Audio: add buffer (un)queuing to Source.

And also add an implementation for Source::type().

src/Magnum/Audio/Source.cpp

@@ -25,7 +25,10 @@
 
 #include "Source.h"
 
+#include <algorithm>
+
 #include <Corrade/Containers/Array.h>
+#include <Corrade/Containers/Reference.h>
 
 #include "Magnum/Audio/Buffer.h"
 
@@ -38,6 +41,32 @@ Source& Source::setBuffer(Buffer* buffer) {
     return *this;
 }
 
+Source& Source::queueBuffers(Containers::ArrayView<Containers::Reference<Buffer>> buffers) {
+    Containers::Array<ALuint> ids(buffers.size());
+    for(std::size_t i = 0; i < ids.size(); i++)
+        ids[i] = buffers[i]->id();
+    alSourceQueueBuffers(_id, ids.size(), ids.data());
+    return *this;
+}
+
+std::size_t Source::unqueueBuffers(Containers::ArrayView<Containers::Reference<Buffer>> buffers) {
+    ALint processedBuffers;
+    alGetSourcei(_id, AL_BUFFERS_PROCESSED, &processedBuffers);
+
+    if(!processedBuffers) return 0;
+
+    Containers::Array<ALuint> unqueuedIds(processedBuffers);
+    alSourceUnqueueBuffers(_id, unqueuedIds.size(), unqueuedIds.data());
+    auto isNotUnqueued = [&unqueuedIds](Containers::Reference<Buffer> buffer){
+        for(ALuint id : unqueuedIds) {
+            if(buffer->id() == id)
+                return false;
+        }
+        return true;
+    };
+    return std::remove_if(buffers.begin(), buffers.end(), isNotUnqueued) - buffers.begin();
+}
+
 namespace {
 
 Containers::Array<ALuint> sourceIds(const std::initializer_list<std::reference_wrapper<Source>>& sources) {

src/Magnum/Audio/Source.h

@@ -35,6 +35,8 @@
 #include <vector>
 #include <al.h>
 
+#include <Corrade/Containers/Containers.h>
+
 #include "Magnum/Magnum.h"
 #include "Magnum/Audio/Audio.h"
 #include "Magnum/Audio/visibility.h"
@@ -507,6 +509,28 @@ class MAGNUM_AUDIO_EXPORT Source {
          */
         Source& setBuffer(Buffer* buffer);
 
+        /**
+         * @brief Queue buffers
+         * @param buffers       Buffers to queue
+         * @return Reference to self (for method chaining)
+         *
+         * Changes source type to @ref Type::Streaming. The buffers must be
+         * already filled with data.
+         * @see @ref type(), @fn_al_keyword{SourceQueueBuffers}
+         */
+        Source& queueBuffers(Containers::ArrayView<Containers::Reference<Buffer>> buffers);
+
+        /**
+         * @brief Unqueue buffers
+         * @param buffers       Buffers to unqueue
+         * @return The number of unqueued buffers
+         *
+         * The unqueued buffers will be listed in the prefix of the array. Use
+         * @ref ArrayView::prefix() to get it.
+         * @see @fn_al_keyword{SourceUnqueueBuffers}
+         */
+        std::size_t unqueueBuffers(Containers::ArrayView<Containers::Reference<Buffer>> buffers);
+
         /*@}*/
 
         /** @{ @name State management */
@@ -734,6 +758,12 @@ inline Source& Source::operator=(Source&& other) {
     return *this;
 }
 
+inline auto Source::type() const -> Type {
+    ALint type;
+    alGetSourcei(_id, AL_SOURCE_TYPE, &type);
+    return Type(type);
+}
+
 inline auto Source::state() const -> State {
     ALint state;
     alGetSourcei(_id, AL_SOURCE_STATE, &state);