From 64d9d7b3eb7cece81da8b2cb56eb0f50d87a5964 Mon Sep 17 00:00:00 2001
From: chai <chaifix@163.com>
Date: Fri, 1 Mar 2019 08:50:34 +0800
Subject: *misc

---
 Source/Asura.Engine/Graphics/STBDecoder.cpp | 69 +++++++++++++++++++++++++++++
 1 file changed, 69 insertions(+)
 create mode 100644 Source/Asura.Engine/Graphics/STBDecoder.cpp

(limited to 'Source/Asura.Engine/Graphics/STBDecoder.cpp')

diff --git a/Source/Asura.Engine/Graphics/STBDecoder.cpp b/Source/Asura.Engine/Graphics/STBDecoder.cpp
new file mode 100644
index 0000000..d4d578f
--- /dev/null
+++ b/Source/Asura.Engine/Graphics/STBDecoder.cpp
@@ -0,0 +1,69 @@
+#include "STBDecoder.h"
+
+#include "Exceptions/Exception.h"
+#include "stb/stb_image.h"
+
+namespace AsuraEngine
+{
+	namespace Graphics
+	{
+
+		bool STBDecoder::CanDecode(const Filesystem::DataBuffer* buffer)
+		{
+			int w = 0;
+			int h = 0;
+			int comp = 0;
+
+			int status = stbi_info_from_memory((const stbi_uc *)buffer->data, buffer->size, &w, &h, &comp);
+
+			return status == 1 && w > 0 && h > 0;
+		}
+
+		void STBDecoder::Decode(const Filesystem::DataBuffer* db, ImageData* imageData)
+		{
+			if (!db)
+				throw Exception("Could not decode image with stb decoder because of null databuffer.");
+			if (!imageData)
+				throw Exception("Could not decode image with stb decoder because of null output image data.");
+			const stbi_uc *buffer = (const stbi_uc *)db->data;
+			int bufferlen = db->size; 
+			int width, height;
+			int comp = 0;
+			byte* data = nullptr;
+			PixelFormat format = PIXELFORMAT_UNKNOWN;
+			std::size_t size = 0;
+
+			if (stbi_is_hdr_from_memory(buffer, bufferlen))
+			{
+				// 4个channel都是float
+				data = (byte*)stbi_loadf_from_memory(buffer, bufferlen, &width, &height, &comp, STBI_rgb_alpha);
+				format = PIXELFORMAT_RGBA32F;
+				size = width * height * 4 * sizeof(float);
+			}
+			else
+			{
+				data = (byte*)stbi_load_from_memory(buffer, bufferlen, &width, &height, &comp, STBI_rgb_alpha);
+				format = PIXELFORMAT_ASTC_8x5;
+				size = width * height * 4;
+			}
+			if (data)
+			{
+				// 保证内存被释放，做一个防护，理论上不会出现没有释放的情况，因为image data是一次性的，image才是多次的。
+				if (imageData->pixels)
+					delete[] imageData->pixels;
+				imageData->pixels = (byte*)data;
+				imageData->format = format;
+				imageData->width = width;
+				imageData->height = height;
+			}
+			else
+			{
+				const char *err = stbi_failure_reason();
+				if (err == nullptr)
+					err = "unknown error";
+				throw Exception("Could not decode image with stb_image (%s).", err);
+			}
+		}
+
+	}
+}
\ No newline at end of file
-- 
cgit v1.1-26-g67d0