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276 lines
8.8 KiB
276 lines
8.8 KiB
#include <stdio.h>
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#include <stdlib.h>
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#include <windows.h>
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#include <png.h>
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#include <pngstruct.h>
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#include <pnginfo.h>
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#include "decoder-apng.h"
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#include <assert.h>
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#include <tchar.h>
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#define SASSERT(x) assert(x)
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struct IPngReader
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{
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virtual png_size_t read(png_bytep data, png_size_t length) = 0;
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};
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struct IPngReader_Mem : public IPngReader
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{
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const char *pbuf;
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png_size_t nLen;
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IPngReader_Mem(const char *_pbuf,png_size_t _nLen):pbuf(_pbuf),nLen(_nLen){}
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png_size_t read(png_bytep data, png_size_t length)
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{
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if(nLen < length) length = nLen;
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memcpy(data,pbuf,length);
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pbuf += length;
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nLen -= length;
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return length;
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}
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};
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struct IPngReader_File: public IPngReader
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{
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FILE *f;
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IPngReader_File(FILE *_f):f(_f){}
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png_size_t read(png_bytep data, png_size_t length)
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{
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return fread(data,1,length,f);
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}
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};
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void
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mypng_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
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{
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if (png_ptr == NULL)
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return;
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IPngReader * pMem = (IPngReader*)png_ptr->io_ptr;
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png_size_t rc = pMem->read(data,length);
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if(rc < length)
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{
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png_error(png_ptr,"read error");
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}
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}
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APNGDATA * loadPng(IPngReader *pSrc)
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{
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png_bytep dataFrame;
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png_uint_32 bytesPerRow;
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png_uint_32 bytesPerFrame;
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png_bytepp rowPointers;
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png_byte sig[8];
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png_structp png_ptr_read;
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png_infop info_ptr_read;
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pSrc->read(sig,8);
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if(!png_check_sig(sig,8))
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{
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return NULL;
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}
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png_ptr_read = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
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info_ptr_read = png_create_info_struct(png_ptr_read);
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if (setjmp(png_jmpbuf(png_ptr_read)))
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{
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png_destroy_read_struct(&png_ptr_read, &info_ptr_read, NULL);
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return NULL;
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}
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png_set_read_fn(png_ptr_read,pSrc,mypng_read_data);
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png_set_sig_bytes(png_ptr_read, 8);
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if ((png_ptr_read->bit_depth < 8) ||
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(png_ptr_read->color_type == PNG_COLOR_TYPE_PALETTE) ||
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(info_ptr_read->valid & PNG_INFO_tRNS))
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png_set_expand(png_ptr_read);
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png_set_add_alpha(png_ptr_read, 0xff, PNG_FILLER_AFTER);
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png_set_interlace_handling(png_ptr_read);
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png_set_gray_to_rgb(png_ptr_read);
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png_set_strip_16(png_ptr_read);
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png_read_info(png_ptr_read, info_ptr_read);
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png_read_update_info(png_ptr_read, info_ptr_read);
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bytesPerRow = png_ptr_read->width * 4;
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bytesPerFrame = bytesPerRow * png_ptr_read->height;
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APNGDATA * apng = (APNGDATA*) malloc(sizeof(APNGDATA));
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memset(apng,0,sizeof(APNGDATA));
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apng->nWid = png_ptr_read->width;
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apng->nHei = png_ptr_read->height;
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//图像帧数据
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dataFrame = (png_bytep)malloc(bytesPerRow * apng->nHei);
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memset(dataFrame,0,bytesPerFrame);
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//获得扫描行指针
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rowPointers = (png_bytepp)malloc(sizeof(png_bytep)* apng->nHei);
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for(int i=0;i<apng->nHei;i++)
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rowPointers[i] = dataFrame + bytesPerRow * i;
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if (!png_get_valid(png_ptr_read, info_ptr_read, PNG_INFO_acTL))
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{//load png doesn't has this trunk.
