Method Thumbnail

src/Frame.cpp:543–675

Thumbnail the frame image to the specified path. The image format is determined from the extension (i.e. image.PNG, image.JPEG)

// Thumbnail the frame image to the specified path.  The image format is determined from the extension (i.e. image.PNG, image.JPEG)
void Frame::Thumbnail(std::string path, int new_width, int new_height, std::string mask_path, std::string overlay_path,
		std::string background_color, bool ignore_aspect, std::string format, int quality, float rotate, ScaleType scale_mode) {

	// Create blank thumbnail image & fill background color
	auto thumbnail = std::make_shared<QImage>(
		new_width, new_height, QImage::Format_RGBA8888_Premultiplied);
	thumbnail->fill(QColor(QString::fromStdString(background_color)));

	// Create painter
	QPainter painter(thumbnail.get());
	painter.setRenderHints(QPainter::Antialiasing | QPainter::SmoothPixmapTransform | QPainter::TextAntialiasing, true);

	// Get preview image
	std::shared_ptr<QImage> previewImage = GetImage();

	// Update the image to reflect the correct pixel aspect ration (i.e. to fix non-squar pixels)
	if (pixel_ratio.num != 1 || pixel_ratio.den != 1)
	{
		// Calculate correct DAR (display aspect ratio)
		int aspect_width = previewImage->size().width();
		int aspect_height = previewImage->size().height() * pixel_ratio.Reciprocal().ToDouble();

		// Resize to fix DAR
		previewImage = std::make_shared<QImage>(previewImage->scaled(
			aspect_width, aspect_height,
			Qt::IgnoreAspectRatio, Qt::SmoothTransformation));
	}

	// Resize frame image
	Qt::AspectRatioMode aspect_ratio_mode = Qt::KeepAspectRatio;
	if (ignore_aspect) {
		aspect_ratio_mode = Qt::IgnoreAspectRatio;
	} else {
		switch (scale_mode) {
			case SCALE_CROP:
				aspect_ratio_mode = Qt::KeepAspectRatioByExpanding;
				break;
			case SCALE_STRETCH:
				aspect_ratio_mode = Qt::IgnoreAspectRatio;
				break;
			case SCALE_FIT:
			case SCALE_NONE:
			default:
				aspect_ratio_mode = Qt::KeepAspectRatio;
				break;
		}
	}

	previewImage = std::make_shared<QImage>(previewImage->scaled(
		new_width, new_height,
		aspect_ratio_mode, Qt::SmoothTransformation));

	// Composite frame image onto background (centered)
	int x = (new_width - previewImage->size().width()) / 2.0; // center
	int y = (new_height - previewImage->size().height()) / 2.0; // center
	painter.setCompositionMode(QPainter::CompositionMode_SourceOver);