Add decoded image data structure

- Stores decoded pixel data ready for GPU upload
- Supports RGBA8, RGB8, and DDS formats
- Separates CPU decoding from GPU upload phases

src/EterLib/DecodedImageData.h

@@ -0,0 +1,59 @@
+#ifndef __INC_ETERLIB_DECODEDIMAGEDATA_H__
+#define __INC_ETERLIB_DECODEDIMAGEDATA_H__
+
+#include <vector>
+#include <cstdint>
+#include <d3d9.h>
+
+// Decoded image data for GPU upload
+struct TDecodedImageData
+{
+	enum EFormat
+	{
+		FORMAT_UNKNOWN = 0,
+		FORMAT_RGBA8,
+		FORMAT_RGB8,
+		FORMAT_DDS,
+	};
+
+	std::vector<uint8_t> pixels;
+	int width;
+	int height;
+	EFormat format;
+	D3DFORMAT d3dFormat;
+	bool isDDS;
+	int mipLevels;
+
+	TDecodedImageData()
+		: width(0)
+		, height(0)
+		, format(FORMAT_UNKNOWN)
+		, d3dFormat(D3DFMT_UNKNOWN)
+		, isDDS(false)
+		, mipLevels(1)
+	{
+	}
+
+	void Clear()
+	{
+		pixels.clear();
+		width = 0;
+		height = 0;
+		format = FORMAT_UNKNOWN;
+		d3dFormat = D3DFMT_UNKNOWN;
+		isDDS = false;
+		mipLevels = 1;
+	}
+
+	bool IsValid() const
+	{
+		return width > 0 && height > 0 && !pixels.empty();
+	}
+
+	size_t GetDataSize() const
+	{
+		return pixels.size();
+	}
+};
+
+#endif // __INC_ETERLIB_DECODEDIMAGEDATA_H__