use Pad builders for optional name definition

Also, apply auto-naming in the following cases

* When building from a non wildcard-named template, the name of the template is
  automatically assigned to the Pad. User can override with a specific name by
  calling `name()` on the `PadBuilder`.
* When building with a target and no name was provided via the above, the
  GhostPad is named after the target.

See https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/issues/448
Auto-naming discussion: https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1255#note_1891181

Part-of: <https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/-/merge_requests/1197>

3 files changed, 55 insertions, 64 deletions

diff --git a/utils/fallbackswitch/src/fallbacksrc/custom_source/imp.rs b/utils/fallbackswitch/src/fallbacksrc/custom_source/imp.rs
index 2159f27a3..b158fa1ba 100644
--- a/utils/fallbackswitch/src/fallbacksrc/custom_source/imp.rs
+++ b/utils/fallbackswitch/src/fallbacksrc/custom_source/imp.rs
@@ -292,9 +292,10 @@ impl CustomSource {
             (self.obj().pad_template("video_%u").unwrap(), name)
         };
 
-        let ghost_pad = gst::GhostPad::builder_with_template(&templ, Some(&name))
-            .build_with_target(pad)
-            .unwrap();
+        let ghost_pad = gst::GhostPad::builder_from_template_with_target(&templ, pad)
+            .unwrap()
+            .name(name)
+            .build();
 
         let stream = Stream {
             source_pad: pad.clone(),
diff --git a/utils/fallbackswitch/src/fallbacksrc/imp.rs b/utils/fallbackswitch/src/fallbacksrc/imp.rs
index 8ba75c5ae..4be3ed44c 100644
--- a/utils/fallbackswitch/src/fallbacksrc/imp.rs
+++ b/utils/fallbackswitch/src/fallbacksrc/imp.rs
@@ -943,8 +943,7 @@ impl FallbackSrc {
         ])
         .unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some("src"), &queue.static_pad("src").unwrap()).unwrap();
+        let ghostpad = gst::GhostPad::with_target(&queue.static_pad("src").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
@@ -1002,8 +1001,7 @@ impl FallbackSrc {
         ])
         .unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some("src"), &queue.static_pad("src").unwrap()).unwrap();
+        let ghostpad = gst::GhostPad::with_target(&queue.static_pad("src").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
@@ -1204,7 +1202,9 @@ impl FallbackSrc {
             .obj()
             .pad_template(if is_audio { "audio" } else { "video" })
             .unwrap();
-        let ghostpad = gst::GhostPad::builder_with_template(&templ, Some(&templ.name()))
+        let ghostpad = gst::GhostPad::builder_from_template_with_target(&templ, &srcpad)
+            .unwrap()
+            .name(templ.name())
             .proxy_pad_chain_function({
                 move |pad, parent, buffer| {
                     let parent = parent.and_then(|p| p.parent());
@@ -1215,8 +1215,7 @@ impl FallbackSrc {
                     )
                 }
             })
-            .build_with_target(&srcpad)
-            .unwrap();
+            .build();
 
         let _ = ghostpad.set_active(true);
 
@@ -1612,14 +1611,11 @@ impl FallbackSrc {
         gst::Element::link_many([&videoconvert, &videoscale, &imagefreeze, &capsfilter]).unwrap();
 
         let ghostpad =
-            gst::GhostPad::with_target(Some("sink"), &videoconvert.static_pad("sink").unwrap())
-                .unwrap();
+            gst::GhostPad::with_target(&videoconvert.static_pad("sink").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some("src"), &capsfilter.static_pad("src").unwrap())
-                .unwrap();
+        let ghostpad = gst::GhostPad::with_target(&capsfilter.static_pad("src").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
@@ -1660,14 +1656,11 @@ impl FallbackSrc {
         gst::Element::link_many([&videoconvert, &videoscale, &capsfilter]).unwrap();
 
         let ghostpad =
-            gst::GhostPad::with_target(Some("sink"), &videoconvert.static_pad("sink").unwrap())
-                .unwrap();
+            gst::GhostPad::with_target(&videoconvert.static_pad("sink").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some("src"), &capsfilter.static_pad("src").unwrap())
-                .unwrap();
+        let ghostpad = gst::GhostPad::with_target(&capsfilter.static_pad("src").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
@@ -1708,14 +1701,11 @@ impl FallbackSrc {
         gst::Element::link_many([&audioconvert, &audioresample, &capsfilter]).unwrap();
 
         let ghostpad =
-            gst::GhostPad::with_target(Some("sink"), &audioconvert.static_pad("sink").unwrap())
-                .unwrap();
+            gst::GhostPad::with_target(&audioconvert.static_pad("sink").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some("src"), &capsfilter.static_pad("src").unwrap())
-                .unwrap();
+        let ghostpad = gst::GhostPad::with_target(&capsfilter.static_pad("src").unwrap()).unwrap();
         ghostpad.set_active(true).unwrap();
         bin.add_pad(&ghostpad).unwrap();
 
