perf hists browser: Implement horizontal scrolling

Do it using the recently introduced ui_brower scrolling mode, setting
ui_browser.columns to the number of sort columns and then, when
rendering each line, skipping as many initial columns as the user
pressed the right arrow.

As the user presses the left arrow, the ui_browser code will remove the
scrolling counter and the left scrolling takes place.

The right arrow key was an alias for ENTER, so people used to press it
may get a bit annoyed at first, sorry! Ditto for ESC and the left key.

Callchains can be left as is or we can, when rendering the Symbol
column, store the at what position on the screen it is and then
using ui_browser__gotorc() to print it from there, i.e. the callchain
would move around with the symbol.

Leaving it as is, i.e. at a fixed position, close to the left, saves
precious screen real state for it, so I'm inclined to leave it as is
now.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: Chandler Carruth <chandlerc@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-ccqq9sabgfge5dwbqjwh71ij@git.kernel.orgSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/browsers/hists.c

@@ -784,11 +784,12 @@ static int hist_browser__show_entry(struct hist_browser *browser,
 			.size		= sizeof(s),
 			.ptr		= &arg,
 		};
+		int column = 0;
 
 		hist_browser__gotorc(browser, row, 0);
 
 		perf_hpp__for_each_format(fmt) {
-			if (perf_hpp__should_skip(fmt))
+			if (perf_hpp__should_skip(fmt) || column++ < browser->b.horiz_scroll)
 				continue;
 
 			if (current_entry && browser->b.navkeypressed) {
@@ -861,14 +862,16 @@ static int advance_hpp_check(struct perf_hpp *hpp, int inc)
 	return hpp->size <= 0;
 }
 
-static int hists__scnprintf_headers(char *buf, size_t size, struct hists *hists)
+static int hists_browser__scnprintf_headers(struct hist_browser *browser, char *buf, size_t size)
 {
+	struct hists *hists = browser->hists;
 	struct perf_hpp dummy_hpp = {
 		.buf    = buf,
 		.size   = size,
 	};
 	struct perf_hpp_fmt *fmt;
 	size_t ret = 0;
+	int column = 0;
 
 	if (symbol_conf.use_callchain) {
 		ret = scnprintf(buf, size, "  ");
@@ -877,7 +880,7 @@ static int hists__scnprintf_headers(char *buf, size_t size, struct hists *hists)
 	}
 
 	perf_hpp__for_each_format(fmt) {
-		if (perf_hpp__should_skip(fmt))
+		if (perf_hpp__should_skip(fmt)  || column++ < browser->b.horiz_scroll)
 			continue;
 
 		ret = fmt->header(fmt, &dummy_hpp, hists_to_evsel(hists));
@@ -896,7 +899,7 @@ static void hist_browser__show_headers(struct hist_browser *browser)
 {
 	char headers[1024];
 
-	hists__scnprintf_headers(headers, sizeof(headers), browser->hists);
+	hists_browser__scnprintf_headers(browser, headers, sizeof(headers));
 	ui_browser__gotorc(&browser->b, 0, 0);
 	ui_browser__set_color(&browser->b, HE_COLORSET_ROOT);
 	ui_browser__write_nstring(&browser->b, headers, browser->b.width + 1);
@@ -1806,8 +1809,17 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 	memset(options, 0, sizeof(options));
 	memset(actions, 0, sizeof(actions));
 
-	perf_hpp__for_each_format(fmt)
+	perf_hpp__for_each_format(fmt) {
 		perf_hpp__reset_width(fmt, hists);
+		/*
+		 * This is done just once, and activates the horizontal scrolling
+		 * code in the ui_browser code, it would be better to have a the
+		 * counter in the perf_hpp code, but I couldn't find doing it here
+		 * works, FIXME by setting this in hist_browser__new, for now, be
+		 * clever 8-)
+		 */
+		++browser->b.columns;
+	}
 
 	if (symbol_conf.col_width_list_str)
 		perf_hpp__set_user_width(symbol_conf.col_width_list_str);