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Diffstat (limited to 'src/opengl/qopenglwindow.cpp')
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diff --git a/src/opengl/qopenglwindow.cpp b/src/opengl/qopenglwindow.cpp new file mode 100644 index 0000000000..8cdf134bfd --- /dev/null +++ b/src/opengl/qopenglwindow.cpp @@ -0,0 +1,698 @@ +/**************************************************************************** +** +** Copyright (C) 2016 The Qt Company Ltd. +** Contact: https://www.qt.io/licensing/ +** +** This file is part of the QtOpenGL module of the Qt Toolkit. +** +** $QT_BEGIN_LICENSE:LGPL$ +** Commercial License Usage +** Licensees holding valid commercial Qt licenses may use this file in +** accordance with the commercial license agreement provided with the +** Software or, alternatively, in accordance with the terms contained in +** a written agreement between you and The Qt Company. For licensing terms +** and conditions see https://www.qt.io/terms-conditions. For further +** information use the contact form at https://www.qt.io/contact-us. +** +** GNU Lesser General Public License Usage +** Alternatively, this file may be used under the terms of the GNU Lesser +** General Public License version 3 as published by the Free Software +** Foundation and appearing in the file LICENSE.LGPL3 included in the +** packaging of this file. Please review the following information to +** ensure the GNU Lesser General Public License version 3 requirements +** will be met: https://www.gnu.org/licenses/lgpl-3.0.html. +** +** GNU General Public License Usage +** Alternatively, this file may be used under the terms of the GNU +** General Public License version 2.0 or (at your option) the GNU General +** Public license version 3 or any later version approved by the KDE Free +** Qt Foundation. The licenses are as published by the Free Software +** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3 +** included in the packaging of this file. Please review the following +** information to ensure the GNU General Public License requirements will +** be met: https://www.gnu.org/licenses/gpl-2.0.html and +** https://www.gnu.org/licenses/gpl-3.0.html. +** +** $QT_END_LICENSE$ +** +****************************************************************************/ + +#include "qopenglwindow.h" +#include <QtGui/QOpenGLFramebufferObject> +#include <QtGui/QOpenGLPaintDevice> +#include <QtGui/QOpenGLFunctions> +#include <QtGui/QOpenGLTextureBlitter> +#include <QtGui/private/qpaintdevicewindow_p.h> +#include <QtGui/private/qopenglextensions_p.h> +#include <QtGui/private/qopenglcontext_p.h> +#include <QtGui/QMatrix4x4> +#include <QtGui/QOffscreenSurface> + +QT_BEGIN_NAMESPACE + +/*! + \class QOpenGLWindow + \inmodule QtOpenGL + \since 5.4 + \brief The QOpenGLWindow class is a convenience subclass of QWindow to perform OpenGL painting. + + QOpenGLWindow is an enhanced QWindow that allows easily creating windows that + perform OpenGL rendering using an API that is compatible with QOpenGLWidget + and is similar to the legacy QGLWidget. Unlike QOpenGLWidget, QOpenGLWindow + has no dependency on the widgets module and offers better performance. + + A typical application will subclass QOpenGLWindow and reimplement the following + virtual functions: + + \list + + \li initializeGL() to perform OpenGL resource initialization + + \li resizeGL() to set up the transformation matrices and other window size dependent resources + + \li paintGL() to issue OpenGL commands or draw using QPainter + + \endlist + + To schedule a repaint, call the update() function. Note that this will not + immediately result in a call to paintGL(). Calling update() multiple times in + a row will not change the behavior in any way. + + This is a slot so it can be connected to a \l QTimer::timeout() signal to + perform animation. Note however that in the modern OpenGL world it is a much + better choice to rely on synchronization to the vertical refresh rate of the + display. See \l{QSurfaceFormat::setSwapInterval()}{setSwapInterval()} on a + description