[sysprof/wip/visualizers] line-visualizer-row: restrict data points to visible range

[Christian Hergert <chergert src gnome org>]

commit 0766bd6b93b250e84fef1b75cfc4430c935038f6
Author: Christian Hergert <chergert redhat com>
Date:   Thu Sep 29 14:59:02 2016 -0700

    line-visualizer-row: restrict data points to visible range
    
    We don't want to cache all the datapoints from the underlying
    capture, just the datapoints for the visible region (and some
    at the edges so we get proper cairo_curve_to() x,y coordinates).
    
    This isn't a major optimization yet until we start supporting
    much larger capture sizes. But that will mostly be improved with
    capture indexes anyway.

 lib/sp-line-visualizer-row.c |   26 ++++++++++++++++++++++----
 1 files changed, 22 insertions(+), 4 deletions(-)
---
diff --git a/lib/sp-line-visualizer-row.c b/lib/sp-line-visualizer-row.c
index 2e42955..04c5149 100644
--- a/lib/sp-line-visualizer-row.c
+++ b/lib/sp-line-visualizer-row.c
@@ -451,10 +451,12 @@ sp_line_visualizer_row_set_time_range (SpVisualizerRow *row,
                                        gint64           begin_time,
                                        gint64           end_time)
 {
+  SpLineVisualizerRow *self = (SpLineVisualizerRow *)row;
+
   g_assert (SP_IS_LINE_VISUALIZER_ROW (row));
   g_assert (begin_time <= end_time);
 
-  sp_line_visualizer_row_queue_reload (SP_LINE_VISUALIZER_ROW (row));
+  sp_line_visualizer_row_queue_reload (self);
 }
 
 static void
@@ -741,6 +743,10 @@ sp_line_visualizer_row_load_data_worker (GTask        *task,
 {
   LoadData *load = task_data;
   g_autoptr(GArray) counter_ids = NULL;
+  SpCaptureCondition *left, *right;
+  gint64 ext_begin_time;
+  gint64 ext_end_time;
+  gint64 ext;
 
   g_assert (G_IS_TASK (task));
   g_assert (SP_IS_LINE_VISUALIZER_ROW (source_object));
@@ -755,10 +761,22 @@ sp_line_visualizer_row_load_data_worker (GTask        *task,
       g_array_append_val (counter_ids, line_info->id);
     }
 
-  sp_capture_cursor_add_condition (load->cursor,
-                                   sp_capture_condition_new_where_counter_in (counter_ids->len,
-                                                                              (guint 
*)(gpointer)counter_ids->data));
+  /*
+   * Add a little extra time to the visible range so that we can get any datapoints
+   * that might be overlapping the region a bit. This helps so that we can draw
+   * appropriate data points that need a proper x,y coordinate outside the
+   * visible area for cairo_curve_to().
+   */
+  ext = (load->end_time - load->begin_time) / 3;
+  ext_begin_time = load->begin_time - ext;
+  ext_end_time = load->end_time + ext;
+
+  left = sp_capture_condition_new_where_counter_in (counter_ids->len, (guint *)(gpointer)counter_ids->data);
+  right = sp_capture_condition_new_where_time_between (ext_begin_time, ext_end_time);
+  sp_capture_cursor_add_condition (load->cursor, sp_capture_condition_new_and (left, right));
+
   sp_capture_cursor_foreach (load->cursor, sp_line_visualizer_row_load_data_frame_cb, load);
+
   g_task_return_pointer (task, g_steal_pointer (&load->cache), (GDestroyNotify)point_cache_unref);
 }