add stb image loader (avatar png support)

src/image_loader_stb.cpp

@@ -0,0 +1,65 @@
+#include "./image_loader_stb.hpp"
+
+#include <stb/stb_image.h>
+
+ImageLoaderSTB::ImageInfo ImageLoaderSTB::loadInfoFromMemory(const uint8_t* data, uint64_t data_size) {
+	ImageInfo res;
+
+	int x,y;
+	if (stbi_info_from_memory(data, data_size, &x, &y, nullptr) == 0) {
+		return res; // failed to load
+	}
+
+	res.width = x;
+	res.height = y;
+
+	return res;
+}
+
+ImageLoaderSTB::ImageResult ImageLoaderSTB::loadFromMemoryRGBA(const uint8_t* data, uint64_t data_size) {
+	ImageResult res;
+
+	int x = 0;
+	int y = 0;
+	{ // try gif before to support animations
+		int* delays = nullptr;
+		int z = 0; // number of frames
+		uint8_t* img_data = stbi_load_gif_from_memory(data, data_size, &delays, &x, &y, &z, nullptr, 4);
+
+		if (img_data) {
+			res.width = x;
+			res.height = y;
+
+			const size_t stride = x * y * 4;
+
+			// TODO: test this with asan
+			for (int i = 0; i < z; i++) {
+				auto& new_frame = res.frames.emplace_back();
+				new_frame.ms = delays[i];
+				new_frame.data.insert(new_frame.data.cbegin(), img_data + (i*stride), img_data + ((i+1)*stride));
+			}
+
+			stbi_image_free(delays); // hope this is right
+			stbi_image_free(img_data);
+			return res;
+		}
+	}
+
+	uint8_t* img_data = stbi_load_from_memory(data, data_size, &x, &y, nullptr, 4);
+
+	if (img_data == nullptr) {
+		// not readable
+		return res;
+	}
+
+	res.width = x;
+	res.height = y;
+
+	auto& new_frame = res.frames.emplace_back();
+	new_frame.ms = 0;
+	new_frame.data.insert(new_frame.data.cbegin(), img_data, img_data+(x*y*4));
+
+	stbi_image_free(img_data);
+	return res;
+}
+