The V C++ GUI Framework:Command Objects

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The V CommandObject structure is used to define the contents of [vDialogs] and [vCommandPane]s. Each element of a CommandObject defines a control (such as a Button or Scroll Bar) of a particular CmdType with an associated string and attributes, including size and position within the dialog.

This section is intended to be a complete reference for CommandObjects. It is organized into the following sections:

CommandObject

Used to define commands to dialogs and command panes.

Synopsis

Header:
<v/v_defs.h>
Type name:
CommandObject
Part of:
vDialog, vCommandPane

Description

This structure is used to define command items in dialogs and command panes. You will define a static array of CommandObject items. This array is then passed to the AddDialogCmds method of a dialog class such as vDialog or vModalDialog, or the constructor of a vCommandPane object, or more typically, a class derived from one of those.

Definition

typedef struct CommandObject
  {
    CmdType cmdType;    // what kind of item is this
    ItemVal cmdId;      // unique id for the item
    ItemVal retVal;     // initial value of object
    char* title;        // string
    void* itemList;     // used when cmd needs a list
    CmdAttribute attrs; // list of attributes
    int Sensitive;      // if item is sensitive or not
    ItemVal cFrame;     // Frame used for an item
    ItemVal cRightOf;   // Item placed left of this id
    ItemVal cBelow;     // Item placed below this one
    int size;           // Used for size information
    char* tip;          // ToolTip string
  } CommandObject;

Structure Members

CmdType cmdType

This value determines what kind of command item this is. The types of commands are explained in the section [#Commands Commands].

ItemVal cmdId

This unique id for the command defined by the programmer. Each command item belonging to a dialog should have a unique id, and it is advisable to use some scheme to be sure the ids are unique. The V system does not do anything to check for duplicate ids, and the behavior is undefined for duplicate ids. The id for a command is passed to the DialogCommand method of the dialog, as well as being used for calls to the various SetX and GetX methods. There are many predefined values that can be used for ids as described in the section [#stdvals Standard V Values].

The values you use for your id in menus and controls should be limited to being less than 30,000. The predefined V values are all above 30,000, and are reserved. There is no enforcement of this policy. It is up to you to pick reasonable values.

The type ItemVal exists for historical reasons, and is equivalent to an int, and will remain so. Thus, the easiest way to assign and maintain unique ids for your controls is to use a C++ enum. As many as possible examples in this manual will use enums, but examples using the old style const ItemVal declarations may continue to exist. There is more discussion of assigning ids in the following example.

int retVal

The use of this value depends on the type of command. For buttons, for example, this value will be passed (along with the cmdId) to the DialogCommand method. The retVal is also used for the initial on/off state of check boxes and radio buttons. For some commands, retVal is unused. Note that the static storage provided in the declaration is not used to hold the value internally. You should use GetValue to retrieve the current value of a command object.

char* title
This is used for the label or text string used for command items.

void* itemList
This is used to pass values to commands that need lists or strings. The ListCmd is an example. Note the void * to allow arbitrary lists.

CmdAttribute attrs
Some command items use attributes to describe their behavior. These attributes are summarized in the [#CmdAttribute CmdAttribute] section.

int Sensitive
This is used to determine if an item is sensitive or not. Note that the static storage provided in the declaration is used by the V system to track the value, and should be changed by the SetValue method rather than directly. Thus dialogs sharing the same static declaration will all have the same value. This is usually desired behavior.

ItemVal cFrame
Command items may be placed within a frame. If this value is 0 (or better, the symbol NoFrame), the command will be placed in the main dialog area. If a value is supplied, then the command will be placed within the frame with the id cFrame.

ItemVal cRightOf, ItemVal cBelow
These are used to describe the placement of a command within a dialog. Ids of other commands in the same dialog are used to determine placement. The current command will be placed to the right of the command cRightOf, and below the command cBelow. The commands left and above don't necessarily have to be adjacent. By careful use of these values, you can design very attractive dialogs. You can control the width of command objects by padding the label with blanks. Thus, for example, you can design a dialog with all buttons the same size.

You can also use the CA_Hidden attribute to selectively hide command objects that occupy the same location in the dialog. Thus, you might have a button labeled Hide right of and below the same command object as another button labeled UnHide. By giving one of the two buttons the CA_Hidden attribute, only one will be displayed. Then you can use SetValue at runtime to switch which button is displayed in the same location. The bigger of the two command objects will control the spacing.

int size
The size parameter can be used for some command objects to specify size. For example, for labeled Button commands, the size specifies the minimum width in pixels of the button. It is also used in various other command objects as needed. A value of zero for size always means use the default size. Thus, you can take advantage of how C++ handles declarations and write CommandObject declarations that leave off the size values, which default to zero. Many of the examples in this reference do not specify these values.

char* tip
The tip parameter is used to specify an optional ToolTip string for use with a command object. If you provide a string here, that string will be automatically displayed after the user holds the mouse over that control. The exact delay before the tip is shown, and the format of the tip box is somewhat platform dependent, and all platforms might not support tool tips. (Currently, only OS/2 does not support tips.) Note that if you use a tip, you must be sure to include a value (usually 0) for the size parameter!

