LibQREncode 二维码转BMP
LibQREncode qrcode to BMP
我正在使用库创建二维码 qrencode.h
这个创作工作很好，但如何将 qrcode 输出到 C++ 中的 BMP 文件？
此时此刻我有这段代码：
const char* szSourceSring = QRCODE_TEXT;
unsigned int unWidth, x, y, l, n, unWidthAdjusted, unDataBytes;
unsigned char* pRGBData, *pSourceData, *pDestData;
QRcode* pQRC;
FILE* f;
if (pQRC = QRcode_encodeString(szSourceSring, 4, QR_ECLEVEL_H, QR_MODE_8, 1))
{
unWidth = pQRC->width;
unWidthAdjusted = unWidth * OUT_FILE_PIXEL_PRESCALER * 3;
if (unWidthAdjusted % 4)
unWidthAdjusted = (unWidthAdjusted / 4 + 1) * 4;
unDataBytes = unWidthAdjusted * unWidth * OUT_FILE_PIXEL_PRESCALER;
// Allocate pixels buffer
if (!(pRGBData = (unsigned char*)malloc(unDataBytes)))
{
printf("Out of memory");
}
// Preset to white
memset(pRGBData, 0xff, unDataBytes);
// Prepare bmp headers
BITMAPFILEHEADER kFileHeader;
kFileHeader.bfType = 0x4D42; // "BM"
kFileHeader.bfSize = sizeof(BITMAPFILEHEADER) +
sizeof(BITMAPINFOHEADER) +
unDataBytes;
kFileHeader.bfReserved1 = 0;
kFileHeader.bfReserved2 = 0;
kFileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) +
sizeof(BITMAPINFOHEADER);
BITMAPINFOHEADER kInfoHeader;
kInfoHeader.biSize = sizeof(BITMAPINFOHEADER);
kInfoHeader.biWidth = unWidth * OUT_FILE_PIXEL_PRESCALER;
kInfoHeader.biHeight = -((int)unWidth * OUT_FILE_PIXEL_PRESCALER);
kInfoHeader.biPlanes = 1;
kInfoHeader.biBitCount = 24;
kInfoHeader.biCompression = BI_RGB;
kInfoHeader.biSizeImage = 0;
kInfoHeader.biXPelsPerMeter = 0;
kInfoHeader.biYPelsPerMeter = 0;
kInfoHeader.biClrUsed = 0;
kInfoHeader.biClrImportant = 0;
// Convert QrCode bits to bmp pixels
pSourceData = pQRC->data;
for(y = 0; y < unWidth; y++)
{
pDestData = pRGBData + unWidthAdjusted * y * OUT_FILE_PIXEL_PRESCALER;
for(x = 0; x < unWidth; x++)
{
if (*pSourceData & 1)
{
for(l = 0; l < OUT_FILE_PIXEL_PRESCALER; l++)
{
for(n = 0; n < OUT_FILE_PIXEL_PRESCALER; n++)
{
*(pDestData + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_B;
*(pDestData + 1 + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_G;
*(pDestData + 2 + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_R;
}
}
}
pDestData += 3 * OUT_FILE_PIXEL_PRESCALER;
pSourceData++;
}
}
// Output the bmp file
/*if (((f = fopen(OUT_FILE, "r")) != NULL))
{*/
f = fopen(OUT_FILE, "wb");
fwrite(&kFileHeader, sizeof(BITMAPFILEHEADER), 14, f);
fwrite(&kInfoHeader, sizeof(BITMAPINFOHEADER), 40, f);
fwrite(pRGBData, sizeof(unsigned char), unDataBytes, f);
fclose(f);
/* }
else
{
printf("Unable to open file");
}
*/
// Free data
free(pRGBData);
QRcode_free(pQRC);
}
else
{
printf("NULL returned");
}
但不知何故，这会创建一个带有损坏 headers 的 BMP。每当我打开 bmp 文件时，它都会显示：
"BMP Image has unsupported header size"
我做错了什么？
是否可以保存为 png 而不是 BMP？
我可以访问 libPNG 图书馆
这里是一个代码示例，它转储了一个从二维码创建的 24 bpp bmp 文件。您看到的错误可能不是由 QR-Code 库引起的，而是由 bmp 文件代码引起的。
此示例创建的 bmp 文件与我的 Windows 8.1 打包的图像查看器一起工作正常。如果您也没有看到错误，则可以检查每个二进制输出中的差异以查明问题所在。如果你愿意。
这个问题被标记为"C++"和"C++11"，所以这个例子使用C++ std库进行文件输出，没有使用malloc。 （但几乎同样糟糕——我在某些容器代码中使用 new 和 delete，其中首选 std::vector 成员……不要告诉任何人）。此外，此示例将每条数据直接写入文件，而不是使用文件大小的中间缓冲区，如 pDestData.
