Category Archives: Presentation Server

Contains posts about the OpenInsight Presentation Server, which is the module responsible for managing GUI windows and controls on the Windows Desktop.

A focus on the FOCUS property

There are two methods for setting the input focus in OpenInsight, and there is a subtle implementation difference that can impact your applications if you’re not careful how you apply them.

The first method is to use an object’s own FOCUS property and set it to TRUE$ like so:

Call Set_Property_Only( @Window : ".EDL_SURNAME", "FOCUS", TRUE$ )

This moves the focus to the specified object, but the event queue will be flushed both before and after the focus has been set, thereby preventing any events raised as a result of the focus being moved from being processed.  This method was originally designed for use with validation routines so the focus could be reset to an invalid control “safely”.

The second method is to use the SYSTEM object’s FOCUS property:

Call Set_Property_Only( "SYSTEM", "FOCUS", @Window : ".EDL_SURNAME" )

This moves the focus, but any events triggered as a result of moving the focus (like LOSTFOCUS and GOTFOCUS events) will be processed.

That all sounds straightforward enough, but using the first method can lead to unexpected results if you are relying on an event already in the queue that you subsequently need – not a common situation but one we encountered recently while converting an old form to v10.  In our case we had a menu failing to show when the focus was on a specific control, and it turned out that the LOSTFOCUS event for the control was setting it’s FOCUS property to TRUE$.  This had the effect of killing a pending MENUDROPDOWN event (new in v10) that created the menu to display, hence no menu.

In this case the solution is to use the SYSTEM BLOCKEVENTS property to turn off events being triggered while the focus is moved and then restore event processing afterwards:

Call Set_Property_Only( "SYSTEM", "BLOCKEVENTS", TRUE$ )
Call Set_Property_Only( "SYSTEM", "FOCUS", @Window : ".EDL_SURNAME" )
Call Set_Property_Only( "SYSTEM", "BLOCKEVENTS", FALSE$ )

This prevented any LOSTFOCUS and GOTFOCUS events from being raised, but the MENUDROPDOWN event was still in the queue.

Using the SYSTEM FOCUS and BLOCKEVENTS properties in this way is a far “safer” alternative when moving the focus because you have full control over how events are handled, and I would always advocate using this method over using a control’s own FOCUS property.

 

Coloring your tabs with the ITEMSTYLE property

A new facility introduced in version 10 is the ability to set the styling information for the tabs in the TabControl using the new ITEMSTYLE and ITEMSTYLES properties, and in this post we’ll explain how to use them.

TabStates and ItemStyles

Each tab in a TabControl can be in one of the following states at runtime:

  • Normal (Unselected tab)
  • Hot (Mouse is over a Normal tab)
  • Disabled
  • Selected
  • Hot Selected (Mouse is over the selected tab)

And for each one of these states you can specify the following styling information for the tabs:

  • ForeColor
  • BackColorFrom
  • BackColorTo
  • Bold
  • Italic
  • Underline
  • Translucency
  • CloseButton ForeColor
  • CloseButton BackColor

To do this at run-time you can use one of the following properties:

  • The ITEMSTYLE property
  • The ITEMSTYLES property

and we’ll take a look at each of these in turn.

 

The ITEMSTYLE property

   prevStyle = Get_Property( ctrlEntID, "ITEMSTYLE", itemState )
   currStyle = Set_Property( ctrlEntID, "ITEMSTYLE", newStyle, itemState )

This property allows you to get or set the ITEMSTYLE for a single state.  The property itself is an @fm-delimited array of styling information like so:

    <1> ForeColor             (COLORREF)
    <2> BackColor From        (COLORREF)
    <3> BackColor To          (COLORREF)
    <4> Bold                  (1/0)
    <5> Italic                (1/0)
    <6> Underline             (1/0)
    <7> Translucency          (0-100)
    <8> CloseButton ForeColor (COLORREF)
    <9> CloseButton BackColor (COLORREF)

Equates for these array positions can be found in the PS_TABCONTROL_EQUATES insert record:

   equ TCIS_POS_FORECOLOR$           to 1 ; * // COLORREF
   equ TCIS_POS_BACKCOLOR_FROM$      to 2 ; * // COLORREF
   equ TCIS_POS_BACKCOLOR_TO$        to 3 ; * // COLORREF
   equ TCIS_POS_BOLD$                to 4 ; * // Boolean
   equ TCIS_POS_ITALIC$              to 5 ; * // Boolean
   equ TCIS_POS_UNDERLINE$           to 6 ; * // Boolean
   equ TCIS_POS_TRANSLUCENCY$        to 7 ; * // UInt (0-100)
   equ TCIS_POS_CLOSEBTNFORECOLOR$   to 8 ; * // COLORREF
   equ TCIS_POS_CLOSEBTNBACKCOLOR$   to 9 ; * // COLORREF

