PureBasic Forums - English

I'm completely new to PureBasic, and I'm just trying to figure out exactly how it works. It seems to me from my brief beginner's foray into it, that unlike Visual Basic where the visual interface drives the program and bits of code are only executed when some sort of object-oriented event occurs, with PB everything is actually generated from code which is executed sequentially, like the old-style console-type QBasics did. Is that right?

In visual basic each "gadget" on the window has its own set of subs that get called automatically depending on what type of interaction occurs with them, but in PB this doesn't seem to be the case. When opening a Window, one has to use some sort of Repeat-Until type loop in order to keep it open and catch any actions taken by the user. Without that loop (which is not used in VB) the Window will just close itself as soon as it opens. So everything has to be executed through nested If..Endif statements to catch all possible types of user action. Am I correct?

If my understanding is correct, how does one set up a visual interface that can respond to the user using any of the numerous gadgets that might be present on the main window? Nested and re-nested IF blocks? If you're treating a Window basically like a Console, I'm not sure how you are able to catch all the various different kinds of events that happen on a Window with gadgets.

paleozord wrote:When opening a Window, one has to use some sort of Repeat-Until type loop in order to keep it open and catch any actions taken by the user. Without that loop (which is not used in VB) the Window will just close itself as soon as it opens. So everything has to be executed through nested If..Endif statements to catch all possible types of user action. Am I correct?

...

One other quick question. If I use the Visual Designer to create a simple start-up window, and select RUN from the project menu, it runs fine, and the Window appears and stays there. But if I then use Generate Code, and try to run it from the Code Editor, the window disappears as soon as it appears. Why does the program not behave identically from the Code Editor and the Visual Designer?

Also, once you have designed a form visually and have switched over to editing code for it, is there no way to return to visual design to add or change things, while keeping your code intact? The visual designer and code editor do not seem to be intrinsically linked together to reflect changes on either side, the way they are in VB.

paleozord wrote:By the way, I presume that one can do all GUI-related tasks without making any OS-specific API calls, so that programs will work on all supported platforms without the need to make any changes to code?

I actually find it an intriguing idea to have a full GUI application that's in fact programmed in a
top-down sequenially executed style.

;Enumeration to set gadget Id's
Enumeration
  #Win1 ;=0
  #Btn1 ;=1
EndEnumeration

;Procedure declarations
Declare OpenMainWindow()
Declare Button1_Click()



;Start program execution by opening a window with a button on it
OpenMainWindow()

;Then loop while looking for events to react to. This an event handler
Repeat
  Event = WaitWindowEvent()
  Select Event 
    Case #PB_Event_Gadget
      Select EventGadgetID()
        Case #Btn1
         Button1_Click()
      EndSelect
  EndSelect
Until Event = #PB_Event_CloseWindow

;Dropped down here from the eventhandler above, end the program
End



;Procedures, not executed unless called from somewhere
Procedure OpenMainWindow()
  Flags = #PB_Window_ScreenCentered | #PB_Window_Systemmenu
  If OpenWindow(#Win1, 0, 0, 300, 200, Flags, "Program Template")
    ;Create a new gadget list for the current window
    If CreateGadgetList(WindowID())
      ;Add a button
      ButtonGadget(#Btn1, 100, 160, 80, 20, "Click Me")
    EndIf
  EndIf
EndProcedure

Procedure Button1_Click()
  MessageRequester("", "Button1 Clicked!")
EndProcedure