src/apps/cortex/support/ScrollHelpers.h

   1 /*
   2  * Copyright (c) 1999-2000, Eric Moon.
   3  * All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions, and the following disclaimer.
  11  *
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions, and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  *
  16  * 3. The name of the author may not be used to endorse or promote products
  17  *    derived from this software without specific prior written permission.
  18  *
  19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR "AS IS" AND ANY EXPRESS OR
  20  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  21  * OF TITLE, NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
  23  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  24  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  25  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
  26  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
  27  * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  29  */
  30
  31
  32 // ScrollHelpers.h
  33 // e.moon 9mar99
  34 //
  35 // An interface/driver view combination to simplify the task
  36 // of redirecting a scroll bar: an invisible proxy view
  37 // forwards scroll requests back to a scroll-handler.
  38
  39 #ifndef __EMOON_ScrollHelpers_H__
  40 #define __EMOON_ScrollHelpers_H__
  41
  42 #include <View.h>
  43 #include "debug_tools.h"
  44
  45 class IScrollTarget {
  46 public:                 // interface
  47         virtual void handleScrollBy(float xDelta, float yDelta)=0;
  48 };
  49
  50 class ScrollProxyView : public BView {
  51         typedef BView _inherited;
  52 public:
  53         ScrollProxyView(IScrollTarget* pTarget, BRect frame) :
  54                 m_pTarget(pTarget),
  55                 BView(frame, "scrollProxy", B_FOLLOW_LEFT|B_FOLLOW_TOP, 0) {}
  56         virtual ~ScrollProxyView() {}
  57
  58         virtual void ScrollTo(BPoint where) {
  59                 float xDelta = where.x - Bounds().left;
  60                 float yDelta = where.y - Bounds().top;
  61                 _inherited::ScrollTo(where);
  62                 ASSERT(m_pTarget);
  63                 m_pTarget->handleScrollBy(xDelta, yDelta);
  64         }
  65
  66 protected:
  67         IScrollTarget*          m_pTarget;
  68 };
  69
  70 #endif /* __EMOON_ScrollHelpers_H__ */