QuickTime 4 Reference

Creating a Path Using Only Off-Curve Points

Listing 3 shows how you can create a path using only off-curve control points. The path defined in this example contains four control points.

Listing 3 Creating a path using only off-curve control points



 
ComponentInstance vectorCodec;

Handle streamH;

Handle pathH;

gxPoint points[4];

Boolean isOnCurve[4];

int i;



/* open the vector codec component */

OpenADefaultComponent (decompressorComponentType,

                        kVectorCodecType, &vectorCodec);



/* create a new vector data stream */

CurveCreateVectorStream (vectorCodec, streamH);



/* specify the points for the path and whether each one is on it */

points[0].x = ff(50);

points[0].y = ff(50);

isOnCurve[0] = FALSE;

points[1].x = ff(150);

points[1].y = ff(50);

isOnCurve[1] = FALSE;

points[2].x = ff(150);

points[2].y = ff(150);

isOnCurve[2] = FALSE;

points[3].x = ff(50);

points[3].y = ff(150);

isOnCurve[3] = FALSE;



/* create the path and add the points to it */

CurveNewPath (vectorCodec, &pathH);

for (i = 0; i <= 3; i++)

    CurveInsertPointIntoPath (vectorCodec, &points[i], pathH,

                              1, i, isOnCurve[i]);



/* add the path to the vector data stream */

CurveAddPathAtomToVectorStream (vectorCodec, pathH, streamH);



/* mark the end of the vector data stream by adding a 

   kCurveEndAtom atom to the stream */

CurveAddZeroAtomToVectorStream (vectorCodec, streamH);



/* use the vector codec here to decompress and display the vector data */



/* dispose of stream and path handles when done */

DisposeHandle (streamH);

DisposeHandle (pathH);

The four off-curve control points in this example form a square; the path that they define is a rounded square, as shown in Figure 59 .

Figure 59 A rounded path shape

Notice that the path is filled with the even-odd shape fill, which is the default for path shapes. You could, however, specify any shape fill for this path except the open-frame shape fill. The open-frame shape fill requires that the first and last points of the contour be on-curve points, and this path has no on-curve points.