Example

The following example defines a simple dialog with a message label on the top row, a check box on the second row, two buttons in a horizontally organized frame on the third row, and an OK button on the bottom row. The ids in this example are defined using an enum. Remember that your ids must be less than 30,000, and using 0 is not a good idea. Thus, the enum in this example gives the ids values from 101 to 106. An alternative used in V code prior to release 1.13 was to provide const declarations to define meaningful symbolic values for the ids. Many examples of this type of id declaration will likely persist.

It also helps to use a consistent naming convention for ids. The quick reference appendix lists suggested prefixes for each control type under the CmdType section. For example, use an id of the form btnXXX for buttons. Predefined ids follow the form M_XXX.

V-ref-dlgcmd.gif

enum {lbl1 = 101, frm1, btn1, btn2}
static CommandObject Sample[] =
  {
    {C_Label, lbl1, 0,"Sample",NoList,CA_MainMsg,isSens,NoFrame,0,0},
    {C_Frame, frm1, 0, "", NoList,CA_None,isSens,NoFrame,0,lbl1},
    {C_Button, btn1, 0, "Button 1", NoList, CA_None, isSens,frm1,0,0,0,
         "Tip for Button 1"},
    {C_Button, btn2, 0, "Button 2", NoList, CA_None, isSens,frm1,btn1,0,0,
         "Tip for Button 2"},
    {C_Button, M_OK, M_OK, " OK ", NoList, CA_DefaultButton, 
        isSens, NoFrame,0,frm1},
    {C_EndOfList,0,0,0,0,CA_None,0,0,0}
  };

CommandObject Commands

This section describes how each of the command objects available in V is used to build dialogs.

V provides several different kinds of command items that are used in dialogs. The kind of command is specified in the cmdType field of the CommandObject structure when defining a dialog. This section describes current dialog commands available with V. They will be constructed by V to conform to the conventions of the host windowing system. Each command is named by the value used to define it in the [#CommandObject CommandObject] structure.

List of commands

#C_Blank, #C_BoxedLabel, #C_Button, #C_CheckBox, #C_ColorButton, #C_ComboBox, #C_EndOfList, #C_Frame, #C_Icon, #C_IconButton, #C_Label, #C_ColorLabel, #C_List, #C_ProgressBar, #C_RadioButton, #C_Slider, #C_Spinner, #C_Text, #C_TextIn, #C_ToggleButton, #C_ToggleFrame, #C_ToggleIconButton

Commands

C_Blank

A Blank can help you control the layout of your dialogs. The Blank object will occupy the space it would take if it were a C_Label, but nothing will be displayed. This is especially useful for leaving space between other command objects, and getting nice layouts with RightOfs and Belows. You control the size of the Blank by providing a string with an appropriate number of blanks for the title field.

C_BoxedLabel

V-ref-boxlabel.gif

This command object is just like a C_Label, but drawn with a surrounding box. See C_Label.

C_Button

V-ref-button.gif

A Button is one of the primary command input items used in dialog boxes. When the user clicks on a Button, the values set in the cmdId and retVal fields are passed to the DialogCommand method. In practice, the retVal field is not really used for buttons - the cmdId field is used in the switch statement of the DialogCommand method.

A button is defined in a CommandObject array. This is a typical definition:

{C_Button, btnId, 0,"Save",NoList,CA_None,isSens,NoFrame,0,0}

The retVal field can be used to hold any value you wish. For example, the predefined color button frame (see vColor) uses the cmdId field to identify each color button, and uses the retVal field to hold the index into the standard V color array. If you don't need to use the retVal, a safe convention is to a 0 for the retVal. You can put any label you wish in the title field.

If you provide the attribute CA_DefaultButton to the CmdAttribute field, then this button will be considered the default button for the dialog. The default button will be visually different than other buttons (usually a different border), and pressing the Return key is the same as clicking on the button.

The size of the button in pixels can be controlled by using the CommandObject element size. By specifying the attribute CA_Size and providing a value for the size element, you can control the size of the button. Note the that the size element is the last one of a CommandObject, and can left out of a declaration, which results in the compiler generating a zero value.

You can change the label of a button with: SetString(btnId, "New Label"). You can change the sensitivity of a button with SetValue(btnID, OnOrOff, Sensitive).

C_CheckBox

V-ref-chkbox.gif

A CheckBox is usually used to set some option on or off. A CheckBox command item consists of a check box and an associated label. When the user clicks on the check box, the DialogCommand method is invoked with the Id set to the cmdId and the Val set to the current state of the CheckBox. The system takes care of checking and unchecking the displayed check box - the user code tracks the logical state of the check box.

A CheckBox is defined in a CommandObject array. This is a typical definition:

{C_CheckBox, chkId, 1,"Show Details",NoList,CA_None,isSens,NoFrame,0,0}

The retVal is used to indicate the initial state of the check box. You should use the GetValue method to get the current state of a check box. You can also track the state dynamically in the DialogCommand method. You can put any label you wish in the title field.

You can change the label of a check box with: SetString(chkId, "New Label"). You can change the sensitivity of a check box with SetValue(chkID, OnOrOff,Sensitive). You can change the checked state with SetValue(chkID, OnOrOff, Checked).

If the user clicks the Cancel button and your code calls the default DialogCommand method, V will automatically reset any check boxes back to their original state, and call the DialogCommand method an additional time with the original value if the state has changed. Thus, your code can track the state of check boxes as the user checks them, yet rely on the behavior of the Cancel button to reset changed check boxes to the original state.

