Hi all,
I've been experimenting with drawing in to a cached Image on my own Thread to keep complicated draw routines off the Message Thread, and I have discovered some strange memory behaviour in the OSXTypeface. Just to note that I'm seeing this using the tip of the Juce repo.
When drawing in to a Graphics object generated on a Thread which isn't the Message Thread (i.e. not one handed to the Component::paint() method), I am seeing constant allocation of memory stacking up over time in the OSXTypeface::getGlyphPositions method.
To be clear, this is NOT a memory leak. The memory is all freed correctly when the app is closed.
The problem appears only when I use one of the text drawing methods of the Graphics object.
Below is the simplest way to recreate the issue, simply place this in to a GUI App and attach Instruments (look for __NSDictionaryl):
MainContentComponent::MainContentComponent()
: m_Image(Image::ARGB, 600, 400, true)
, m_Lock()
{
setSize (600, 400);
// Start the timer which will repaint the Image.
Timer::startTimer(20);
// Start the timer which will actually draw the Image.
HighResolutionTimer::startTimer(20);
}
MainContentComponent::~MainContentComponent()
{
Timer::stopTimer();
HighResolutionTimer::stopTimer();
}
void MainContentComponent::paint (Graphics& g)
{
ScopedLock lock(m_Lock);
// Here, we just draw the Image which has been drawn in to elsewhere.
g.drawImageAt(m_Image, 0, 0);
}
void MainContentComponent::timerCallback()
{
// Ensure that all calls to repaint()/paint() happen on proper Thread.
repaint();
}
void MainContentComponent::hiResTimerCallback()
{
ScopedLock lock(m_Lock);
// Here, we are creating a temporary Graphics context and drawing some text into it.
Graphics g(m_Image);
g.fillAll (Colour (0xff001F36));
g.setFont (Font (16.0f));
g.setColour (Colours::white);
g.drawText ("Hello World!", getLocalBounds(), Justification::centred, true);
}
There is a screenshot here: http://postimg.org/image/ug5pul53b/ which shows the increasing memory allocation, etc.