Docs 0.11.0

#include "ofxCvContourFinder.h"



//--------------------------------------------------------------------------------
static bool sort_carea_compare( const CvSeq* a, const CvSeq* b) {
	
	// use opencv to calc size, then sort based on size
	float areaa = cvContourArea(a, CV_WHOLE_SEQ);
	float areab = cvContourArea(b, CV_WHOLE_SEQ);
	
	return (areaa > areab);
}




//--------------------------------------------------------------------------------
ofxCvContourFinder::ofxCvContourFinder() {
    _width = 0;
    _height = 0;
	myMoments = (CvMoments*)malloc( sizeof(CvMoments) );
	reset();
}

//--------------------------------------------------------------------------------
ofxCvContourFinder::~ofxCvContourFinder() {
	free( myMoments );
}

//--------------------------------------------------------------------------------
void ofxCvContourFinder::reset() {
    cvSeqBlobs.clear();
    blobs.clear();
    nBlobs = 0;
}

//--------------------------------------------------------------------------------
int ofxCvContourFinder::findContours( ofxCvGrayscaleImage&  input,
									  int minArea,
									  int maxArea,
									  int nConsidered,
									  bool bFindHoles,
                                      bool bUseApproximation) {

    // get width/height disregarding ROI
    IplImage* ipltemp = input.getCvImage();
    _width = ipltemp->width;
    _height = ipltemp->height;

	reset();

	// opencv will clober the image it detects contours on, so we want to
    // copy it into a copy before we detect contours.  That copy is allocated
    // if necessary (necessary = (a) not allocated or (b) wrong size)
	// so be careful if you pass in different sized images to "findContours"
	// there is a performance penalty, but we think there is not a memory leak
    // to worry about better to create mutiple contour finders for different
    // sizes, ie, if you are finding contours in a 640x480 image but also a
    // 320x240 image better to make two ofxCvContourFinder objects then to use
    // one, because you will get penalized less.

    inputCopy.setUseTexture(false);
	if( inputCopy.getWidth() == 0 ) {
		inputCopy.allocate( _width, _height );
	} else if( inputCopy.getWidth() != _width || inputCopy.getHeight() != _height ) {
        // reallocate to new size
        inputCopy.clear();
        inputCopy.allocate( _width, _height );
	}

    inputCopy.setROI( input.getROI() );
    inputCopy = input;

	CvSeq* contour_list = NULL;
	contour_storage = cvCreateMemStorage( 1000 );
	storage	= cvCreateMemStorage( 1000 );

	int retrieve_mode
        = (bFindHoles) ? CV_RETR_LIST : CV_RETR_EXTERNAL;
	cvFindContours( inputCopy.getCvImage(), contour_storage, &contour_list,
                    sizeof(CvContour), retrieve_mode, bUseApproximation ? CV_CHAIN_APPROX_SIMPLE : CV_CHAIN_APPROX_NONE );
	CvSeq* contour_ptr = contour_list;

	// put the contours from the linked list, into an array for sorting
	while( (contour_ptr != NULL) ) {
		float area = cvContourArea(contour_ptr, CV_WHOLE_SEQ, bFindHoles); // oriented=true for holes
		if(bFindHoles && area < 0) { // areas can be non negative in the case of holes
			area = fabs(area);
		}
		if((area > minArea) && (area < maxArea)) {
			cvSeqBlobs.push_back(contour_ptr);
		}
		contour_ptr = contour_ptr->h_next;
	}


	// sort the pointers based on size
	if( cvSeqBlobs.size() > 1 ) {
        sort( cvSeqBlobs.begin(), cvSeqBlobs.end(), sort_carea_compare );
	}