#include <iostream>
#include <fstream>
// A fake (or "somewhat limited") QR Code data container
struct Qrc {
int dimsize; // the width and height
unsigned char* data; // buffer which contains the elements
Qrc() {
static const unsigned int bin[] = { // encodes an important secret message
0xfc8b7d7f,0xa801a83,0xd6e54d76,0xaa9eb2ed,0x43ed05db,0xb8786837,0x55555fe0,
0x5a4c807f,0xcf315c00,0x6e8019ce,0xc7819e0d,0xd4857ba8,0x4ac5e347,0xf6f349ba,
0xd433ccdd,0x2998361e,0x4453fab3,0x526d9085,0x81f38924,0xb4da0811,0x84b3131a,
0x9639915e,0x3b74a4ff,0x42aa0c11,0x4127be16,0x1f4350,0xff620296,0xad54de1,
0xd38c2272,0xa3f76155,0x5366a7ab,0x9bdd2257,0x300d5520,0x85842e7f,0 };
dimsize = 33;
data = new unsigned char[dimsize * dimsize];
auto p = data;
auto endp = p + dimsize * dimsize;
for(unsigned int b : bin) {
for(int i=0; i<32; ++i) {
if(p == endp) break;
*(p++) = b & (1 << i) ? 255 : 0;
} } }
Qrc(const Qrc&) = delete;
Qrc& operator = (const Qrc&) = delete;
~Qrc() { delete [] data; }
};
struct BIH { // a private definition of BITMAPINFOHEADER
unsigned int sz;
int width, height;
unsigned short planes;
short bits;
unsigned int compress, szimage;
int xppm, yppm;
unsigned int clrused, clrimp;
};
void SaveBmp(const char* filename, const Qrc& qrc) {
// Asker's Qrc struct delivered as a pointer, from a C API, but this example doesn't mimic that.
std::ofstream ofs(filename, std::ios_base::out | std::ios_base::binary);
if(!ofs) {
std::cout << "Writing " << filename << " failed\n";
return;
}
const int side_len = qrc.dimsize; // width and height of the (square) QR Code
const int pixel_side_len = 4; // QRC element's size in the bmp image (in pixels)
const int bmp_line_bytes = side_len * pixel_side_len * 3;
const int bmp_line_pad_bytes = (4 - bmp_line_bytes % 4) % 4; // bmp line data padding size
const int bmp_data_size = side_len * (bmp_line_bytes + bmp_line_pad_bytes);
BIH bih = { sizeof(bih) };
bih.width = side_len * pixel_side_len; // element count * element size
bih.height = -side_len * pixel_side_len; // negative height => data begins at top of image
bih.planes = 1;
bih.bits = 24;
const int header_size = sizeof(bih) + 14; // size of the bmp file header
const int filesize = header_size + bmp_data_size; // size of the whole file
ofs.write("BM", 2);
ofs.write(reinterpret_cast<const char*>(&filesize), 4);
ofs.write("[=10=][=10=][=10=][=10=]", 4); // 2x 16-bit reserved fields
ofs.write(reinterpret_cast<const char*>(&header_size), 4);
ofs.write(reinterpret_cast<const char*>(&bih), sizeof(bih));
// pixel colors, as Blue, Green, Red char-valued triples
// the terminating null also makes these usable as 32bpp BGRA values, with Alpha always 0.
static const char fg_color[] = "[=10=][=10=][=10=]";
static const char bg_color[] = "\xff\xff\xff";
auto pd = qrc.data;
// send pixel data directly to the bmp file
// QRC elements are expanded into squares
// whose sides are "pixel_side_len" in length.
for(int y=0; y<side_len; ++y) {
for(int j=0; j<pixel_side_len; ++j) {
auto pdj = pd;
for(int x=0; x<side_len; ++x) {
for(int i=0; i<pixel_side_len; ++i) {
// *pdj will be 0 or 255 (from "fake" Qrc)
// Using "*pdj & 1" here, just to match asker's code
// without knowing why this was done.