of the swap interval. With a swap interval of \c 1, which is the + case on most systems by default, the + \l{QOpenGLContext::swapBuffers()}{swapBuffers()} call, that is executed + internally by QOpenGLWindow after each repaint, will block and wait for + vsync. This means that whenever the swap is done, an update can be scheduled + again by calling update(), without relying on timers. + + To request a specific configuration for the context, use setFormat() + like for any other QWindow. This allows, among others, requesting a + given OpenGL version and profile, or enabling depth and stencil + buffers. + + Unlike QWindow, QOpenGLWindow allows opening a painter on itself and perform + QPainter-based drawing. + + QOpenGLWindow supports multiple update behaviors. The default, + \c NoPartialUpdate is equivalent to a regular, OpenGL-based QWindow or the + legacy QGLWidget. In contrast, \c PartialUpdateBlit and \c PartialUpdateBlend are + more in line with QOpenGLWidget's way of working, where there is always an + extra, dedicated framebuffer object present. These modes allow, by + sacrificing some performance, redrawing only a smaller area on each paint and + having the rest of the content preserved from of the previous frame. This is + useful for applications than render incrementally using QPainter, because + this way they do not have to redraw the entire window content on each + paintGL() call. + + Similarly to QOpenGLWidget, QOpenGLWindow supports the Qt::AA_ShareOpenGLContexts + attribute. When enabled, the OpenGL contexts of all QOpenGLWindow instances will share + with each other. This allows accessing each other's shareable OpenGL resources. + + For more information on graphics in Qt, see \l {Graphics}. + */ + +/*! + \enum QOpenGLWindow::UpdateBehavior + + This enum describes the update strategy of the QOpenGLWindow. + + \value NoPartialUpdate Indicates that the entire window surface will + redrawn on each update and so no additional framebuffers are needed. + This is the setting used in most cases and is equivalent to how drawing + directly via QWindow would function. + + \value PartialUpdateBlit Indicates that the drawing performed in paintGL() + does not cover the entire window. In this case an extra framebuffer object + is created under the hood, and rendering performed in paintGL() will target + this framebuffer. This framebuffer is then blitted onto the window surface's + default framebuffer after each paint. This allows having QPainter-based drawing + code in paintGL() which only repaints a smaller area at a time, because, unlike + NoPartialUpdate, the previous content is preserved. + + \value PartialUpdateBlend Similar to PartialUpdateBlit, but instead of using + framebuffer blits, the contents of the extra framebuffer is rendered by + drawing a textured quad with blending enabled. This, unlike PartialUpdateBlit, + allows alpha blended content and works even when the glBlitFramebuffer is + not available. Performance-wise this setting is likely to be somewhat slower + than PartialUpdateBlit. + */ + +/*! + \fn void QOpenGLWindow::frameSwapped() + + This signal is emitted after the potentially blocking + \l{QOpenGLContext::swapBuffers()}{buffer swap} has been done. Applications + that wish to continuously repaint synchronized to the vertical refresh, + should issue an update() upon this signal. This allows for a much smoother + experience compared to the traditional usage of timers. +*/ + +// GLES2 builds won't have these constants with the suffixless names +#ifndef GL_READ_FRAMEBUFFER +#define GL_READ_FRAMEBUFFER 0x8CA8 +#endif +#ifndef GL_DRAW_FRAMEBUFFER +#define GL_DRAW_FRAMEBUFFER 0x8CA9 +#endif + +class QOpenGLWindowPaintDevice : public QOpenGLPaintDevice +{ +public: + QOpenGLWindowPaintDevice(QOpenGLWindow *window) : m_window(window) { } + void ensureActiveTarget() override; + + QOpenGLWindow *m_window; +}; + +class QOpenGLWindowPrivate : public QPaintDeviceWindowPrivate +{ + Q_DECLARE_PUBLIC(QOpenGLWindow) +public: + QOpenGLWindowPrivate(QOpenGLContext *shareContext, QOpenGLWindow::UpdateBehavior