You must also use the index parameter with the Get_Property and Set_Property to specify the tab state that you are setting, which is an integer between 1 and 5:

   equ TCIS_NORMAL$                   to 1
   equ TCIS_HOT$                      to 2
   equ TCIS_DISABLED$                 to 3
   equ TCIS_SELECTED$                 to 4
   equ TCIS_HOTSELECTED$              to 5

Example: Setting the Hot and Hot Selected styles

   $insert colors
   $insert logical

   // Set the mouseover text to change to red 
   itemStyle = ""
   itemStyle<TCIS_POS_FORECOLOR$> = RED$
   
   Call Set_Property_Only( ctrlEntID, "ITEMSTYLE", |
                           itemStyle,              |
                           TCIS_HOT$ )

   // Set the mouseover text for a selected item to change to red
   // and bold
   itemStyle = ""
   itemStyle<TCIS_POS_FORECOLOR$> = RED$
   itemStyle<TCIS_POS_BOLD$>      = TRUE$
   
   Call Set_Property_Only( ctrlEntID, "ITEMSTYLE", |
                           itemStyle,              |
                           TCIS_HOTSELECTED$ )

 

The ITEMSTYLES property

   prevStyles = Get_Property( ctrlEntID, "ITEMSTYLES" ) 
   currStyles = Set_Property( ctrlEntID, "ITEMSTYLES", newStyles )

This property is very similar to the ITEMSTYLE property except that it allows you to get or set the styles for all states at once.

The property itself is an @fm/@vm delimited array: each state is delimited by @fm, and the styling information for each state is delimited by @vm.

   <1> ItemStyle for the Normal State
   <2> ItemStyle for the Hot State
   <3> ItemStyle for the Disabled State
   <4> ItemStyle for the Selected State
   <5> ItemStyle for the Hot Selected State

(You will note these map onto the “TCIS_” state equates shown above)

For each one of these states the ItemStyle information is an @vm delimited array using the same structure as for the ITEMSTYLE property, i.e:

   <0,1> ForeColor             (COLORREF)
   <0,2> BackColor From        (COLORREF) 
   <0,3> BackColor To          (COLORREF) 
   <0,4> Bold                  (1/0) 
   <0,5> Italic                (1/0) 
   <0,6> Underline             (1/0) 
   <0,7> Translucency          (0-100) 
   <0,8> CloseButton ForeColor (COLORREF) 
   <0,9> CloseButton BackColor (COLORREF)

So you can use the “TCIS_POS_” equates shown above as well.

Example: Setting the Hot and Hot Selected styles using ITEMSTYLES

   $insert colors
   $insert logical

   itemStyles = Get_Property( ctrlEntID, "ITEMSTYLES" )

   // Set the mouseover text to change to red 
   itemStyles<TCIS_HOT$, TCIS_POS_FORECOLOR$> = RED$
   
   // Set the mouseover text for a selected item to change to red 
   // and bold
   itemStyles<TCIS_HOTSELECTED$,TCIS_POS_FORECOLOR$> = RED$
   itemStyles<TCIS_HOTSELECTED$,TCIS_POS_BOLD$>      = TRUE$
   
   Call Set_Property_Only( ctrlEntID, "ITEMSTYLES", itemStyles )

 

Setting ItemStyles in the Form Designer

Item styling for the tab control can also be specified at design time by using the “ItemStyles” property that is available when you select the tab control in the form designer.  When you click the button for this property you will see an ItemStyles editor dialog that lets you specify the styling information:

TabControl ItemStyles Editor

(Note that in the current release (10.0.6) you will not see this applied to the design control – this will be fixed in an upcoming release)

Tracking the SAVEWARN property

As veteran OpenInsight programmers know, the system uses a simple boolean flag (exposed as the SAVEWARN property) to determine if the contents of a data-bound form have changed.  This flag can be updated in several ways, the most common being:

  • From the LOSTFOCUS event of a control.
  • From the POSCHANGED, INSERTROW and DELETEROW events of an EDITTABLE control.
  • From setting a control’s DEFPROP property.
  • From the CLOSE event of a form when the control with focus is inspected to see if it has changed.

