加载png图片并转换为DIB HBITMAP

static void pngReaderCallback(png_structp png_ptr, png_bytep data, png_size_t length) { ImageSource* isource = (ImageSource*)png_get_io_ptr(png_ptr); if(isource->offset + length <= isource->size) { memcpy(data, (unsigned char *)isource->data + isource->offset, length); isource->offset += length; } else { png_error(png_ptr,"pngReaderCallback failed"); } } static HBITMAP LoadPNGFromMemory(void * lpData, UINT size, HDC hdc, BYTE **m_ppBits, int &width, int &height) { HBITMAP hBitBmp=NULL; if (lpData==NULL || size==0) return NULL; png_structp png_ptr; png_infop info_ptr; /* initialize stuff */ png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL); if (!png_ptr) return NULL; info_ptr = png_create_info_struct(png_ptr); if (!info_ptr) return NULL; if (setjmp(png_jmpbuf(png_ptr))) { png_destroy_read_struct(&png_ptr, &info_ptr, 0); return false; } ImageSource imgsource; imgsource.data = lpData; imgsource.size = size; imgsource.offset = 0; png_set_read_fn(png_ptr, &imgsource, pngReaderCallback); png_read_info(png_ptr, info_ptr); unsigned long x,y,i; BYTE r,g,b,a; png_bytep * row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * info_ptr->height); if (row_pointers) { for (y=0; yheight; y++) row_pointers[y] = (png_byte*) malloc(info_ptr->rowbytes); png_read_image(png_ptr, row_pointers); BITMAPINFOHEADER m_bmpHeader; memset(&m_bmpHeader,NULL,sizeof(m_bmpHeader)); m_bmpHeader.biSize = sizeof(m_bmpHeader); m_bmpHeader.biBitCount = 32;; m_bmpHeader.biCompression = BI_RGB; m_bmpHeader.biWidth = info_ptr->width; m_bmpHeader.biHeight = info_ptr->height; m_bmpHeader.biPlanes = 1; BYTE *pBits; hBitBmp = CreateDIBSection(hdc, (BITMAPINFO *)&m_bmpHeader, DIB_RGB_COLORS, (void **)&pBits, NULL, 0); if (hBitBmp && (pBits)) { width=info_ptr->width; height=info_ptr->height; for (y=0; yheight; y++) { memcpy(pBits+(info_ptr->height-y-1)*info_ptr->rowbytes, row_pointers[y], info_ptr->rowbytes); } *m_ppBits=pBits; for (y=0; yheight; y++) { for (x=0; xwidth; x++) { i=(info_ptr->height-1-y)*info_ptr->width*4+x*4; r=pBits[i+0]; g=pBits[i+1]; b=pBits[i+2]; a=pBits[i+3]; // RGBA -> BGRA and to AlphaBend() Colors pBits[i+0]=BYTE(b * a / 255); pBits[i+1]=BYTE(g * a / 255); pBits[i+2]=BYTE(r * a / 255); } } } for (y=0; yheight; y++) { free(row_pointers[y]); } free(row_pointers); } // free memory png_destroy_read_struct(&png_ptr, &info_ptr, 0); return hBitBmp; }