	// now, we have cvSeqBlobs.size() contours, sorted by size in the array
    // cvSeqBlobs let's get the data out and into our structures that we like
	for( int i = 0; i < MIN(nConsidered, (int)cvSeqBlobs.size()); i++ ) {
		blobs.push_back( ofxCvBlob() );
		float area = cvContourArea( cvSeqBlobs[i], CV_WHOLE_SEQ, bFindHoles ); // oriented=true for holes
		CvRect rect	= cvBoundingRect( cvSeqBlobs[i], 0 );
		cvMoments( cvSeqBlobs[i], myMoments );

		blobs[i].area                     = bFindHoles ? fabs(area) : area; // only return positive areas
		blobs[i].length 			      = cvArcLength(cvSeqBlobs[i]);
		blobs[i].boundingRect.x           = rect.x;
		blobs[i].boundingRect.y           = rect.y;
		blobs[i].boundingRect.width       = rect.width;
		blobs[i].boundingRect.height      = rect.height;
		blobs[i].centroid.x 			  = (myMoments->m10 / myMoments->m00);
		blobs[i].centroid.y 			  = (myMoments->m01 / myMoments->m00);

		if(bFindHoles) {
			// for some reason, changing the orientation when looking for holes
			// yields negative areas for non holes and positive areas for holes
			//
			// negating the value here works, even though it feels like a hack
			blobs[i].hole                 = -area < 0 ? true : false; // negative area denotes a hole
		}
		else {
			blobs[i].hole                 = false; // no holes
		}

		// get the points for the blob:
		CvPoint           pt;
		CvSeqReader       reader;
		cvStartReadSeq( cvSeqBlobs[i], &reader, 0 );

    	for( int j=0; j < cvSeqBlobs[i]->total; j++ ) {
			CV_READ_SEQ_ELEM( pt, reader );
            blobs[i].pts.push_back( ofPoint((float)pt.x, (float)pt.y) );
		}
		blobs[i].nPts = blobs[i].pts.size();

	}

    nBlobs = blobs.size();

	// Free the storage memory.
	// Warning: do this inside this function otherwise a strange memory leak
	if( contour_storage != NULL ) { cvReleaseMemStorage(&contour_storage); }
	if( storage != NULL ) { cvReleaseMemStorage(&storage); }

	return nBlobs;

}

//--------------------------------------------------------------------------------
void ofxCvContourFinder::draw( float x, float y, float w, float h ) const {

    float scalex = 0.0f;
    float scaley = 0.0f;
    if( _width != 0 ) { scalex = w/_width; } else { scalex = 1.0f; }
    if( _height != 0 ) { scaley = h/_height; } else { scaley = 1.0f; }

    if(bAnchorIsPct){
        x -= anchor.x * w;
        y -= anchor.y * h;
    }else{
        x -= anchor.x;
        y -= anchor.y;
    }

    ofPushStyle();
	// ---------------------------- draw the bounding rectangle
	ofSetHexColor(0xDD00CC);
    ofPushMatrix();
    ofTranslate( x, y, 0.0 );
    ofScale( scalex, scaley, 0.0 );

	ofNoFill();
	for( int i=0; i<(int)blobs.size(); i++ ) {
		ofDrawRectangle( blobs[i].boundingRect.x, blobs[i].boundingRect.y,
                        blobs[i].boundingRect.width, blobs[i].boundingRect.height );
	}

	// ---------------------------- draw the blobs
	ofSetHexColor(0x00FFFF);

	for( int i=0; i<(int)blobs.size(); i++ ) {
		ofNoFill();
		ofBeginShape();
		for( int j=0; j<blobs[i].nPts; j++ ) {
			ofVertex( blobs[i].pts[j].x, blobs[i].pts[j].y );
		}
		ofEndShape();

	}
	ofPopMatrix();
	ofPopStyle();
}


//----------------------------------------------------------
void ofxCvContourFinder::draw(const ofPoint & point) const{
	draw(point.x, point.y);
}

//----------------------------------------------------------
void ofxCvContourFinder::draw(const ofRectangle & rect) const{
	draw(rect.x, rect.y, rect.width, rect.height);
}

//--------------------------------------------------------------------------------
void ofxCvContourFinder::setAnchorPercent( float xPct, float yPct ){
    anchor.x = xPct;
    anchor.y = yPct;
    bAnchorIsPct = true;
}

//--------------------------------------------------------------------------------
void ofxCvContourFinder::setAnchorPoint( int x, int y ){
    anchor.x = x;
    anchor.y = y;
    bAnchorIsPct = false;
}

//--------------------------------------------------------------------------------
void ofxCvContourFinder::resetAnchor(){
    anchor.set(0,0);
    bAnchorIsPct = false;
}