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png_read_image(png_ptr_read,rowPointers);
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apng->pdata =dataFrame;
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apng->nFrames =1;
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}else
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{//load apng
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apng->nFrames = png_get_num_frames(png_ptr_read, info_ptr_read);//获取总帧数
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png_bytep data = (png_bytep)malloc( bytesPerFrame * apng->nFrames);//为每一帧分配内存
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png_bytep curFrame = (png_bytep)malloc(bytesPerFrame);
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memset(curFrame,0,bytesPerFrame);
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apng->nLoops = png_get_num_plays(png_ptr_read, info_ptr_read);
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apng->pDelay = (unsigned short*)malloc(sizeof(unsigned short)*apng->nFrames);
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for(int iFrame = 0;iFrame<apng->nFrames;iFrame++)
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{
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//读帧信息头
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png_read_frame_head(png_ptr_read, info_ptr_read);
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//计算出帧延时信息
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if (png_get_valid(png_ptr_read, info_ptr_read, PNG_INFO_fcTL))
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{
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png_uint_16 delay_num = info_ptr_read->next_frame_delay_num,
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delay_den = info_ptr_read->next_frame_delay_den;
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if (delay_den==0 || delay_den==100)
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apng->pDelay[iFrame] = delay_num;
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else
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if (delay_den==10)
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apng->pDelay[iFrame] = delay_num*10;
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else
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if (delay_den==1000)
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apng->pDelay[iFrame] = delay_num/10;
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else
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apng->pDelay[iFrame] = delay_num*100/delay_den;
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}else
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{
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apng->pDelay[iFrame] = 0;
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}
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//读取PNG帧到dataFrame中，不含偏移数据
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png_read_image(png_ptr_read, rowPointers);
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{//将当前帧数据绘制到当前显示帧中:1)获得绘制的背景；2)计算出绘制位置; 3)使用指定的绘制方式与背景混合
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//1)计算出绘制位置
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png_bytep lineDst=curFrame+info_ptr_read->next_frame_y_offset*bytesPerRow + 4 * info_ptr_read->next_frame_x_offset;
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png_bytep lineSour=dataFrame;
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//2)使用指定的绘制方式与背景混合
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switch(info_ptr_read->next_frame_blend_op)
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{
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case PNG_BLEND_OP_OVER:
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{
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for(unsigned int y=0;y<info_ptr_read->next_frame_height;y++)
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{
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png_bytep lineDst1=lineDst;
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png_bytep lineSour1=lineSour;
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for(unsigned int x=0;x<info_ptr_read->next_frame_width;x++)
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{
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png_byte alpha = lineSour1[3];
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*lineDst1++ = ((*lineDst1)*(255-alpha)+(*lineSour1++)*alpha)>>8;
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*lineDst1++ = ((*lineDst1)*(255-alpha)+(*lineSour1++)*alpha)>>8;
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*lineDst1++ = ((*lineDst1)*(255-alpha)+(*lineSour1++)*alpha)>>8;
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*lineDst1++ = ((*lineDst1)*(255-alpha)+(*lineSour1++)*alpha)>>8;
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}
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lineDst += bytesPerRow;
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lineSour+= bytesPerRow;
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}
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}
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break;
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case PNG_BLEND_OP_SOURCE:
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{
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for(unsigned int y=0;y<info_ptr_read->next_frame_height;y++)
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{
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memcpy(lineDst,lineSour,info_ptr_read->next_frame_width*4);
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lineDst += bytesPerRow;
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lineSour+= bytesPerRow;
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}
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}
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break;
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default:
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SASSERT(FALSE);
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break;
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}
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png_bytep targetFrame = data + bytesPerFrame * iFrame;
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memcpy(targetFrame,curFrame,bytesPerFrame);
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lineDst=curFrame+info_ptr_read->next_frame_y_offset*bytesPerRow + 4 * info_ptr_read->next_frame_x_offset;
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//3)处理当前帧绘制区域
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switch(info_ptr_read->next_frame_dispose_op)
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{
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case PNG_DISPOSE_OP_BACKGROUND://clear background
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{
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for(unsigned int y=0;y<info_ptr_read->next_frame_height;y++)
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{
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memset(lineDst,0,info_ptr_read->next_frame_width*4);
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lineDst += bytesPerRow;
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}
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}
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break;
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case PNG_DISPOSE_OP_PREVIOUS://copy previous frame
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if(iFrame>0)
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{
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memcpy(curFrame,targetFrame-bytesPerFrame,bytesPerFrame);
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}
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break;
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case PNG_DISPOSE_OP_NONE://using current frame, doing nothing
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break;
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default:
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SASSERT(0);
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break;
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}
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}
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}
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free(curFrame);
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free(dataFrame);
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apng->pdata =data;
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}
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free(rowPointers);
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png_read_end(png_ptr_read,info_ptr_read);
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png_destroy_read_struct(&png_ptr_read, &info_ptr_read, NULL);
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return apng;
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}
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APNGDATA * LoadAPNG_from_file( const wchar_t * pszFileName )
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{
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FILE *f = _wfopen(pszFileName,L"rb");
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if(!f) return NULL;
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IPngReader_File file(f);
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APNGDATA *pRet = loadPng(&file);
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fclose(f);
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return pRet;
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}
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APNGDATA * LoadAPNG_from_memory(const char * pBuf, size_t nLen )
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{
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IPngReader_Mem mem(pBuf,nLen);
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return loadPng(&mem);
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}
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void APNG_Destroy( APNGDATA *apng )
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{
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if(apng)
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{
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if(apng->pdata) free(apng->pdata);
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if(apng->pDelay) free(apng->pDelay);
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free(apng);
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}
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} |