@@ -1891,8 +1881,10 @@ impl FallbackSrc {
 
         gst::Element::link_many([&converters, &queue, &clocksync]).unwrap();
 
-        let ghostpad =
-            gst::GhostPad::with_target(Some(type_), &clocksync.static_pad("src").unwrap()).unwrap();
+        let ghostpad = gst::GhostPad::builder_with_target(&clocksync.static_pad("src").unwrap())
+            .unwrap()
+            .name(type_)
+            .build();
         let _ = ghostpad.set_active(true);
         source.source.add_pad(&ghostpad).unwrap();
 
diff --git a/utils/fallbackswitch/src/fallbackswitch/imp.rs b/utils/fallbackswitch/src/fallbackswitch/imp.rs
index 5db9ba0e5..bea69f1a3 100644
--- a/utils/fallbackswitch/src/fallbackswitch/imp.rs
+++ b/utils/fallbackswitch/src/fallbackswitch/imp.rs
@@ -1043,7 +1043,7 @@ impl ObjectSubclass for FallbackSwitch {
 
     fn with_class(klass: &Self::Class) -> Self {
         let templ = klass.pad_template("src").unwrap();
-        let srcpad = gst::Pad::builder_with_template(&templ, Some("src"))
+        let srcpad = gst::Pad::builder_from_template(&templ)
             .query_function(|pad, parent, query| {
                 FallbackSwitch::catch_panic_pad_function(
                     parent,
@@ -1334,42 +1334,40 @@ impl ElementImpl for FallbackSwitch {
 
         let pad_serial = self.sink_pad_serial.fetch_add(1, Ordering::SeqCst);
 
-        let pad = gst::PadBuilder::<super::FallbackSwitchSinkPad>::from_template(
-            templ,
-            Some(format!("sink_{pad_serial}").as_str()),
-        )
-        .chain_function(|pad, parent, buffer| {
-            FallbackSwitch::catch_panic_pad_function(
-                parent,
-                || Err(gst::FlowError::Error),
-                |fallbackswitch| fallbackswitch.sink_chain(pad, buffer),
-            )
-        })
-        .chain_list_function(|pad, parent, bufferlist| {
-            FallbackSwitch::catch_panic_pad_function(
-                parent,
-                || Err(gst::FlowError::Error),
-                |fallbackswitch| fallbackswitch.sink_chain_list(pad, bufferlist),
-            )
-        })
-        .event_function(|pad, parent, event| {
-            FallbackSwitch::catch_panic_pad_function(
-                parent,
-                || false,
-                |fallbackswitch| fallbackswitch.sink_event(pad, event),
-            )
-        })
-        .query_function(|pad, parent, query| {
-            FallbackSwitch::catch_panic_pad_function(
-                parent,
-                || false,
-                |fallbackswitch| fallbackswitch.sink_query(pad, query),
-            )
-        })
-        .activatemode_function(|pad, _parent, mode, activate| {
-            Self::sink_activatemode(pad, mode, activate)
-        })
-        .build();
+        let pad = gst::PadBuilder::<super::FallbackSwitchSinkPad>::from_template(templ)
+            .name(format!("sink_{pad_serial}").as_str())
+            .chain_function(|pad, parent, buffer| {
+                FallbackSwitch::catch_panic_pad_function(
+                    parent,
+                    || Err(gst::FlowError::Error),
+                    |fallbackswitch| fallbackswitch.sink_chain(pad, buffer),
+                )
+            })
+            .chain_list_function(|pad, parent, bufferlist| {
+                FallbackSwitch::catch_panic_pad_function(
+                    parent,
+                    || Err(gst::FlowError::Error),
+                    |fallbackswitch| fallbackswitch.sink_chain_list(pad, bufferlist),
+                )
+            })
+            .event_function(|pad, parent, event| {
+                FallbackSwitch::catch_panic_pad_function(
+                    parent,
+                    || false,
+                    |fallbackswitch| fallbackswitch.sink_event(pad, event),
+                )
+            })
+            .query_function(|pad, parent, query| {
+                FallbackSwitch::catch_panic_pad_function(
+                    parent,
+                    || false,
+                    |fallbackswitch| fallbackswitch.sink_query(pad, query),
+                )
+            })
+            .activatemode_function(|pad, _parent, mode, activate| {
+                Self::sink_activatemode(pad, mode, activate)
+            })
+            .build();
 
         pad.set_active(true).unwrap();
         self.obj().add_pad(&pad).unwrap();