Add ImageFrameGenerator for static custom emoji.

CMakeLists.txt

@@ -47,6 +47,7 @@ PRIVATE
     ui/effects/cross_line.h
     ui/effects/fade_animation.cpp
     ui/effects/fade_animation.h
+    ui/effects/frame_generator.cpp
     ui/effects/frame_generator.h
     ui/effects/gradient.cpp
     ui/effects/gradient.h

ui/effects/frame_generator.cpp

@@ -0,0 +1,58 @@
+// This file is part of Desktop App Toolkit,
+// a set of libraries for developing nice desktop applications.
+//
+// For license and copyright information please follow this link:
+// https://github.com/desktop-app/legal/blob/master/LEGAL
+//
+#include "ui/effects/frame_generator.h"
+
+#include "ui/image/image_prepare.h"
+
+namespace Ui {
+
+ImageFrameGenerator::ImageFrameGenerator(const QByteArray &bytes)
+: _bytes(bytes) {
+}
+
+int ImageFrameGenerator::count() {
+	return 1;
+}
+
+FrameGenerator::Frame ImageFrameGenerator::renderNext(
+		QImage storage,
+		QSize size,
+		Qt::AspectRatioMode mode) {
+	storage = Images::Read({
+		.content = _bytes,
+	}).image;
+	if (storage.isNull()) {
+		return {};
+	}
+	auto scaled = storage.scaled(
+		size,
+		mode,
+		Qt::SmoothTransformation
+	).convertToFormat(QImage::Format_ARGB32_Premultiplied);
+	if (scaled.size() == size) {
+		return { .image = std::move(scaled) };
+	}
+	auto result = QImage(size, QImage::Format_ARGB32_Premultiplied);
+	result.fill(Qt::transparent);
+
+	const auto skipx = (size.width() - scaled.width()) / 2;
+	const auto skipy = (size.height() - scaled.height()) / 2;
+	const auto fromPerLine = scaled.bytesPerLine();
+	const auto toPerLine = result.bytesPerLine();
+	const auto lineBytes = scaled.width() * 4;
+	auto from = scaled.constBits();
+	auto to = result.bits() + (skipx * 4) + (skipy * fromPerLine);
+	for (auto y = 0, height = scaled.height(); y != height; ++y) {
+		memcpy(to, from, lineBytes);
+		from += fromPerLine;
+		to += toPerLine;
+	}
+
+	return { .image = std::move(result) };
+}
+
+} // namespace Ui

ui/effects/frame_generator.h

@@ -26,4 +26,19 @@ public:
 		Qt::AspectRatioMode mode = Qt::IgnoreAspectRatio) = 0;
 };
 
+class ImageFrameGenerator final : public Ui::FrameGenerator {
+public:
+	explicit ImageFrameGenerator(const QByteArray &bytes);
+
+	int count() override;
+	Frame renderNext(
+		QImage storage,
+		QSize size,
+		Qt::AspectRatioMode mode = Qt::IgnoreAspectRatio) override;
+
+private:
+	QByteArray _bytes;
+
+};
+
 } // namespace Ui