RE: MI-L MapBasic Centroid question

[Carlos Montalvillo]

Hello Francois,      This is an extract from the Mapbasic Help :   >Setting a Centroid >The Centroid of a Region and Polyline can now be set by using the Alter Object command with the syntax noted below: >Alter Object Obj Geography OBJ_GEO_CENTROID, PointObj >Note that PointObj is a point object.  This differs from other values input by Alter Object Geography, which are all >scalars.  A point is needed in this instance because we need two values which define a point.  The Point that is >input is checked to make sure it is a valid Centroid (i.e., it is inside the region).  If the Obj is not a region or >polyline, or if PointObj is not a point object, or if the point is not a valid centroid, then an error is returned. >An easy way to center an X and Y value for a centroid is as follows:   >Alter Object Obj Geography OBJ_GEO_CENTROID, CreatePoint(X, Y)   >The user can also query the centroid by using the ObjectGeography function as follows:   >PointObj = ObjectGeography(Obj, OBJ_GEO_CENTROID)   >Note that there are other ways to get the Centroid, including the Centroid(), CentroidX(), and CentroidY() >functions.  These functions remain unchanged. >OBJ_GEO_CENTROID is defined in mapbasic.def.      And this is an extract from the MapInfo Help :   >Changing A Region's Centroid >Autolabels, thematic bar and pie charts, and point objects created by geocoding are drawn at the object's centroid. >You can move a region's centroid which will in turn affect the location of all future objects drawn in this region. >However, autolabels, and geocoded point objects drawn prior to changing an object's centroid remain unchanged. >To move a region's centroids: >1. Choose Map > Layer Control > Display > Show Centroids, the centroids are displayed. >2. Click the Select button in the Main Toolbar to access the Select tool. >3. Select the object whose centroid you want to move. >4. Click on the Reshape button in the Drawing Toolbar. >5. Click on the centroid and drag it to another location within the object.      Hope this help,      Carlos Montalvillo G�mez    SGSMap - Ingenieros Consultores    Camino de Portuetxe, 83    20018 - San Sebastian - Espa�a    Tel (+34) 943 31 74 90    http://www.sgsmap.com/    mailto:[EMAIL PROTECTED]   ----- Original Message ----- From: CABRIEL Francois To: [EMAIL PROTECTED] Sent: Friday, October 20, 2000 12:46 PM Subject: MI-L MapBasic Centroid question Hello, I have a problem with MapBasic 5.0 : Is there an easy way to modify the object centroid of a polygon? (the only way i see actually is to create a new object with the clause Center (newCenterX,newCenterY); may be its possible to use Alter Object, but how?) TIA ------------------------------------------------- Fran�ois CABRIEL Service Analyse Spatiale Conseil R�gional Provence-Alpes-C�te d'Azur T�l�phone   = 04.91.57.50.57 poste 5848 Internet = [EMAIL PROTECTED] ========================== _______________________________________________________________________ List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, send e-mail to [EMAIL PROTECTED] and put "unsubscribe MapInfo-L" in the message body.