client API: add qthelper.hpp

This provides some helper functions and classes for C++/Qt. As the top
of qthelper.hpp says, this is built on top of the client API, and is a
mere helper provided for convenience.

Maybe this should be a separate library, but on the other hand I don't
see much of a point in that. It's also header-only, but C++ people like
such things. This makes it easier for us, because we don't need to care
about ABI compatibility.

The client API doesn't change, but bump it so that those who are using
this header can declare a proper dependency.

4 files changed, 237 insertions, 2 deletions

diff --git a/DOCS/client-api-changes.rst b/DOCS/client-api-changes.rst
index b1274cad7b..a72bf9e398 100644
--- a/DOCS/client-api-changes.rst
+++ b/DOCS/client-api-changes.rst
@@ -25,6 +25,7 @@ API changes
 
 ::
 
+ 1.8    - add qthelper.hpp
  1.7    - add mpv_command_node(), mpv_command_node_async()
  1.6    - modify "core-idle" property behavior
         - MPV_EVENT_LOG_MESSAGE now always sends complete lines
diff --git a/libmpv/client.h b/libmpv/client.h
index 084f6e6e6c..7f545866aa 100644
--- a/libmpv/client.h
+++ b/libmpv/client.h
@@ -162,7 +162,7 @@ extern "C" {
  * relational operators (<, >, <=, >=).
  */
 #define MPV_MAKE_VERSION(major, minor) (((major) << 16) | (minor) | 0UL)
-#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 7)
+#define MPV_CLIENT_API_VERSION MPV_MAKE_VERSION(1, 8)
 
