kwin/effects/backgroundcontrast/contrast.h
Vlad Zahorodnii 9f2cb0ae1b Provide expected presentation time to effects
Effects are given the interval between two consecutive frames. The main
flaw of this approach is that if the Compositor transitions from the idle
state to "active" state, i.e. when there is something to repaint,
effects may see a very large interval between the last painted frame and
the current. In order to address this issue, the Scene invalidates the
timer that is used to measure time between consecutive frames before the
Compositor is about to become idle.

While this works perfectly fine with Xinerama-style rendering, with per
screen rendering, determining whether the compositor is about to idle is
rather a tedious task mostly because a single output can't be used for
the test.

Furthermore, since the Compositor schedules pointless repaints just to
ensure that it's idle, it might take several attempts to figure out
whether the scene timer must be invalidated if you use (true) per screen
rendering.

Ideally, all effects should use a timeline helper that is aware of the
underlying render loop and its timings. However, this option is off the
table because it will involve a lot of work to implement it.

Alternative and much simpler option is to pass the expected presentation
time to effects rather than time between consecutive frames. This means
that effects are responsible for determining how much animation timelines
have to be advanced. Typically, an effect would have to store the
presentation timestamp provided in either prePaint{Screen,Window} and
use it in the subsequent prePaint{Screen,Window} call to estimate the
amount of time passed between the next and the last frames.

Unfortunately, this is an API incompatible change. However, it shouldn't
take a lot of work to port third-party binary effects, which don't use the
AnimationEffect class, to the new API. On the bright side, we no longer
need to be concerned about the Compositor getting idle.

We do still try to determine whether the Compositor is about to idle,
primarily, because the OpenGL render backend swaps buffers on present,
but that will change with the ongoing compositing timing rework.
2020-12-10 07:14:42 +00:00

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C++

/*
SPDX-FileCopyrightText: 2010 Fredrik Höglund <fredrik@kde.org>
SPDX-FileCopyrightText: 2014 Marco Martin <mart@kde.org>
SPDX-License-Identifier: GPL-2.0-or-later
*/
#ifndef CONTRAST_H
#define CONTRAST_H
#include <kwineffects.h>
#include <kwinglplatform.h>
#include <kwinglutils.h>
#include <QVector>
#include <QVector2D>
namespace KWaylandServer
{
class ContrastManagerInterface;
}
namespace KWin
{
class ContrastShader;
class ContrastEffect : public KWin::Effect
{
Q_OBJECT
public:
ContrastEffect();
~ContrastEffect() override;
static bool supported();
static bool enabledByDefault();
static QMatrix4x4 colorMatrix(qreal contrast, qreal intensity, qreal saturation);
void reconfigure(ReconfigureFlags flags) override;
void prePaintScreen(ScreenPrePaintData &data, std::chrono::milliseconds presentTime) override;
void prePaintWindow(EffectWindow *w, WindowPrePaintData &data, std::chrono::milliseconds presentTime) override;
void drawWindow(EffectWindow *w, int mask, const QRegion &region, WindowPaintData &data) override;
void paintEffectFrame(EffectFrame *frame, const QRegion &region, double opacity, double frameOpacity) override;
bool provides(Feature feature) override;
bool isActive() const override;
int requestedEffectChainPosition() const override {
return 76;
}
bool eventFilter(QObject *watched, QEvent *event) override;
public Q_SLOTS:
void slotWindowAdded(KWin::EffectWindow *w);
void slotWindowDeleted(KWin::EffectWindow *w);
void slotPropertyNotify(KWin::EffectWindow *w, long atom);
void slotScreenGeometryChanged();
private:
QRegion contrastRegion(const EffectWindow *w) const;
bool shouldContrast(const EffectWindow *w, int mask, const WindowPaintData &data) const;
void updateContrastRegion(EffectWindow *w);
void doContrast(EffectWindow *w, const QRegion &shape, const QRect &screen, const float opacity, const QMatrix4x4 &screenProjection);
void uploadRegion(QVector2D *&map, const QRegion &region);
void uploadGeometry(GLVertexBuffer *vbo, const QRegion &region);
private:
ContrastShader *shader;
long net_wm_contrast_region;
QRegion m_paintedArea; // actually painted area which is greater than m_damagedArea
QRegion m_currentContrast; // keeps track of the currently contrasted area of non-caching windows(from bottom to top)
QHash< const EffectWindow*, QMatrix4x4> m_colorMatrices;
QHash< const EffectWindow*, QMetaObject::Connection > m_contrastChangedConnections; // used only in Wayland to keep track of effect changed
KWaylandServer::ContrastManagerInterface *m_contrastManager = nullptr;
};
inline
bool ContrastEffect::provides(Effect::Feature feature)
{
if (feature == Contrast) {
return true;
}
return KWin::Effect::provides(feature);
}
} // namespace KWin
#endif