add: Timer

src/ltk/base/timer.cr

@@ -0,0 +1,55 @@
+module Ltk
+  alias TimerProc = Proc(Void?)
+
+  class Timer
+    property interval : Time::Span
+    property stop_at : Time?
+    property timer_event : TimerProc? = nil
+    property timeout_event : TimerProc? = nil
+    getter start_at : Time? = nil
+    getter? looping = false
+
+    def initialize(@interval = 1, @stop_at = nil)
+    end
+
+    def initialize(@interval = 1, @stop_at = nil, &@timer_event)
+    end
+
+    def start
+      @start_at = Time.now
+      @looping = true
+      run
+    end
+
+    def stop
+      @looping = false
+      if @timeout_event.is_a? TimerProc
+        @timeout_event.as(TimerProc).call
+      end
+    end
+
+    private def run
+      spawn do
+        interval = @interval
+        while @looping
+          sleep interval
+          if @timer_event.is_a? TimerProc
+            @timer_event.as(TimerProc).call
+          end
+
+          if stop_at = @stop_at
+            stop if stop_at <= Time.now
+          end
+        end
+      end
+    end
+
+    def remaining_time : Time::Span
+      if @looping && @start_at.is_a?(Time)
+        Time.now - @start_at.as(Time)
+      else
+        Time::Span.new nanoseconds: 0
+      end
+    end
+  end
+end