canvas render: stop render_pre/post cb if it didn't render.

Summary:
Basically, render_pre/post should be called only if rendering happens.
Unfortunately, this behavior had been broken by some mistakes.

As far as I understand after reading history carefully,
this issue introduced for fixing unpair of pre/post cbs.

In case of async render, the post callback would be triggered in
evas_render_pipe_wakeup(), it means POST callbake shouldn't be tiggered in
evas_render_updates_internal(). If that post callback were removed in
evas_render_updates_internal(), then in case of sync_render,
POST callback won't be triggered. So previously, the PRE/POST couldn't get
paired.

I guess cedric put a mistake that nothing2rendering which brought
the pre/post pair issue, even he said that patch fix the unpair of them.
(But actually that patch brought the issue!)

See this: dc841ed9b2ccf880df2d7590ea46d95e03e8752f

Whatever it was intented or not, that patch totally insane, even
non-descripting.

If we just trigger post cb only if sync render or no_rendered case,
We could make satisfication for both cases.

@fix

Reviewers: #committers, devilhorns, zmike

Reviewed By: #committers, zmike

Subscribers: cedric, #committers, zmike

Tags: #efl

Differential Revision: https://phab.enlightenment.org/D6573

1 files changed, 3 insertions, 7 deletions

diff --git a/src/lib/evas/canvas/evas_render.c b/src/lib/evas/canvas/evas_render.c
index 3256ae1185..f03a6a5cab 100644
--- a/src/lib/evas/canvas/evas_render.c
+++ b/src/lib/evas/canvas/evas_render.c
@@ -3171,11 +3171,7 @@ evas_render_updates_internal(Evas *eo_e,
 
    e = evas = efl_data_scope_get(eo_e, EVAS_CANVAS_CLASS);
    if (e->inside_post_render) return EINA_FALSE;
-   if (!e->changed)
-     {
-        _cb_always_call(eo_e, EVAS_CALLBACK_RENDER_PRE, NULL);
-        goto nothing2render;
-     }
+   if (!e->changed) return EINA_FALSE;
 
    if (e->rendering)
      {
@@ -3707,14 +3703,14 @@ evas_render_updates_internal(Evas *eo_e,
 
    evas_module_clean();
 
-   // Send a RENDER_POST when we are rendering synchronously or when there is no update done asynchronously
+   /* Send a RENDER_POST when we are rendering synchronously or,
+      when do_async but no drawing. This gurantees pre-post pair. */
    if (!do_async || !rendering)
      {
         Evas_Event_Render_Post post;
         Eina_List *l1, *l2;
         Render_Updates *ru;
 
-     nothing2render:
         post.updated_area = NULL;
         EINA_LIST_FOREACH(e->outputs, l1, out)
           {