缩放算法优化步骤详解

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背景

假设数据存放在在unsigned char* m_pData 里面，宽和高分别是：m_nDataWidth m_nDataHeight

给定缩放比例：fXZoom fYZoom，返回缩放后的unsigned char* dataZoom

这里采用最简单的缩放算法即：

根据比例计算原图和缩放后图坐标的对应关系：缩放后图坐标*缩放比例 = 原图坐标

原始代码 未优化

#pragma onceclass zoomBlock{public:zoomBlock() {};~zoomBlock();void zoomDataSSE128(unsigned char* dataZoom, float  fXZoom, float fYZoom);void zoomData(unsigned char* dataZoom, float  fXZoom, float fYZoom);void test(float  fXZoom =0.5, float fYZoom=0.5);void init(int DataWidth, int DataHeight);private:void computeSrcValues(int* srcValues, size_t size, float zoom, int dataSize);private:unsigned char* m_pData = nullptr;float m_fXZoom = 1 ;//x轴缩放比例  m_nXZoom=1时 不缩放float m_fYZoom = 1 ;//y轴缩放比例int m_nDataWidth = 0;int m_nDataHeight = 0;};#include "zoomBlock.h"#include #include #include#define SAFE_DELETE_ARRAY(p) { if( (p) != NULL ) delete[] (p); (p) = NULL; }zoomBlock::~zoomBlock(){SAFE_DELETE_ARRAY(m_pData);}void zoomBlock::init(int DataWidth, int DataHeight){m_nDataWidth = DataWidth;m_nDataHeight = DataHeight;m_pData = new unsigned char[m_nDataWidth* m_nDataHeight];for (int i = 0; i