Method GetFrame

src/effects/Caption.cpp:108–369

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> Caption::GetFrame(std::shared_ptr<openshot::Frame> frame, int64_t frame_number)
{
	// Process regex (if needed)
	process_regex();

	// Get the Clip and Timeline pointers (if available)
	Clip* clip = (Clip*) ParentClip();
	Timeline* timeline = NULL;
	Fraction fps;
	QSize image_size(1, 1);

	if (clip && clip->ParentTimeline() != NULL) {
		timeline = (Timeline*) clip->ParentTimeline();
	} else if (this->ParentTimeline() != NULL) {
		timeline = (Timeline*) this->ParentTimeline();
	}

	// Get the FPS from the parent object (Timeline or Clip's Reader)
	if (timeline != NULL) {
		fps = timeline->info.fps;
		image_size = QSize(timeline->info.width, timeline->info.height);
	} else if (clip != NULL && clip->Reader() != NULL) {
		fps = clip->Reader()->info.fps;
		image_size = QSize(clip->Reader()->info.width, clip->Reader()->info.height);
	}

	if (!frame->has_image_data) {
		// Give audio-only files a full frame image of solid color
		frame->AddColor(image_size.width(), image_size.height(), "#000000");
	}

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

	// Calculate scale factor, to keep different resolutions from
	// having dramatically different font sizes
	double timeline_scale_factor = frame_image->width() / 600.0;

	// Load timeline's new frame image into a QPainter
	QPainter painter(frame_image.get());
	painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);

	// Composite a new layer onto the image
	painter.setCompositionMode(QPainter::CompositionMode_SourceOver);

	// Font options and metrics for caption text
	double font_size_value = font_size.GetValue(frame_number) * timeline_scale_factor;
	QFont font(QString(font_name.c_str()), int(font_size_value));
	font.setPixelSize(std::max(font_size_value, 1.0));
	QFontMetricsF metrics = QFontMetricsF(font);

	// Get current keyframe values
	double left_value = left.GetValue(frame_number);
	double top_value = top.GetValue(frame_number);
	double fade_in_value = fade_in.GetValue(frame_number) * fps.ToDouble();
	double fade_out_value = fade_out.GetValue(frame_number) * fps.ToDouble();
	double right_value = right.GetValue(frame_number);
	double background_corner_value = background_corner.GetValue(frame_number) * timeline_scale_factor;