void QGLPaintDevice::beginPaint()
{
// Make sure our context is the current one:
QGLContext *ctx = context();
ctx->makeCurrent();
ctx->d_func()->refreshCurrentFbo();
// Record the currently bound FBO so we can restore it again
// in endPaint() and bind this device's FBO
//
// Note: m_thisFBO could be zero if the paint device is not
// backed by an FBO (e.g. window back buffer). But there could
// be a previous FBO bound to the context which we need to
// explicitly unbind. Otherwise the painting will go into
// the previous FBO instead of to the window.
m_previousFBO = ctx->d_func()->current_fbo;
if (m_previousFBO != m_thisFBO) {
ctx->d_func()->setCurrentFbo(m_thisFBO);
ctx->contextHandle()->functions()->glBindFramebuffer(GL_FRAMEBUFFER, m_thisFBO);
}
// Set the default fbo for the context to m_thisFBO so that
// if some raw GL code between beginNativePainting() and
// endNativePainting() calls QGLFramebufferObject::release(),
// painting will revert to the window surface's fbo.
ctx->d_ptr->default_fbo = m_thisFBO;
}
void QGLPaintDevice::endPaint()
{
// Make sure the FBO bound at beginPaint is re-bound again here:
QGLContext *ctx = context();
ctx->d_func()->refreshCurrentFbo();
if (m_previousFBO != ctx->d_func()->current_fbo) {
ctx->d_func()->setCurrentFbo(m_previousFBO);
ctx->contextHandle()->functions()->glBindFramebuffer(GL_FRAMEBUFFER, m_previousFBO);
}
ctx->d_ptr->default_fbo = 0;
}
void QGLPaintDevice::ensureActiveTarget()
{
QGLContext* ctx = context();
if (ctx != QGLContext::currentContext())
ctx->makeCurrent();
ctx->d_func()->refreshCurrentFbo();
if (ctx->d_ptr->current_fbo != m_thisFBO) {
ctx->d_func()->setCurrentFbo(m_thisFBO);
ctx->contextHandle()->functions()->glBindFramebuffer(GL_FRAMEBUFFER, m_thisFBO);
}
ctx->d_ptr->default_fbo = m_thisFBO;
}