 /**
  * Return the MPV_CLIENT_API_VERSION the mpv source has been compiled with.
diff --git a/libmpv/qthelper.hpp b/libmpv/qthelper.hpp
new file mode 100644
index 0000000000..07bf194a1d
--- /dev/null
+++ b/libmpv/qthelper.hpp
@@ -0,0 +1,234 @@
+/* Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/**
+ * Note: these helpers are provided for convenience for C++/Qt applications.
+ * This is based on the public API in client.h, and it does not encode any
+ * knowledge that is not known or guaranteed outside of the C client API. You
+ * can even copy and modify this code as you like, or implement similar things
+ * for other languages.
+ */
+
+#include <cstring>
+
+#include <QVariant>
+#include <QString>
+#include <QList>
+#include <QHash>
+
+#include <mpv/client.h>
+
+namespace mpv {
+namespace qt {
+
+static inline QVariant node_to_variant(const mpv_node *node)
+{
+    switch (node->format) {
+    case MPV_FORMAT_STRING:
+        return QVariant(QString::fromUtf8(node->u.string));
+    case MPV_FORMAT_FLAG:
+        return QVariant(static_cast<bool>(node->u.flag));
+    case MPV_FORMAT_INT64:
+        return QVariant(static_cast<qlonglong>(node->u.int64));
+    case MPV_FORMAT_DOUBLE:
+        return QVariant(node->u.double_);
+    case MPV_FORMAT_NODE_ARRAY: {
+        mpv_node_list *list = node->u.list;
+        QVariantList qlist;
+        for (int n = 0; n < list->num; n++)
+            qlist.append(node_to_variant(&list->values[n]));
+        return QVariant(qlist);
+    }
+    case MPV_FORMAT_NODE_MAP: {
+        mpv_node_list *list = node->u.list;
+        QVariantMap qmap;
+        for (int n = 0; n < list->num; n++) {
+            qmap.insert(QString::fromUtf8(list->keys[n]),
+                        node_to_variant(&list->values[n]));
+        }
+        return QVariant(qmap);
+    }
+    default: // MPV_FORMAT_NONE, unknown values (e.g. future extensions)
+        return QVariant();
+    }
+}
+
+struct node_builder {
+    node_builder(const QVariant& v) {
+        set(&node_, v);
+    }
+    ~node_builder() {
+        free_node(&node_);
+    }
+    mpv_node *node() { return &node_; }
+private:
+    Q_DISABLE_COPY(node_builder)
+    //node_builder(node_builder const&); // disallow
+    //node_builder& operator=(node_builder const&); // disallow
+    mpv_node node_;
+    mpv_node_list *create_list(mpv_node *dst, bool is_map, int num) {
+        dst->format = is_map ? MPV_FORMAT_NODE_MAP : MPV_FORMAT_NODE_ARRAY;
+        mpv_node_list *list = new mpv_node_list();
+        dst->u.list = list;
+        if (!list)
+            goto err;
+        list->values = new mpv_node[num]();
+        if (!list->values)
+            goto err;
+        if (is_map) {
+            list->keys = new char*[num]();
+            if (!list->keys)
+                goto err;
+        }
+        return list;
+    err:
+        free_node(dst);
+        return NULL;
+    }
+    char *dup_qstring(const QString &s) {
+        QByteArray b = s.toUtf8();
+        char *r = new char[b.size() + 1];
+        if (r)
+            std::memcpy(r, b.data(), b.size() + 1);
+        return r;
+    }
+    bool test_type(const QVariant &v, QMetaType::Type t) {
+        // The Qt docs say: "Although this function is declared as returning
+        // "QVariant::Type(obsolete), the return value should be interpreted
+        // as QMetaType::Type."
+        // So a cast really seems to be needed to avoid warnings (urgh).
+        return static_cast<int>(v.type()) == static_cast<int>(t);
+    }
+    void set(mpv_node *dst, const QVariant &src) {
+        if (test_type(src, QMetaType::QString)) {
+            dst->format = MPV_FORMAT_STRING;
+            dst->u.string = dup_qstring(src.toString());
+            if (!dst->u.string)
+                goto fail;
+        } else if (test_type(src, QMetaType::Bool)) {
+            dst->format = MPV_FORMAT_FLAG;
+            dst->u.flag = src.toBool() ? 1 : 0;
+        } else if (test_type(src, QMetaType::Int) ||
+                   test_type(src, QMetaType::LongLong) ||
+                   test_type(src, QMetaType::UInt) ||
+                   test_type(src, QMetaType::ULongLong))
+        {
+            dst->format = MPV_FORMAT_INT64;
+            dst->u.int64 = src.toLongLong();
+        } else if (test_type(src, QMetaType::Double)) {
+            dst->format = MPV_FORMAT_DOUBLE;
+            dst->u.double_ = src.toDouble();
+        } else if (src.canConvert<QVariantList>()) {
+            QVariantList qlist = src.toList();
+            mpv_node_list *list = create_list(dst, false, qlist.size());
+            if (!list)
+                goto fail;
+            for (int n = 0; n < qlist.size(); n++)
+                set(&list->values[n], qlist[n]);
+        } else if (src.canConvert<QVariantMap>()) {
+            QVariantMap qmap = src.toMap();
+            mpv_node_list *list = create_list(dst, true, qmap.size());
+            if (!list)
+                goto fail;
+            for (int n = 0; n < qmap.size(); n++) {
+                list->keys[n] = dup_qstring(qmap.keys()[n]);
+                if (!list->keys[n]) {
+                    free_node(dst);
+                    goto fail;
+                }
+                set(&list->values[n], qmap.values()[n]);
+            }
+        } else {
+            goto fail;
+        }
+        return;
+    fail:
+        dst->format = MPV_FORMAT_NONE;
+    }
+    void free_node(mpv_node *dst) {
+        switch (dst->format) {
+        case MPV_FORMAT_STRING:
+            delete[] dst->u.string;
+            break;
+        case MPV_FORMAT_NODE_ARRAY:
+        case MPV_FORMAT_NODE_MAP: {
+            mpv_node_list *list = dst->u.list;
+            if (list) {
+                for (int n = 0; n < list->num; n++) {
+                    if (list->keys)
+                        delete list->keys[n];
+                    if (list->values)
+                        free_node(&list->values[n]);
+                }
+            }
+            delete[] list->keys;
+            delete[] list->values;
+            delete list;
+            break;
+        }
+        default: ;
+        }
+        dst->format = MPV_FORMAT_NONE;
+    }
+};
+
+/**
+ * RAII wrapper that calls mpv_free_node_contents() on the pointer.
+ */
+struct node_autofree {
+    mpv_node *ptr;
+    node_autofree(mpv_node *a_ptr) : ptr(a_ptr) {}
+    ~node_autofree() { mpv_free_node_contents(ptr); }
+};
+
+/**
+ * Return the given property as mpv_node converted to QVariant, or QVariant()
+ * on error.
+ *
+ * @param name the property name
+ */
+static inline QVariant get_property_variant(mpv_handle *ctx, const QString &name)
+{
+    mpv_node node;
+    if (mpv_get_property(ctx, name.toUtf8().data(), MPV_FORMAT_NODE, &node) < 0)
+        return QVariant();
+    node_autofree f(&node);
+    return node_to_variant(&node);
+}
+
+/**
+ * Set the given property as mpv_node converted from the QVariant argument.
+ */
+static inline int set_property_variant(mpv_handle *ctx, const QString &name,
+                                       const QVariant &v)
+{
+    node_builder node(v);
+    return mpv_set_property(ctx, name.toUtf8().data(), MPV_FORMAT_NODE, node.node());
+}
+
+/**
+ * mpv_command_node() equivalent. Returns QVariant() on error (and
+ * unfortunately, the same on success).
+ */
+static inline QVariant command_variant(mpv_handle *ctx, const QVariant &args)
+{
+    node_builder node(args);
+    mpv_node res;
+    if (mpv_command_node(ctx, node.node(), &res) < 0)
+        return QVariant();
+    node_autofree f(&res);
+    return node_to_variant(&res);
+}
+
+}
+}
diff --git a/wscript_build.py b/wscript_build.py
index f7df1c5aad..3f2cc68ffc 100644
--- a/wscript_build.py
+++ b/wscript_build.py
@@ -505,7 +505,7 @@ def build(ctx):
             PRIV_LIBS    = get_deps(),
         )
 
-        headers = ["client.h"]
+        headers = ["client.h", "qthelper.hpp"]
         for f in headers:
             ctx.install_as(ctx.env.INCDIR + '/mpv/' + f, 'libmpv/' + f)