- src
   |
   |- main.rs (your code goes here)
   |- xlsgen.rs (xlsgen interface layer (available from the xlsgen install package))
- Cargo.toml (known dependency declaration (winapi))

cd \tmp\rust\simple
cargo build

cd \tmp\rust\simple
cargo run

  let _hr = unsafe { 
               (*p_worksheet).put_float(4, 2, 4.5);
            };	

use winapi::{Class, Interface};

macro_rules! new_pointer {
     ($param:ident, $type:ty) => {let mut $param: *mut $type = unsafe { std::mem::zeroed() };}
}

new_pointer!(p_engine, xlsgen::IXlsEngine);

use winapi::um::winnt::{LPWSTR};
use winapi::{Class, Interface};
use std::ffi::{OsStr, OsString};
use std::os::windows::ffi::OsStrExt;
use std::os::windows::ffi::OsStringExt;
use std::slice;

pub mod xlsgen;


// *** MACROS begin here ***

macro_rules! retVal {
    ($param:ident) => {&mut $param as *mut _ as *mut _}
}

macro_rules! new_pointer {
    ($param:ident, $type:ty) => {let mut $param: *mut $type = unsafe { std::mem::zeroed() };}
}

macro_rules! release_pointer {
    ($param:ident) => { unsafe { (&mut * $param).Release() }; }
}

macro_rules! release_bstr_string {
    ($param:ident) => { unsafe { winapi::um::oleauto::SysFreeString( $param as LPWSTR ) }; }
}


// *** MACROS end here ***

// unicode strings (Rust stores strings using UTF8 encoding, not UTF16) so we have to convert back and forth

fn to_wstring(string: &str) -> Vec<u16> {
    let mut v: Vec<u16> = OsStr::new(string).encode_wide().collect();
    v.push(0); // EOL
    v
}

fn from_wstring(string: LPWSTR) -> String {
    let string_slice = unsafe {
        let len = winapi::um::oleauto::SysStringLen(string);
        slice::from_raw_parts(string, len as usize)
    };

    OsString::from_wide(string_slice).into_string().unwrap()
}


fn main() {

    println!("step1");

    let _hr = unsafe { winapi::um::objbase::CoInitialize(std::ptr::null_mut()) };

    println!("step2");

    new_pointer!(p_engine, xlsgen::IXlsEngine);

    let _hr = unsafe { winapi::um::combaseapi::CoCreateInstance(
			&xlsgen::XlsEngine::uuidof(), 
			std::ptr::null_mut(), 
			winapi::shared::wtypesbase::CLSCTX_INPROC_SERVER, 
			&xlsgen::IXlsEngine::uuidof(), 
			retVal!(p_engine))
	        };

    println!("step3 {}", _hr);

    new_pointer!(p_workbook, xlsgen::IXlsWorkbook);

    let _hr = unsafe { (*p_engine).new(to_wstring("d:\\tmp\\eer.xlsx").as_ptr(), retVal!(p_workbook)) };

    new_pointer!(p_worksheet1, xlsgen::IXlsWorksheet);

    let _hr = unsafe { (*p_workbook).addworksheet(to_wstring("sheet 1").as_ptr(), retVal!(p_worksheet1)) };	

    new_pointer!(p_worksheet2, xlsgen::IXlsWorksheet);

    let _hr = unsafe { (*p_workbook).addworksheet(to_wstring("sheet 2").as_ptr(), retVal!(p_worksheet2)) };	

    println!("step4");

    let mut i_wksht_count : i32 = 0;

    let _hr = unsafe { (*p_workbook).get_worksheetcount(&mut i_wksht_count) };

    println!("step4a {}, wkshtCount = {}", _hr, i_wksht_count);

    unsafe { (*p_workbook).put_factorizedstringsmode(true) };

    let mut b_factorized : bool = false;

    let _hr = unsafe { (*p_workbook).get_factorizedstringsmode(&mut b_factorized) };

    println!("step4ab {}, bFactorized = {}", _hr, b_factorized);