The source code for the V vDebugDialog class provides a good example of using check boxes (at least for the X version). It is found in v/src/vdebug.cxx.

C_ColorButton

V-ref-color.gif

A color command button. This works exactly the same as a C_Button except that the button may be colored. You use C_ColorButton for the cmdType field, and provide a pointer to a vColor structure in the itemList field using a (void*) cast. The label is optional.

The retVal field of a color button is not used. You can generate a square color button of a specified size by specifying an empty label ("") and a size value greater than 0. When you specify the size field, the color button will be a colored square size pixels per side. When used within a CA_NoSpace frame, this feature would allow you to build a palette of small, tightly spaced color buttons. In fact, V provides a couple of such palettes in v/vcb2x4.h and v/vcb2x8.h. These include files, as well as the other details of the vColor class are described in the section vColor in the Drawing chapter.

There are two ways to change to color of a button. The most direct way is to change each of the RGB values in three successive calls to SetValue using Red, Green, and finally Blue as the ItemSetType to change the RGB values. The call with Blue causes the color to be updated. I know this isn't the most elegant way to do this, but it fits with the SetValue model.

An alternate way is to change the value of the original vColor used to define the initial color of the control, and then call SetValue with the ChangeColor set type.

This is a short example of defining a red button, and then changing it.

    static vColor btncolor(255,0,0};  // define red
    ...

    // part of a CommandObject definition
    {C_ColorButton, cbt1, 0, "", (void*)&btncolor,
        CA_None, isSens, NoFrame, 0, btnXXX},

    ...
    // Code to change the color by some arbitrary values
    btncolor.Set(btncolor.r()+127, btncolor.g()+63, btncolor.b()+31);
#ifdef ByColor    // by vColor after changing btncolor
    SetValue(cbt1,0,btncolor);
#else          // by individual colors
    SetValue(cbt1,(ItemVal)btncolor.r(),Red);
    SetValue(cbt1,(ItemVal)btncolor.g(),Green);
    // This final call with Blue causes color to update in dialog
    SetValue(cbt1,(ItemVal)btncolor.b(),Blue);
#endif
    ...

C_ComboBox

V-ref-combobox.gif

A combo box is a drop-down list. It normally appears as box with text accompanied by some kind of down arrow button. You pass a list of alternative text values in the itemList field of the CommandObject structure. You also must set the retVal field to the index (starting at 0) of the item in the list that is the default value for the combo box text title.

If the user clicks the arrow, a list pops up with a set of alternative text values for the combo box label. If the user picks one of the alternatives, the popup closes and the new value fills the text part of the combo box. V supports up to 32 items in the combo box list. You need to use a C_List if you need more than 32 items.

With default attributes, a combo box will send a message to DialogCommand whenever a user picks a selection from the combo box dialog. This can be useful for monitoring the item selected. If you define the combo box with the attribute CA_NoNotify, the dialog in not notified on each pick. You can use GetValue to retrieve the index of the item shown in the combo box text field.

You can preselect the value by using SetValue. You can change the contents of the combo list by using vDialog::SetValue with either ChangeList or ChangeListPtr. See vDialog::SetValue for more details.

Example

The following is a simple example of using a combo box in a modal dialog. This example does not process items as they are clicked, and does not show code that would likely be in an overridden DialogCommand method. The code interface to a list and a combo box is very similar - the interaction with the user is different. This example will initially fill the combo box label with the text of comboList[2].

enum { cbxId = 300 };
char* comboList[] =
  {
    "First 0",   // The first item in the list
     ...
    "Item N",    // The last item in the list
    0            // 0 terminates the list
  };
  ...
CommandObject ComboList[] =
  {
    {C_ComboBox, cbxId, 2, "A Combo Box", (void*)comboList,
       CA_NoNotify,isSens,NoFrame,0,0},
    {C_Button, M_OK, M_OK, " OK ", NoList,
       CA_DefaultButton, isSens, NoFrame, 0, ListId},
    {C_EndOfList,0,0,0,0,CA_None,0,0,0}
  };
    ...
    vModalDialog cd(this);    // create list dialog
    int cid, cval;
    ...
    cd.AddDialogCmds(comboList);   // Add commands to dialog
    cid = ld.ShowModalDialog("",cval);  // Wait for OK
    cval = ld.GetValue(cbxId);  // Retrieve the item selected

C_EndOfList

This is not really a command, but is used to denote end of the command list when defining a CommandObject structure.

C_Frame

V-ref-frame.gif

The frame is a line around a related group of dialog command items. The dialog window itself can be considered to be the outermost frame. Just as the placement of commands within the dialog can be controlled with the cRightOf and cBelow fields, the placement of controls within the frame use the same fields. You then specify the id of the frame with the cFrame field, and then relative position within that frame.

The title field of a frame is not used.

You may supply the CA_NoBorder attribute to any frame, which will cause the frame to be drawn without a border. This can be used as a layout tool, and is especially useful to force buttons to line up in vertical columns.

See the section CommandObject for an example of defining a frame.

C_Icon

V-ref-icon.gif

A display only icon. This works exactly the same as a C_Label except that an icon is displayed instead of text. You use C_Icon for the cmdType field, and provide a pointer to the vIcon object in the itemList field using a (void*) cast. You should also provide a meaningful label for the title field since some versions of V may not support icons.

