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Image Control
The image control displays an image. The image is not re-sized to fit the control. The control is re-sized to fit the image (see the one exception under style& below). The image must come from a resource file.

If image resizing is needed, consider the ImageX control.

• Syntax:
  

  Control Add Image, hDlg, id&, image$, x, y, xx, yy, _
                                        style&, extsytle& CALL callback
  

• Source Code Example:
  This short example creates a complete application with a single image control. When clicked, the image control responds with a message. This tutorial page discusses most of the statements used, however the DDT, Controls, Messages, and Callback tutorials provide background information that may be helpful in understanding the example.

     #Compile Exe
     #Include "Win32API.inc"
     #Resource "pb-test.pbr"
     Global hDlg As Dword
     Function PBMain() As Long
        Dialog New Pixels, 0, "Image Test",300,300,200,200, _
                                        %WS_SysMenu, 0 To hDlg
        Control Add Image, hDlg, 100,"cowgirl", 50,50,100,100, %SS_Notify
        Dialog Show Modal hDlg Call DlgProc
     End Function
  
     CallBack Function DlgProc() As Long
        If Cb.Msg = %WM_Command And Cb.Ctl = 100 And _
                          Cb.CtlMsg = %STN_Clicked Then
           MsgBox "Pushed!"
        End If
     End Function
  

  In this example, the image "cowgirl" is stored in a resource file, available from here. Also note that the #INCLUDE "Win32API.inc" is required because it contains the %STN_CLICKED message named constant.

  An additional example of a callback function is provided further down this page.

• Visual Examples:
  And here are a few examples of what you can do with the image control in PowerBASIC. Variations on the Control Add Image statement were used to create the examples. In some cases, other Control statements were used to modify the results.

  

  There are few options. You can display the image at it's normal size and you can put a border around it. If you make the control smaller or bigger than the image, the control resizes itself to fit the image.

  The exception is that if %ss_centerimage is used in style&, the image is centered in the image control and the control does not resize. If the control is smaller than the image, the image is clipped. If the control is larger than the image, the pixel color at 0,0 in the image is used to form a border around the image.

Arguments
The Control Add statement is used to create all new controls. Here are the statement's arguments and any special significance to the image control.

• hDlg
  The dialog handle to which the image control is to be added. The value was returned by the DIALOG NEW statement.

• id&
  The id& argument is a control identifier assigned by the programmer. It must be a value of 1-65535. Values of 100+ are suggested, as PowerBASIC pre-assigns identifiers with special meaning. Numeric equates are suggested over the use of literal values.

• image$
  The name of an image from a resource file is used in image$, such as "cowgirl". Or, the integer identifier from the resource file may be used, entered into image$ as "#100".

• x,y and xx,yy
  The integer x,y and xx,yy dimensions use the same units as the parent dialog. (x,y) is the upper/left coordinates of the control. (xx,yy) is the width/height of the control.

  Since the image control resizes to fit the image the (xx,yy) dimensions are ignored unless %ss_centerimage is used in style&. In that case, the image control does not resize and the image is centered within the control as was discussed above.

• style& and extstyle&
  The style& and extstyle& arguments (listed below) are optional. If not supplied, default values are used (see the table below). If values are supplied, they completely replace default values (i.e., the entered values are not in addition to the default values).

• CALL
  The "CALL callback" section is optional. If not supplied, the callback function of the parent dialog is used. An example callback function for image controls is provided further down this page. The #MESSAGE COMMAND compiler directive can be used to prevent sending %WS_NOTIFY messages to the callback function. By default, both %WS_NOTIFY and %WS_COMMAND messages are sent.

Usage Notes
As noted earlier, images must come from PowerBASIC resource files.

Note that the #INCLUDE "Win32API.inc" is required because it contains the %STN_CLICKED message named constant.

The %SS_NOTIFY style must be included to received the %stn_click and %stn_dblclk notifications.

Image Control-Specific PowerBASIC Statements
Although PowerBASIC provides control-specific statements for some controls (Treeview, Imagelist, ...), there are no IMAGE PowerBASIC statements.

Messages, Notifications, Styles, and ExtSstyles
There are four types of named constants in the following table. All are pulled from the MSDN web site.

• Notifications - event notifications a control receives
• Messages - controls may send these
• Styles - affect the visual look of a control
• ExtStyles - additional values that affect the visual look

The first column contains control-specific named constants and the second column contains generic window named constants (image controls are windows).

