101 lines
3.1 KiB
C++
101 lines
3.1 KiB
C++
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/* @doc INTERNAL
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*
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* @module _DFREEZE.CPP Implementation for classes handle freezing the display |
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*
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* This module implements non-inline members used by logic to handle freezing the display
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*
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* History: <nl>
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* 2/8/96 ricksa Created
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*
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* Copyright (c) 1995-1997, Microsoft Corporation. All rights reserved.
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*/
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#include "_common.h"
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#include "_disp.h"
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#include "_dfreeze.h"
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ASSERTDATA
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/*
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* CAccumDisplayChanges::GetUpdateRegion(pcpStart, pcchDel, pcchNew,
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* pfUpdateCaret, pfScrollIntoView)
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* @mfunc
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* Get region for display to update
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*/
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void CAccumDisplayChanges::GetUpdateRegion(
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LONG *pcpStart, //@parm where to put the cpStart
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LONG *pcchDel, //@parm where to put the del char count
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LONG *pcchNew, //@parm where to put the new char count
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BOOL *pfUpdateCaret, //@parm whether caret update is needed
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BOOL *pfScrollIntoView, //@parm whether to scroll caret into view
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BOOL *pfNeedRedisplay) //@parm whether it needs redisplay
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{
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LONG cchDel;
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*pcpStart = _cpMin;
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if(pfUpdateCaret)
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*pfUpdateCaret = _fUpdateCaret;
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if(pfScrollIntoView)
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*pfScrollIntoView = _fScrollIntoView;
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if (pfNeedRedisplay)
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*pfNeedRedisplay = _fNeedRedisplay;
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if(_cpMin == CP_INFINITE)
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return;
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cchDel = _cpMax - _cpMin;
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if(pcchDel)
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*pcchDel = cchDel;
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*pcchNew = cchDel + _delta;
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_cpMin = CP_INFINITE;
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}
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/*
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* CAccumDisplayChanges::UpdateRecalcRegion(cpStartNew, cchDel, cchNew)
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*
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* @mfunc
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* Merge new update with region to be recalculated
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*/
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void CAccumDisplayChanges::UpdateRecalcRegion(
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LONG cpStartNew, //@parm Start of update
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LONG cchDel, //@parm Count of chars to delete
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LONG cchNew) //@parm Count of chars to add
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{
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if(CP_INFINITE == _cpMin)
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{
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// Object is empty so just assign values
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_cpMin = cpStartNew;
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_cpMax = cpStartNew + cchDel;
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_delta = cchNew - cchDel;
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return;
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}
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// The basic idea of this algorithm is to merge the updates so that
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// they appear to the display sub-system as if only one replace range
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// has occured. To do this we keep track of the start of the update
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// (_cpMin) relative to the original text and the end of the update
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// (_cpMax) relative to the original text and the change in the count
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// of text (_delta). We can recreate cchDel from _cpMost - _cpMin and
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// cchNew from cchDel + _delta.
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// Do we need to update _cpMin? - we only need to update _cpMin if the
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// current update begins before the last update because the final update
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// need only know the very start of the range updated.
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if(cpStartNew < _cpMin)
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_cpMin = cpStartNew;
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// Do we need to udpate _cpMax? - we only need to update _cpMax if the
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// current update implies a _cpMax that is greater than the current one.
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// Note that because prior updates affect where the _cpMax is located
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// we need to compare againt the proposed _cpMax against the current
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// _cpMax adjusted by the change in the text since the beginning of the
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// updates.
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if(cpStartNew + cchDel > _cpMax + _delta)
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_cpMax = cpStartNew + cchDel - _delta;
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// Increment the total change by the change for this update.
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_delta += cchNew - cchDel;
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}
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