re: Need to Track Drag on the screen.

[David D Webb]

There used to be a sample app posted on PalmSources's site called 
SignatureCapture.

Here's a code peice that I've used to build a full sig capture control.  It 
uses a Gadget control.  It calls a function AddPoint that stores the points in 
a buffer and takes a parameter of true or false whether its a starting point.

-Dave


/**************************************************************************************************
 * FUNCTION:       SigCapSingleFormHandleEvent
 *
 * DESCRIPTION:    Handles processing of events for the SigCapture form.
 
**************************************************************************************************/
Boolean SigCapSingleFormHandleEvent(EventPtr eventP)
{
    FormPtr          frmP = FrmGetActiveForm();
    Boolean          handled = false;
    UInt16           objIndex;
    RectangleType    r;
    
    switch (eventP->eType) {
        case frmOpenEvent:
            FrmDrawForm(frmP);

            FrmGetObjectBounds (frmP, FrmGetObjectIndex (frmP, 
SigCapSingleInput1Gadget), &r);
            WinEraseRectangle (&r, 1); // clear box
            WinDrawRectangleFrame(roundFrame, &r); // draw border
            MemHandleUnlock (sigHandle1);

            handled = true;
            break;
    
        case penDownEvent:

            objIndex = FrmGetObjectIndex (frmP, SigCapSingleInput1Gadget);
            FrmGetObjectBounds (frmP, objIndex, &r);
            // Check to see if pen down is in the first gadget
            if (RctPtInRectangle (eventP->screenX, eventP->screenY, &r)) {  
                GadgetTapped (1, SigCapSingleInput1Gadget);
                handled = true;
            }
            break;
    }
    return(handled);
}


/**************************************************************************************************
 * FUNCTION:    GadgetTapped
 *
 * DESCRIPTION: Handles processing of strokes on the gadget for the Signature 
capture.
 
**************************************************************************************************/
void GadgetTapped(UInt16 SigBox, UInt16 GadgetID)
{
    UInt16           objIndex;
    FormPtr          frmP;
    RectangleType    r;  
    Int16            x, y, x1 = 0, y1 = 0;
    Boolean          penDown;

    frmP = FrmGetActiveForm();

    objIndex = FrmGetObjectIndex (frmP, GadgetID);
    FrmGetObjectBounds (frmP, objIndex, &r);

    do {
        PenGetPoint (&x, &y, &penDown);

        if (y != y1 || x != x1) {  // Throw away all of the repeat events with 
the same coordinates
            // If all points are in the bounds of the gadget and this isn't the 
first point 
            if (RctPtInRectangle (x, y, &r) && RctPtInRectangle (x1, y1, &r) && 
x1 && y1) {
                WinDrawLine (x, y, x1, y1);  // Draw a line on the Palm from 
the previous pen point to the new point
                AddPoint (x - x1, y - y1, false);
            } else if (RctPtInRectangle (x, y, &r)) { // add a starter point
                AddPoint (x - r.topLeft.x, y - r.topLeft.y, true); 
            }
            x1 = x;
            y1 = y;
        }
    } while (penDown);
}

-- 
For information on using the PalmSource Developer Forums, or to unsubscribe, 
please see http://www.palmos.com/dev/support/forums/