It is checked during the CLEAR and CLOSE events to see if it has been set and an “Unsaved Changes” warning issued to the user if so.  Most of the time this system works quite well, but (as anyone who has spent several years working with OI systems knows) sometimes it gets triggered when you least expect it, and you’re left with no clue as to why.

To help with this situation the next version of OpenInsight introduces SAVEWARN tracking, so you can see which parts of the system update the SAVEWARN property and when they actually do it. In previous versions the system updated the SAVEWARN flag directly (it’s a simple variable in the “window common area”) but this has been changed to use the Set_Property function so it can be monitored effectively from a single point.

To track SAVEWARN you have two choices:

  • Use the SYSMSG event
  • Use the System Monitor

 

Using the SYSMSG event to track SAVEWARN

Every time SAVEWARN is set a standard SYSMSG event is raised with a SAVEWARNINFO code; the system itself does nothing with this message, but it’s there for you to use if you wish.  This option is probably more suited for run-time tracing as it’s something you could add to your applications easily if you needed to.

The PS_EQUATES insert record defines the SAVEWARNINFO message number that you can intercept:

equ SYSMSG_SAVEWARNINFO$ to 21  ; // Save warn has been changed - null msg

The Auxiliary parameter passed to the  SYSMSG event contains information that describes why the SAVEWARN property was changed.

 

Using the System Monitor to track SAVEWARN

The SetDebugger() function has been updated to support a new method called “SAVEWARN” that enables SAVEWARN tracking so that changes are displayed in the System Monitor.  This option is probably more suited to development use rather than run-time.

From the System Monitor execute:

setdebugger savewarn 1

to turn on tracing, and:

setdebugger savewarn 0

to turn it off.

E.g:

SAVEWARN tracing in the System Monitor

SAVEWARN tracing in the System Monitor

Setting the SAVEWARN property

If you wish to set SAVEWARN yourself you may use the “index” parameter to pass a description for the change, so this can be picked up in any tracing scenario like so:

Call Set_Property_Only( @Window, "SAVEWARN", TRUE$, "From My Stuff" )

This description is then passed in the Auxiliary parameter of the  SYSMSG event as noted above.

 

Hopefully you will find this facility useful if you ever suffer from problems with SAVEWARN in the future.

EditTables – The Sub-Object Interface

One of the changes we wanted to make with EditTables in v10 was to expose all of their runtime functionality easily through the normal property/method API.  Some of this was already available in previous versions, but usually involved a method to set a plethora of style bits, which is not really satisfactory unless you’re a C++ programmer (as we have been reminded by various developers on several occasions!).

Besides the EditTable as a whole, there are essentially three other main programmable areas:

  1. Columns
  2. Rows
  3. Cells

Providing unique properties and methods to address the capabilities of these areas is not really practicable, as it leads to an “explosion” of property names: For example, accessing the “text” associated with each of these would require three new properties such as:

  • COLUMNTEXT
  • ROWTEXT
  • CELLTEXT

Of course that’s only three, but considering that each of the aforementioned areas has something like 30 properties, you would suddenly add 90+ new property names to the product!  Bear in mind also that columns, rows and cells each have many properties like TEXT in common, so a new name for each of these seems extremely wasteful and unnecessary.

(We could also have used something similar like the existing TEXTBYPOS method to achieve this, but then we’d have 30’ish new “BYPOS” methods instead, and methods aren’t properties anyway).

So, to keep the property namespace under control we decided to use this commonality and implement a set of  “sub-objects” instead, one for each area.  Unsurprisingly these are named:

  • COLUMNS
  • ROWS
  • CELLS  

Each of these sub-objects are indexed and can be used to access a specific column, row or cell in the EditTable.  They all share many common properties and methods, but also expose a few type-specific ones as well.   As an example, this is how to set the CUEBANNER property for each sub-object:

ctrlEntID  = @window : ".EDT_TEST"
cueBanner  = "Test"

// Set the CUEBANNER for the second column
call set_Property( ctrlEntID : ".COLUMNS", "CUEBANNER", cueBanner, 2 )
// Set the CUEBANNER for the third row
call set_Property( ctrlEntID : ".ROWS", "CUEBANNER", cueBanner, 3 )

// Set the CUEBANNER for the cell at column 5, row 7
call set_Property( ctrlEntID : ".CELLS", "CUEBANNER", cueBanner, 5 : @fm : 7 )

// And here's the same using Object Notation Syntax
@ctrlEntID.columns{2}->cueBannner = cueBanner
@ctrlEntID.rows{3}->cueBannner    = cueBanner
@ctrlEntID.cells{5,7}->cueBannner = cueBanner

We’ll take a look at each of these sub-objects in turn over the next few posts to examine their functionality in more detail.

