Lifetime of Data for for TYPE_32FC1, TYPE_16UC1, TYPE_16S1, and TYPE_MONO

[cturcotte-qnx]

Improve lifetime of data_ptr in Rviz through the use of shared pointers.

The formats TYPE_32FC1, TYPE_16UC1, TYPE_16S1, and TYPE_MONO create a vector buffer inside the setFormatAndNormalizeDataIfNecessary function. This could cause memory leaks if they are not properly deallocated.

A change made using shared pointers for YUV422 and YUV422_YUY2 format images inside ros_image_texture.cpp could be a solution to this problem.

As seen in pull request #701

[clalancette]

Actually, it is much worse than a memory leak. For instance, looking at this code:

rviz/rviz_default_plugins/src/rviz_default_plugins/displays/image/ros_image_texture.cpp

Lines 277 to 288 in 94f6dd6

	} else if ( // NOLINT enforces bracket on the same line, which makes code unreadable
	image_data.encoding_ == sensor_msgs::image_encodings::TYPE_16UC1 ||
	image_data.encoding_ == sensor_msgs::image_encodings::TYPE_16SC1 ||
	image_data.encoding_ == sensor_msgs::image_encodings::MONO16)
	{
	image_data.size_ /= sizeof(uint16_t);
	std::vector<uint8_t> buffer = normalize<uint16_t>(
	reinterpret_cast<const uint16_t *>(image_data.data_ptr_),
	image_data.size_);
	image_data.pixel_format_ = Ogre::PF_BYTE_L;
	image_data.data_ptr_ = &buffer[0];
	} else if (image_data.encoding_.find("bayer") == 0) {

We enter the scope, do a stack allocation of a std::vector, and then take the address of that. But then we leave the scope, which will destroy the std::vector. That means that image_data.data_ptr is holding onto a pointer to garbage data.