You can't dynamically change the icon.

C_IconButton

V-ref-iconbtn.gif

A command button Icon. This works exactly the same as a C_Button except that an icon is displayed for the button instead of text. You use C_IconButton for the cmdType field, and provide a pointer to the vIcon object in the itemList field using a (void*) cast. You should also provide a meaningful label for the title field since some versions of V may not support icons.

You can't dynamically change the icon. The button will be sized to fit the icon. Note that the v/icons directory contains quite a few icons suitable for using on command bars.

C_Label

C_ColorLabel

This places a label in a dialog. A label is defined in a CommandObject array. This is a typical definition:

{C_Label, lblId,0,"Select Options",NoList,CA_None,isSens,NoFrame,0,0, 0,0}

While the value of a label can be changed with SetString(lblId, "New Label"), they are usually static items. If the label is defined with the CA_MainMsg attribute, then that label position will be used to fill the the message provided to the ShowDialog method.

A C_ColorLabel is a label that uses the List parameter of the CommandObject array to specify a vColor. You can specify the color and change the color in the same fashion as described in the C_ColorButton command.

C_List

V-ref-list.gif

A list is a scrollable window of text items. The list can be made up of any number of items, but only a limited number are displayed in the list scroll box. The default will show eight items at a time. The number of rows can be controlled as explained later.

The user uses the scroll bar to show various parts of the list. Normally, when the user clicks on a list item, the DialogCommand is invoked with the id of the List command in the Id parameter, and the index into the list of the item selected in the Val parameter. This value may be less than zero, which means the user has unselected an item, and your code should properly handle this situation. This only means the user has selected the given item, but not that the selection is final. There usually must be a command Button such as OK to indicate final selection of the list item.

If the List is defined with the attribute CA_NoNotify, DialogCommand is not called with each pick. You must then use GetValue to get which item in the list was selected.

It is possible to preselect a given list item with the SetValue method. Use the GetValue to retrieve the selected item's index after the OK button is selected. A value less than zero means no item was selected.

The number of rows displayed can be controlled by using the CommandObject element size. By specifying the attribute CA_Size and providing a value for the size element, you can specify how many rows to show. If you don't specify a size, 8 rows will be displayed. Vwill support between 1 and 32 rows. Note the that the size element is the last one of a CommandObject, and can left out of a declaration, which results in the compiler generating a zero value, giving the default 8 rows.

The width in pixels (approximately) of the list can be controlled by specifying the CA_ListWidth attribute and providing a value to the retVal parameter, which is otherwise unused for a list object. This implementation isn't perfect - you may have to play with the interaction between the width you specify, and the font used in a list control.

Change the contents of the list with vDialog::SetValue using either ChangeList or ChangeListPtr. See vDialog::SetValue for more details.

The [vslist.htm vSList] class provides a very useful set of utilities for working with C_List lists.

Example

The following is a simple example of using a list box in a modal dialog. This example does not process items as they are clicked. This list will be displayed in 12 rows.

enum {lstId = 200 };
char* testList[] =
  {
    "First 0",   // The first item in the list
     ...
    "Item N",    // The last item in the list
    0            // 0 terminates the list
  };
  ...
CommandObject ListList[] =
  {
    {C_List, lstId, 0, "A List", (void*)testList,
       CA_NoNotify | CA_Size,isSens,NoFrame,0,0,12},
    {C_Button, M_OK, M_OK, " OK ", NoList,
       CA_DefaultButton, isSens, NoFrame, 0, lstId},
    {C_EndOfList,0,0,0,0,CA_None,0,0,0}
  };
    ...
    vModalDialog ld(this);    // create list dialog
    int lid, lval;
    ...
    ld.AddDialogCmds(ListList);   // Add commands to dialog
    ld.SetValue(lstId,8,Value);  // pre-select 8th item
    lid = ld.ShowModalDialog("",lval);  // Wait for OK
    lval = ld.GetValue(lstId);  // Retrieve the item selected

C_ProgressBar

V-ref-progress.gif

Bar to show progress. Used with CA_Vertical or CA_Horizontal attributes to control orientation. You change the value of the progress bar with SetValue(ProgID, val, Value), where val is a value between 0 and 100, inclusive. Normally, the progress bar will show both a graphical indication of the value, and a text indication of the value between 0 and 100.

If you don't want the text value (for example, your value represents something other than 0 to 100), then define the progress bar with the CA_NoLabel attribute. Use the CA_Percent attribute to have a % added to the displayed value. You can also use CA_Small or CA_Large to make the progress bar smaller or larger than normal. If you need a text value display for ranges other than 0 to 100, you can build a CA_NoSpace frame with a progress bar and a text label that you modify yourself.

