trace-graph: Work on fixing the zooming and horizontal scrolling

For some reason zooming in too much will cause the horizontal
scrolling to get out of sync. This is probably a rounding error
or some other strange bug. This patch cleans some of the code
up and fixes parts of it. But there's still a bug to swat.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 44 insertions, 41 deletions

diff --git a/trace-graph.c b/trace-graph.c
index a92293f..8505169 100644
--- a/trace-graph.c
+++ b/trace-graph.c
@@ -30,7 +30,7 @@
 #include "trace-local.h"
 #include "trace-graph.h"
 
-#define DEBUG_LEVEL     1
+#define DEBUG_LEVEL     2
 #if DEBUG_LEVEL > 0
 # define dprintf(l, x...)                       \
         do {                                    \
@@ -460,13 +460,23 @@ motion_notify_event(GtkWidget *widget, GdkEventMotion *event, gpointer data)
         return TRUE;
 }
 
-static void update_graph(struct graph_info *ginfo, gdouble percent)
+static int update_graph(struct graph_info *ginfo, gdouble percent)
 {
-        ginfo->full_width *= percent;
-        ginfo->resolution =
-                (gdouble)ginfo->full_width / (gdouble)(ginfo->end_time -
-                                                       ginfo->start_time);
-        ginfo->start_x *= percent;
+        gint full_width = ginfo->full_width * percent;
+        gdouble resolution = (gdouble)full_width / (gdouble)(ginfo->end_time -
+                                                             ginfo->start_time);
+
+        /* Check if we are too big */
+        if (!resolution || full_width <= 0)
+                return -1;
+
+        ginfo->full_width = full_width;
+        ginfo->resolution = resolution;
+        ginfo->start_x = (ginfo->view_start_time - ginfo->start_time) *
+                ginfo->resolution;
+
+        dprintf(1, "new resolution = %f\n", resolution);
+        return 0;
 }
 
 static void update_graph_to_start_x(struct graph_info *ginfo)
@@ -479,10 +489,10 @@ static void update_graph_to_start_x(struct graph_info *ginfo)
                 return;
         }
 
-        ginfo->view_start_time = ginfo->start_x / ginfo->resolution +
+        ginfo->view_start_time = (gdouble)ginfo->start_x / ginfo->resolution +
                 ginfo->start_time;
 
-        ginfo->view_end_time = width / ginfo->resolution +
+        ginfo->view_end_time = (gdouble)width / ginfo->resolution +
                 ginfo->view_start_time;
 
         g_assert (ginfo->view_start_time < ginfo->end_time);
@@ -499,6 +509,7 @@ static void reset_graph(struct graph_info *ginfo, gdouble view_width)
 
 static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
 {
+        guint64 start_time;
         gdouble view_width;
         gdouble new_width;
         gdouble select_width;
@@ -510,26 +521,22 @@ static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
         g_assert(start < end);
         g_assert(ginfo->vadj);
 
-        dprintf(1, "*** started with ");
-        print_time(start / ginfo->resolution + ginfo->view_start_time);
-        dprintf(1, "\n");
+        start_time = ginfo->start_time +
+                (ginfo->start_x + start) / ginfo->resolution;
 
         view_width = gtk_adjustment_get_page_size(ginfo->vadj);
         select_width = end - start;
         percent = view_width / select_width;
 
-        update_graph(ginfo, percent);
+        dprintf(1, "view width=%f select width=%f percent=%f\n",
+                view_width, select_width, percent);
+
+        if (update_graph(ginfo, percent) < 0)
+                return;
 
         curr_width = ginfo->draw->allocation.width;
         new_width = curr_width * percent;
 
-        dprintf(1, "width=%d\n", ginfo->draw->allocation.width);
-        if (ginfo->vadj) {
-                dprintf(1, "adj:%f-%f\n", gtk_adjustment_get_upper(ginfo->vadj),
-                       gtk_adjustment_get_lower(ginfo->vadj));
-        } else
-                dprintf(1, "no adjustment\n");
-
         ginfo->draw_width = new_width;
         dprintf(1, "zoom in draw_width=%d full_width=%d\n",
                ginfo->draw_width, ginfo->full_width);
@@ -550,6 +557,7 @@ static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
 
                 mid = start + (end - start) / 2;
                 mid *= percent;
+                mid += ginfo->start_x;
 
                 /*
                  * mid now points to the center of the viewable area
@@ -568,27 +576,18 @@ static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
 
                 new_start = mid - MAX_WIDTH / 2;
                 new_end = new_start + MAX_WIDTH;
+
                 if (new_start < 0) {
-                        /* First check if there's a start available in full */
-                        if (ginfo->start_x) {
-                                ginfo->start_x += new_start;
-                                if (ginfo->start_x < 0) {
-                                        new_start = ginfo->start_x;
-                                        ginfo->start_x = 0;
-                                } else
-                                        new_start = 0;
-                        }
-                        new_end += -new_start;
+                        mid += new_start;
                         new_start = 0;
                 } else if (new_end > ginfo->full_width) {
                         new_start -= new_end - ginfo->full_width;
+                        mid += new_end - ginfo->full_width;
                         new_end = ginfo->full_width;
                         g_assert(new_start >= 0);
                 }
 
-                ginfo->start_x += new_start;
-
-                update_graph_to_start_x(ginfo);
+                ginfo->start_x = new_start;
 
                 dprintf(1, "new start/end =%d/%d full:%d  start_time:",
                        new_start, new_end, ginfo->full_width);
@@ -596,10 +595,15 @@ static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
                 dprintf(1, "\n");
 
                 /* Adjust start to be the location for the vadj */
-                start = (mid - new_start) / percent - (end - start) / 2;
-        }
+                start = (mid - new_start) - view_width / 2;
+        } else
+                start *= percent;
+
+        update_graph_to_start_x(ginfo);
+
+        ginfo->vadj_value = start;
+        ginfo->vadj_value = (start_time - ginfo->view_start_time) * ginfo->resolution;
 
-        ginfo->vadj_value = (gdouble)start * view_width / select_width;
         if (ginfo->vadj_value > (ginfo->draw_width - view_width))
                 ginfo->vadj_value = ginfo->draw_width - view_width;
 
@@ -623,13 +627,11 @@ static void zoom_in_window(struct graph_info *ginfo, gint start, gint end)
 static gboolean
 value_changed(GtkWidget *widget, gpointer data)
 {
-#if 0
-        struct graph_info *ginfo = data;
+//      struct graph_info *ginfo = data;
         GtkAdjustment *adj = GTK_ADJUSTMENT(widget);
 
-        printf("value = %f\n",
+        dprintf(2, "value = %f\n",
                gtk_adjustment_get_value(adj));
-#endif
 
         return TRUE;
 
@@ -660,7 +662,8 @@ static void zoom_out_window(struct graph_info *ginfo, gint start, gint end)
         curr_width = ginfo->draw->allocation.width;
         new_width = curr_width / divider;
 
-        update_graph(ginfo, 1 / divider);
+        if (update_graph(ginfo, 1 / divider) < 0)
+                return;
 
         dprintf(1, "width=%d\n", ginfo->draw->allocation.width);