyne.NewPos(left, u.offset-50))
+}
+
+func (u underLayout) MinSize(_ []fyne.CanvasObject) fyne.Size {
+	return fyne.Size{}
+}
+
+type unpad struct {
+	top, bottom bool
+}
+
+func (u unpad) Layout(objs []fyne.CanvasObject, s fyne.Size) {
+	pad := theme.Padding()
+	var pos fyne.Position
+	if u.top {
+		pos.Y = -pad
+	}
+	size := s
+	if u.top {
+		size.Height += pad
+	}
+	if u.bottom {
+		size.Height += pad
+	}
+	for _, o := range objs {
+		o.Move(pos)
+		o.Resize(size)
+	}
+}
+
+func (u unpad) MinSize(_ []fyne.CanvasObject) fyne.Size {
+	return fyne.NewSize(100, 100)
+}