qt: add qthelper.hpp hat was deprecated in libmpv

The Qt examples use it out of convenience. Upstream libmpv deprecated it
and declared it as unmaintained, so everyone who wants to continue using
it has to copy it and maintain it.

5 files changed, 357 insertions, 4 deletions

diff --git a/libmpv/common/qthelper.hpp b/libmpv/common/qthelper.hpp
new file mode 100644
index 0000000..fb30e2f
--- /dev/null
+++ b/libmpv/common/qthelper.hpp
@@ -0,0 +1,353 @@
+#ifndef LIBMPV_QTHELPER_H_
+#define LIBMPV_QTHELPER_H_
+
+#include <mpv/client.h>
+
+#include <cstring>
+
+#include <QVariant>
+#include <QString>
+#include <QList>
+#include <QHash>
+#include <QSharedPointer>
+#include <QMetaType>
+
+namespace mpv {
+namespace qt {
+
+// Wrapper around mpv_handle. Does refcounting under the hood.
+class Handle
+{
+    struct container {
+        container(mpv_handle *h) : mpv(h) {}
+        ~container() { mpv_terminate_destroy(mpv); }
+        mpv_handle *mpv;
+    };
+    QSharedPointer<container> sptr;
+public:
+    // Construct a new Handle from a raw mpv_handle with refcount 1. If the
+    // last Handle goes out of scope, the mpv_handle will be destroyed with
+    // mpv_terminate_destroy().
+    // Never destroy the mpv_handle manually when using this wrapper. You
+    // will create dangling pointers. Just let the wrapper take care of
+    // destroying the mpv_handle.
+    // Never create multiple wrappers from the same raw mpv_handle; copy the
+    // wrapper instead (that's what it's for).
+    static Handle FromRawHandle(mpv_handle *handle) {
+        Handle h;
+        h.sptr = QSharedPointer<container>(new container(handle));
+        return h;
+    }
+
+    // Return the raw handle; for use with the libmpv C API.
+    operator mpv_handle*() const { return sptr ? (*sptr).mpv : 0; }
+};
+
+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)
+    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;
+            list->num = qlist.size();
+            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;
+            list->num = qmap.size();
+            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.
+ *
+ * @deprecated use get_property() instead
+ *
+ * @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.
+
+ * @deprecated use set_property() instead
+ */
+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());
+}
+
+/**
+ * Set the given option as mpv_node converted from the QVariant argument.
+ *
+ * @deprecated use set_property() instead
+ */
+static inline int set_option_variant(mpv_handle *ctx, const QString &name,
+                                     const QVariant &v)
+{
+    node_builder node(v);
+    return mpv_set_option(ctx, name.toUtf8().data(), MPV_FORMAT_NODE, node.node());
+}
+
+/**
+ * mpv_command_node() equivalent. Returns QVariant() on error (and
+ * unfortunately, the same on success).
+ *
+ * @deprecated use command() instead
+ */
+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);
+}
+
+/**
+ * This is used to return error codes wrapped in QVariant for functions which
+ * return QVariant.
+ *
+ * You can use get_error() or is_error() to extract the error status from a
+ * QVariant value.
+ */
+struct ErrorReturn
+{
+    /**
+     * enum mpv_error value (or a value outside of it if ABI was extended)
+     */
+    int error;
+
+    ErrorReturn() : error(0) {}
+    explicit ErrorReturn(int err) : error(err) {}
+};
+
+/**
+ * Return the mpv error code packed into a QVariant, or 0 (success) if it's not
+ * an error value.
+ *
+ * @return error code (<0) or success (>=0)
+ */
+static inline int get_error(const QVariant &v)
+{
+    if (!v.canConvert<ErrorReturn>())
+        return 0;
+    return v.value<ErrorReturn>().error;
+}
+
+/**
+ * Return whether the QVariant carries a mpv error code.
+ */
+static inline bool is_error(const QVariant &v)
+{
+    return get_error(v) < 0;
+}
+
+/**
+ * Return the given property as mpv_node converted to QVariant, or QVariant()
+ * on error.
+ *
+ * @param name the property name
+ * @return the property value, or an ErrorReturn with the error code
+ */
+static inline QVariant get_property(mpv_handle *ctx, const QString &name)
+{
+    mpv_node node;
+    int err = mpv_get_property(ctx, name.toUtf8().data(), MPV_FORMAT_NODE, &node);
+    if (err < 0)
+        return QVariant::fromValue(ErrorReturn(err));
+    node_autofree f(&node);
+    return node_to_variant(&node);
+}
+
+/**
+ * Set the given property as mpv_node converted from the QVariant argument.
+ *
+ * @return mpv error code (<0 on error, >= 0 on success)
+ */
+static inline int set_property(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.
+ *
+ * @param args command arguments, with args[0] being the command name as string
+ * @return the property value, or an ErrorReturn with the error code
+ */
+static inline QVariant command(mpv_handle *ctx, const QVariant &args)
+{
+    node_builder node(args);
+    mpv_node res;
+    int err = mpv_command_node(ctx, node.node(), &res);
+    if (err < 0)
+        return QVariant::fromValue(ErrorReturn(err));
+    node_autofree f(&res);
+    return node_to_variant(&res);
+}
+
+}
+}
+
+Q_DECLARE_METATYPE(mpv::qt::ErrorReturn)
+
+#endif
diff --git a/libmpv/qml/main.h b/libmpv/qml/main.h
index 448707c..f0447c0 100644
--- a/libmpv/qml/main.h
+++ b/libmpv/qml/main.h
@@ -5,7 +5,7 @@
 
 #include <mpv/client.h>
 #include <mpv/render_gl.h>
-#include <mpv/qthelper.hpp>
+#include "../common/qthelper.hpp"
 
 class MpvRenderer;
 
diff --git a/libmpv/qml_direct/main.h b/libmpv/qml_direct/main.h
index c872b56..e73af34 100644
--- a/libmpv/qml_direct/main.h
+++ b/libmpv/qml_direct/main.h
@@ -5,7 +5,7 @@
 
 #include <mpv/client.h>
 #include <mpv/opengl_cb.h>
-#include <mpv/qthelper.hpp>
+#include "../common/qthelper.hpp"
 
 class MpvRenderer : public QObject
 {
diff --git a/libmpv/qt/qtexample.cpp b/libmpv/qt/qtexample.cpp
index 5f4e86e..161cc0e 100644
--- a/libmpv/qt/qtexample.cpp
+++ b/libmpv/qt/qtexample.cpp
@@ -17,7 +17,7 @@
 #include <QJsonDocument>
 #endif
 
-#include <mpv/qthelper.hpp>
+#include "../common/qthelper.hpp"
 
 #include "qtexample.h"
 
diff --git a/libmpv/qt_opengl/mpvwidget.h b/libmpv/qt_opengl/mpvwidget.h
index 849e033..ec134ac 100644
--- a/libmpv/qt_opengl/mpvwidget.h
+++ b/libmpv/qt_opengl/mpvwidget.h
@@ -4,7 +4,7 @@
 #include <QtWidgets/QOpenGLWidget>
 #include <mpv/client.h>
 #include <mpv/render_gl.h>
-#include <mpv/qthelper.hpp>
+#include "../common/qthelper.hpp"
 
 class MpvWidget Q_DECL_FINAL: public QOpenGLWidget
 {