Capture (SCREENSHOT)

The capture operator creates an action that captures the currently rendered visual state of the user interface as a PNG image or as HTML markup. The captured content is written into a property when a target property is specified, or sent to the client and opened by the operating system otherwise.

Capture target

The capture target determines which portion of the user interface is captured:

• Document body — the whole page body of the user's web client. The action does not depend on any form being open and can be called from any action context.
• Form — the main container of the form in whose context the action is executing. The action expects a form context.
• Container — a specific container of the form in whose context the action is executing, identified by its container SID from the form's design. The action expects a form context and the form must contain a container with the specified SID.

If a form or container target is specified but the required context is missing, the action fails with an error.

Capture format

The captured content can be produced in one of two formats:

• Image — a PNG screenshot of the target rendered as it appears on the screen. The target property must accept either IMAGEFILE or one of the generic file types FILE, NAMEDFILE.
• HTML — the inner HTML markup of the target. The target property must accept either HTMLFILE or one of the generic file types FILE, NAMEDFILE.

The target property must be parameterless.

Capture destination

The captured content is written to the target property when a target property is specified. Otherwise the generated file is sent to the client and opened by the operating system.

Client support

The capture operator runs only in the web client. It relies on the live DOM in the browser to render the screenshot; on the desktop client the action is not supported and any attempt to execute it fails.

Language

To create the action, use the SCREENSHOT operator.

Examples

CLASS Report;
name = DATA ISTRING[100] (Report);
image = DATA IMAGEFILE (Report);
html = DATA HTMLFILE (Report);

FORM dashboard
    OBJECTS r = Report
    PROPERTIES(r) name, image, html
;

DESIGN dashboard {
    NEW chartBox {
        caption = 'Chart';
        MOVE PROPERTY(image(r));
    }
}

captureToClient ()  {
    SCREENSHOT; // delivered to the client and opened by the OS
}

captureViewport (Report r)  {
    LOCAL img = IMAGEFILE ();
    SCREENSHOT TO img;
    image(r) <- img();
}

captureForm (Report r)  {
    LOCAL img = IMAGEFILE ();
    SCREENSHOT FORM TO img;
    image(r) <- img();
}

captureChart (Report r)  {
    LOCAL img = IMAGEFILE ();
    SCREENSHOT chartBox TO img;
    image(r) <- img();
}

captureFormHtml (Report r)  {
    LOCAL page = HTMLFILE ();
    SCREENSHOT HTML FORM TO page;
    html(r) <- page();
}