Example

The following shows how to define a progress bar, and how to set its value. <code>

enum{frm1 = 200, lbl1, pbrH, pbrV, ... };
  static CommandObject Cmds[] =
  {
    ...
    // Progress Bar in a frame
    {C_Frame, frm1, 0, "",NoList,CA_None,isSens,NoFrame, 0,0},
    {C_Label, lbl1, 0, "Progress",NoList,CA_None,isSens,frm1,0,0},
    {C_ProgressBar, pbrH, 50, "", NoList,
        CA_Horizontal,isSens,frm1, 0, lbl1},  // Horiz, with label

    {C_ProgressBar, pbrV, 50, "", NoList,  // Vertical, no value
      CA_Vertical | CA_Small, isSens,NoFrame, 0, frm1},
    ...
  };
  ...
  // Set the values of both bars to same
  SetValue(pbrH,retval,Value);    // The horizontal bar
  SetValue(pbrV,retval,Value);    // The vertical bar

C_RadioButton

V-ref-radiob.gif

Radio buttons are used to select one and only one item from a group. When the user clicks on one button of the group, the currently set button is turned off, and the new button is turned on. Note that for each radio button press, two events are generated. One a call to DialogCommand with the id of the button being turned off, and the other a call with the id of the button being turned on. The order of these two events is not guaranteed. The retVal field indicates the initial on or off state, and only one radio button in a group should be on.

Radio buttons are grouped by frame. You will typically put a group of radio buttons together in a frame. Any buttons not in a frame (in other words, those just in the dialog window) are grouped together.

Radio buttons are handled very much like check boxes. Your code should dynamically monitor the state of each radio button with the DialogCommand method. Selecting Cancel will automatically generate calls to DialogCommand to restore the each of the buttons to the original state.

You can use SetValue with a Value parameter to change the settings of the buttons at runtime. SetValue will enforce a single button on at a time.

Example

The following example of defining and using radio buttons was extracted from the sample file v/examp/mydialog.cpp. It starts with the button RB1 pushed.

enum {
    frmV1 = 200, rdb1, rdb2, rdb3, ...
...
  };
...
static CommandObject DefaultCmds[] =
  {
    {C_Frame, frmV1, 0,"Radios",NoList,CA_Vertical,isSens,NoFrame,0,0},
    {C_RadioButton, rdb1, 1, "KOB",  NoList,CA_None,isSens, fmV1,0,0},
    {C_RadioButton, rdb2, 0, "KOAT", NoList,CA_None, isSens,frmV1,0,0},
    {C_RadioButton, rdb3, 0, "KRQE", NoList,CA_None, isSens,frmV1,0,0},
    {C_Button, M_Cancel,M_Cancel,"Cancel",NoList,CA_None,
        isSens, NoFrame, 0, frmV1},
    {C_Button, M_OK, M_OK, " OK ", NoList, CA_DefaultButton, 
        isSens, NoFrame, M_Cancel, frmV1},
    {C_EndOfList,0,0,0,0,CA_None,0,0,0}
  };
...
void myDialog::DialogCommand(ItemVal Id, ItemVal Val, CmdType Ctype)
  {
    switch (Id)              // switch on command id
      {
        case rdb1:            // Radio Button KOB
            // do something useful - current state is in retval
            break;
        ...
        // cases for other radio buttons

      }
    // let the super class handle M_Cancel and M_OK
    vDialog::DialogCommand(id,retval,ctype);
  }

C_Slider

V-ref-slider.gif

Used to enter a value with a slider handle. The slider will provide your program with a value between 0 and 100, inclusive. Your program can then scale that value to whatever it needs.

V will draw sliders in one of three sizes. Use CA_Small for a small slider (which may not be big enough to return all values between 0 and 100 on all platforms), CA_Large to get a larger than normal slider, and no attribute to get a standard size slider that will return all values between 0 and 100. Use the CA_Vertical and CA_Horizontal attributes to specify orientation of the slider.

When the user changes the value of the slider, the DialogCommand method is called with the id of the slider for the Id value, and the current value of the slider for the Retval value. You can use SetVal to set a value for the slider.

Example

The following example shows the definition line of a slider, and a code fragment from an overridden DialogCommand method to get the value of the dialog and update a C_Text item with the current value of the slider. The slider starts with a value of 50.

enum { frm1 = 80, sld1, txt1 };
CommandObject Commands[] =
  {
    ...
    {C_Frame, frm1, 0, "",NoList,CA_None,isSens,NoFrame,0,0},
    {C_Slider, sld1, 50, "",NoList,CA_Horizontal,isSens,frm1,0,0},
    {C_Text, txt1, 0, "", "50",CA_None,isSens, frm1, sld1, 0},
    ...
  };
  ...
void testDialog::DialogCommand(ItemVal id,
  ItemVal retval, CmdType ctype)
  { 
    ...
    switch (id)     // Which dialog command item?
      {
        ...
        case sld1:    // The slider
          {
            char buff[20];
            sprintf(buff,"%d",retval);  // To string
            SetString(txt1,buff);      // Show value
          }
        ...
      }
    ...
  }

C_Spinner

V-ref-spinner.gif

This command item is used to provide an easy way for the user to enter a value from a list of possible values, or in a range of values. Depending on the attributes supplied to the CommandObject definition, the user will be able to select from a short list of text values, from a range of integers, or starting with some initial integer value. As the user presses either the up or down arrow, the value changes to the next permissible value. The retVal field specifies the initial value of the integer, or the index of the initial item of the text list. You use the GetValue method to retrieve the final value from the C_Spinner.

You can change the contents of the spinner list by using vDialog::SetValue with either ChangeList or ChangeListPtr. See vDialog::SetValue for more details.

