使用 jna 在 java 中获取鼠标类型

Question

非常感谢@deFreitas

我正在尝试在 java 中创建远程控制程序。我的问题是我使用 robot class 的屏幕截图从远程计算机获取图像，因此我看不到远程光标。我知道我可以在屏幕截图上绘制光标图像，但我怎样才能获得全局光标类型。

我搜索了很多，最接近的是这段代码：

public interface User32 extends com.sun.jna.Library {
  public static User32 INSTANCE = (User32) com.sun.jna.Native
          .loadLibrary("User32", User33.class);
  public com.sun.jna.platform.win32.WinDef.HCURSOR GetCursor();

}

但我不明白如何从 HCursor class 获取光标类型... 有没有办法获取类型甚至光标位图？

编辑： 我找到了这个函数：

WinNT.HANDLE LoadImage(WinDef.HINSTANCE hinst,
                   String name,
                   int type,
                   int xDesired,
                   int yDesired,
                   int load)

但我不知道该给它哪种类型。我看到的每个网站都加载图像或特定的光标类型……

Answer 1

有可能，基本上你需要GetCursorInfo and LoadImage

BOOL GetCursorInfo(PCURSORINFO pci)

它获取当前游标句柄并将其存储在 PCURSORINFO.hCursor 中，这是实际的游标，但没有指示器知道它是什么类型，请注意它是 Windows 而不是 JNA 限制.不管怎样，如果你使用

HANDLE WINAPI LoadImage(...,PCTSTR cursorId,...)

它将 return 给定游标类型 ID 的句柄，here a list 包含所有可用的游标 ID。这样你就可以使用 LoadImage 加载所有游标然后只用 GetCursorInfo 结果做一个等于，匹配的结果是实际的游标类型。这是一个使用 JNA

的工作 JAVA 程序

import com.sun.jna.Memory;
import com.sun.jna.Native;
import com.sun.jna.Pointer;
import com.sun.jna.Structure;
import com.sun.jna.platform.win32.*;

import java.io.IOException;
import java.util.*;

/**
 * https://msdn.microsoft.com/pt-br/library/windows/desktop/ms648029(v=vs.85).aspx
 * Test cursors - https://developer.mozilla.org/en-US/docs/Web/CSS/cursor
 * Chromium cursor map -  https://github.com/mageddo/chromium/blob/master/webkit/glue/webcursor_win.cc
 * Load icon example - https://github.com/java-native-access/jna/blob/master/contrib/platform/test/com/sun/jna/platform/win32/GDI32Test.java#L54
 * understanding makeintresource - 
 * all possible windows error codes - https://msdn.microsoft.com/en-us/library/windows/desktop/ms681386(v=vs.85).aspx
 * Cursor ids - https://msdn.microsoft.com/en-us/library/windows/desktop/ms648391(v=vs.85).aspx
 *
 */
public class Main {

    public static void main(String[] args) throws Exception {
        while(true){
            final Main main = new Main();
            System.out.println(main.getCurrentCursor());
            Thread.sleep(2000);
        }
    }

    private final Map<WinNT.HANDLE, Cursor> cursors;
    private final User32 user32;

    public Main(){
        user32 = User32.INSTANCE;
        cursors = loadCursors();
    }


    /**
     * Load all possible cursors to a map
     */
    private Map<WinNT.HANDLE, Cursor> loadCursors() {
        final Map<WinNT.HANDLE, Cursor> cursors = new HashMap<>();
        for (final Cursor cursor : Cursor.values()) {

            final Memory memory = new Memory(Native.getNativeSize(Long.class, null));
            memory.setLong(0, cursor.getCode());
            final Pointer resource = memory.getPointer(0);
            final WinNT.HANDLE hcursor = this.user32.LoadImageA(
                null, resource, WinUser.IMAGE_CURSOR, 0, 0, WinUser.LR_SHARED
            );
            if(hcursor == null || Native.getLastError() != 0){
                throw new Error("Cursor could not be loaded: " + String.valueOf(Native.getLastError()));
            }

            cursors.put(hcursor, cursor);
        }
        return Collections.unmodifiableMap(cursors);
    }

    public Cursor getCurrentCursor(){
        final CURSORINFO cursorinfo = new CURSORINFO();
        final int success = this.user32.GetCursorInfo(cursorinfo);
        if(success != 1){
            throw new Error("Could not retrieve cursor info: " + String.valueOf(Native.getLastError()));
        }

        // you can use the address printed here to map the others cursors like ALL_SCROLL
        System.out.printf("currentPointer=%s%n", cursorinfo.hCursor);
        // some times cursor can be hidden, in this case it will be null
        if(cursorinfo.hCursor != null && cursors.containsKey(cursorinfo.hCursor)){
            return cursors.get(cursorinfo.hCursor);
        }
        return null;
    }

//  typedef struct {
//      DWORD   cbSize;
//      DWORD   flags;
//      HCURSOR hCursor;
//      POINT   ptScreenPos;
//  } CURSORINFO, *PCURSORINFO, *LPCURSORINFO;
    public static class CURSORINFO extends Structure {

        public int cbSize;
        public int flags;
        public WinDef.HCURSOR hCursor;
        public WinDef.POINT ptScreenPos;

        public CURSORINFO() {
            this.cbSize = Native.getNativeSize(CURSORINFO.class, null);
        }
        @Override
        protected List<String> getFieldOrder() {
            return Arrays.asList("cbSize", "flags", "hCursor", "ptScreenPos");
        }
    }

    public interface User32 extends com.sun.jna.Library {
        User32 INSTANCE = Native.loadLibrary("User32.dll", User32.class);

        //      BOOL WINAPI GetCursorInfo(
//          _Inout_ PCURSORINFO pci
//      );
        int GetCursorInfo(CURSORINFO cursorinfo);

//      HANDLE WINAPI LoadImage(
//          _In_opt_ HINSTANCE hinst,
//          _In_     LPCTSTR   lpszName,
//          _In_     UINT      uType,
//          _In_     int       cxDesired,
//          _In_     int       cyDesired,
//          _In_     UINT      fuLoad
//      );
        WinNT.HANDLE LoadImageA(
            WinDef.HINSTANCE hinst,
            Pointer lpszName,
            int uType,
            int cxDesired,
            int cyDesired,
            int fuLoad
        );
    }

    public enum Cursor {
        APPSTARTING(32650),
        NORMAL(32512),
        CROSS(32515),
        HAND(32649),
        HELP(32651),
        IBEAM(32513),
        NO(32648),
        SIZEALL(32646),
        SIZENESW(32643),
        SIZENS(32645),
        SIZENWSE(32642),
        SIZEWE(32644),
        UP(32516),
        WAIT(32514),
        PEN(32631)
        ;

        private final int code;

        Cursor(final int code) {
            this.code = code;
        }

        public int getCode() {
            return code;
        }
    }
}

Obs: 并不是所有可能的游标都有可用的资源id（比如放大，缩小），这是因为系统默认游标是15，其他的是自定义游标软件（如 chrome、firefox）这样 windows 无法识别它是哪种光标。

JNA版本

compile group: 'net.java.dev.jna', name: 'jna', version: '4.5.0'
compile group: 'net.java.dev.jna', name: 'jna-platform', version: '4.5.0'

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