Centre image at start (or on zoom reset)

This just sets the scroll bars to the middle position, which is not
necessarily the middle of the detector.  Still, it's better than
starting at the edge every time.

3 files changed, 18 insertions, 0 deletions

diff --git a/src/crystfel_gui.c b/src/crystfel_gui.c
index 5d71172e..daac90ab 100644
--- a/src/crystfel_gui.c
+++ b/src/crystfel_gui.c
@@ -1022,6 +1022,7 @@ int main(int argc, char *argv[])
 
 	proj.cur_frame = 0;
 	update_imageview(&proj);
+	crystfel_image_view_reset_zoom(CRYSTFEL_IMAGE_VIEW(proj.imageview));
 
 	toolbar = gtk_hbox_new(FALSE, 0.0);
 
diff --git a/src/crystfelimageview.c b/src/crystfelimageview.c
index 795d628c..96f49803 100644
--- a/src/crystfelimageview.c
+++ b/src/crystfelimageview.c
@@ -739,6 +739,7 @@ GtkWidget *crystfel_image_view_new()
 	iv->refl_box_size = 1.0;
 	iv->label_refls = 1;
 	iv->need_rerender = 0;
+	iv->need_recentre = 0;
 
 	g_signal_connect(G_OBJECT(iv), "destroy",
 	                 G_CALLBACK(destroy_sig), iv);
@@ -911,6 +912,15 @@ static double auto_scale_top(const struct image *image)
 }
 
 
+static void center_adjustment(GtkAdjustment *adj)
+{
+	double min = gtk_adjustment_get_lower(adj);
+	double max = gtk_adjustment_get_upper(adj);
+	double page = gtk_adjustment_get_page_size(adj);
+	gtk_adjustment_set_value(adj, min+(max-min-page)/2.0);
+}
+
+
 static int rerender_image(CrystFELImageView *iv)
 {
 	int i;
@@ -956,6 +966,11 @@ static int rerender_image(CrystFELImageView *iv)
 		iv->zoom = 1.0/iv->image->detgeom->panels[0].pixel_pitch;
 	}
 	configure_scroll_adjustments(iv);
+	if ( iv->need_recentre ) {
+		center_adjustment(iv->hadj);
+		center_adjustment(iv->vadj);
+		iv->need_recentre = 0;
+	}
 
 	iv->need_rerender = 0;
 	redraw(iv);
@@ -980,6 +995,7 @@ void crystfel_image_view_reset_zoom(CrystFELImageView *iv)
 	iv->detector_w = 1.0;
 	iv->detector_h = 1.0;
 	iv->zoom = -1.0;
+	iv->need_recentre = 1;
 	iv->need_rerender = 1;
 	redraw(iv);
 }
diff --git a/src/crystfelimageview.h b/src/crystfelimageview.h
index 9e1bf4a1..8d51a48b 100644
--- a/src/crystfelimageview.h
+++ b/src/crystfelimageview.h
@@ -68,6 +68,7 @@ struct _crystfelimageview
 
 	/* Redraw/scroll stuff */
 	int                  need_rerender;
+	int                  need_recentre;
 	GtkScrollablePolicy  hpol;
 	GtkScrollablePolicy  vpol;
 	GtkAdjustment       *hadj;