Method validatePaperThumbnail

Telegram/SourceFiles/boxes/background_box.cpp:642–684

}

void BackgroundBox::Inner::validatePaperThumbnail(
		const Paper &paper) const {
	if (!paper.thumbnail.isNull()) {
		return;
	}
	const auto localThumbnail = paper.data.localThumbnail();
	if (!localThumbnail) {
		if (const auto document = paper.data.document()) {
			if (!paper.dataMedia) {
				paper.dataMedia = document->createMediaView();
				paper.dataMedia->thumbnailWanted(paper.data.fileOrigin());
			}
			if (!paper.dataMedia->thumbnail()) {
				return;
			}
		} else if (!paper.data.backgroundColors().empty()) {
			paper.thumbnail = Ui::PixmapFromImage(
				Ui::GenerateBackgroundImage(
					st::backgroundSize * style::DevicePixelRatio(),
					paper.data.backgroundColors(),
					paper.data.gradientRotation()));
			paper.thumbnail.setDevicePixelRatio(style::DevicePixelRatio());
			return;
		} else {
			return;
		}
	}
	const auto thumbnail = localThumbnail
		? localThumbnail
		: paper.dataMedia->thumbnail();
	auto original = thumbnail->original();
	if (paper.data.isPattern()) {
		original = Ui::PreparePatternImage(
			std::move(original),
			paper.data.backgroundColors(),
			paper.data.gradientRotation(),
			paper.data.patternOpacity());
	}
	paper.thumbnail = Ui::PixmapFromImage(TakeMiddleSample(
		original,
		st::backgroundSize));
	paper.thumbnail.setDevicePixelRatio(style::DevicePixelRatio());
}

bool BackgroundBox::Inner::forChannel() const {
	return _forPeer && _forPeer->isChannel();