将数据写出成一个灰度png图片
写了一个简单的类，用于将数据直接写出成一个png图片
不多说，且看代码
首先类的定义
pngHandle.h
//
// Created by L on 18-10-26.
//
#ifndef PNG_PNGHANDLE_H
#define PNG_PNGHANDLE_H
#include "png.h"
class pngHandle{
public:
~pngHandle();
pngHandle();
pngHandle(const int width,const int height);
void setSize(const int width,const int height);
bool setBackground(unsigned char value);
bool setValue(int x,int y,unsigned char value);
bool write(char * filename);
private:
bool isSetSize;
char bit_depth_;//图像深度
char color_type_;
int width_; //图寬
int height_;//图高
void setBitDepth(char bit_depth);
void setColortype(char color_type);
unsigned char *buffer;// 0 <= gray < 255
};
#endif //PNG_PNGHANDLE_H
然后类的实现
pngHandle.cpp
//
// Created by L on 18-10-26.
//
#include <iostream>
#include "pngHandle.h"
pngHandle::~pngHandle(){
delete[] buffer;
}
pngHandle::pngHandle():
isSetSize(false)
{
setBitDepth(8);
setColortype(0);
}
pngHandle::pngHandle(const int width, const int height):
isSetSize(false)
{
setBitDepth(8);
setColortype(0);
setSize(width, height);
setBackground(0xff);//默认设置白色
}
void pngHandle::setSize(const int width,const int height){
width_ = width;
height_ = height;
buffer = new unsigned char[width_*height_];
isSetSize = true;
}
bool pngHandle::setBackground(unsigned char value) {
if(!isSetSize){
std::cerr<<"Warning: can't set background, because size wasn't set!"<<std::endl;
return false;
}
for(int i = 0;i < width_*height_;i++){
buffer[i] = value;
}
return true;
}
bool pngHandle::setValue(int x, int y, unsigned char value){
if(!isSetSize){
std::cerr<<"Warning: can't set color, because size wasn't set!"<<std::endl;
return false;
}
if((x >= height_) || (y >= width_)) {
std::cerr<<"Warning: beyond the boundary!"<<std::endl;
return false;
}
buffer[x*width_+y] = value;
return true;
}
void pngHandle::setBitDepth(char bit_depth) {
bit_depth_ = bit_depth;
}
void pngHandle::setColortype(char color_type){
color_type_ = color_type;
}
bool pngHandle::write(char *filename) {
FILE * fp = fopen(filename,"wb");
if (!fp) {
std::cerr << "Warning: could not open png file: " << filename << std::endl;
return false;
}
//创建png_struct
png_structp png_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING,
(png_voidp)NULL,NULL,NULL);
if (!png_ptr) {
fclose(fp);
std::cerr << "Warning: could not create png_ptr" << std::endl;
return false;
}
//分配内存并初始化图像信息
png_infop info_ptr = png_create_info_struct(png_ptr);
if (!info_ptr) {
png_destroy_write_struct(&png_ptr,(png_infopp)NULL);
std::cerr << "Warning: could not create info_ptr" << std::endl;
return false;
}
//设置输出控制
png_init_io(png_ptr, fp);
png_set_IHDR(png_ptr, info_ptr,
width_, height_, // width, height
bit_depth_, // bits per pixel -- 16 does not work with blockbuster
color_type_, // non-alpha options are PNG_COLOR_TYPE_RGB,PNG_COLOR_TYPE_GRAY,
PNG_INTERLACE_NONE,
PNG_COMPRESSION_TYPE_DEFAULT,
PNG_FILTER_TYPE_DEFAULT);
png_write_info(png_ptr, info_ptr);
png_byte * row_pointers[height_];
for (int i = 0; i < height_; ++i)
{
row_pointers[i] = (png_byte*)(buffer+i*width_);
}
png_write_image(png_ptr, row_pointers);
png_write_end(png_ptr, NULL);
//清空内存
if (info_ptr != NULL) png_free_data(png_ptr, info_ptr, PNG_FREE_ALL, -1);
if (png_ptr != NULL) png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
if (row_pointers != NULL) free(row_pointers);
if (fp != NULL) fclose(fp);
}
最后给一个简单的使用例子
#include "pngHandle.h"
int main() {
int width = 800;
int height = 600;
pngHandle png(width,height);
for(int x =height/4 ;x<height/2;x++){
for(int y=0; y<width ; y++)
{
png.setValue(x,y,0x00);
}
}
for(int x =0 ;x<height;x++){
for(int y=width/3; y<width/2 ; y++)
{
png.setValue(x,y,205);
}
}
png.write("mypng.png");
return 0;
}