Extracting cursor image with Java

I wonder if there is a way to extract image objects from cursor objects in Java

For example: for this purpose:

Image img = extractCursorImage(Cursor.getDefaultCursor());

Then you can draw on the toolbar button (that's what I want)

Solution

The cursor class is very abstract - everything important is delegated to native code, so you can't just draw one in the context of graphics There is no direct and obvious way to meet the needs of predefined icons or performing this operation in native code

The following is some code for drawing built-in windows cursors using JNA library If you can use JNA, you can avoid using the C compiler

I may make too many native calls, but the cost is not high for one-time icon generation

hand cursor drawn in Java http://f.imagehost.org/0709/hand.png

Code to display the cursor as a java image:

public class LoadCursor {

  public static void draw(BufferedImage image,int cursor,int diFlags) {
    int width = image.getWidth();
    int height = image.getHeight();

    User32 user32 = User32.INSTANCE;
    Gdi32 gdi32 = Gdi32.INSTANCE;

    Pointer hIcon = user32
        .LoadCursorW(Pointer.NULL,cursor);
    Pointer hdc = gdi32.CreateCompatibleDC(Pointer.NULL);
    Pointer bitmap = gdi32.CreateCompatibleBitmap(hdc,width,height);

    gdi32.SelectObject(hdc,bitmap);
    user32.DrawIconEx(hdc,hIcon,height,Pointer.NULL,diFlags);

    for (int x = 0; x < width; x++) {
      for (int y = 0; y < width; y++) {
        int rgb = gdi32.GetPixel(hdc,x,y);
        image.setRGB(x,y,rgb);
      }
    }

    gdi32.DeleteObject(bitmap);
    gdi32.DeleteDC(hdc);
  }

  public static void main(String[] args) {
    final int width = 128;
    final int height = 128;

    BufferedImage image = new BufferedImage(width,BufferedImage.TYPE_INT_ARGB);
    draw(image,User32.IDC_HAND,User32.DI_NORMAL);
    BufferedImage mask = new BufferedImage(width,BufferedImage.TYPE_INT_RGB);
    draw(mask,User32.DI_MASK);
    applyMask(image,mask);

    JLabel icon = new JLabel();
    icon.setIcon(new ImageIcon(image));

    JFrame frame = new JFrame();
    frame.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
    frame.setContentPane(icon);
    frame.pack();
    frame.setVisible(true);
  }

  private static void applyMask(BufferedImage image,BufferedImage mask) {
    int width = image.getWidth();
    int height = image.getHeight();
    for (int x = 0; x < width; x++) {
      for (int y = 0; y < height; y++) {
        int masked = mask.getRGB(x,y);
        if ((masked & 0x00FFFFFF) == 0) {
          int rgb = image.getRGB(x,y);
          rgb = 0xFF000000 | rgb;
          image.setRGB(x,rgb);
        }
      }
    }
  }

}

User32. Dll interface:

public interface User32 extends Library {

  public static User32 INSTANCE = (User32) Native
      .loadLibrary("User32",User32.class);

  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_ARROW = 32512;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_IBEAM = 32513;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_WAIT = 32514;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_CROSS = 32515;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_UPARROW = 32516;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZENWSE = 32642;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZENESW = 32643;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZEWE = 32644;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZENS = 32645;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZEALL = 32646;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_NO = 32648;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_HAND = 32649;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_APPSTARTING = 32650;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_HELP = 32651;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_ICON = 32641;
  /** @see #LoadCursorW(Pointer,int) */
  public static final int IDC_SIZE = 32640;

  /** @see #DrawIconEx(Pointer,int,Pointer,int) */
  public static final int DI_COMPAT = 4;
  /** @see #DrawIconEx(Pointer,int) */
  public static final int DI_DEFAULTSIZE = 8;
  /** @see #DrawIconEx(Pointer,int) */
  public static final int DI_IMAGE = 2;
  /** @see #DrawIconEx(Pointer,int) */
  public static final int DI_MASK = 1;
  /** @see #DrawIconEx(Pointer,int) */
  public static final int DI_NORMAL = 3;
  /** @see #DrawIconEx(Pointer,int) */
  public static final int DI_APPBANDING = 1;

  /** http://msdn.microsoft.com/en-us/library/ms648391(VS.85).aspx */
  public Pointer LoadCursorW(Pointer hInstance,int lpCursorName);

  /** http://msdn.microsoft.com/en-us/library/ms648065(VS.85).aspx */
  public boolean DrawIconEx(Pointer hdc,int xLeft,int yTop,Pointer hIcon,int cxWidth,int cyWidth,int istepIfAniCur,Pointer hbrFlickerFreeDraw,int diFlags);

}

Gdi32. Dll interface:

public interface Gdi32 extends Library {

  public static Gdi32 INSTANCE = (Gdi32) Native
      .loadLibrary("Gdi32",Gdi32.class);

  /** http://msdn.microsoft.com/en-us/library/dd183489(VS.85).aspx */
  public Pointer CreateCompatibleDC(Pointer hdc);

  /** http://msdn.microsoft.com/en-us/library/dd183488(VS.85).aspx */
  public Pointer CreateCompatibleBitmap(Pointer hdc,int nWidth,int nHeight);

  /** http://msdn.microsoft.com/en-us/library/dd162957(VS.85).aspx */
  public Pointer SelectObject(Pointer hdc,Pointer hgdiobj);

  /** http://msdn.microsoft.com/en-us/library/dd145078(VS.85).aspx */
  public int SetPixel(Pointer hdc,int X,int Y,int crColor);

  /** http://msdn.microsoft.com/en-us/library/dd144909(VS.85).aspx */
  public int GetPixel(Pointer hdc,int nXPos,int nYPos);

  /** http://msdn.microsoft.com/en-us/library/dd183539(VS.85).aspx */
  public boolean DeleteObject(Pointer hObject);

  /** http://msdn.microsoft.com/en-us/library/dd183533(VS.85).aspx */
  public boolean DeleteDC(Pointer hdc);

}