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Description
Add a static graphic control to a dialog. You can use this surface to draw via the Canvas functions.
Syntax
hndl = CONTROL ADD CANVAS [Name ControlName], hwnd, ctrlID, txt, xPos, yPos, Width, Height [, [Style] [, [ExStyle]]] [[,] CALL CallBack]
Returns
Number
Control window handler.
Parameters
Name |
Type |
Optional |
Meaning |
ControlName |
String |
Yes |
Optional name for the control.
This name must be globally unique, and is used to create a global variable to be used with control name methods and properties. |
hwnd |
Number |
No |
Handle of the dialog containing the control |
ctrlID |
Number |
No |
Control identifier |
txt |
String |
No |
A text expression representing the text you want to assign to the control. |
xPos |
Number |
No |
Horizontal position of the control inside the dialog |
yPos |
Number |
No |
Vertical position of the control inside the dialog |
Width |
Number |
No |
Control width |
Height |
Number |
No |
Control height |
Style |
Number |
Yes |
Optional primary style of the canvas control. This value can be a combination of the values below, combined together with the OR operator to form a bitmask. If style is omitted, the default combination is: %WS_CHILD OR %WS_VISIBLE OR %SS_OWNERDRAW.
%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 graphic control. %WS_BORDER Add a thin line border around the graphic control. %WS_DLGFRAME Create a graphic control that has a border of the style typically used with dialog boxes. |
ExStyle |
Number |
Yes |
Optional extended style of the Canvas control. This value can be a combination of the values below, combined together with the OR operator to form a bitmask. If exstyle is omitted, there is no default extended style.
%WS_EX_CLIENTEDGE Apply a sunken edge border to the control. %WS_EX_STATICEDGE Apply a three-dimensional border style to the control (intended to be used for items that do not accept user input). |
CallBack |
Function |
Yes |
Optional name of a Callback Function that receives all %WM_COMMAND and %WM_NOTIFY messages for the control.
If a callback for the control is not designated, you must create a dialog Callback Function to process messages from your control.
If the 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. |
Remarks
A canvas control is typically used with graphic statements to draw graphs, pictures, text, etc. After you create a graphic control, you must use Canvas_Attach to choose it for use with other statements and functions.
A canvas 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 CBMSG = %WM_COMMAND, CBCTL holding the ID of the control, and CBCTLMSG holding one of the following values:
%STN_CLICKED
Sent when the user clicks a mouse button on the graphic control (unless the image control has been disabled).
%STN_DBLCLK
Sent when the user double-clicks on a graphic control (unless the control has been disabled).
%STN_DISABLE
Sent when a graphic control has been disabled.
%STN_ENABLE
Sent when a graphic control has been enabled.
Restrictions
See also
Examples
