some questions about runs, glyphs, chars, bytes, clusters

[august <august alien mur at>]

Hi, 

	I am making some tests to try and learn more about Pango.  Right now
	I am trying to step through a layout line by line, run by run, and
	then word by word.

	I was hoping someone might be able to help me out with some
	questions.

	Here is what I am doing.
	
	static char * text = { " flower power "};
	// I get the layout
	PangoLayout *layout;
	layout = pango_layout_new(pango_context);
	pango_layout_set_text(layout, text, -1);
	pango_layout_context_changed(layout);


	// I then get iterators for lines and stuff
	PangoLayoutIter* p_iter = 0;
	p_iter = pango_layout_get_iter(layout);
	PangoLayoutLine* p_line = pango_layout_iter_get_line(p_iter);
	GSList* current_run = p_line->runs;
	PangoLayoutRun* p_run=(PangoLayoutRun*)current_run->data;

	// I then try to get attribute info for this run
	PangoLogAttr * logattrs = (PangoLogAttr *) malloc( 
			(p_run->item->num_chars +1 ) * sizeof(PangoLogAttr) );
	pango_break(text+ p_run->item->offset, p_run->item->length,
			  &p_run->item->analysis, logattrs,
			  p_run->item->num_chars+1);	

	// Am I doing this wrong?
	// This then gives me a PangoLogAttr for every byte char in the text
	// string, correct?  But, since there could be more than one char for 
	// a glyph, where do I check for word_end?

	// Can someone tell me here what num_chars refers to in the item?
	// is that character bytes? 
	// is that not always the same as item->length?
	// Also, what is the difference between a byte, a character, a glyph,
	// and a cluster in Pango?  In the docs and naming of variables, is
	// it consistently named?

	// Then, I try to step through the run by glyph and logattr to see
	// where words start and end
	// Is this correct? 

   for(int i=0;i<p_run->glyphs->num_glyphs;i++) {
		j=p_run->glyphs->log_clusters[i];
		// I print out some info about the word start and end
		printf("\t\tword_start:%d, ", logattrs[j].is_word_start);
		printf("word_end:%d \n", logattrs[j].is_word_end);
	}


	The funny thing that I notice heres is that the "f" and the "l" in
	"flower" is considered one glyph.  Is that right?


	Sorry if my questions are basic.  I can see how complex type layout
	is now that I am getting my hands dirty.  Any help would be greatly
	appreciated.

	thank you -august.