added resizer

lib/danbooru_image_resizer/Resize.h

@@ -0,0 +1,41 @@
+#ifndef RESIZE_H
+#define RESIZE_H
+
+#include <stdint.h>
+
+class JPEGCompressor;
+
+class Resizer
+{
+public:
+	Resizer(JPEGCompressor *Compressor);
+	~Resizer();
+
+	// BPP is 3 or 4, indicating RGB or RGBA.
+	void SetSource(int Width, int Height, int BPP);
+	bool SetDest(int Width, int Height, int Quality);
+
+	/*
+	 * Resize part of an image.
+	 *
+	 * [FirstRow,LastRow) is a range indicating which elements in src[] are available.
+	 * On return, any rows in [0,DiscardRow) are no longer needed and can be deleted.
+	 */
+	bool Run(const uint8_t *const *src, int FirstRow, int LastRow, int &DiscardRow);
+	const char *GetError() const;
+
+private:
+	JPEGCompressor *m_Compressor;
+	uint8_t *m_OutBuf;
+
+	int m_SourceWidth;
+	int m_SourceHeight;
+	int m_SourceBPP;
+
+	int m_DestWidth;
+	int m_DestHeight;
+
+	float m_CurrentY;
+};
+
+#endif