Mac Forum / Programming / Mac Programming / November 2004

Thank you. Great work. It would be nice if Apple documented that it
doesn't send MouseMoved events to an HIView, only to a Window.

Thank you, this looks like it is exactly what I needed.  I very much
appreciate your time and help.

---Phoenix...

I installed your code in my sample app, and while it appears to
work great for MouseMoved events, there was a problem with
MouseDragged events.

It only sees MouseDragged events if I hold the right button of
my 4 button mouse down. The left and center and thumb buttons
are all ignored, and chords of buttons are all ignored.

. . . . . . . .

Ah, I just fixed it while I was writing this: I had a
ControlHitTestDoer mixed in to my view. Once I removed it,
everything worked as expected.

## What this does: is use a multibutton mouse as a multicolored pen.
This is working code.

Depending what chord of the multiple buttons you hold down, this draws
in a different color. Mouse motion over the pane with all buttons up
will also draw.

At least in 10.3, you can resize the window without any problem.

Here is the interesting part of the source code:

struct PointColor {
  HIPoint pt;
  UInt32  color;
  PointColor(const HIPoint& inPt, UInt32 inColor) :
     pt(inPt), color(inColor) {}
};

typedef std::vector<PointColor>  VectorPoint;

namespace {

bool operator == (const HIPoint& a, const HIPoint& b){
  return  a.x == b.x and a.y == b.y;
}

bool ShouldAppend(const VectorPoint& v, const HIPoint& p, UInt32 inColor){
  if(0 == v.size()){
     return true;
  }
  return not (p == v[v.size() - 1].pt and inColor == v[v.size() - 1].color);
}

} // end anonymous namespace

// ---------------------------------------------------------------------------
// DoControlDraw                    Event Handler        [protected]
OSStatus MouseMovedView::DoControlDraw(
  PPx::SysCarbonEvent& /* ioEvent */,
  ControlRef           /* inControl */,
  ControlPartCode         /* inPartCode */,
  RgnHandle            /* inClipRgn */,
  CGContextRef         inContext){

  HIRect   frame;            // Get bounding box in local coordinates
  GetLocalFrame(frame);  
  CGContextStrokeRectWithWidth(inContext, frame, mLineWidth);

  if(2 <= mPoints.size()){
     int iCount = mPoints.size();
     int lastColor = -1;
     for(VectorPoint::const_iterator i = mPoints.begin();i != mPoints.end(); ++i){
        if(lastColor != i->color){
           CGContextDrawPath(inContext, kCGPathStroke);
           CGContextBeginPath(inContext);
           CGContextMoveToPoint(inContext, i->pt.x, i->pt.y);
           CGContextSetLineWidth(inContext, 1);
           CGContextSetRGBStrokeColor(inContext,
              (1 & i->color) ? .9 : 0,
              (2 & i->color) ? .9 : 0,
              (4 & i->color) ? .9 : 0,
              (8 & i->color) ? .9 : .4);
           lastColor = i->color;
        }
        CGContextAddLineToPoint(inContext, i->pt.x, i->pt.y);
     }
     CGContextDrawPath(inContext, kCGPathStroke);
  }
  return noErr;
}

// ---------------------------------------------------------------------------
OSStatus MouseMovedView::MouseMotion(const HIPoint& inMouseLoc, UInt32 inColor){
  HIPoint localMouseLoc;
  OSStatus err;
  if(noErr == (err = GlobalToLocal(inMouseLoc, localMouseLoc)) and ShouldAppend(mPoints, localMouseLoc, inColor)){
     mPoints.push_back(PointColor(localMouseLoc, inColor));
     HIViewSetNeedsDisplay(GetSysView(), true);
     return noErr;
  }else{
     return err;
  }
}

// ---------------------------------------------------------------------------
// DoMouseMoved   Event Handler        [protected]
OSStatus MouseMovedView::DoMouseMoved(PPx::SysCarbonEvent& /*ioEvent*/, const HIPoint& inMouseLoc){
  return MouseMotion(inMouseLoc, 0);
}

namespace PPx {
namespace SysEventParam {

PPx_Declare_SysEventParam_Traits( TabletPointRec, typeTabletPointRec );
PPx_Declare_SysEventParam_Traits( TabletProximityRec, typeTabletProximityRec );

}  // SysEventParam
}  // PPx

// ---------------------------------------------------------------------------
// DoMouseDragged Event Handler        [protected]
/// just for fun, we handle digitizing tablets too.
OSStatus MouseMovedView::DoMouseDragged(PPx::SysCarbonEvent& ioEvent, const HIPoint& inMouseLoc){
  UInt32 modifiers = 0;
  UInt32 tabletType = 0;
  UInt32   mouseChord = 0;
  TabletPointRec pointRec;
  TabletProximityRec proximityRec;
  PPx::SysEventParam::Get(ioEvent, kEventParamMouseChord, mouseChord);
  // chord is | of:
  // 0x1 if left button down
  // 0x2 if right button down
  // 0x4 if middle button down
  // 0x8 if thumb button down
  // if you don't have a multibutton mouse, you can use these modifier bits instead. (appropriately shifted)
  PPx::SysEventParam::Get(ioEvent, kEventParamKeyModifiers, modifiers);
  if(noErr == PPx::SysEventParam::GetOptional(ioEvent, kEventParamTabletEventType, tabletType)){
     switch(tabletType){
     case kEventTabletPoint:    PPx::SysEventParam::Get(ioEvent, kEventParamTabletPointRec, pointRec);        break;
     case kEventTabletProximity:   PPx::SysEventParam::Get(ioEvent, kEventParamTabletProximityRec, proximityRec);   break;
     }
  }
  return MouseMotion(inMouseLoc, mouseChord);
}

// ---------------------------------------------------------------------------
// GlobalToLocal  conversion        [private]
OSStatus MouseMovedView::GlobalToLocal(const HIPoint& inMouseLoc, HIPoint& outPoint)const{
  OSStatus status = noErr;
  HIViewRef   sysView = GetSysView();
  PPx::Window* window = PPx::Window::GetWindowObject(GetControlOwner(sysView));
  if(NULL == window){ return paramErr; }
  Rect contentBounds;
  status = GetWindowBounds(window->GetSysWindow(), kWindowGlobalPortRgn, &contentBounds);
  outPoint = CGPointMake(inMouseLoc.x - contentBounds.left, inMouseLoc.y - contentBounds.top);
  if(noErr == status){ status = HIViewConvertPoint(&outPoint, window->GetContentView()->GetSysView(),   sysView); }
  return status;
}