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我需要一种简单的方法将包含RGB数据的缓冲区转换为jpeg。我已经尝试过使用libjpeg,但我根本无法让它正常工作。例如,在保存缓冲区作为位图产生这样的:RGB缓冲区到JPEG缓冲区,这里有什么问题?
使用的libjpeg编码在存储器中的相同图像产生这样的:
并直接保存图像到文件只是中止没有发出警告,错误或任何事情。
我当然需要一些可行的东西!
这是我在做什么
void OnKeyPress(unsigned char key, int x, int y) {
if (key != static_cast<unsigned char>('p'))
return;
int width = g_current_width;
int height = g_current_height;
boost::scoped_array<boost::uint8_t> buffer(new boost::uint8_t[3 * width * height]);
glReadBuffer(GL_FRONT);
glReadPixels(0, 0, width, height, GL_RGB, GL_UNSIGNED_BYTE,
reinterpret_cast<GLvoid *>(buffer.get()));
glReadBuffer(GL_BACK);
FlipImage(buffer.get(), width, height);
// Generate a BMP files for testing purposes
SaveRGB("screenshot.bmp", buffer.get(), width, height);
jpeg_compress_struct cinfo;
jpeg_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr);
jerr.trace_level = 10;
jpeg_create_compress(&cinfo);
boost::uint8_t *jpeg_buffer_raw = NULL;
unsigned long outbuffer_size = 0;
jpeg_mem_dest(&cinfo, &jpeg_buffer_raw, &outbuffer_size);
cinfo.image_width = width;
cinfo.image_height = height;
cinfo.input_components = 3;
cinfo.in_color_space = JCS_RGB;
jpeg_set_defaults(&cinfo);
jpeg_set_quality(&cinfo, 100, true);
jpeg_start_compress(&cinfo, true);
int row_stride = width * 3;
JSAMPROW row_pointer[1];
int counter = 0;
std::cout << boost::format("height: %d\n") % height;
boost::uint8_t *r_buffer = buffer.get();
while (cinfo.next_scanline < cinfo.image_height) {
row_pointer[0] = &r_buffer[cinfo.next_scanline * row_stride];
jpeg_write_scanlines(&cinfo, row_pointer, 1);
std::cout << boost::format("current line: %d\n") % (counter++);
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
std::ofstream jpegfile("screenshot.jpg");
jpegfile.write(reinterpret_cast<const char*>(jpeg_buffer_raw), outbuffer_size);
jpegfile.flush();
// calling free(jpeg_buffer_raw); or delete[] jpeg_buffer_raw; generates an error
}
怎么样你叫libjpeg?向我们展示代码。 – Thomas
SO是一个问答网站。你的问题是什么? –
SO伙计们,我用我使用的代码更新了这个问题。 – Sambatyon