updateBehavior) + : updateBehavior(updateBehavior) + , hasFboBlit(false) + , shareContext(shareContext) + { + if (!shareContext) + this->shareContext = qt_gl_global_share_context(); + } + + ~QOpenGLWindowPrivate(); + + static QOpenGLWindowPrivate *get(QOpenGLWindow *w) { return w->d_func(); } + + void bindFBO(); + void initialize(); + + void beginPaint(const QRegion ®ion) override; + void endPaint() override; + void flush(const QRegion ®ion) override; + + QOpenGLWindow::UpdateBehavior updateBehavior; + bool hasFboBlit; + QScopedPointer<QOpenGLContext> context; + QOpenGLContext *shareContext; + QScopedPointer<QOpenGLFramebufferObject> fbo; + QScopedPointer<QOpenGLWindowPaintDevice> paintDevice; + QOpenGLTextureBlitter blitter; + QColor backgroundColor; + QScopedPointer<QOffscreenSurface> offscreenSurface; +}; + +QOpenGLWindowPrivate::~QOpenGLWindowPrivate() +{ + Q_Q(QOpenGLWindow); + if (q->isValid()) { + q->makeCurrent(); // this works even when the platformwindow is destroyed + paintDevice.reset(nullptr); + fbo.reset(nullptr); + blitter.destroy(); + q->doneCurrent(); + } +} + +void QOpenGLWindowPrivate::initialize() +{ + Q_Q(QOpenGLWindow); + + if (context) + return; + + if (!q->handle()) + qWarning("Attempted to initialize QOpenGLWindow without a platform window"); + + context.reset(new QOpenGLContext); + context->setShareContext(shareContext); + context->setFormat(q->requestedFormat()); + if (!context->create()) + qWarning("QOpenGLWindow::beginPaint: Failed to create context"); + if (!context->makeCurrent(q)) + qWarning("QOpenGLWindow::beginPaint: Failed to make context current"); + + paintDevice.reset(new QOpenGLWindowPaintDevice(q)); + if (updateBehavior == QOpenGLWindow::PartialUpdateBlit) + hasFboBlit = QOpenGLFramebufferObject::hasOpenGLFramebufferBlit(); + + q->initializeGL(); +} + +void QOpenGLWindowPrivate::beginPaint(const QRegion ®ion) +{ + Q_UNUSED(region); + Q_Q(QOpenGLWindow); + + initialize(); + context->makeCurrent(q); + + const int deviceWidth = q->width() * q->devicePixelRatio(); + const int deviceHeight = q->height() * q->devicePixelRatio(); + const QSize deviceSize(deviceWidth, deviceHeight); + if (updateBehavior > QOpenGLWindow::NoPartialUpdate) { + if (!fbo || fbo->size() != deviceSize) { + QOpenGLFramebufferObjectFormat fboFormat; + fboFormat.setAttachment(QOpenGLFramebufferObject::CombinedDepthStencil); + const int samples = q->requestedFormat().samples(); + if (samples > 0) { + if (updateBehavior != QOpenGLWindow::PartialUpdateBlend) + fboFormat.setSamples(samples); + else + qWarning("QOpenGLWindow: PartialUpdateBlend does not support multisampling"); + } + fbo.reset(new QOpenGLFramebufferObject(deviceSize, fboFormat)); + markWindowAsDirty(); + } + } else { + markWindowAsDirty(); + } + + paintDevice->setSize(QSize(deviceWidth, deviceHeight)); + paintDevice->setDevicePixelRatio(q->devicePixelRatio()); + context->functions()->glViewport(0, 0, deviceWidth, deviceHeight); + + context->functions()->glBindFramebuffer(GL_FRAMEBUFFER, context->defaultFramebufferObject()); + + q->paintUnderGL(); + + if (updateBehavior > QOpenGLWindow::NoPartialUpdate) + fbo->bind(); +} + +void QOpenGLWindowPrivate::endPaint() +{ + Q_Q(QOpenGLWindow); + + if (updateBehavior > QOpenGLWindow::NoPartialUpdate) + fbo->release(); + + context->functions()->glBindFramebuffer(GL_FRAMEBUFFER, context->defaultFramebufferObject()); + + if (updateBehavior == QOpenGLWindow::PartialUpdateBlit && hasFboBlit) { + const int deviceWidth = q->width() * q->devicePixelRatio(); + const int deviceHeight = q->height() * q->devicePixelRatio(); + QOpenGLExtensions extensions(context.data()); + extensions.glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo->handle()); + extensions.glBindFramebuffer(GL_DRAW_FRAMEBUFFER, context->defaultFramebufferObject()); + extensions.glBlitFramebuffer(0, 0, deviceWidth, deviceHeight, + 0, 0, deviceWidth, deviceHeight, + GL_COLOR_BUFFER_BIT, GL_NEAREST); + } else if (updateBehavior > QOpenGLWindow::NoPartialUpdate) { + if (updateBehavior == QOpenGLWindow::PartialUpdateBlend) { + context->functions()->glEnable(GL_BLEND); + context->functions()->glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); + } + if (!blitter.isCreated()) + blitter.create(); + + QRect windowRect(QPoint(0, 0), fbo->size()); + QMatrix4x4 target = QOpenGLTextureBlitter::targetTransform(windowRect, windowRect); + blitter.bind(); + blitter.blit(fbo->texture(), target, QOpenGLTextureBlitter::OriginBottomLeft); + blitter.release(); + + if (updateBehavior == QOpenGLWindow::PartialUpdateBlend) + context->functions()->glDisable(GL_BLEND); + } + + q->paintOverGL(); +} + +void QOpenGLWindowPrivate::bindFBO() +{ + if (updateBehavior > QOpenGLWindow::NoPartialUpdate) + fbo->bind(); + else + QOpenGLFramebufferObject::bindDefault(); +} + +void QOpenGLWindowPrivate::flush(const QRegion ®ion) +{ + Q_UNUSED(region); + Q_Q(QOpenGLWindow); + context->swapBuffers(q); + emit q->frameSwapped(); +} + +void QOpenGLWindowPaintDevice::ensureActiveTarget() +{ + QOpenGLWindowPrivate::get(m_window)->bindFBO(); +} + +/*! + Constructs a new QOpenGLWindow with the given \a parent and \a updateBehavior. + + \sa QOpenGLWindow::UpdateBehavior + */ +QOpenGLWindow::QOpenGLWindow(QOpenGLWindow::UpdateBehavior updateBehavior, QWindow *parent) + : QPaintDeviceWindow(*(new QOpenGLWindowPrivate(nullptr, updateBehavior)), parent) +{ + setSurfaceType(QSurface::OpenGLSurface); +} + +/*! + Constructs a new QOpenGLWindow with the given \a parent and \a updateBehavior. The QOpenGLWindow's context will share with \a shareContext. + + \sa QOpenGLWindow::UpdateBehavior shareContext +*/ +QOpenGLWindow::QOpenGLWindow(QOpenGLContext *shareContext, UpdateBehavior updateBehavior, QWindow *parent) + : QPaintDeviceWindow(*(new QOpenGLWindowPrivate(shareContext, updateBehavior)), parent) +{ + setSurfaceType(QSurface::OpenGLSurface); +} + +/*! + Destroys the QOpenGLWindow instance, freeing its resources. + + The OpenGLWindow's context is made current in the destructor, allowing for + safe destruction of any child object that may need to release OpenGL + resources belonging to the context provided by this window. + + \warning if you have objects wrapping OpenGL resources (such as + QOpenGLBuffer, QOpenGLShaderProgram, etc.) as members of a QOpenGLWindow + subclass, you may need to add a call to makeCurrent() in that subclass' + destructor as well. Due to the rules of C++ object destruction, those objects + will be destroyed \e{before} calling this function (but after that the + destructor of the subclass has run), therefore making the OpenGL context + current in this function happens too late for their safe disposal. + + \sa makeCurrent + + \since 5.5 +*/ +QOpenGLWindow::~QOpenGLWindow() +{ + makeCurrent(); +} + +/*! + \return the update behavior for this QOpenGLWindow. +*/ +QOpenGLWindow::UpdateBehavior QOpenGLWindow::updateBehavior() const +{ + Q_D(const QOpenGLWindow); + return d->updateBehavior; +} + +/*! + \return \c true if the window's OpenGL resources, like the context, have + been successfully initialized. Note that the return value is always \c false + until the window becomes exposed (shown). +*/ +bool QOpenGLWindow::isValid() const +{ + Q_D(const QOpenGLWindow); + return d->context && d->context->isValid(); +} + +/*! + Prepares for rendering OpenGL content for this window by making the + corresponding context current and binding the framebuffer object, if there is + one, in that context context. + + It is not necessary to call this function in most cases, because it is called + automatically before invoking paintGL(). It is provided nonetheless to support + advanced, multi-threaded scenarios where a thread different than the GUI or main + thread may want to update the surface or framebuffer contents. See QOpenGLContext + for more information on threading related issues. + + This function is suitable for calling also when the underlying platform window + is already destroyed. This means that it is safe to call this function from + a QOpenGLWindow subclass' destructor. If there is no native window anymore, + an offscreen surface is used instead. This