CaptureMode.screen now working on Windows 10

[apoleo88]

All the other CaptureMode works, but CaptureMode.screen doesn't.

The CapturedData? capturedData will return null, and if the path is specified no file is created.

No error is showing.

[Marco-Nagy]

i have the same issue and i need a solution

[sbamniya]

+1

[pravindodia]

+1

[danteCarvalho]

i have the same problem

[galaxy-s10]

I might be able to suggest a PR

[sbamniya]

This is an issue with the plugin, and while I was working on it, I created some custom script that worked for me. It captures the image in bmp format, and then in the dart code, I convert it to png file to the given path.

screenshot.cc

#include <windows.h>
#include <fstream>
#include <iostream>

extern "C" __declspec(dllexport) void CaptureScreenshot() {
    std::cout << "Starting screenshot capture..." << std::endl;

    int width = GetSystemMetrics(SM_CXSCREEN);
    int height = GetSystemMetrics(SM_CYSCREEN);
    std::cout << "Screen dimensions: " << width << "x" << height << std::endl;

    HDC hdcDesktop = GetDC(NULL); // Get desktop DC
    HDC hdcCompatible = CreateCompatibleDC(hdcDesktop);
    HBITMAP hBitmap = CreateCompatibleBitmap(hdcDesktop, width, height);

    SelectObject(hdcCompatible, hBitmap);

    if (!BitBlt(hdcCompatible, 0, 0, width, height, hdcDesktop, 0, 0, SRCCOPY)) {
        std::cerr << "Failed to perform BitBlt operation." << std::endl;
        DeleteDC(hdcCompatible);
        ReleaseDC(NULL, hdcDesktop);
        return;
    }

    // Prepare bitmap headers
    BITMAPFILEHEADER fileHeader;
    BITMAPINFOHEADER infoHeader;

    BITMAP bmp;
    GetObject(hBitmap, sizeof(BITMAP), &bmp);

    int rowSize = ((bmp.bmWidth * 24 + 31) / 32) * 4; // Rows must be padded to 4 bytes
    int imageSize = rowSize * bmp.bmHeight;

    fileHeader.bfType = 0x4D42; // 'BM' for Bitmap
    fileHeader.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + imageSize;
    fileHeader.bfReserved1 = 0;
    fileHeader.bfReserved2 = 0;
    fileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

    infoHeader.biSize = sizeof(BITMAPINFOHEADER);
    infoHeader.biWidth = bmp.bmWidth;
    infoHeader.biHeight = -bmp.bmHeight; // Negative for top-down DIB
    infoHeader.biPlanes = 1;
    infoHeader.biBitCount = 24; // Assuming 24-bit color depth
    infoHeader.biCompression = BI_RGB;
    infoHeader.biSizeImage = imageSize;
    infoHeader.biXPelsPerMeter = 0;
    infoHeader.biYPelsPerMeter = 0;
    infoHeader.biClrUsed = 0;
    infoHeader.biClrImportant = 0;

    // Create file and write headers and pixel data
    std::ofstream outFile("screenshot.bmp", std::ios::binary);
    if (!outFile) {
        std::cerr << "Failed to create file." << std::endl;
        DeleteDC(hdcCompatible);
        DeleteObject(hBitmap);
        ReleaseDC(NULL, hdcDesktop);
        return;
    }

    // Write BMP headers
    outFile.write(reinterpret_cast<char*>(&fileHeader), sizeof(fileHeader));
    outFile.write(reinterpret_cast<char*>(&infoHeader), sizeof(infoHeader));

    // Write pixel data
    BYTE* buffer = new BYTE[imageSize];
    GetDIBits(hdcCompatible, hBitmap, 0, bmp.bmHeight, buffer, reinterpret_cast<BITMAPINFO*>(&infoHeader), DIB_RGB_COLORS);
    outFile.write(reinterpret_cast<char*>(buffer), imageSize);

    // Cleanup
    delete[] buffer;
    outFile.close();

    DeleteDC(hdcCompatible);
    DeleteObject(hBitmap);
    ReleaseDC(NULL, hdcDesktop);

    std::cout << "Screenshot captured and saved as 'screenshot.bmp'." << std::endl;
}

screen_capture_service.dart

import 'dart:ffi';
import 'dart:io';
import 'dart:typed_data';
import 'package:image/image.dart' as img;

class ScreenCaptureService {
  Future<void> captureScreenshot(String path) async {
    try {
      print('capture screenshot: native.dll');
      final DynamicLibrary nativeLib = DynamicLibrary.open('native.dll');
      final captureScreenshot =
          nativeLib.lookupFunction<Void Function(), void Function()>(
        'CaptureScreenshot',
      );
      print('capturing');
      captureScreenshot();
      await _convertBmpToPng('screenshot.bmp', path);
      print('Screenshot captured successfully');
    } catch (e) {
      print("Failed to capture screenshot: $e");
    }
  }

  Future<void> _convertBmpToPng(String bmpPath, String pngPath) async {
    // Read the BMP file
    final File bmpFile = File(bmpPath);
    final Uint8List bmpBytes = await bmpFile.readAsBytes();
    img.Image? image = img.decodeImage(bmpBytes);

    if (image != null) {
      // Convert to PNG
      List<int> pngBytes = img.encodePng(image);

      // Save the PNG to a specific file location
      final File pngFile = File(pngPath);
      await pngFile.writeAsBytes(pngBytes);
      print('Screenshot converted to PNG and saved successfully');
    } else {
      print('Failed to decode BMP image');
    }
  }
}

native.dll is compiled version of screenshot.cc.

capture.dart

if (Platform.isWindows) {
  final ScreenCaptureService _screenCaptureService = ScreenCaptureService();
  await _screenCaptureService.captureScreenshot("$path/$key.png");
  print('saved file to $path/$key.png');
} else {
  await ScreenCapturer.instance.capture(
      mode: CaptureMode.screen,
      imagePath: "$path/$key.png",
      silent: true,
      copyToClipboard: false);
}