The size of the spin value field in pixels can be controlled by using the CommandObject element size. By specifying the attribute CA_Size and providing a value for the size element, you can control the size of the value field . Note the that the size element is the last one of a CommandObject, and can left out of a declaration, which results in the compiler generating a zero value.

Example

This example shows how to setup the C_Spinner to select a value from a text list (when supplied with a list and the CA_Text attribute), from a range of integers (when supplied a range list), or from a starting value (when no list is provided). The definitions of the rest of the dialog are not included.

  static char* spinList[] =    // a list of colors
    {
      "Red","Green","Blue", 0
    };
  static int minMaxStep[3] =  // specify range of
    {                         // -10 to 10
      -10, 10, 2              // in steps of 2
    };
  enum { spnColor = 300, spnMinMax, spnInt, ... };
  CommandObject SpinDialog[] =
    {
      ...
      {C_Spinner,spnColor,0,"Vbox", // A text list.
        (void*)spinList,CA_Text,     // the list is CA_Text
        isSens,NoFrame, 0,0},
      {C_Spinner,spnMinMax,0,"Vbox", // a range -10 to 10
        (void*)minMaxStep,CA_None,  // by 2's starting at 0
        isSens,NoFrame, 0,0},
      {C_Spinner,spnInt,32,"Vbox",  // int values step by 1
        NoList,CA_None,             // starting at 32
        isSens,NoFrame, 0,0},
      ...
    };

C_Text

V-ref-textbox.gif

This draws boxed text. It is intended for displaying information that might be changed, unlike a label, which is usually constant. The text may be multi-line by using a '\n`. The retVal and title fields are not used. The text to display is passed in the itemList field.

You can use the CA_NoBorder attribute to suppress the border.

A definition of a C_Text item in a CommandObject definition would look like:

{C_Text, txtId, 0, "", "This is an example\nof a two line text.",
         CA_None,isSens,NoFrame, 0, 0, 0,0}, 

You can change the label of text box with: SetString(txtId, "New text to show.").

C_TextIn

V-ref-textin.gif

This command is used for text entry from the user. The text input command item will typically be boxed field that the user can use to enter text.

The strategy for using a TextIn command item is similar to the List command item. You need an OK button, and then retrieve the text after the dialog has been closed.

You can provide a default string in the title field which will be displayed in the TextIn field. The user will be able to edit the default string. Use an empty string to get a blank text entry field. The retVal field is not used.

There are two ways to control the size of the TextIn control. If you specify CA_None, you will get a TextIn useful form most simple input commands. Using CA_Large gets a wider TextIn, while CA_Small gets a smaller TextIn. You can also use the size field of the CommandObject to explicitly specify a width in characters. When you specify a size, that number of characters will fit in the TextIn, but the control does not enforce that size as a limit.

If you specify the attribute CA_Password, then the user's input will either be echoed as asterisks (MS-Windows), or not echoed (X).

If you specify the attribute CA_TextInNotify, then the DialogCommand mehtod for the dialog or tool bar will be called with the ID of the TextIn, and a value of either M_TextInChange or M_TextInLeaveFocus whenever the contents of the TextIn changes, or when the TextIn control loses focus. This capability is useful for validating the value in a TextIn.

Example

The following example demonstrates how to use a TextIn.

CommandObject textInList[] =
  {
    ...
    {C_TextIn, txiId,0,"",NoList,CA_None,isSens,NoFrame,0,0},
    ...
    {C_EndOfList,0,0,0,0,CA_None,0,0,0}
  };
 ...
    vModalDialog md(this);      /// make a dialog
    int ans, val;
    char text_buff[255];        // get text back to this buffer
 ...
    md.AddDialogCmds(textInList);  // add commands
    ans = md.ShowModalDialog("Enter text.", val);  // Show it
    text_buff[0] = 0;          // make an empty string
    (void) md.GetTextIn(txiId, text_buff, 254); // get the string
 ...

C_ToggleButton

V-ref-button.gif

A C_ToggleButton is a combination of a button and a checkbox. When the toggle button is pressed, the vCmdWindow::WindowCommand method is called, just as with a regular command button. However, the system will change the look of the toggle button to indicate it has been pressed. Each click on a C_ToggleButton will cause the button to appear pressed in or pressed out.

The retVal field of the CommandObject definition is used to indicate the initial state of the toggle.

The behavior of a toggle button is like a check box, and not a radio button. This is more flexible, but if you need exclusive radio button like selection, you will have to enforce it yourself using SetValue(toggleId,val,Value).

 // Define a toggle button with id tbtToggle and
 // an initial state of 1, which means pressed in
 {C_ToggleButton,tbtToggle, 1,"", NoList,CA_None,
     isSens, NoFrame, 0, 0},
 ...

 // The case in WindowCommand should be like this:

    case tbtToggle:
      {
	// Always safest to retrieve current value
        ItemVal curval = GetValue(tbtToggle);
        // Now, do whatever you need to
        if (curval)
           ... it is pressed
        else
           ... it is not pressed
        break;
      }

C_ToggleFrame

V-ref-frame.gif

A C_ToggleFrame is V's answer to the Windows Tab control. While Vdoesn't have real Tab controls, using a combination of C_ToggleFrames and either radio buttons or toggle buttons, you can design very nice multi-frame dialogs.

