CONTROL ADD IMAGEX statement

Purpose

Add a stretched image control to a dialog. This is typically used to display bitmaps and icons, which are automatically stretched or condensed to fill the controls client area.

Syntax

CONTROL ADD IMAGEX, hDlg, id&, image$, x, y, xx, yy [, [style&] [, [exstyle&]]] [[,] CALL callback]

hDlg

Handle of the dialog in which the image will be created. The dialog will become the parent of the control.

id&

Unique identifier for the image in the range 1 to 65535, frequently specified with numeric equates for clarity of the code. For example, the equate %BackgroundIMG is more informative than a literal value such as 497. If you will not be changing the image in the control after it is created, you may use -1 for the id&; however, best practice suggests identifiers should start at 100 to avoid conflict with any of the standard predefined identifiers.

image$

Name of the bitmap or icon in the resource file. If the image resource uses an integral identifier, image$ should begin with a Number symbol (#) followed by the identifier in an ASCII format, e.g., "#998" or FORMAT$(rcid&, "\##"). Otherwise, use the text identifier name for the image.

x, y

Integral expressions, variables, or numeric literal values, specifying the location of the control inside the dialog client area. x is the horizontal position, and y is the vertical position. 0,0 refers to the upper left corner of the dialog box client area. Coordinates are specified in the same terms (pixels or dialog units) as the parent dialog.

Integral expression, variable, or numeric literal value, specifying the width of the image. The width is given in the same terms (pixels or dialog units) as the parent dialog.

Integral expression, variable, or numeric literal value, specifying the height of the image. The height is given in the same terms (pixels or dialog units) as the parent dialog.

style&

Primary style of the stretched image control. In addition to the image control styles listed below, the initial image format may be specified explicitly as either %SS_ICON or %SS_BITMAP, or you may choose not to specify the image format at all.

If the image format is specified, it must match the format of the file specified in image$. However, if the image format is not specified, PowerBASIC will examine the file to determine the correct image format to use.

This value can be a combination of any values below, combined together with the OR operator to form a bitmask:

%SS_BITMAP	Display only bitmap images. Also see %SS_ICON. (persistent)
%SS_ICON	Display only icon images. Also see %SS_ICON. (persistent)
%SS_NOTIFY	Send %STN_CLICKED and %STN_DBLCLK notification messages to the Callback Function when the user clicks or double-clicks the control.
%SS_SUNKEN	Draw a half-sunken border around the image control.
%WS_GROUP	Define the start of a group of controls. The first control in each group should also use %WS_TABSTOP style. The next %WS_GROUP control in the tab order defines the end of this group and the start of a new group. Groups configured this way permit the arrow keys to shift focus between the controls within the group, and focus can jump from group to group with the usual TAB and SHIFT+TAB keys. Both tab stops and groups are permitted to wrap from the end of the tab order back to the start.

exstyle&

Extended style of the stretched image control. The default extended image style comprises %WS_EX_LEFT. The default extended style is used if both the primary and extended parameters are omitted from the CONTROL ADD IMAGEX statement, in the same manner as style& above.

The extended stretched image style value can be a combination of any values below, combined together with the OR operator to form a bitmask:

%WS_EX_CLIENTEDGE	Apply a sunken edge border to the control.
%WS_EX_LEFT	The control has generic "left-aligned" properties. (default)
%WS_EX_RIGHT	The control has generic "right-aligned" properties. This style has an effect only if the shell language is Hebrew, Arabic, or another language that supports reading order alignment.
%WS_EX_STATICEDGE	Apply a three-dimensional border style to the control (intended to be used for items that do not accept user input).
%WS_EX_TRANSPARENT	Controls/windows beneath the control are drawn before the control is drawn. The control is deemed transparent because elements behind the control have already been painted - the control itself is not drawn differently. True transparency is achieved by using Regions - see MSDN for more information.

callback

Optional name of a Callback Function that receives all %WM_COMMAND and %WM_NOTIFY messages for the control. See the #MESSAGES metastatement to choose which messages will be received. If a callback for the control is not designated, you must create a dialog Callback Function to process messages from your control.

In general, when the control Callback Function processes a message, it should return TRUE (non-zero) to prevent the message being passed unnecessarily to the dialog callback (if one exists). The dialog callback should also return TRUE if the notification message is processed by that Callback Function. Otherwise, the DDT engine processes unhandled messages.

Remarks

The bitmap or icon used in the image is resized to fit the control. If your control is 64 dialog units wide and your icon or bitmap is only 32, it will be stretched to cover the entire control. For best results, icons should be 32x32 pixels.

An image control will only send notification messages to a callback if the %SS_NOTIFY style is used. Notification messages are sent to the Callback Function with CB.MSG = %WM_COMMAND, CB.CTL holding the ID (id&) of the control, and CB.CTLMSG holding the following values:

%STN_CLICKED	Sent when the user clicks a mouse button on the image control (unless the image control has been disabled).
%STN_DBLCLK	Sent when the user double-clicks on an image control (unless the control has been disabled).
%STN_DISABLE	Sent when an image control has been disabled.
%STN_ENABLE	Sent when an image control has been enabled.

When a Callback Function receives a %WM_COMMAND message, it should explicitly test the value of CB.CTL and CB.CTLMSG to guarantee it is responding appropriately to the notification message.

Restrictions

Under Windows 95/98/ME, an attempt to stretch an icon significantly above 64x64 may fail due to internal limits that vary between those particular versions of Windows. Bitmaps are not affected in this manner. Windows NT/2000/XP systems do not impose any comparable limitations on either icons or bitmaps.