ofs.write(*pdj & 1 ? fg_color : bg_color, 3);
}
++pdj;
}
if(bmp_line_pad_bytes) {
ofs.write("[=10=][=10=][=10=]", bmp_line_pad_bytes);
}
}
pd += side_len;
}
}
int main() {
SaveBmp("MyQrCode.bmp", Qrc());
}
我正在使用库创建二维码 qrencode.h 这个创作工作很好，但如何将 qrcode 输出到 C++ 中的 BMP 文件？ 此时此刻我有这段代码：
const char* szSourceSring = QRCODE_TEXT;
unsigned int unWidth, x, y, l, n, unWidthAdjusted, unDataBytes;
unsigned char* pRGBData, *pSourceData, *pDestData;
QRcode* pQRC;
FILE* f;
if (pQRC = QRcode_encodeString(szSourceSring, 4, QR_ECLEVEL_H, QR_MODE_8, 1))
{
unWidth = pQRC->width;
unWidthAdjusted = unWidth * OUT_FILE_PIXEL_PRESCALER * 3;
if (unWidthAdjusted % 4)
unWidthAdjusted = (unWidthAdjusted / 4 + 1) * 4;
unDataBytes = unWidthAdjusted * unWidth * OUT_FILE_PIXEL_PRESCALER;
// Allocate pixels buffer
if (!(pRGBData = (unsigned char*)malloc(unDataBytes)))
{
printf("Out of memory");
}
// Preset to white
memset(pRGBData, 0xff, unDataBytes);
// Prepare bmp headers
BITMAPFILEHEADER kFileHeader;
kFileHeader.bfType = 0x4D42; // "BM"
kFileHeader.bfSize = sizeof(BITMAPFILEHEADER) +
sizeof(BITMAPINFOHEADER) +
unDataBytes;
kFileHeader.bfReserved1 = 0;
kFileHeader.bfReserved2 = 0;
kFileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) +
sizeof(BITMAPINFOHEADER);
BITMAPINFOHEADER kInfoHeader;
kInfoHeader.biSize = sizeof(BITMAPINFOHEADER);
kInfoHeader.biWidth = unWidth * OUT_FILE_PIXEL_PRESCALER;
kInfoHeader.biHeight = -((int)unWidth * OUT_FILE_PIXEL_PRESCALER);
kInfoHeader.biPlanes = 1;
kInfoHeader.biBitCount = 24;
kInfoHeader.biCompression = BI_RGB;
kInfoHeader.biSizeImage = 0;
kInfoHeader.biXPelsPerMeter = 0;
kInfoHeader.biYPelsPerMeter = 0;
kInfoHeader.biClrUsed = 0;
kInfoHeader.biClrImportant = 0;
// Convert QrCode bits to bmp pixels
pSourceData = pQRC->data;
for(y = 0; y < unWidth; y++)
{
pDestData = pRGBData + unWidthAdjusted * y * OUT_FILE_PIXEL_PRESCALER;
for(x = 0; x < unWidth; x++)
{
if (*pSourceData & 1)
{
for(l = 0; l < OUT_FILE_PIXEL_PRESCALER; l++)
{
for(n = 0; n < OUT_FILE_PIXEL_PRESCALER; n++)
{
*(pDestData + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_B;
*(pDestData + 1 + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_G;
*(pDestData + 2 + n * 3 + unWidthAdjusted * l) = PIXEL_COLOR_R;
}
}
}
pDestData += 3 * OUT_FILE_PIXEL_PRESCALER;
pSourceData++;
}
}
// Output the bmp file
/*if (((f = fopen(OUT_FILE, "r")) != NULL))
{*/
f = fopen(OUT_FILE, "wb");
fwrite(&kFileHeader, sizeof(BITMAPFILEHEADER), 14, f);
fwrite(&kInfoHeader, sizeof(BITMAPINFOHEADER), 40, f);
fwrite(pRGBData, sizeof(unsigned char), unDataBytes, f);
fclose(f);
/* }
else
{
printf("Unable to open file");
}
*/
// Free data
free(pRGBData);
QRcode_free(pQRC);
}
else
{
printf("NULL returned");
}
但不知何故，这会创建一个带有损坏 headers 的 BMP。每当我打开 bmp 文件时，它都会显示：
"BMP Image has unsupported header size"
我做错了什么？
是否可以保存为 png 而不是 BMP？
我可以访问 libPNG 图书馆
这里是一个代码示例，它转储了一个从二维码创建的 24 bpp bmp 文件。您看到的错误可能不是由 QR-Code 库引起的，而是由 bmp 文件代码引起的。
此示例创建的 bmp 文件与我的 Windows 8.1 打包的图像查看器一起工作正常。如果您也没有看到错误，则可以检查每个二进制输出中的差异以查明问题所在。如果你愿意。
这个问题被标记为"C++"和"C++11"，所以这个例子使用C++ std库进行文件输出，没有使用malloc。 （但几乎同样糟糕——我在某些容器代码中使用 new 和 delete，其中首选 std::vector 成员……不要告诉任何人）。此外，此示例将每条数据直接写入文件，而不是使用文件大小的中间缓冲区，如 pDestData.