A Toggle Frame works just like a regular C_Frame except that you can use SetValue with a type Value to hide or make visible all controls contained or nested in the toggle frame. (Note: setting the Value of a toggle frame is not the same as setting its Hidden attribute.)

The strategy for using toggle frames follows. First, you will usually use two or more toggle frames together. In the dialog CommandObject definition, you first define one radio button or one toggle button for each toggle frame used in the dialog. You then define a regular bordered C_Frame positioned below the radio/toggle buttons. Then place CA_NoBorder toggle frames inside that outer frame. The outer frame will be the border for all the toggle frames. Inside each toggle frame, you define controls in the normal way.

You must select just one of the toggle frames to be initially visible. This will correspond to the checked radio button or pressed toggle button. The remaining toggle frames and their controls should all be defined using the CA_Hidden attribute.

You then hide and unhide toggle frames by responding to the vDialog::DialogCommand messages generated when a radio button or toggle button is pressed. You SetValue(togID, 1, Value) to show a toggle pane and all its controls, and SetValue(togID, 0, Value) to hide all its controls.

The following example shows how to define and control toggle frames:

    enum {lbl1 = 400, tbt1, tbt2, tbt3, frm1, tfr1, tfr2,
          btnA1, btnB1, btnA2, btnB2 };
    static CommandObject DefaultCmds[] =
      {
        // A label, then 2 toggle buttons to select toggle frames
        {C_Label,lbl1,0,"Tab Frame Demo",NoList,CA_None,isSens,
                 NoFrame,0,0},
        {C_ToggleButton,tbt1,1,"Tab 1",NoList, CA_None, isSens, 
                 lbl1, 0, 0},
        {C_ToggleButton,tbt2,0,"Tab 2",NoList, CA_None, isSens, 
                 lbl1, tbt, 0},
        {C_ToggleButton,tbt3,0,"Tab 3",NoList, CA_None, isSens,
                 lbl1, tbt2 0},

        // A Master frame to give uniform border to toggle frames
        {C_Frame,frm1,0, "", NoList,CA_None,isSens,lbl1,0,tbt1},

        // Toggle Frame 1 - default frame on
        {C_ToggleFrame, tfr1,1,"",NoList, CA_NoBorder,isSens,frm1,0,0},
        {C_Button,btnA1,0,"Button A(1)",NoList,CA_None,isSens,tfr1,0,0},
        {C_Button,btnB1,0,"Button B(1)",NoList,CA_None,isSens,tfr1,
                  0,btnA1},

        // Toggle Frame 2 - default off (CA_Hidden!)
        {C_ToggleFrame,tfr2,0,"",NoList,CA_NoBorder | CA_Hidden,
                isSens,frm1,0,0},
        {C_Button,btnA2,0,"Button A(2)",NoList,CA_Hidden,isSens,tfr2,0,0},
        {C_Button,btnB2,0,"Button B(2)",NoList,CA_Hidden,isSens,tfr2,
                  btnA2,0},

        {C_EndOfList,0,0,0,0,CA_None,0,0,0}
      };


    ...

    // In the DialogCommand method:

    switch (id)         // We will do some things depending on value
      {
        case tbt1:       // For toggle buttons, assume toggle to ON
          {
            SetValue(id,1,Value);     // turn on toggle button
            SetValue(tbt2,0,Value);    // other one off
            SetValue(tfr2,0,Value);    // Toggle other frame off
            SetValue(tfr1,1,Value);    // and ours on
            break;
          }

        case tbt2:       // Toggle 2
          {
            SetValue(id,1,Value);     // turn on toggle button
            SetValue(tbt1,0,Value);    // other off
            SetValue(tfr1,0,Value);    // Toggle other off
	    SetValue(tfr2,1,Value);    // and ours on
            break;
          }

      }
    // All commands should also route through the parent handler
    vDialog::DialogCommand(id,retval,ctype);
  }

C_ToggleIconButton

V-ref-iconbtn.gif

A C_ToggleIconButton is a combination of an icon button and a checkbox. When the toggle icon button is pressed, the vCmdWindow::WindowCommand method is called, just as with a regular icon button. However, the system will change the look of the toggle icon button to indicate it has been pressed. This is useful for good looking icon based interfaces to indicate to a user that some option has been selected. An additional press will change the appearance back to a normal icon button. The retVal field of the CommandObject definition is used to indicate the initial state of the toggle.

The behavior of a toggle icon button is like a check box, and not a radio button. This is more flexible, but if you need exclusive radio button like selection, you will have to enforce it yourself using SetValue(toggleId,val,Value).


 // Define a toggle icon button with id tibToggle and
 // an initial state of 1, which means pressed
 {C_ToggleIconButton,tibToggle, 1,"", &anIcon,CA_None,
     isSens, NoFrame, 0, 0},
 ...

 // The case in WindowCommand should be like this:

    case tibToggle:
      {
        // Always safest to retrieve current value
        ItemVal curval = GetValue(tibToggle);
        // Now, do whatever you need to
        if (curval)
           ... it is pressed
        else
           ... it is not pressed
        break;
      }

CmdAttribute

These attributes are used when defining command items. They are used to modify default behavior. These attributes are bit values, and some can be combined with an OR operation. Note that not all attributes can be used with all commands.

