PolyBtn, a polygon button class

• Download demo project - 28 Kb

Introduction

CPolyBtn is a simple CButton derivative that allows you to create buttons that aren't rectangles or circles or any other typical geometric shape; with CPolyBtn, you specify the button shape by providing a series of points that define a polygon.

What can it do?

CPolyBtn does all of the normal button stuff: rollovers, bitmaps, tooltips, focus colors, fill colors, disabled colors, etc..

How can I use it?

You create a button on your dialog, then create a member variable of type CPolyBtn. You know, the standard stuff. Then, in your CDialog's InitInstance, before calling CDialog::InitInstance you create a std::vector of CPoint objects, one for each polygon point, where the points are arranged in clockwise order, then assign the vector to the CPolyBtn. CPolyBtn will determine highlight and shadow colors for each edge, set up the regions and handle everything else.

   // make a triangle button
   std::vector<CPoint> pts;

   const int triEdgeSize = 16;

   pts.push_back(CPoint(0,0));
   pts.push_back(CPoint(triEdgeSize,0));
   pts.push_back(CPoint(0,triEdgeSize));

   m_zoomInBtn.SetPoints(pts);
   m_zoomInBtn.SetBMPOffset(2,2);
   m_zoomInBtn.SetBMPID(IDB_ZOOM_IN, RGB(255,255,255), IDB_ZOOM_IN_DISABLED, <BR>                        RGB(255,255,255));

At this point, you can also add bitmaps, set text positions, etc..

For those of you who demand control, CPolyBtn also provides a way for you to specify the colors for each edge manually (normal, highlight, focused, disabled, etc..). This method takes more work, of course. But if you need that much control, the option is there.

Other options

// optionally set the colors used.
void SetColors(COLORREF highlight, COLORREF down, COLORREF focus, <BR>               COLORREF disabled, COLORREF rollover);
 
// set the color to fill with. default ::GetSysColor(COLOR_BTNFACE);
void SetFillColor(COLORREF fillClr);
  
// draw bitmap at this offset
void SetBMPOffset(int x, int y);
  
// draw window text at this offset
void SetTextOffset(int x, int y);
 
// optional tooltip
void SetTooltipText(LPCTSTR lpszText, BOOL bActivate = TRUE);
void ActivateTooltip(BOOL bEnable = TRUE);
 
// when using the SetPoints method, you can decide to highlight lines 
// that are more than -45 degrees below horizontal (default false)
void AllowHighlightOnGtrNeg45(bool b);
 
// should the button change color when the mouse moves over ? (default false)
void AllowRollover(bool b);

Issues

In general, I'm not crazy about the way the edges are drawn. Because there's no good way to shrink a polygon, it's hard to draw the button edge like a normal button where the edges are actually two parallel lines, with different colors. So, the edges here are always a single pixel wide. Another example of where this is an issue is in the "focus" rendering: normally, button focus is indicated by drawing a dashed rectangle inside the border. But, since there's no simple way to determine what 'inside' means for all arbitrary polygons, CPolyBtn doesn't bother; it handles focus by drawing the edges with the PS_DOT pen style. (sure, there are complex ways to find the inside of a polygon, but that's more work than i wanted to put into this, and i didn't need it anyway).

Anyway...

If you come up with any improvements on this, feel free to share!

And remember, be excellent to each other.