Method apply_keyframes

src/Clip.cpp:1324–1397

Apply keyframes to the source frame (if any)

// Apply keyframes to the source frame (if any)
void Clip::apply_keyframes(std::shared_ptr<Frame> frame, QSize timeline_size) {
	// Skip out if video was disabled or only an audio frame (no visualisation in use)
	if (!frame->has_image_data) {
		// Skip the rest of the image processing for performance reasons
		return;
	}

	// Get image from clip, and create transparent background image
	std::shared_ptr<QImage> source_image = frame->GetImage();
	std::shared_ptr<QImage> background_canvas = std::make_shared<QImage>(timeline_size.width(),
                                                                         timeline_size.height(),
																		 QImage::Format_RGBA8888_Premultiplied);
	background_canvas->fill(QColor(Qt::transparent));

	// Get transform from clip's keyframes
	QTransform transform = get_transform(frame, background_canvas->width(), background_canvas->height());

	// Load timeline's new frame image into a QPainter
	QPainter painter(background_canvas.get());
	painter.setRenderHint(QPainter::TextAntialiasing, true);
	if (!transform.isIdentity()) {
		painter.setRenderHint(QPainter::SmoothPixmapTransform, true);
	}
	// Apply transform (translate, rotate, scale)
	painter.setTransform(transform);

	// Composite a new layer onto the image
	painter.setCompositionMode(static_cast<QPainter::CompositionMode>(composite));

	// Apply opacity via painter instead of per-pixel alpha manipulation
	const float alpha_value = alpha.GetValue(frame->number);
	if (alpha_value != 1.0f) {
		painter.setOpacity(alpha_value);
		painter.drawImage(0, 0, *source_image);
		// Reset so any subsequent drawing (e.g., overlays) isn’t faded
		painter.setOpacity(1.0);
	} else {
		painter.drawImage(0, 0, *source_image);
	}

	if (timeline) {
		Timeline *t = static_cast<Timeline *>(timeline);

		// Draw frame #'s on top of image (if needed)
		if (display != FRAME_DISPLAY_NONE) {
			std::stringstream frame_number_str;
			switch (display) {
				case (FRAME_DISPLAY_NONE):
					// This is only here to prevent unused-enum warnings
					break;

				case (FRAME_DISPLAY_CLIP):
					frame_number_str << frame->number;
					break;

				case (FRAME_DISPLAY_TIMELINE):
					frame_number_str << round((Position() - Start()) * t->info.fps.ToFloat()) + frame->number;
					break;