Flashing is basically animation. All you need is an ImageMorph and to add stepping using the step method.
step is the method that does the animation loop (step = frame)
stepTime you return how much time will be spend be spend per step

this is my step method from my project ChronosManager which basically does the seconds indicator animation, each second basically display a different image that is appropriate for that second.

step
������ "super step."

������ self managerModel mode = 'clock'
������ ������ ifTrue: [ time := DateAndTime current.
������ ������ ������ timeStr color: Color white ].
������ self managerModel mode = 'timer' | (self managerModel mode = 'stopwatch')
������ ������ ifTrue:
������ ������ ������ [ time := ('0:' , self managerModel timeDisplay) asDuration minutes asDuration.
������ ������ ������ self managerModel phase = 'work'
������ ������ ������ ������ ifTrue: [ timeStr color: Color green ].
������ ������ ������ self managerModel phase = 'break'
������ ������ ������ ������ ifTrue: [ timeStr color: Color red ] ].
������ secondsTimer form: (self secondsTimerForm at: time seconds + 1).
������ self setTimeLabel.
������ World submorphs do: [ :each| (each isKindOf: TaskbarMorph) ifTrue: [each�� updateTaskButtons]]

stepTime
������ ^ 1000

you use the form: message to change the image of the morph
form is create like this
��Form fromFileNamed: wp / ('images/panels/mainPanel/secondsTimer/secondsTimer0001.png')

wd here references the pharo directory (working directory) which you can assign like this

wd := FileSystem disk workingDirectory .

On Mon, Nov 28, 2016 at 10:43 PM William L. Cleveland <wlc1@columbia.edu> wrote:
I want to write code to flash a color image of a person in a window for a short period of time. The duration of the flash is important, not the frequency of the flashes, which will be low and probably controlled by pressing a key.

Ideally, the duration should be an integral number of frames, starting from 1 and increasing to a much larger number. With a 60 Hz monitor, one frame would be 0.0167 seconds. The images would be low to moderate resolution, e.g. 70K to 1 Mb

Can this be done entirely in Pharo or would it be necessary to use the Unified FFI with operating system commands? If it can be done in Pharo, what are the classes needed to display an image filed in from the hard drive?

I am using a 27 inch iMAC (10.11.6) with 4GHz, 8 GB ram, and��AMD Radeon R9 M395X 4096 MB video card.��Pharos is new to me but I wrote Smalltalk code with VisualWorks a few years��back.

Thanks very much.

Lou��Cleveland