CanvasClear

int CanvasClear (int panelHandle, int controlID, Rect rect);

Purpose

Restores the specified rectangular area of a canvas control to the background color of the canvas control.

You can set the background color of the canvas control through the ATTR_PICT_BGCOLOR attribute.

Unlike other canvas drawing operations, CanvasClear can clear the canvas control beyond the canvas clipping rectangle.

Parameters

Input
Name Type Description
panelHandle integer Specifier for a particular panel that is currently in memory. You obtain this handle from LoadPanel, NewPanel, or DuplicatePanel.
controlID integer The defined constant, located in the .uir header file, that you assigned to the control in the User Interface Editor, or the ID returned by NewCtrl or DuplicateCtrl.
rect Rect Rect structure that specifyies the location and size of the rectangle to clear.

Use VAL_ENTIRE_OBJECT to specify the entire canvas.

The Rect structure is defined as follows:

typedef struct
   {
   int top;
   int left;
   int height;
   int width;
   } Rect;


You can create a Rect without having to declare a variable by using the following function:

Rect MakeRect (int top, int left, int height, int width);

Example

CanvasClear (panelHandle, controlID, VAL_ENTIRE_OBJECT);

Return Value

Name Type Description
status integer Return value indicating whether the function was successful. A negative number indicates that an error occurred.

Code Error Message String
xx Success