Method GetFrame

src/effects/Outline.cpp:49–103

This method is required for all derived classes of EffectBase, and returns a modified openshot::Frame object

// This method is required for all derived classes of EffectBase, and returns a
// modified openshot::Frame object
std::shared_ptr<openshot::Frame> Outline::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
	float widthValue = width.GetValue(frame_number);
	int blueValue = color.blue.GetValue(frame_number);
	int greenValue = color.green.GetValue(frame_number);
	int redValue = color.red.GetValue(frame_number);
	int alphaValue = color.alpha.GetValue(frame_number);
	
	if (widthValue <= 0.0 || alphaValue <= 0) {
		// If alpha or width is zero, return the original frame
		return frame;
	}

	// Get the frame's image
	std::shared_ptr<QImage> frame_image = frame->GetImage();

	float sigmaValue = widthValue / 3.0;
	if (sigmaValue <= 0.0)
		sigmaValue = 0.01;
	cv::Mat cv_image = QImageToBGRACvMat(frame_image);

	// Extract alpha channel for the mask
	std::vector<cv::Mat> channels(4);
	cv::split(cv_image, channels);
	cv::Mat alpha_mask = channels[3].clone();

	// Create the outline mask
	cv::Mat outline_mask;
	cv::GaussianBlur(alpha_mask, outline_mask, cv::Size(0, 0), sigmaValue, sigmaValue, cv::BorderTypes::BORDER_DEFAULT);
	cv::threshold(outline_mask, outline_mask, 0, 255, cv::ThresholdTypes::THRESH_BINARY);

	// Antialias the outline edge & apply Canny edge detection
	cv::Mat edge_mask;
	cv::Canny(outline_mask, edge_mask, 250, 255);

	// Apply Gaussian blur only to the edge mask
	cv::Mat blurred_edge_mask;
	cv::GaussianBlur(edge_mask, blurred_edge_mask, cv::Size(0, 0), 0.8, 0.8, cv::BorderTypes::BORDER_DEFAULT);
	cv::bitwise_or(outline_mask, blurred_edge_mask, outline_mask);

	cv::Mat final_image;

	// Create solid color source mat (cv::Scalar: red, green, blue, alpha)
	cv::Mat solid_color_mat(cv::Size(cv_image.cols, cv_image.rows), CV_8UC4, cv::Scalar(redValue, greenValue, blueValue, alphaValue));

	// Place outline first, then the original image on top
	solid_color_mat.copyTo(final_image, outline_mask);
	cv_image.copyTo(final_image, alpha_mask);

	std::shared_ptr<QImage> new_frame_image = BGRACvMatToQImage(final_image);

	// FIXME: The shared_ptr::swap does not work somehow
	*frame_image = *new_frame_image;
	return frame;
}

cv::Mat Outline::QImageToBGRACvMat(std::shared_ptr<QImage>& qimage) {
	cv::Mat cv_img(qimage->height(), qimage->width(), CV_8UC4, (uchar*)qimage->constBits(), qimage->bytesPerLine());