native.cpp

#include "native.hpp"
#define NOMINMAX
#include <windows.h>
#include <vector>
#include <cstring>
#include <algorithm>
#include <SFML/System/String.hpp>

sf::Image takeDesktopScreenshot()
{
    const int w = GetSystemMetrics(SM_CXSCREEN);
    const int h = GetSystemMetrics(SM_CYSCREEN);

    HWND dwin = GetDesktopWindow();
    HDC ddc = GetDC(dwin);
    HDC dc2 = CreateCompatibleDC(ddc);
    HBITMAP bitmap = CreateCompatibleBitmap(ddc, w, h);
    SelectObject(dc2, bitmap);
    BitBlt(dc2, 0, 0, w, h, ddc, 0, 0, SRCCOPY | CAPTUREBLT);

    BITMAPINFO bitmapinfo;
    std::memset(&bitmapinfo, 0x0, sizeof(BITMAPINFO));
    bitmapinfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
    bitmapinfo.bmiHeader.biWidth = w;
    bitmapinfo.bmiHeader.biHeight = -h;
    bitmapinfo.bmiHeader.biPlanes = 1;
    bitmapinfo.bmiHeader.biBitCount = 32;
    bitmapinfo.bmiHeader.biCompression = BI_RGB;

    std::vector<sf::Uint8> buff(w * h * 4);
    std::memset(buff.data(), 0xff, buff.size());
    GetDIBits(dc2, bitmap, 0, h, buff.data(), &bitmapinfo, DIB_RGB_COLORS);
    for(int i = 0; i < buff.size() / 4; ++i)
        std::swap(buff[i * 4 + 0], buff[i * 4 + 2]);

    DeleteObject(bitmap);
    DeleteDC(dc2);
    ReleaseDC(dwin, ddc);

    sf::Image ret;
    ret.create(w, h, buff.data());
    return ret;
}

void setDesktopWallpaper(const char * filename)
{
    const auto need = GetCurrentDirectoryW(0, NULL) - 1;
    std::vector<WCHAR> buff(need + 100);
    GetCurrentDirectoryW(buff.size(), buff.data());
    sf::String cwd = sf::String::fromUtf16(buff.data(), buff.data() + need);
    cwd += '\\';
    cwd += filename;
    SystemParametersInfoW(SPI_SETDESKWALLPAPER, 0u, (void*)cwd.toWideString().c_str(), 0u);
}