 

EditTables – The new “CELL” events

The OpenInsight EditTable has always supported a set of cell-related common events that are fired when a user interacts with the control:

  • CHAR
  • CHANGED
  • CLICK
  • DBLCLK
  • OPTIONS

In order to process these events properly however, it is necessary to know which cell they relate to, and this can ostensibly be found by using the NOTIFYPOS property, which is set to the position of the cell that raised the event.

In theory this approach works well, but in practice it can exhibit problems:  Events in OpenInsight are nearly always raised in an asynchronous fashion, which means that if two of those events where executed in quick succession for different cells, then NOTIFYPOS could be set to the position of the second cell, before the Basic+ event handler could process the event for the first cell, thereby leading to incorrect results.

In order to handle this better the EditTable now supports a series of corresponding “CELL” events:

  • CELLCHAR
  • CELLCHANGED
  • CELLCLICK
  • CELLDBLCLK
  • CELLOPTIONS

The only difference here is that these events pass the indexes of the cell that raised them as arguments to the event handler, thereby preserving their origin accurately.

E.g. The signature for the old CHANGED event looks like this:

Function Changed( CtrlEntID, CtrlClassID, NewData )

Whilst the signature for the CELLCHANGED event looks like this:

Function CellChanged( CtrlEntID, CtrlClassID, ColNum, RowNum, NewData )

Note that when a “CELL” event is defined the EditTable will non longer raise the ordinary event to prevent the notification from being processed twice.

(One useful example of the benefits of having the “CELL” events is that you can now use the new CELLCHANGED event for cell validation, rather than the usual POSCHANGED event, due to the fact that you know precisely where the change originated from. You also know that there actually was a change, rather than having to compare the cell’s current contents to it’s GOTFOCUSVALUE to discover this).

 

 

 

EditTables – Deleting and Inserting Rows

Support for deleting and inserting rows in the EditTable control has always been somewhat basic, exposing only minimum functionality that allows you to control how a user inserts or deletes a row in the grid.  We’ve enhanced this for version 10 by providing some fine-grain control over the row insertion and deletion process that we’ll describe below.

Imposing limits

Firstly, a couple of new properties have been implemented that allow you to set limits on the number of rows a user can add or remove from the EditTable via the keyboard: These are the MAXROWLIMIT and MINROWLIMIT properties.

MAXROWLIMIT property

When MAXROWLIMIT is set the user cannot use the Insert key to insert more rows than the number specified by this property.  The default value is “0”, which means there is no maximum limit.   Note that this property does not apply to programmatic INSERT method operations or data set by the LIST or ARRAY properties.

MINROWLIMIT property

When MINROWLIMIT is set the user cannot use the Delete key to delete EditTable rows once the minimum limit has been reached. The default value is “0”, which means there is no minimum row limit.   Note that this property does not apply to programmatic DELETE method operations or data set by the LIST or ARRAY properties.

Blocking the “Insert” and “Delete” keys

Previous versions of the EditTable allowed you to set a “Protected” property at design time that stopped all row insert and delete operations by the user.  Unfortunately, this was not actually exposed run-time (unless you adjusted a bit-flag the control’s STYLE property), so in version 10 we’ve expanded the old “Protected” property into two new properties called ALLOWROWDELETE and ALLOWROWINSERT.  These can used at both run-time and design-time.

ALLOWROWDELETE property

When set to False the user cannot use the Delete key to delete rows within an edit table.  The default value of this property is True.

ALLOWROWINSERT property

When set to False the user cannot use the Insert key to insert new rows within an edit table.  The default value of this property is True.

Managing the “Insert” and “Delete” keys

Finally, we made some changes to the way the actual inserts and deletes take place to give you an opportunity to intercept them for even more control.  In previous versions of OpenInsight the EditTable notified you of an insert or delete operation after it had taken place, via the INSERTROW and DELETEROW events respectively.  This means that if you wanted to ‘prevent’ the modification based on some run-time criteria you had to effectively undo it, which usually included some sort of unpleasant visual effect as the insert or delete was rolled back (it also resulted in a loss of formatting information or other cell-specific data that you would have to reapply).

