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39
40#include "platformsurfacefilter_p.h"
41
42#include <Qt3DRender/private/abstractrenderer_p.h>
43
44#include <QMetaObject>
45#include <QPlatformSurfaceEvent>
46#include <QOffscreenSurface>
47#include <QtGui/qwindow.h>
48
49QT_BEGIN_NAMESPACE
50
51namespace Qt3DRender {
52namespace Render {
53
54QSemaphore PlatformSurfaceFilter::m_surfacesSemaphore(1);
55QHash<QSurface *, bool> PlatformSurfaceFilter::m_surfacesValidity;
56
57// Surface protection
58// The surface is accessible from multiple threads at 3 potential places
59// 1) In here (the frontend) when we receive an event
60// 2) In the RenderViewJobs
61// 3) In the Renderer for the submission
62// * We don't need any protection in 2) as we are just copying the pointer
63// but not performing any access to the texture as all the information
64// we need has been cached in the RenderSurfaceSelector element
65// * This leaves us with case 1 and 3. It is important that if the surface
66// is about to be destroyed that we let the time to the submission thread
67// to complete whatever it is doing with a surface before we have the time
68// to process the AboutToBeDestroyed event. For that we have lockSurface, releaseSurface
69// on the PlatformSurfaceFilter. But that's not enough, you need to be sure that
70// the surface is still valid. When locked, you can use isSurfaceValid to check
71// if a surface is still accessible.
72// A Surface is valid when it has been created and becomes invalid when AboutToBeDestroyed
73// has been called
74// SurfaceLocker is a convenience type to perform locking an surface validity check
75
76PlatformSurfaceFilter::PlatformSurfaceFilter(QObject *parent)
77 : QObject(parent)
78 , m_obj(nullptr)
79 , m_surface(nullptr)
80{
81 qRegisterMetaType<QSurface *>(typeName: "QSurface*");
82}
83
84PlatformSurfaceFilter::~PlatformSurfaceFilter()
85{
86 if (m_obj)
87 m_obj->removeEventFilter(obj: this);
88}
89
90bool PlatformSurfaceFilter::eventFilter(QObject *obj, QEvent *e)
91{
92 if (obj == m_obj && e->type() == QEvent::PlatformSurface) {
93 QPlatformSurfaceEvent *ev = static_cast<QPlatformSurfaceEvent *>(e);
94
95 switch (ev->surfaceEventType()) {
96 case QPlatformSurfaceEvent::SurfaceCreated:
97 // set validy to true
98 {
99 markSurfaceAsValid();
100 break;
101 }
102
103 case QPlatformSurfaceEvent::SurfaceAboutToBeDestroyed:
104 // set validity to false
105 {
106 SurfaceLocker lock(m_surface);
107 // If we remove it, the call to isSurfaceValid will
108 // implicitely return false
109 PlatformSurfaceFilter::m_surfacesValidity.remove(akey: m_surface);
110 break;
111 }
112
113 default:
114 qCritical(msg: "Unknown surface type");
115 Q_UNREACHABLE();
116 }
117 }
118
119 if (obj == m_obj && e->type() == QEvent::Expose) {
120 QExposeEvent *ev = static_cast<QExposeEvent *>(e);
121 Q_UNUSED(ev);
122 // We could use this to tell to ignore the RenderView
123 // at submission time since it's not exposed
124 }
125 return false;
126}
127
128void PlatformSurfaceFilter::lockSurface()
129{
130 PlatformSurfaceFilter::m_surfacesSemaphore.acquire(n: 1);
131}
132
133void PlatformSurfaceFilter::releaseSurface()
134{
135 PlatformSurfaceFilter::m_surfacesSemaphore.release(n: 1);
136}
137
138bool PlatformSurfaceFilter::isSurfaceValid(QSurface *surface)
139{
140 // Should be called only when the surface is locked
141 // with the semaphore
142 return m_surfacesValidity.value(akey: surface, adefaultValue: false);
143}
144
145void PlatformSurfaceFilter::markSurfaceAsValid()
146{
147 SurfaceLocker lock(m_surface);
148 PlatformSurfaceFilter::m_surfacesValidity.insert(akey: m_surface, avalue: true);
149}
150
151SurfaceLocker::SurfaceLocker(QSurface *surface)
152 : m_surface(surface)
153{
154 PlatformSurfaceFilter::lockSurface();
155}
156
157SurfaceLocker::~SurfaceLocker()
158{
159 PlatformSurfaceFilter::releaseSurface();
160}
161
162bool SurfaceLocker::isSurfaceValid() const
163{
164 return PlatformSurfaceFilter::isSurfaceValid(surface: m_surface);
165}
166
167} // namespace Render
168} // namespace Qt3DRender
169
170QT_END_NAMESPACE
171

source code of qt3d/src/render/backend/platformsurfacefilter.cpp