output: Add option to preview the contents of the current cycle_view

Add the 'cycleViewPreview.core' option to rc.xml to enable previews of
the selected view when cycling between windows. Default this option to
be disabled to match current behavior.

docs/labwc-config.5.scd

@@ -31,6 +31,10 @@ Configuration must be wrapped in a <labwc_config> root-node.
 *<core><adaptiveSync>* [yes|no]
  Enable adaptive sync. Default is no.
 
+*<core><cycleViewPreview>* [yes|no]
+ Preview the contents of the selected window when cycling between windows.
+ Default is no.
+
 # FOCUS
 
 *<focus><followMouse>* [yes|no]

docs/rc.xml.all

@@ -11,6 +11,7 @@
  <decoration>server</decoration>
  <gap>0</gap>
  <adaptiveSync>no</adaptiveSync>
+ <cycleViewPreview>no</cycleViewPreview>
  </core>
 
  <!--

include/config/rcxml.h

@@ -48,6 +48,9 @@ struct rcxml {
  /* window snapping */
  int snap_edge_range;
  bool snap_top_maximize;
+
+ /* cycle view (alt+tab) */
+ bool cycle_preview_contents;
 };
 
 extern struct rcxml rc;

src/config/rcxml.c

@@ -378,6 +378,8 @@ entry(xmlNode *node, char *nodename, char *content)
  rc.snap_edge_range = atoi(content);
  } else if (!strcasecmp(nodename, "topMaximize.snapping")) {
  rc.snap_top_maximize = get_bool(content);
+ } else if (!strcasecmp(nodename, "cycleViewPreview.core")) {
+ rc.cycle_preview_contents = get_bool(content);
  }
 }
 
@@ -476,6 +478,7 @@ rcxml_init()
  rc.screen_edge_strength = 20;
  rc.snap_edge_range = 1;
  rc.snap_top_maximize = true;
+ rc.cycle_preview_contents = false;
 }
 
 static struct {

src/output.c

@@ -802,6 +802,15 @@ output_render(struct output *output, pixman_region32_t *damage)
 
  /* 'alt-tab' border */
  if (output->server->cycle_view) {
+ /* If the 'cycle_preview_contents' option is set in
+ * rc.xml, render the contents of the cycle_view over
+ * all other views (except for the OSD)
+ */
+ if (rc.cycle_preview_contents) {
+ render_view_toplevels(output->server->cycle_view, output, damage);
+ render_view_popups(output->server->cycle_view, output, damage);
+ }
+
  render_cycle_box(output, damage, output->server->cycle_view);
  render_osd(output, damage, output->server);
  }