In version 10 we’ve added a new Boolean property called ROWEVENTMODE. When set to False (the default) row insertion and deletion via the keyboard behaves in exactly the same way as previous versions of OpenInsight.  When set to True however, the INSERTROW or DELETEROW event happens before the actual operation takes place, and at this point you can do the following:

  1. If you’re using an EventScript you can return FALSE$ and the operation will be cancelled.
  2. If you’re using a code called from a QuickEvent you can set the EventStatus flag in your code to prevent the operation from proceeding further, just as you would currently do in a WINDOW CLOSE event to cancel it.

 

E.g. Stopping a row being deleted in a DELETEROW EventScript handler.

// Assumes "RowEventMode" is "True" 
//
// Check to see if there is anything in column 2 of the deleted data,
// and if so stop the delete via the event return value. 

$insert logical
if bLen( rowData<2> ) then
   // Stop the delete
   retVal = FALSE$
end else
   retVal = TRUE$
end

return retVal

 

E.g. Stopping a row being deleted in a DELETEROW QuickEvent handler

// Assumes "RowEventMode" is "True" 
//
// Check to see if there is anything in column 2 of the deleted data,
// and if so stop the delete via the Event Status 

$insert logical 
if bLen( rowData<2> ) then
   // Stop the delete
   call set_EventStatus( TRUE$ )
end

return

Of course, once you’ve allowed the Insert or Delete operation to take place you may also want to do some post-processing, and for this we’ve provided two new events: INSERTEDROW and DELETEDROW.  These have the same signature as their INSERTROW and DELETEROW counterparts and are executed after the row modification has taken place (Note that these are only fired if the ROWEVENTMODE is True).

It is also worth noting that, as with previous versions of OpenInsight, using the DELETE and INSERT methods to programatically modify the EditTable contents will not trigger the INSERTROW or DELETEROW events (or any subsequent INSERTEDROW and DELETEDROW events either).

The EDITSTATECHANGED event

One of the requirements we needed when developing the new IDE was the ability to detect when the state of a control changed in such a fashion that might affect the operations that could be performed on it.

A classic example of this is highlighting text in an edit control so that it can be cut or copied, or perhaps replaced with a paste operation: At this point an item like a Cut or a Paste button might need enabling so the UI is in sync with the state of the control.

To enable this functionality several controls now support a new event called EDITSTATECHANGED, which is fired when the “edit state” is changed.  The edit state is defined as one of the following operations:

  • Undo
  • Redo
  • Cut
  • Copy
  • Paste
  • Select All

So, if a user takes an action in the control that enables or disables one of these options you can respond to it via the EDITSTATECHANGED event.

The EDITSTATECHANGED event passes a single parameter called “EditState“, which is a dynamic array of Boolean flags with the following structure:

<1> CanUndo      : TRUE$ if the control allows an UNDO operation
<2> CanRedo      : TRUE$ if the control allows a REDO operation
<3> CanCut       : TRUE$ if the control allows a CUT operation
<4> CanCopy      : TRUE$ if the control allows a COPY operation
<5> CanPaste     : TRUE$ if the control allows a PASTE operation
<6> CanSelectAll : TRUE$ if the control allows a SELECTALL 
                 : operation

(You may notice that these flags closely follow the items in a standard “Edit” menu).

Here’s a simple example to set the state of some Cut/Copy/Paste buttons:

   objxArray =        @window : ".BTN_CUT"
   propArray =        "ENABLED"
   dataArray =        editState<0,3>

   objxArray := @rm : @window : ".BTN_COPY"
   propArray := @rm : "ENABLED"
   dataArray := @rm : editState<0,4>
   
   objxArray := @rm : @window : ".BTN_PASTE"
   propArray := @rm : "ENABLED"
   dataArray := @rm : editState<0,5>

   call Set_Property_Only( objxArray, propArray, dataArray )

The following controls support the EDITSTATECHANGED event:

  • COMBOBOX
  • EDITLINE
  • EDITBOX
  • EDITTABLE
  • LISTBOX
  • PROPERTYGRID

(Disclaimer: This article is based on preliminary information and may be subject to change in the final release version of OpenInsight 10).

(EDIT: 8th May 2018 – Variable name changed from NewEditState to EditState to match released version)