From 4ca304898887c881c853bcc1b4bd92fbaa4353e7 Mon Sep 17 00:00:00 2001
From: Green Sky <Green-Sky@users.noreply.github.com>
Date: Mon, 7 Apr 2025 16:18:32 +0200
Subject: [PATCH] add lossless webp encoding

---
 src/chat_gui/send_image_popup.cpp | 15 ++++++++++-----
 src/image_loader_webp.cpp         | 26 +++++++++++++++++++-------
 2 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/src/chat_gui/send_image_popup.cpp b/src/chat_gui/send_image_popup.cpp
index b4d9389..680c49e 100644
--- a/src/chat_gui/send_image_popup.cpp
+++ b/src/chat_gui/send_image_popup.cpp
@@ -473,17 +473,17 @@ void SendImagePopup::render(float time_delta) {
 
 	if (compress) {
 		ImGui::SameLine();
-		ImGui::Combo("##compression_type", &current_compressor, "webp\0jpeg\0png\0qoi\0");
+		ImGui::Combo("##compression_type", &current_compressor, "webp\0webp lossless\0jpeg\0png\0qoi\0");
 
 		ImGui::Indent();
 		// combo "webp""webp-lossless""png""jpg?"
 		// if lossy quality slider (1-100) default 80
-		if (current_compressor == 0 || current_compressor == 1) {
+		if (current_compressor == 0 || current_compressor == 2) {
 			const uint32_t qmin = 1;
 			const uint32_t qmax = 100;
 			recalc_size |= ImGui::SliderScalar("quality", ImGuiDataType_U32, &quality, &qmin, &qmax);
 		}
-		if (current_compressor == 2) {
+		if (current_compressor == 1 || current_compressor == 3) {
 			const uint32_t qmin = 0;
 			const uint32_t qmax = 9;
 			recalc_size |= ImGui::SliderScalar("compression_level", ImGuiDataType_U32, &compression_level, &qmin, &qmax);
@@ -529,16 +529,21 @@ void SendImagePopup::render(float time_delta) {
 					_on_send(new_data, ".webp");
 				}
 			} else if (current_compressor == 1) {
+				new_data = ImageEncoderWebP{}.encodeToMemoryRGBA(tmp_img, {{"compression_level", compression_level}});
+				if (!new_data.empty()) {
+					_on_send(new_data, ".webp");
+				}
+			} else if (current_compressor == 2) {
 				new_data = ImageEncoderSTBJpeg{}.encodeToMemoryRGBA(tmp_img, {{"quality", quality}});;
 				if (!new_data.empty()) {
 					_on_send(new_data, ".jpg");
 				}
-			} else if (current_compressor == 2) {
+			} else if (current_compressor == 3) {
 				new_data = ImageEncoderSTBPNG{}.encodeToMemoryRGBA(tmp_img, {{"png_compression_level", compression_level}});;
 				if (!new_data.empty()) {
 					_on_send(new_data, ".png");
 				}
-			} else if (current_compressor == 3) {
+			} else if (current_compressor == 4) {
 				new_data = ImageEncoderQOI{}.encodeToMemoryRGBA(tmp_img, {});;
 				if (!new_data.empty()) {
 					_on_send(new_data, ".qoi");
diff --git a/src/image_loader_webp.cpp b/src/image_loader_webp.cpp
index 85a848b..1fba8b8 100644
--- a/src/image_loader_webp.cpp
+++ b/src/image_loader_webp.cpp
@@ -92,6 +92,13 @@ std::vector<uint8_t> ImageEncoderWebP::encodeToMemoryRGBA(const ImageResult& inp
 	if (extra_options.count("quality")) {
 		quality = extra_options.at("quality");
 	}
+	bool lossless = false;
+	int compression_level = 6;
+	if (extra_options.count("compression_level")) {
+		// if compression_level is set, we assume lossless
+		lossless = true;
+		compression_level = extra_options.at("compression_level");
+	}
 
 	// start encoding
 
@@ -113,15 +120,20 @@ std::vector<uint8_t> ImageEncoderWebP::encodeToMemoryRGBA(const ImageResult& inp
 		return {};
 	}
 
-	int prev_timestamp = 0;
-	for (const auto& frame : input_image.frames) {
-		WebPConfig config;
-		if (!WebPConfigPreset(&config, WebPPreset::WEBP_PRESET_DEFAULT, quality)) {
-			std::cerr << "IEWebP error: WebPConfigPreset()\n";
+	WebPConfig config;
+	if (!WebPConfigPreset(&config, WebPPreset::WEBP_PRESET_DEFAULT, quality)) {
+		std::cerr << "IEWebP error: WebPConfigPreset()\n";
+		return {};
+	}
+	if (lossless) {
+		if (!WebPConfigLosslessPreset(&config, compression_level)) {
+			std::cerr << "IEWebP error: WebPConfigLosslessPreset()\n";
 			return {};
 		}
-		//WebPConfigLosslessPreset(&config, 6); // 9 for max compression
+	}
 
+	int prev_timestamp = 0;
+	for (const auto& frame : input_image.frames) {
 		WebPPicture frame_webp;
 		if (!WebPPictureInit(&frame_webp)) {
 			std::cerr << "IEWebP error: WebPPictureInit()\n";
@@ -135,7 +147,7 @@ std::vector<uint8_t> ImageEncoderWebP::encodeToMemoryRGBA(const ImageResult& inp
 		}
 
 		if (!WebPAnimEncoderAdd(enc.get(), &frame_webp, prev_timestamp, &config)) {
-			std::cerr << "IEWebP error: WebPAnimEncoderAdd()\n";
+			std::cerr << "IEWebP error: WebPAnimEncoderAdd(): " << frame_webp.error_code << "\n";
 			WebPPictureFree(&frame_webp);
 			return {};
 		}