Attributes

CA_DefaultButton Used with a C_Button to indicate that this button will be the default button. The user can activate the default button by pressing the Enter key as well as using the mouse. It will most often be associated with the OK button.

CA_Hidden Sometimes you may find it useful to have a command object that is not displayed at first. By using the CA_Hidden attribute, the command object will not be displayed. The space it will require in the dialog or dialog pane will still be allocated, but the command will not be displayed. You can then unhide (or hide) the command using the SetValue method: SetValue(CmdID, TrueOrFalse, Hidden).

CA_Horizontal Command will have horizontal orientation. This attribute is used with Sliders and Progress Bars.

CA_Large The object should be larger than usual. It can be used with Lists, Progress Bars, Sliders, Text Ins, and Value Boxes.

CA_MainMsg Used with a C_Label to indicate that its string will be replaced with the message supplied to the ShowDialog method.

CA_NoBorderCA_NoBorder specifies that the object is to be displayed with no border.

CA_NoLabel Used for progress bars to suppress display of the value label.

CA_NoNotify Used for combo boxes and lists. When specified, the program will not be notified for each selection of a combo box item or a list item. When specified, the program is notified only when the combo box button is pressed, and must then use GetValue to retrieve the item selected in the combo box list. For lists, you will need another command button in the dialog to indicate list selection is done.

CA_NoSpace Used for frames, this attribute causes the command objects within the frame to be spaced together as tightly as possible. Normally, command objects have a space of several pixels between them when laid out in a dialog. The CA_NoSpace attribute is especially useful for producing a tightly spaced set of command buttons.

CA_None No special attributes. Used as a symbolic filler when defining items, and is really zero.

CA_Percent Used with progress bars to add a % to the value label.

CA_Size The size element of the CommandObject is being used to specify a size for the control. This is used with buttons, spin controls, and lists.

CA_Small The object should be smaller than usual. It can be used with Progress Bars and Text Ins. On Progress Bars, CA_Small means that the text value box will not be shown.

CA_Text Used for Spinners to specify that a text list of possible values has been supplied.

CA_TextInNotify Used for Text Ins. When used, the DialogCommand method will be called with the id of the TextIn, and an attribute of either M_TextInChange or M_TextInLeaveFocus. This allows your program to validate TextIn input values.

CA_Vertical Command will have vertical orientation. This attribute is used with Sliders and Progress Bars.


Predefined ItemVals

A useful collection of predefined values. Most are useful for defining dialogs, buttons, and menus.

When defining dialogs, menus, and command bars, you are required to provide an id for each item. There are many common operations used in GUI designs, and V�provides various predefined values for building your programs. The natural interpretation of most of these values should be obvious, and the descriptions are kept to a minimum. Most of the definitions describe the accepted practice for menu or button items with the given title. While these ItemVals can be used anywhere, some have ``standard'' usage.

Control Values

M_About Shows an informative message about current application.

M_All Select all.

M_Cancel Cancel. Usually used with a dialog. V�will automatically reset dialog commands to their original state when a M_Cancel is selected from a vDialog descended object.

M_Clear Used to clear a screen.

M_Close Used to close a file. The user is usually prompted to save or ignore changes if any were made to the file. This is usually not used to close a menu.

M_Copy Copy the highlighted text or item, and save into the clipboard.

M_Cut Cut the highlighted text or item from the file, and usually save into the clipboard.

M_Delete Delete the selected item or text - usually does not copy into the clipboard.

M_Done Done with operation.

M_Edit Typically a menu bar button to pulldown an edit menu.

M_Exit Exit from the program - checking to see if files need to be saved, of course.

M_File Typically a menu bar button to pulldown a file menu.

M_Find Find a pattern.

M_FindAgain Find pattern again.

M_Font Typically a menu bar button to pulldown a font menu.

M_FontSelect Select a font. (This is different from the M_Font value in that M_Font is intended as a main menu bar item, while this one is for a pulldown menu.

M_Format Typically a menu bar button to pulldown a format menu, which allows the user to select formatting options.

M_Help Show help.

M_Insert Typically a menu bar button to pulldown an insert menu.

M_Line M_Line is one of a few of these values that gets special treatment by the system. It is required for defining line separators in menus.

M_New Used to create a new file.

M_No Answer No.

M_None Select none.

M_OK OK, accept operation or information. Causes return from dialog.

M_Open Used to open an existing file.

M_Options Typically a menu bar button to pulldown an options menu.

M_Paste Paste the contents of the clipboard into the insertion point of the current file or item.

M_Preferences Set preferences.

M_Print Print current file.

M_PrintPreview On screen preview how the current file would look if printed.

M_Replace Replace pattern.

M_Save Used to save current file in its current name.

M_SaveAs Save current file under new name.

M_Search Typically a menu bar button to pulldown a search menu.

M_SetDebug Set debug stuff.

M_Test Typically a menu bar button to pulldown a test menu.

M_Tools Typically a menu bar button to pulldown a tools menu.

M_UnDo Undo the last action.

M_View Typically a menu bar button to pulldown a view menu, which allows the user to select different views of the document.

M_Window Typically a menu bar button to pulldown a window menu, which lets the user select different windows.

M_Yes Answer Yes.

See Also

Footnotes

1 This is necessary keep things as chars and still allow a possible 256 entries, since 256 is 28+1, and a color map with 0 entries doesn't make sense.