Algorithm to fire sequential keystrokes - algorithm

Question

I want to write an algorithm to sequentially press keys F1-F3. My form has these controls:
lblF1
textboxF1
lblF2
textboxF2
lblF3
textboxF3
btnStart
In textboxF1-textboxF3 the time in seconds is entered. This when the program is to press the hotkey. It is important that the program can't press two keys at once, for example F1 and F2. It may not press more than one key in a second. When I click on btnStart it calls Run().
This is how I tried to resolve this:
static int counterF1 = 9999;
static int counterF2 = 9999;
static int counterF3 = 9999;
public void Run()
{
counterF1 = 9999;
counterF2 = 9999;
counterF3 = 9999;
while (true)
{
Loop();
}
}
public void Loop()
{
bool used = false;
if (counterF1 >= (int)textboxF1.text)
{
counterF1 = PressKey(VK_F1);
used = true;
}
if (counterF2 >= (int)textboxF2.text)
{
counterF2 = PressKey(VK_F2);
used = true;
}
if (counterF3 >= (int)textboxF3.text)
{
counterF3 = PressKey(VK_F3);
used = true;
}
if (used == false)
{
IncrementCounters();
Delay(1000);
}
}
public double PressKey(uint key)
{
myPostMessageA(hWindow, WM_KEYDOWN, (uint)key, (uint)key);
IncrementCounters();
return 1; //return 1 because one second
}
public void IncrementCounters()
{
counterF1++;
counterF2++;
counterF3++;
}
But often it doesn't press any key (it is possible it is too late, but can't be an omission). Can you explain how to make an algorithm for this?

Answer 1

We will use a class KeyStroke that stores the necessary data for a special key:
public class KeyStroke
{
public int period { get; set; } // Period in which to hit key
public int next { get; set; } // ticks to the next hit of this key
public int VK { get; set; } //KeyCode
}
public List<KeyStroke> keys = new List<KeyStroke>();
An Initialize() method is needed to read the data from the text boxes and to init the simulation. We utilize a timer with the interval of one second to run the simulation. In my example, I don't read from textboxes, but use constant values. Add the input and error handling. If you use WPF, you can bind the KeyStroke objects to the textboxes.
void Init()
{
//Initialize keys with according periods from input
keys.Clear();
keys.Add(new KeyStroke() { VK = VK_F1, period = 1, next = 1 });
keys.Add(new KeyStroke() { VK = VK_F2, period = 10, next = 10 });
keys.Add(new KeyStroke() { VK = VK_F3, period = 5, next = 5 });
//sort keys by period (descending), in order to handle long period keys, too
keys.Sort((first, second) => second.period.CompareTo(first.period));
//Start the program
var t = new DispatcherTimer();
t.Interval = TimeSpan.FromSeconds(1);
t.Tick += new EventHandler(t_Tick);
t.Start();
}
The tick event is similar to yours:
void t_Tick(object sender, EventArgs e)
{
bool used = false;
foreach (var key in keys)
{
if (key.next <= 0 && !used)
{
PressKey(key.VK);
key.next = key.period;
used = true;
}
key.next--;
}
}