ofCairoRenderer stops working after setting ofScale(0, 0);

[dimitre]

I've noticed ofCairoRenderer stops working after setting ofScale(0, 0)
Maybe there is some destructive scale happening there. easy to reproduce.
Thanks

[arturoc]

I imagine what you mean is that it doesn't work afterwards even changing back the scale? It might be introducing some NaNs and never recover from it

[dimitre]

@arturoc yes this is what I mean.

[dimitre]

EDIT: found some more details.
Cairo preserves the matrix (translate, scale) across frames, so if you actually call something like:

	ofScale(0.5, 0.5);
	ofDrawCircle(100,100,100);

it accumulates, shrinking the size. The same happens with ofTranslate
one way of solving it would be reseting matrix before each draw, something like

		cairo_matrix_t matrix;
		cairo_matrix_init_scale(&matrix,xAmnt,yAmnt);
		cairo_set_matrix(cr,&matrix);

and the same for translation.

but this is almost like another issue.
The original issue pointed here is related to Cairo itself,
not very beautiful but if we want to contour this issue we can do something like :

void ofCairoRenderer::scale(float xAmnt, float yAmnt, float zAmnt ){
		if (xAmnt == 0 || yAmnt == 0) return;

ideas?

[dimitre]

one possible solution is adding some lines to setupGraphicsDefaults, so it resets the matrix in new frames.
But only if we start using cairo with the second optional parameter = true

ofSetCurrentRenderer(cairo, true);

//----------------------------------------------------------
void ofCairoRenderer::setupGraphicDefaults(){
	setStyle(ofStyle());
	path.setMode(ofPath::COMMANDS);
	path.setUseShapeColor(false);
	clear();
	
// new lines
	cairo_matrix_t matrix;
	cairo_matrix_init_scale(&matrix, 1.0, 1.0);
	cairo_matrix_init_translate(&matrix, 0.0, 0.0);
	cairo_set_matrix(cr,&matrix);
};

[dimitre]

Closed by #6991