ensures that OpenGL resource + cleanup operations in the destructor will always work, as long as + this function is called first. + + \sa QOpenGLContext, context(), paintGL(), doneCurrent() + */ +void QOpenGLWindow::makeCurrent() +{ + Q_D(QOpenGLWindow); + + if (!isValid()) + return; + + // The platform window may be destroyed at this stage and therefore + // makeCurrent() may not safely be called with 'this'. + if (handle()) { + d->context->makeCurrent(this); + } else { + if (!d->offscreenSurface) { + d->offscreenSurface.reset(new QOffscreenSurface(screen())); + d->offscreenSurface->setFormat(d->context->format()); + d->offscreenSurface->create(); + } + d->context->makeCurrent(d->offscreenSurface.data()); + } + + d->bindFBO(); +} + +/*! + Releases the context. + + It is not necessary to call this function in most cases, since the widget + will make sure the context is bound and released properly when invoking + paintGL(). + + \sa makeCurrent() + */ +void QOpenGLWindow::doneCurrent() +{ + Q_D(QOpenGLWindow); + + if (!isValid()) + return; + + d->context->doneCurrent(); +} + +/*! + \return The QOpenGLContext used by this window or \c 0 if not yet initialized. + */ +QOpenGLContext *QOpenGLWindow::context() const +{ + Q_D(const QOpenGLWindow); + return d->context.data(); +} + +/*! + \return The QOpenGLContext requested to be shared with this window's QOpenGLContext. +*/ +QOpenGLContext *QOpenGLWindow::shareContext() const +{ + Q_D(const QOpenGLWindow); + return d->shareContext; +} + +/*! + The framebuffer object handle used by this window. + + When the update behavior is set to \c NoPartialUpdate, there is no separate + framebuffer object. In this case the returned value is the ID of the + default framebuffer. + + Otherwise the value of the ID of the framebuffer object or \c 0 if not + yet initialized. + */ +GLuint QOpenGLWindow::defaultFramebufferObject() const +{ + Q_D(const QOpenGLWindow); + if (d->updateBehavior > NoPartialUpdate && d->fbo) + return d->fbo->handle(); + else if (QOpenGLContext *ctx = QOpenGLContext::currentContext()) + return ctx->defaultFramebufferObject(); + else + return 0; +} + +extern Q_GUI_EXPORT QImage qt_gl_read_framebuffer(const QSize &size, bool alpha_format, bool include_alpha); + +/*! + Returns a copy of the framebuffer. + + \note This is a potentially expensive operation because it relies on + glReadPixels() to read back the pixels. This may be slow and can stall the + GPU pipeline. + + \note When used together with update behavior \c NoPartialUpdate, the returned + image may not contain the desired content when called after the front and back + buffers have been swapped (unless preserved swap is enabled in the underlying + windowing system interface). In this mode the function reads from the back + buffer and the contents of that may not match the content on the screen (the + front buffer). In this case the only place where this function can safely be + used is paintGL() or paintOverGL(). + */ +QImage QOpenGLWindow::grabFramebuffer() +{ + if (!isValid()) + return QImage(); + + makeCurrent(); + + const bool hasAlpha = format().hasAlpha(); + QImage img = qt_gl_read_framebuffer(size() * devicePixelRatio(), hasAlpha, hasAlpha); + img.setDevicePixelRatio(devicePixelRatio()); + return img; +} + +/*! + This virtual function is called once before the first call to paintGL() or + resizeGL(). Reimplement it in a subclass. + + This function should set up any required OpenGL resources and state. + + There is no need to call makeCurrent() because this has already been done + when this function is called. Note however that the framebuffer, in case + partial update mode is used, is not yet available at this stage, so avoid + issuing draw calls from here. Defer such calls to paintGL() instead. + + \sa paintGL(), resizeGL() + */ +void QOpenGLWindow::initializeGL() +{ +} + +/*! + This virtual function is called whenever the widget has been resized. + Reimplement it in a subclass. The new size is passed in \a w and \a h. + + \note This is merely a convenience function in order to provide