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design: gstghostpad: various formatting fixes

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- Add missing markup
- Drop manual padding on some figures

Also fix some minor grammar issues.
This commit is contained in:
Reynaldo H. Verdejo Pinochet 2016-12-21 23:51:46 -08:00
parent 1a5ab06a74
commit 3f89c720e1
1 changed files with 58 additions and 54 deletions
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112
markdown/design/gstghostpad.md
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@ -6,65 +6,67 @@ element.
## Some design requirements
- Must look like a real GstPad on both sides.
- Must look like a real `GstPad` on both sides.
- target of Ghostpad must be changeable
- target can be initially NULL
- a GhostPad is implemented using a private GstProxyPad class:
- a GhostPad is implemented using a private `GstProxyPad` class:
```
GstProxyPad
(------------------)
| GstPad |
|------------------|
| GstPad *target |
(------------------)
| GstPad *internal |
(------------------)
GstProxyPad
(------------------)
| GstPad |
|------------------|
| GstPad *target |
(------------------)
| GstPad *internal |
(------------------)
GstGhostPad
(------------------) -\
| GstPad | |
|------------------| |
| GstPad *target | > GstProxyPad
|------------------| |
| GstPad *internal | |
|------------------| -/
| <private data> |
(------------------)
GstGhostPad
(------------------) -\
| GstPad | |
|------------------| |
| GstPad *target | > GstProxyPad
|------------------| |
| GstPad *internal | |
|------------------| -/
| <private data> |
(------------------)
```
A GstGhostPad (X) is _always_ created together with a GstProxyPad (Y).
The internal pad pointers are set to point to the eachother. The
GstProxyPad pairs have opposite directions, the GstGhostPad has the same
A `GstGhostPad` (X) is _always_ created together with a `GstProxyPad` (Y).
The internal pad pointers are set to point to eachother. The
`GstProxyPad` pairs have opposite directions, the `GstGhostPad` has the same
direction as the (future) ghosted pad (target).
(- X --------)
| |
| target * |
|------------|
| internal *----+
(------------) |
^ V
| (- Y --------)
| | |
| | target * |
| |------------|
+----* internal |
(------------)
```
(- X --------)
| |
| target * |
|------------|
| internal *----+
(------------) |
^ V
| (- Y --------)
| | |
| | target * |
| |------------|
+----* internal |
(------------)
Which we will abbreviate to:
Which we will abbreviate to:
(- X --------)
| |
| target *--------->//
(- X --------)
| |
| target *--------->//
(------------)
|
(- Y --------)
| target *----->//
(------------)
|
(- Y --------)
| target *----->//
(------------)
```
The GstGhostPad (X) is also set as the parent of the GstProxyPad (Y).
The `GstGhostPad` (X) is also set as the parent of the `GstProxyPad` (Y).
The target is a pointer to the internal pads peer. It is an optimisation to
quickly get to the peer of a ghostpad without having to dereference the
@ -75,7 +77,9 @@ is modified.
## Creating a ghostpad with a target:
gst_ghost_pad_new (char *name, GstPad *target)
```
gst_ghost_pad_new (char *name, GstPad *target)
```
1) create new GstGhostPad X + GstProxyPad Y
2) X name set to @name
@ -129,14 +133,14 @@ gst_ghost_pad_new_no_target (char *name, GstPadDirection dir)
```
gst_ghost_pad_set_target (char *name, GstPad *newtarget)
(- X --------)
| |
| target *--------->//
(- X --------)
| |
| target *--------->//
(------------)
|
(- Y --------)
| target *----->//
(------------)
|
(- Y --------)
| target *----->//
(------------)
```
1) assert direction of newtarget == X direction
@ -209,7 +213,7 @@ gst_ghost_pad_set_target (char *name, GstPad *newtarget)
-------)
```
X is a sink GstGhostPad without a target. The internal GstProxyPad Y has
X is a sink `GstGhostPad` without a target. The internal `GstProxyPad` Y has
the same direction as the src pad (peer).
1) link function is called