frame_generator

In header "../third_party/chameleon/source/frame_generator.hpp"

chameleon::frame_generator takes screenshots of the window. Any modification to a Chameleon display before calling chameleon::frame_generator::save_frame_to is guaranteed to appear in the resulting frame.

namespace chameleon {
    class frame_generator : public QQuickItem {
        Q_OBJECT
        public:
        frame_generator();

        /// save_frame_to triggers a frame render and stores the resulting png image to the given file.
        virtual void save_frame_to(const std::string& filename);

        public slots:

        /// sync adapts the renderer to external changes.
        void sync();

        /// cleanup frees the owned renderer.
        void cleanup();

        /// trigger_draw requests a window refresh.
        void trigger_draw();

        /// closing is called when the window is about to be closed.
        void closing();
    };
}

• filename is the absolute path (or relative to the current working directory) of the output file. save_frame_to will fail if the parent directory does not exist.

chameleon::frame_generator is associated with a chameleon::frame_generator_renderer to handle OpenGL calls.

namespace chameleon {
    class frame_generator_renderer : public QObject, public QOpenGLFunctions_3_3_Core {
        Q_OBJECT
        public:
        frame_generator_renderer();

        /// set_rendering_area defines the rendering area.
        virtual void set_rendering_area(QRectF capture_area, int window_height);

        /// save_frame_to waits for a complete render, takes a screenshots and writes it to a file.
        virtual bool save_frame_to(const QString& filename);

        public slots:

        /// before_rendering_callback must be called when the window is about to be rendered.
        void before_rendering_callback();

        /// after_rendering_callback must be called when the window completes a rendering.
        void after_rendering_callback();

        /// closing is called when the window is about to be closed.
        void closing();
    };
}

• capture_area is the rectangle to capture, in screen coordinates.
• window_height is the total window height (used to convert from Qt coordinates to OpenGL coordinates).

before_rendering_callback and after_rendering_callback are used to synchronize screenshots and calls to save_frame_to.

A typical QML instantiation has the following syntax:

FrameGenerator {}