    // write some content
    for r in 1..10 {
       let _hr = unsafe { (*p_worksheet1).put_label(r, 2, to_wstring("hello world").as_ptr()) };	
     }

    // read some content

    println!("step4b");

    new_pointer!(cell_string, LPWSTR);

    println!("step4c");

    let _hr = unsafe { (*p_worksheet1).get_label(3, 2, retVal!(cell_string)) };	

    println!("step5");

    println!("cell value is : {}", from_wstring(cell_string as LPWSTR));

    println!("step6");

    new_pointer!(p_richlabel, xlsgen::IXlsRichLabel);

    println!("step6b");

    let _hr = unsafe { (*p_worksheet1).newrichlabel(retVal!(p_richlabel)) };	

    println!("step6c {}", _hr);

    let _hr = unsafe { (*p_richlabel).put_htmllabel(to_wstring("<span>hello <b>world</b></span>").as_ptr()) };	

    println!("step6d");

    let _hr = unsafe { (*p_worksheet1).put_richlabel(1, 4, p_richlabel) };	

    println!("step6e");

    let _hr = unsafe { (*p_workbook).close(); };

    println!("step7");

    release_bstr_string!(cell_string);
    release_pointer!(p_worksheet1);
    release_pointer!(p_worksheet2);
    release_pointer!(p_workbook);
    release_pointer!(p_engine);

    unsafe { winapi::um::combaseapi::CoUninitialize() };

    println!("step8");

}

(...)

RIDL!{#[uuid(0xD97500CF,0x37CC,0x48fd,0x87,0x72,0x0E,0xBC,0x8F,0x8A,0x93,0x76)]
interface IXlsEngine(IXlsEngineVtbl): IDispatch(IDispatchVtbl) {
    fn new(    // creates a new .xls/.xlsx file with the name (filename or filepath) passed in parameter.
        excelfilename : LPCWSTR,
        workbook : *mut *mut IXlsWorkbook,
    ) -> HRESULT,

(...)

RIDL!{#[uuid(0x12B7B224,0xC026,0x4eb6,0xBA,0x94,0xC4,0x9B,0x91,0x6F,0x77,0x40)]
interface IXlsWorkbook(IXlsWorkbookVtbl): IDispatch(IDispatchVtbl) {
    fn addworksheet(    // creates a new worksheet with the name passed in parameter. The following characters are forbidden : / \\ : * [ ], and the name must be less than 32 characters long.
        name : LPCWSTR,
        worksheet : *mut *mut IXlsWorksheet,
    ) -> HRESULT,

(...)

RIDL!{#[uuid(0xB150D9DA,0x1F10,0x4850,0x9A,0xBB,0x76,0xD9,0x95,0x47,0x96,0xEE)]
interface IXlsWorksheet(IXlsWorksheetVtbl): IDispatch(IDispatchVtbl) {
    fn put_label(    // puts a label in a cell.
        row : i32,
        col : i32,
        label : LPCWSTR,
    ) -> HRESULT,

worksheet->Cell[2][1]->HtmlDate = L"<div format=\"[h]:mm:ss\">30:00:00</div>";

• read existing pivot tables
• write pivot charts (introduced in libre office 5.4.1)
• read cell data validations
• read auto filter and custom filters
• improved writing of custom filters

• for reading and creating XLS files, memory consumption much lowered by defaulting to 4KB blocks instead of 64KB blocks
• for reading chart formatting details from any Excel file, memory leak removal

