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flow_display
Alexandre Marcireau edited this page Jun 1, 2018
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4 revisions
In header "../third_party/chameleon/source/flow_display.hpp".
chameleon::flow_display
displays a stream of flow events. It has a transparent background to be rendered over another display.
namespace chameleon {
class flow_display : public QQuickItem {
Q_OBJECT
Q_INTERFACES(QQmlParserStatus)
Q_PROPERTY(QSize canvas_size READ canvas_size WRITE set_canvas_size)
Q_PROPERTY(float speed_to_length READ speed_to_length WRITE set_speed_to_length)
Q_PROPERTY(float decay READ decay WRITE set_decay)
public:
flow_display();
/// set_canvas_size defines the display coordinates.
/// The canvas size will be passed to the openGL renderer, therefore it should only be set during qml
/// construction.
virtual void set_canvas_size(QSize canvas_size);
/// canvas_size returns the currently used canvas_size.
virtual QSize canvas_size() const;
/// set_speed_to_length defines the length in pixels of the arrow representing a one-pixel-per-microsecond
/// speed. The speed to length will be passed to the openGL renderer, therefore it should only be set
/// during qml construction.
virtual void set_speed_to_length(float speed_to_length);
/// speed_to_length returns the currently used speed_to_length.
virtual float speed_to_length() const;
/// set_decay defines the flow decay.
/// The decay will be passed to the openGL renderer, therefore it should only be set during qml construction.
virtual void set_decay(float decay);
/// decay returns the currently used decay.
virtual float decay() const;
/// paint_area returns the paint area in window coordinates.
virtual QRectF paint_area() const;
/// push adds an event to the display.
template <typename Event>
void push(Event event);
/// componentComplete is called when all the qml values are bound.
virtual void componentComplete() override;
signals:
/// paint_area_changed notifies a paint area change.
void paint_area_changed(QRectF paint_area);
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();
};
}
-
canvas_size
is the pixel array size. As an example, ifx
is in the range[0, 319]
andy
is in the range[0, 239]
,canvas_size
must beQSize(320, 240)
. -
speed_to_length
is used to convert the flow event speeds to their representation length. It is expressed in pixels per pixel-per-microsecond. -
decay
is the exponential decay's time constant in microseconds. -
Event
must have at least the propertiest
,x
,y
,vx
andvy
. -
begin
andend
are the begin and past-the-end iterators to a range ofcanvas_size.width() * canvas_size.height()
objects with at least the propertiest
,vx
andvy
. The object associated with the pixel at coordinates[x, y]
must be at the indexx + y * canvas_size.width()
in the range. -
paint_area
is the rectangle in which the events will actually be drawn.paint_area
has the same shape (ratio of width over height) ascanvas_size
.
chameleon::flow_display
is associated with a chameleon::flow_display_renderer
to handle OpenGL calls.
namespace chameleon {
class flow_display_renderer : public QObject, public QOpenGLFunctions_3_3_Core {
Q_OBJECT
public:
flow_display_renderer(QSize canvas_size, float speed_to_length, float decay);
/// set_rendering_area defines the rendering area.
virtual void set_rendering_area(QRectF paint_area, int window_height);
/// push adds an event to the display.
template <typename Event>
void push(Event event);
/// assign sets all the pixels at once.
template <typename Iterator>
void assign(Iterator begin, Iterator end);
public slots:
/// paint sends commands to the GPU.
void paint();
};
}
-
paint_area
is the rectangle inside clear_area in which the events will actually be drawn.paint_area
has the same shape (ratio of width over height) ascanvas_size
. -
window_height
is the total window height (used to convert from Qt coordinates to OpenGL coordinates).
A typical QML instantiation has the following syntax:
FlowDisplay {
canvas_size: "320x240" // required
speed_to_length: 1e6 // optional, defaults to 1e6
decay: 1e5 // optional, defaults to 1e5
background_color: "#000000" // optional, defaults to "#000000"
}