Make text in a label flash

General
1

I’m trying to make text in a label flash on screen when a button is pressed and am having problems…
It seems a straight forward thing to do using the Label1.TextColor property but I cant seem to make it work
Any takers?

2

Platform? How are you going about it currently? Remember that interface updates don’t happen until the end of a method, so if you’re not using a timer your interface updates are happening all at once so it’s blinking faster than you see.

Without knowing the specifics of your usage, I have to recommend against flashing text for multiple accessibility reasons.

3

[quote=299272:@Tim Parnell]Platform? How are you going about it currently? Remember that interface updates don’t happen until the end of a method, so if you’re not using a timer your interface updates are happening all at once so it’s blinking faster than you see.

Without knowing the specifics of your usage, I have to recommend against flashing text for multiple accessibility reasons.[/quote]

Platform - MAC Desktop
Im using for and next loops to slow down the colour change between 2 colours (without any luck)
Its just a slow flash Im looking for in order to get the attention of the user

4

That’s your problem right there. Interface updates don’t happen until the end of the method, so all of the on and off you set during the loop happens all at once and you only see the end result. Set it up with a timer.

5

For next is an old fashion programming style totally unusable on an event driven platform for what you want to do.

The UI is updated only at the end of the event, so whatever you do in your for next will never show.

What you may want to try is to change the color in the button Keydown event, and put it back in Action event. But since the flash will be the length of the user click, it may be too fast to see.

Better way to proceed, is to use a timer. Code coming.

6
  • Drag a Timer onto the window.
  • Set its period to 200
  • Set its mode to Off
  • In its Action event :

[code]Sub Action() Handles Action
static count as integer

select case count
case 0
Label1.TextColor = &cFFFF0000
case 1
Label1.TextColor = &c00000000
me.Mode = Timer.ModeOff
Count = 0
Return
end select

count = count + 1
End Sub
[/code]

  • In the button MouseDown event :

Function MouseDown(X As Integer, Y As Integer) Handles MouseDown as Boolean Timer1.Mode = Timer.ModeMultiple End Function

Voil. Blink yellow for 1/5th a second.

7

or best way is to creat a subclass of label with its own timer, and a Flash (on/off) property

8

It could also be done as a Label clever subclass :wink:

Edit: Dave just beat me to it.

9

Indeed, if he needs to blink often. He can even add a Blink as Boolean computed property, like in the distant path Dos computers or VT100 terminals did blink.

10

Thanks everybody - WORKING :slight_smile:

11

I am trying to make the subclass I mentioned… and guess I don’t understand something

  // Calling the overridden superclass constructor.
  Super.Constructor
  zTimer=New Timer()
  
  zTimer.Mode=timer.ModeOff
  zTimer.period=250
  zDisplayMode=false
  zFlashColor=&CFF0000 // red
  zTextColor = self.TextColor
  
  AddHandler zTimer.Action, AddressOf Blink

Shouldn’t this (addHandler) cause method BLINK to be called every 1/4 second?

Blink is

Sub BLINK(send as Timer)
  zDisplayMode=Not zDisplayMode
  If zDisplayMode Then 
    Self.TextColor=&cff0000 //zFlashColor
  Else
    Self.TextColor=&c00ff00 //zTextColor
  End If
  Self.Refresh
End Sub

actually it IS… but same as OP, no refresh (and Invalidate is same)

there is a button action that turns the timer on/off

12

What is zDisplayMode ? What is it supposed to do ?

13

Look at BLINK

blink IS changing the colors, but not updating the screen…
the strange thing is when it should be blinking the text is “gold”, when I stop it (shut off timer), it comes up red or green depending on what zDisplaymode was when the timer stopped

14

Working for me. And don’t need a Refresh or Invalidate, changing textcolor automatically causes a redraw.

15

Here is my subclass

https://dl.dropboxusercontent.com/u/17407375/LabelBlink.xojo_binary_project

16

[quote=299301:@Michel Bujardet]Here is my subclass

https://dl.dropboxusercontent.com/u/17407375/LabelBlink.xojo_binary_project[/quote]
well mine is almost identical to your, with a few extra whistles and bells

and Michel… yours won’t run for me at all… NilException in Blink SET, but I can’t find how/where/why that is called before Timer is intialized

// FIX 
  if TimerBlink=nil then return
  if value then 
    TimerBlink.Mode = Timer.ModeMultiple
  else
    TimerBlink.Mode = Timer.ModeOff
  end if
17

it crashes on Linux

Public Property Blink as Boolean

[code]Set
if value then
TimerBlink.Mode = Timer.ModeMultiple
else
TimerBlink.Mode = Timer.ModeOff // crash here
end if
End Set

End Property[/code]

18

See my flashing text in action here - on the 5th number :slight_smile:
http://www.real-soft.co.uk/resources/MAC-Bingo.dmg

(by the way - the reason it flashes on the 5th number is to remind the bingo caller to repeat the first 5 numbers gone) :slight_smile:

19

I just corrected my class. The nil exception was due to the computed property initializing too early.

https://dl.dropboxusercontent.com/u/17407375/LabelBlink.xojo_binary_project

20

Thanks, it’s working now.