可通过位图拖动的C ++窗口

Question

I'm developing a custom window border in c++, well i guess that's what it is. I don't know if i'm doing this the correct way or not, but i would appreciate knowing how to make a draggable window by a bitmap.

there is a bitmap bar i made in photoshop and added to the client area, and i want to be able to drag it just by the bitmap. Currently you can drag it by anywhere in the client area using this code:

case WM_NCHITTEST: {
    LRESULT hit = DefWindowProc(hWnd, message, wParam, lParam);
    if(hit == HTCLIENT) hit = HTCAPTION;
    return hit;
    }
    break;

and I drew the bitmap using this code in the paint section:

DrawBitmap(hdc,"header-bar-1.bmp", 2, 4);

and it looks like so:

You can see the bar at the top, which is what i want to be able to drag it by.

Answer 1

I haven't tried this, but something similar should work:

1. Declare a Boolean value called eg isDragging and set it to false.
2. In the handler of WM_LBUTTONDOWN , if isDragging is false and the mouse is over the bitmap bar (use PtInRect ), set isDragging to true, and confine the cursor into the rectangle of the bitmap by calling ClipCursor . Save the position of the cursor relative to the window upper-left corner.
3. In the handler of WM_MOUSEMOVE , if isDragging is true, move the window (call MoveWindow or SetWindowPos ) in order to restore its position relative to the cursor.
4. In the handler of WM_LBUTTONUP , if isDragging is true, set it to false, and release the cursor by calling ClipCursor appropriately.

(Always take the difference between client coordinates and screen coordinates into account.)