#include <iostream>
#include <fstream>
// A fake (or "somewhat limited") QR Code data container
struct Qrc {
int dimsize; // the width and height
unsigned char* data; // buffer which contains the elements
Qrc() {
static const unsigned int bin[] = { // encodes an important secret message
0xfc8b7d7f,0xa801a83,0xd6e54d76,0xaa9eb2ed,0x43ed05db,0xb8786837,0x55555fe0,
0x5a4c807f,0xcf315c00,0x6e8019ce,0xc7819e0d,0xd4857ba8,0x4ac5e347,0xf6f349ba,
0xd433ccdd,0x2998361e,0x4453fab3,0x526d9085,0x81f38924,0xb4da0811,0x84b3131a,
0x9639915e,0x3b74a4ff,0x42aa0c11,0x4127be16,0x1f4350,0xff620296,0xad54de1,
0xd38c2272,0xa3f76155,0x5366a7ab,0x9bdd2257,0x300d5520,0x85842e7f,0 };
dimsize = 33;
data = new unsigned char[dimsize * dimsize];
auto p = data;
auto endp = p + dimsize * dimsize;
for(unsigned int b : bin) {
for(int i=0; i<32; ++i) {
if(p == endp) break;
*(p++) = b & (1 << i) ? 255 : 0;
} } }
Qrc(const Qrc&) = delete;
Qrc& operator = (const Qrc&) = delete;
~Qrc() { delete [] data; }
};
struct BIH { // a private definition of BITMAPINFOHEADER
unsigned int sz;
int width, height;
unsigned short planes;
short bits;
unsigned int compress, szimage;
int xppm, yppm;
unsigned int clrused, clrimp;
};
void SaveBmp(const char* filename, const Qrc& qrc) {
// Asker's Qrc struct delivered as a pointer, from a C API, but this example doesn't mimic that.
std::ofstream ofs(filename, std::ios_base::out | std::ios_base::binary);
if(!ofs) {
std::cout << "Writing " << filename << " failed\n";
return;
}
const int side_len = qrc.dimsize; // width and height of the (square) QR Code
const int pixel_side_len = 4; // QRC element's size in the bmp image (in pixels)
const int bmp_line_bytes = side_len * pixel_side_len * 3;
const int bmp_line_pad_bytes = (4 - bmp_line_bytes % 4) % 4; // bmp line data padding size
const int bmp_data_size = side_len * (bmp_line_bytes + bmp_line_pad_bytes);
BIH bih = { sizeof(bih) };
bih.width = side_len * pixel_side_len; // element count * element size
bih.height = -side_len * pixel_side_len; // negative height => data begins at top of image
bih.planes = 1;
bih.bits = 24;
const int header_size = sizeof(bih) + 14; // size of the bmp file header
const int filesize = header_size + bmp_data_size; // size of the whole file
ofs.write("BM", 2);
ofs.write(reinterpret_cast<const char*>(&filesize), 4);
ofs.write("[=10=][=10=][=10=][=10=]", 4); // 2x 16-bit reserved fields
ofs.write(reinterpret_cast<const char*>(&header_size), 4);
ofs.write(reinterpret_cast<const char*>(&bih), sizeof(bih));
// pixel colors, as Blue, Green, Red char-valued triples
// the terminating null also makes these usable as 32bpp BGRA values, with Alpha always 0.
static const char fg_color[] = "[=10=][=10=][=10=]";
static const char bg_color[] = "\xff\xff\xff";
auto pd = qrc.data;
// send pixel data directly to the bmp file
// QRC elements are expanded into squares
// whose sides are "pixel_side_len" in length.
for(int y=0; y<side_len; ++y) {
for(int j=0; j<pixel_side_len; ++j) {
auto pdj = pd;
for(int x=0; x<side_len; ++x) {
for(int i=0; i<pixel_side_len; ++i) {
// *pdj will be 0 or 255 (from "fake" Qrc)
// Using "*pdj & 1" here, just to match asker's code
// without knowing why this was done.
ofs.write(*pdj & 1 ? fg_color : bg_color, 3);
}
++pdj;
}
if(bmp_line_pad_bytes) {
ofs.write("[=10=][=10=][=10=]", bmp_line_pad_bytes);
}
}
pd += side_len;
}
}
int main() {
SaveBmp("MyQrCode.bmp", Qrc());
}