an API that is + compatible with QOpenGLWidget. Unlike with QOpenGLWidget, derived classes are + free to choose to override resizeEvent() instead of this function. + + \note Avoid issuing OpenGL commands from this function as there may not be a + context current when it is invoked. If it cannot be avoided, call makeCurrent(). + + \note Scheduling updates from here is not necessary. The windowing systems + will send expose events that trigger an update automatically. + + \sa initializeGL(), paintGL() + */ +void QOpenGLWindow::resizeGL(int w, int h) +{ + Q_UNUSED(w); + Q_UNUSED(h); +} + +/*! + This virtual function is called whenever the window contents needs to be + painted. Reimplement it in a subclass. + + There is no need to call makeCurrent() because this has already + been done when this function is called. + + Before invoking this function, the context and the framebuffer, if there is + one, are bound, and the viewport is set up by a call to glViewport(). No + other state is set and no clearing or drawing is performed by the framework. + + \note When using a partial update behavior, like \c PartialUpdateBlend, the + output of the previous paintGL() call is preserved and, after the additional + drawing perfomed in the current invocation of the function, the content is + blitted or blended over the content drawn directly to the window in + paintUnderGL(). + + \sa initializeGL(), resizeGL(), paintUnderGL(), paintOverGL(), UpdateBehavior + */ +void QOpenGLWindow::paintGL() +{ +} + +/*! + The virtual function is called before each invocation of paintGL(). + + When the update mode is set to \c NoPartialUpdate, there is no difference + between this function and paintGL(), performing rendering in either of them + leads to the same result. + + The difference becomes significant when using \c PartialUpdateBlend, where an + extra framebuffer object is used. There, paintGL() targets this additional + framebuffer object, which preserves its contents, while paintUnderGL() and + paintOverGL() target the default framebuffer, i.e. directly the window + surface, the contents of which is lost after each displayed frame. + + \note Avoid relying on this function when the update behavior is + \c PartialUpdateBlit. This mode involves blitting the extra framebuffer used by + paintGL() onto the default framebuffer after each invocation of paintGL(), + thus overwriting all drawing generated in this function. + + \sa paintGL(), paintOverGL(), UpdateBehavior + */ +void QOpenGLWindow::paintUnderGL() +{ +} + +/*! + This virtual function is called after each invocation of paintGL(). + + When the update mode is set to NoPartialUpdate, there is no difference + between this function and paintGL(), performing rendering in either of them + leads to the same result. + + Like paintUnderGL(), rendering in this function targets the default + framebuffer of the window, regardless of the update behavior. It gets called + after paintGL() has returned and the blit (PartialUpdateBlit) or quad drawing + (PartialUpdateBlend) has been done. + + \sa paintGL(), paintUnderGL(), UpdateBehavior + */ +void QOpenGLWindow::paintOverGL() +{ +} + +/*! + Paint \a event handler. Calls paintGL(). + + \sa paintGL() + */ +void QOpenGLWindow::paintEvent(QPaintEvent *event) +{ + Q_UNUSED(event); + paintGL(); +} + +/*! + Resize \a event handler. Calls resizeGL(). + + \sa resizeGL() + */ +void QOpenGLWindow::resizeEvent(QResizeEvent *event) +{ + Q_UNUSED(event); + Q_D(QOpenGLWindow); + d->initialize(); + resizeGL(width(), height()); +} + +/*! + \internal + */ +int QOpenGLWindow::metric(PaintDeviceMetric metric) const +{ + Q_D(const QOpenGLWindow); + + switch (metric) { + case PdmDepth: + if (d->paintDevice) + return d->paintDevice->depth(); + break; + default: + break; + } + return QPaintDeviceWindow::metric(metric); +} + +/*! + \internal + */ +QPaintDevice *QOpenGLWindow::redirected(QPoint *) const +{ + Q_D(const QOpenGLWindow); + if (QOpenGLContext::currentContext() == d->context.data()) + return d->paintDevice.data(); + return nullptr; +} + +QT_END_NAMESPACE |