Add a function for copying channel contexts

For proxying `IInfoListener::setChannelContextInfos`.

src/common/serialization/vst3/attribute-list.cpp

@@ -16,6 +16,37 @@
 
 #include "attribute-list.h"
 
+#include "pluginterfaces/vst/ivstchannelcontextinfo.h"
+
+/**
+ * Keys for channel context attributes passed in
+ * `IInfoListener::setChannelContextInfos` that contain a string value.
+ */
+const static char* channel_context_string_keys[] = {
+    Steinberg::Vst::ChannelContext::kChannelUIDKey,
+    Steinberg::Vst::ChannelContext::kChannelNameKey,
+    Steinberg::Vst::ChannelContext::kChannelIndexNamespaceKey};
+
+/**
+ * Keys for channel context attributes passed in
+ * `IInfoListener::setChannelContextInfos` that contain an integer value.
+ */
+const static char* channel_context_integer_keys[] = {
+    Steinberg::Vst::ChannelContext::kChannelUIDLengthKey,
+    Steinberg::Vst::ChannelContext::kChannelNameLengthKey,
+    Steinberg::Vst::ChannelContext::kChannelColorKey,
+    Steinberg::Vst::ChannelContext::kChannelIndexKey,
+    Steinberg::Vst::ChannelContext::kChannelIndexNamespaceOrderKey,
+    Steinberg::Vst::ChannelContext::kChannelIndexNamespaceLengthKey,
+    Steinberg::Vst::ChannelContext::kChannelPluginLocationKey};
+
+/**
+ * Keys for channel context attributes passed in
+ * `IInfoListener::setChannelContextInfos` that contain a binary value.
+ */
+const static char* channel_context_binary_keys[] = {
+    Steinberg::Vst::ChannelContext::kChannelImageKey};
+
 YaAttributeList::YaAttributeList(){FUNKNOWN_CTOR}
 
 YaAttributeList::~YaAttributeList() {
@@ -51,6 +82,39 @@ tresult YaAttributeList::write_back(
     return Steinberg::kResultOk;
 }
 
+YaAttributeList YaAttributeList::read_channel_context(
+    Steinberg::Vst::IAttributeList* context) {
+    YaAttributeList attributes{};
+    // Copy over all predefined channel context attributes. `IAttributeList`
+    // does not offer any interface to enumerate the stored keys.
+    Steinberg::Vst::String128 vst_string{0};
+    for (const auto& key : channel_context_string_keys) {
+        vst_string[0] = 0;
+        if (context->getString(key, vst_string, sizeof(vst_string)) ==
+            Steinberg::kResultOk) {
+            attributes.setString(key, vst_string);
+        }
+    }
+
+    int64 vst_integer;
+    for (const auto& key : channel_context_integer_keys) {
+        if (context->getInt(key, vst_integer) == Steinberg::kResultOk) {
+            attributes.setInt(key, vst_integer);
+        }
+    }
+
+    const void* vst_binary_ptr;
+    uint32 vst_binary_size;
+    for (const auto& key : channel_context_binary_keys) {
+        if (context->getBinary(key, vst_binary_ptr, vst_binary_size) ==
+            Steinberg::kResultOk) {
+            attributes.setBinary(key, vst_binary_ptr, vst_binary_size);
+        }
+    }
+
+    return attributes;
+}
+
 tresult PLUGIN_API YaAttributeList::setInt(AttrID id, int64 value) {
     attrs_int[id] = value;
     return Steinberg::kResultOk;

src/common/serialization/vst3/attribute-list.h

@@ -49,6 +49,17 @@ class YaAttributeList : public Steinberg::Vst::IAttributeList {
      */
     tresult write_back(Steinberg::Vst::IAttributeList* stream) const;
 
+    /**
+     * Read the channel context info passed to
+     * `IInfoListener::setChannelContextInfos` into a `YaAttributeList`. We
+     * normally can't serialize any arbitrary `IAttributeList` because there's
+     * no way to enumerate the keys, but in this case the keys are fixed. This
+     * works in a similar was as reading preset meta data in
+     * `IStreamAttributes`.
+     */
+    static YaAttributeList read_channel_context(
+        Steinberg::Vst::IAttributeList* context);
+
     virtual tresult PLUGIN_API setInt(AttrID id, int64 value) override;
     virtual tresult PLUGIN_API getInt(AttrID id, int64& value) override;
     virtual tresult PLUGIN_API setFloat(AttrID id, double value) override;