Magnifying Cursor - CodeProject

Introduction

This program generates a cursor that can magnify the portion on which it hovers.
I wrote this program to help myself make a small image editor. Using this code has made my program a very special one. Try it out.

Using the code

This program copies a part of the device context on to a bitmap. Stretches it and displays the bigger size.

This program uses three classes :-

CDib: This class can load DIBs from file and from resource and also save DIB to disk.
CBitmapDC: This class is derived from CDC. This class creates a bitmap from a given device context.
CMaskedBitmap: This class can draw a bitmap without displaying one specific colour.

//
void CMagnifierView::OnMouseMove(UINT nFlags, CPoint point) 
{
    SetCursor(AfxGetApp()->LoadCursor(IDC_CURSOR1));
    CPoint p = GetScrollPosition();
    CClientDC pdc(this);
    CMemDC dc(&pdc);
    m_dib.Draw(&dc, CPoint(-p.x, -p.y), m_dib.GetDimensions());
    CRect rect1(CPoint(0, 0), m_dib.GetDimensions());
    CRect sel;
    CMaskedBitmap* bitm;
    CMaskedBitmap* bit;
    if(rect1.PtInRect(point))
    {
        CRgn rgn1, rgn2;
        sel = CRect(point.x-(20*1), point.y-(20*1), 
                     point.x+(20*1), point.y+(20*1));
        CBitmapDC bitmap(40*1, 40*1, &dc);
        CBitmapDC bitmap2(120*1, 120*1, &dc);
        rgn1.CreateEllipticRgn(0, 0, 120, 120);
        rgn2.CreateRectRgn(0, 0, 120, 120);
        rgn1.CombineRgn(&rgn2, &rgn1, RGN_DIFF);
        int y = sel.top, x = sel.left;
        for(int i = y; i<y+(40*1);i++)
        {
            for(int j = x; j<x+(40*1); j++)
            {
                COLORREF color = dc.GetPixel(j, i);
                int red = GetRValue(color);
                int green = GetGValue(color);
                int blue = GetBValue(color);
                bitmap.SetPixel(j-x, i-y, color);
            }
        }
        bitm = bitmap.Close();
        CDC dcMem;
        dcMem.CreateCompatibleDC(&dc);
        dcMem.SelectObject(bitm);
        bitmap2.StretchBlt(0, 0, 120*1, 120*1, &dcMem, 
                                     0, 0, 40, 40, SRCCOPY);
        bitmap2.FillRgn(&rgn1, &CBrush(RGB(255, 0, 254)));
        bit = bitmap2.Close();
        dc.SelectObject(&CPen(PS_SOLID, 1, RGB(0, 0, 0)));
        dc.SelectObject(&CBrush(NULL, RGB(0, 0, 0)));
        dc.Ellipse(point.x-(60*1)-1, point.y-(60*1)-1, 
                          point.x+(60*1), point.y+(60*1));
        bit->DrawTransparent(&dc, point.x-(60*1), 
                         point.y-(60*1), RGB(255, 0, 254));
        dc.MoveTo(point.x, point.y-(60*1)-1);
        dc.LineTo(point.x, point.y-(10*1)+1);
        dc.MoveTo(point.x, point.y+(10*1)-1);
        dc.LineTo(point.x, point.y+(60*1)+1);
        dc.MoveTo(point.x-(60*1)-1, point.y);
        dc.LineTo(point.x-(10*1)+1, point.y); 
        dc.MoveTo(point.x+(10*1)-1, point.y);
        dc.LineTo(point.x+(60*1)+1, point.y); 
    }
    CScrollView::OnMouseMove(nFlags, point);
}
//

Points of interest

I like programming applications with very cool looks. Using this cursor, the looks of the programs have been enhanced. Even game programming can use this type of cursor with a bit of enhancement.

History

First update :- 27/01/2003 (Monday)

License

This article has no explicit license attached to it but may contain usage terms in the article text or the download files themselves. If in doubt please contact the author via the discussion board below.

A list of licenses authors might use can be found here