Advanced Color Picker in Fyne2.0 show Black as using my customed theme's primary color which is set before.

[apieceof]

Describe the bug:

Advanced Color Picker in Fyne2.0 won't show my customed theme's primary color which is set before.

To Reproduce:

Steps to reproduce the behaviour:

1. Click on 'Select Theme Color: ' to choose my customed theme which is "Blue","Orange" or "Yellow"
2. Click on 'Customed Theme Color Picker:'
3. Click on 'Advanced'
4. See error

Screenshots:

Example code:

func DemoDialog (tl string, win fyne.Window) {
        isFirstTime := true
	pickChg:= false
	customColor = color.RGBA{A: 255}

	//Select box
	selLabel := widget.NewLabelWithStyle("Select Theme Color: ", fyne.TextAlignCenter, fyne.TextStyle{
		Bold:      false,
		Italic:    false,
		Monospace: true,
	})
	colorSelect = widget.NewSelect([]string{"Light", "Dark", "Blue", "Orange", "Yellow"}, nil)
	colorSelect.SetSelected("Light")

	//Select box onChanged func
	colorSelect.OnChanged = func(value string) {
		selectColor = SelectTheme(colorSelect.Selected, isFirstTime, nil)
		r, g, b, _ := (selectColor).RGBA()
		fmt.Println(r>>8,g>>8,b>>8)
		isFirstTime = false
		pickChg = false
	}

	//Advanced color picker
	advButton := widget.NewButton( "Customed Theme Color Picker: ", func() {
		picker := dialog.NewColorPicker("Pick a Color", "Please pick your color:", func(c color.Color) {
			if customColor != c {
				SelectTheme("Custom", isFirstTime, c)
				isFirstTime = false
			}
			pickChg = true
			customColor = c
		}, win)
		picker.Advanced = true
		picker.Show()})

	//
	selBox := container.NewVBox(selLabel, colorSelect)
	cusBox := container.NewVBox(advButton)

	//
	target := container.NewHBox(selBox, cusBox)

	set := dialog.NewCustomConfirm(tl, "Apply", "Exit", target, func( applyClicked bool ){
		if !applyClicked && !isFirstTime {
			//restore to current
			RestoreTheme()
		}
		if applyClicked  {
			if !pickChg {
				SelectTheme(colorSelect.Selected, isFirstTime, customColor)
			} else {
				SelectTheme("Custom", isFirstTime, customColor)
			}
		}
		isFirstTime = true
	}, win)
	set.Show()
}

func main() {
	// Main menu
	fileMenu := fyne.NewMenu("File", fyne.NewMenuItem("Log", func() { fmt.Println("File -> Log") }))
	helpMenu := fyne.NewMenu("Help", fyne.NewMenuItem("About", func() { fmt.Println("Help -> 
                             About") }))
	settingMenu := fyne.NewMenu("Settings",  fyne.NewMenuItem("Demo Code", func() {
		screen.DemoDialog("Demo", window)}
           ))
	mainMenu := fyne.NewMainMenu(fileMenu, helpMenu, settingMenu)
	window.SetMainMenu(mainMenu)
}
**Where** SelectTheme will go to my customed Theme to replace fyne.Theme interface

func SelectTheme (sel string, shouldBackup bool, customCol color.Color) color.Color{
	if shouldBackup {
		//save cur theme to restore
		frontglobal.BackupTheme = frontglobal.SupTheme
	}
	switch sel {
	default:
		frontglobal.SupTheme.SetThemeParameter(0)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	case "Dark":
		frontglobal.SupTheme.SetThemeParameter(1)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	case "Blue":
		frontglobal.SupTheme.SetThemeParameter(2)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	case "Orange":
		frontglobal.SupTheme.SetThemeParameter(3)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	case "Yellow":
		frontglobal.SupTheme.SetThemeParameter(4)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	case "Custom":
		frontglobal.SupTheme.PrimaryColorSup = customCol
		frontglobal.SupTheme.SetThemeParameter(5)
		fyne.CurrentApp().Settings().SetTheme(frontglobal.SupTheme)
	}
	return frontglobal.SupTheme.PrimaryColorSup
}

Device (please complete the following information):

• OS: Ubuntu
• Version: 18.04.4 LTS
• Go version: go1.15.5 linux/amd64
• Fyne version: 2.0

[andydotxyz]

Please can you provide a minimal code that exhibits the error and that we can compile and run?
There is a chance that the problem you are describing is caused by custom theme code not in this report.

[apieceof]

Hi @andydotxyz,

Here is the short code for more clear explanation of my question:

package main

import (
	"fyne.io/fyne/v2"
	"fyne.io/fyne/v2/app"
	"fyne.io/fyne/v2/container"
	"fyne.io/fyne/v2/dialog"
	"fyne.io/fyne/v2/theme"
	"fyne.io/fyne/v2/widget"
	"image/color"
)

type TestTheme struct {}

func (TestTheme) Color(a fyne.ThemeColorName, b fyne.ThemeVariant) color.Color {
	if a == theme.ColorNamePrimary {
		return color.RGBA{R: 100, G: 100, B: 100, A: 255}
	}
	return theme.DarkTheme().Color(a, b)
}
func (TestTheme) Font(a fyne.TextStyle) fyne.Resource {
	return theme.DarkTheme().Font(a)
}
func (TestTheme) Icon(a fyne.ThemeIconName) fyne.Resource {
	return theme.DarkTheme().Icon(a)
}
func (TestTheme) Size(a fyne.ThemeSizeName) float32 {
	return theme.DarkTheme().Size(a)
}

func main() {
	window := app.NewWithID("example").NewWindow("example")
	settingMenu := fyne.NewMenu("Settings",  fyne.NewMenuItem("Demo Code", func() {
		SettingDialog("Demo", window)},
	))
	mainMenu := fyne.NewMainMenu(settingMenu)
	window.SetMainMenu(mainMenu)
	window.Resize(fyne.NewSize(800, 800))
	fyne.CurrentApp().Settings().SetTheme(TestTheme{})
	window.ShowAndRun()
}

func SettingDialog(tl string, win fyne.Window) {
	//Advanced color picker
	advButton := widget.NewButton( "Test", func() {
		picker := dialog.NewColorPicker("Pick a Color", "Please pick your color:", func(color.Color) {
		}, win)
		picker.Advanced = true
		picker.Show()
	})
	cusBox := container.NewVBox(advButton)
	set := dialog.NewCustomConfirm(tl, "Apply", "Exit", cusBox, nil, win)
	set.Show()
}

[andydotxyz]

Great, thanks - I can see the issue now

[andydotxyz]

It turns out to be an issue with our un-multiply-alpha code.
You can fix this in your code until we update by returning NRGBA instead of RGBA (i.e. not-pre-multiplied).

[andydotxyz]

Feel free to test that fix @apieceof :)