Also, if the PowerBASIC Help file has an entry on the value, it is highlighted in yellow. If the value was noted in PowerBASIC Help as a default value, it is also shown in bold text.

In the values for notifications, descriptions starting with -n and -c refer to events received through the %wm_notify and %wm_command messages. By default, PowerBASIC controls can receive both of these messages.

And here is a short description of many of the named constants corresponding to notifications, styles, and extstyle - particularly those discussed in the PowerBASIC Help topics.

    %ss_bitmap             - display only bitmap images
    %ss_centerimage        - center image. fill border with 0,0 pixel color
    %ss_icon               - display only icon images
    %ss_notify             - sends %stn_clicked/%stn_dblclk messages
    %ss_sunken             - draw half-sunken border
    %stn_clicked           -c mouse click
    %stn_dblclk            -c double slick
    %stn_disable           -c when control has been disabled
    %stn_enable            -c when control has been enabled
    %wm_ctlcolorstatic     -  about to be drawn
    %ws_ex_clientedge      - apply sunken edge border
    %ws_ex_left            - generic left-aligned properties
    %ws_ex_right           - generic right-aligned properties
    %ws_ex_staticedge      - apply 3D border
    %ws_ex_transparent     - draw controls/windows beneath control first
    %ws_group              - starts/ends group. use %ws_tabstop style.

Callback Function
A control can have its own callback function, or use the parent dialog callback function.

A control callback function should return TRUE to indicate it has processed the message. This prevents unnecessarily calling the dialog callback function, which will process the message if no control callback function is available, or if the control callback function returns FALSE.

By default, both %WM_COMMAND and %WM_NOTIFY messages are received. However, if the #MESSAGE COMMAND compiler directive is invoked, the %WM_NOTIFY messages will not be available.

In addition, %ss_notify must be included in style& to receive the %stn_clicked and %stn_dblclk messages.

Here's a sample image control callback function.

   CallBack Function cbImage()
      Select Case CB.MSG
         Case %WM_COMMAND
            Select Case CB.CTLMSG
               Case %stn_clicked
               Case %stn_dblclk
               Case %stn_disable
               Case %stn_enable
         End Select
      End Select
   End Function

In each Case section, add the statements the application needs to respond to the event. Also, be sure to add "Function=1" as appropriate to indicate that the event was handled by the callback function.

CONTROL Statement Syntax
The following table lists the various Control statements (except the ADD statements). Most, but not all, can be used with the image control. A one-line description of the statement and then its syntax are presented.

CONTROL DISABLE	disable
	hDlg, id&
CONTROL ENABLE	enable	hDlg, id&
CONTROL GET CHECK	check state	hDlg, id& TO iResult1&
CONTROL GET CLIENT	top/left location	hDlg, id& TO wide&, high&
CONTROL GET LOC	top/left location	hDlg, id& TO x&, y&
CONTROL GET SIZE	width/height	hDlg, id& TO width&, height&
CONTROL GET TEXT	text	hDlg, id& TO txt$
CONTROL GET USER	get user data	hDlg, id&, index& TO retvar&
CONTROL HANDLE	window handle for control id	hDlg, id& TO hCtl&
CONTROL KILL	remove control	hDlg, id&
CONTROL POST	put message in queue (non-blocking)	hDlg, id&, Msg&, wParam&, lParam&
CONTROL REDRAW	schedule redraw of control	hDlg, id&
CONTROL SEND	send message to control, wait for processing	hDlg, id&, Msg&, wParam&, lParam& TO iResult2&
CONTROL SET CHECK	set check for 3state or checkbox	hDlg, id&, checkstate&
CONTROL SET CLIENT	change size to specific client area size	hDlg, id&, wide&, high&
CONTROL SET COLOR	set fg/bg color	hDlg, id&, fgcolor&, bgcolor&
CONTROL SET FOCUS	set focus	hDlg, id&
CONTROL SET FONT	select font for a control	hDlg, id&, fonthandle&
CONTROL SET LOC	relocate control within dialog	hDlg, id&, x&, y&
CONTROL SET OPTION	set check state of option control	hDlg, id&, minid&, maxid&
CONTROL SET SIZE	change control size	hDlg, id&, width&, height&
CONTROL SET TEXT	change control text	hDlg, id&, text$
CONTROL SET USER	set user data	hDlg, id&, index&, uservalue&
CONTROL SHOW STATE	toggle visibility	hDlg, id&, showstate& TO iResult3&

If you have any suggestions or corrections, please let me know.