• Rendering of treemaps and sunbursts. (outputs : PNG, PDF, SVG)
• Avoid chart element overlap wherever possible, for instance make sure the legend never overlaps with the plot area
• Additional chart element formatting that were not supported in past xlsgen versions

xlsgen::IXlsChartPtr chartTreemap = worksheet->NewChart(xlsgen::charttype_treemap,
                                                     9, //row1
                                                     2, //col1
                                                     25, //row2
                                                     9 //col2
                                                     );

chartTreemap->MainTitle->Label = L"treemap";
xlsgen::IXlsChartDynamicDataSourceSeriesPtr s1 = chartTreemap->DynamicDataSource->AddSerie();
s1->SeriesValuesFormula = L"=Sheet1!$D$2:$D$6";
s1->DataLabelsFormula   = L"=Sheet1!$A$2:$C$6"; // Categories with 3 levels of depth

chartTreemap->ExtractAsPNG(L"treemap.png");

xlsgen::IXlsChartPtr chartSunburst = worksheet->NewChart(xlsgen::charttype_sunburst,
                                                     27, //row1
                                                     2, //col1
                                                     43, //row2
                                                     9 //col2
                                                     );

chartSunburst->MainTitle->Label = L"sunburst";
xlsgen::IXlsChartDynamicDataSourceSeriesPtr s2 = chartSunburst->DynamicDataSource->AddSerie();
s2->SeriesValuesFormula = L"=Sheet1!$D$2:$D$6";
s2->DataLabelsFormula   = L"=Sheet1!$B$2:$C$6";  // Categories with 2 levels of depth

chartSunburst->ExtractAsSVG(L"sunburst.svg");

xlsgen::IXlsTextBoxPtr textbox001s0 = wksht001->NewTextBox(4, 3, 9, 7, 38, 208, 128, 896);
xlsgen::IXlsRichLabelPtr richLabel001s000c0 = wksht001->NewRichLabel();
richLabel001s000c0->HtmlLabel = L"<font color=#000000 size=11 name=\"Calibri\"><b>This is </b></font><font color=#00B0F0 size=11 name=\"Calibri\"><b>blue </b></font>" \
L"<font color=#000000 size=11 name=\"Calibri\"><b>text</b></font>";
textbox001s0->RichLabel = richLabel001s000c0;

xlsgen::IXlsTextBoxPtr textbox001s0 = wksht001->NewTextBox(4, 3, 9, 7, 38, 208, 128, 896);

xlsgen::IXlsStylePtr styleDefault = wksht001->NewStyle();
styleDefault->Font->Bold = TRUE;
styleDefault->Apply();

xlsgen::IXlsStylePtr styleBlue = styleDefault->Duplicate();
styleBlue->Font->Color = 0x0000FF;
styleBlue->Apply();

xlsgen::IXlsRichLabelPtr richLabel001s000c0 = wksht001->NewRichLabel();
richLabel001s000c0->Label(L"This is ", styleDefault);
richLabel001s000c0->Label(L"blue ", styleBlue);
richLabel001s000c0->Label(L"text", styleDefault);

textbox001s0->RichLabel = richLabel001s000c0;

• Unicode fonts : prior to this, only ANSI characters in Excel files would be encoded correctly in PDF files. That would leave much of eastern languages unsupported. With Unicode fonts, PDF files use whatever character from whatever encoding.

• Font embedding : the embedding of the subset of fonts actually used in the Excel file ensures that PDF readers can accurately display characters for viewing and printing purposes. This is activated by default, meaning that such PDF files are bigger in size from those not embedding the fonts. For this reason, font embedding can be disabled by setting the boolean value to the corresponding export option :
  
  

  C/C++ code

  worksheet->Export->Options->FontEmbedding = FALSE;

• improved character spacing : even though PDF is character-based, fonts are not. Accurate spacing depends on actual glyph bounding boxes and this is taken care of to improve the reading of words in PDF files.

Single thread calculations (notice the 24% overall usage and the bottom right chart)

Mlutithread calculations (notice the 100% overall usage and all charts)

int nbCores = workbook->CalculationOptions->MultithreadCores;

And then, creating n worker threads for next calculations is just as simple :

workbook->CalculationOptions->MultithreadCores = n;

workbook->CalculateFormulas();