// Modified by:
// Created: 05/25/99
// RCS-ID: $Id$
-// Copyright: (c) wxWindows team
+// Copyright: (c) wxWidgets team
// Licence: wxWindows licence
/////////////////////////////////////////////////////////////////////////////
// declarations
// ============================================================================
-#ifdef __GNUG__
- #pragma implementation "dcbase.h"
-#endif
-
// ----------------------------------------------------------------------------
// headers
// ----------------------------------------------------------------------------
#endif
#include "wx/dc.h"
+#include "wx/math.h"
-#include <math.h>
-
-// bool wxDCBase::sm_cacheing = FALSE;
+// bool wxDCBase::sm_cacheing = false;
// ============================================================================
// implementation
// ============================================================================
+#if WXWIN_COMPATIBILITY_2_6
+void wxDCBase::BeginDrawing()
+{
+}
+
+void wxDCBase::EndDrawing()
+{
+}
+#endif // WXWIN_COMPATIBILITY_2_6
+
// ----------------------------------------------------------------------------
// special symbols
// ----------------------------------------------------------------------------
wxPoint *points = new wxPoint[n];
int i = 0;
- for ( wxNode *node = list->GetFirst(); node; node = node->GetNext(), i++ )
+ for ( wxList::compatibility_iterator node = list->GetFirst(); node; node = node->GetNext(), i++ )
{
wxPoint *point = (wxPoint *)node->GetData();
points[i].x = point->x;
wxPoint *points = new wxPoint[n];
int i = 0;
- for ( wxNode *node = list->GetFirst(); node; node = node->GetNext(), i++ )
+ for ( wxList::compatibility_iterator node = list->GetFirst(); node; node = node->GetNext(), i++ )
{
wxPoint *point = (wxPoint *)node->GetData();
points[i].x = point->x;
delete [] points;
}
+void
+wxDCBase::DoDrawPolyPolygon(int n,
+ int count[],
+ wxPoint points[],
+ wxCoord xoffset, wxCoord yoffset,
+ int fillStyle)
+{
+ if ( n == 1 )
+ {
+ DoDrawPolygon(count[0], points, xoffset, yoffset, fillStyle);
+ return;
+ }
+
+ int i, j, lastOfs;
+ wxPoint* pts;
+ wxPen pen;
+
+ for (i = j = lastOfs = 0; i < n; i++)
+ {
+ lastOfs = j;
+ j += count[i];
+ }
+ pts = new wxPoint[j+n-1];
+ for (i = 0; i < j; i++)
+ pts[i] = points[i];
+ for (i = 2; i <= n; i++)
+ {
+ lastOfs -= count[n-i];
+ pts[j++] = pts[lastOfs];
+ }
+
+ pen = GetPen();
+ SetPen(wxPen(*wxBLACK, 0, wxTRANSPARENT));
+ DoDrawPolygon(j, pts, xoffset, yoffset, fillStyle);
+ SetPen(pen);
+ for (i = j = 0; i < n; i++)
+ {
+ DoDrawLines(count[i], pts+j, xoffset, yoffset);
+ j += count[i];
+ }
+ delete[] pts;
+}
+
// ----------------------------------------------------------------------------
// splines
// ----------------------------------------------------------------------------
DrawSpline(&point_list);
- for( wxNode *node = point_list.GetFirst(); node; node = node->GetNext() )
+ for( wxList::compatibility_iterator node = point_list.GetFirst(); node; node = node->GetNext() )
{
wxPoint *p = (wxPoint *)node->GetData();
delete p;
point->x = (int) x;
point->y = (int) y;
wx_spline_point_list.Append((wxObject*)point);
- return TRUE;
+ return true;
}
static void wx_spline_draw_point_array(wxDCBase *dc)
{
dc->DrawLines(&wx_spline_point_list, 0, 0 );
- wxNode *node = wx_spline_point_list.GetFirst();
+ wxList::compatibility_iterator node = wx_spline_point_list.GetFirst();
while (node)
{
wxPoint *point = (wxPoint *)node->GetData();
delete point;
- delete node;
+ wx_spline_point_list.Erase(node);
node = wx_spline_point_list.GetFirst();
}
}
double cx1, cy1, cx2, cy2, cx3, cy3, cx4, cy4;
double x1, y1, x2, y2;
- wxNode *node = points->GetFirst();
+ wxList::compatibility_iterator node = points->GetFirst();
+ if (node == wxList::compatibility_iterator())
+ // empty list
+ return;
+
p = (wxPoint *)node->GetData();
x1 = p->x;
wx_spline_add_point(x1, y1);
- while ((node = node->GetNext()) != NULL)
+ while ((node = node->GetNext())
+#if !wxUSE_STL
+ != NULL
+#endif // !wxUSE_STL
+ )
{
p = (wxPoint *)node->GetData();
x1 = x2;
#endif // wxUSE_SPLINES
+// ----------------------------------------------------------------------------
+// Partial Text Extents
+// ----------------------------------------------------------------------------
+
+
+// Each element of the widths array will be the width of the string up to and
+// including the corresponding character in text. This is the generic
+// implementation, the port-specific classes should do this with native APIs
+// if available and if faster. Note: pango_layout_index_to_pos is much slower
+// than calling GetTextExtent!!
+
+#define FWC_SIZE 256
+
+class FontWidthCache
+{
+public:
+ FontWidthCache() : m_scaleX(1), m_widths(NULL) { }
+ ~FontWidthCache() { delete []m_widths; }
+
+ void Reset()
+ {
+ if (!m_widths)
+ m_widths = new int[FWC_SIZE];
+
+ memset(m_widths, 0, sizeof(int)*FWC_SIZE);
+ }
+
+ wxFont m_font;
+ double m_scaleX;
+ int *m_widths;
+};
+
+static FontWidthCache s_fontWidthCache;
+
+bool wxDCBase::DoGetPartialTextExtents(const wxString& text, wxArrayInt& widths) const
+{
+ int totalWidth = 0;
+
+ const size_t len = text.Length();
+ widths.Empty();
+ widths.Add(0, len);
+
+ // reset the cache if font or horizontal scale have changed
+ if ( !s_fontWidthCache.m_widths ||
+ !wxIsSameDouble(s_fontWidthCache.m_scaleX, m_scaleX) ||
+ (s_fontWidthCache.m_font != GetFont()) )
+ {
+ s_fontWidthCache.Reset();
+ s_fontWidthCache.m_font = GetFont();
+ s_fontWidthCache.m_scaleX = m_scaleX;
+ }
+
+ // Calculate the position of each character based on the widths of
+ // the previous characters
+ int w, h;
+ for ( size_t i = 0; i < len; i++ )
+ {
+ const wxChar c = text[i];
+ unsigned int c_int = (unsigned int)c;
+
+ if ((c_int < FWC_SIZE) && (s_fontWidthCache.m_widths[c_int] != 0))
+ {
+ w = s_fontWidthCache.m_widths[c_int];
+ }
+ else
+ {
+ GetTextExtent(c, &w, &h);
+ if (c_int < FWC_SIZE)
+ s_fontWidthCache.m_widths[c_int] = w;
+ }
+
+ totalWidth += w;
+ widths[i] = totalWidth;
+ }
+
+ return true;
+}
+
+
// ----------------------------------------------------------------------------
// enhanced text drawing
// ----------------------------------------------------------------------------
width0 = width;
if ( bitmap.Ok() )
{
- DrawBitmap(bitmap, x, y, TRUE /* use mask */);
+ DrawBitmap(bitmap, x, y, true /* use mask */);
wxCoord offset = bitmap.GetWidth() + 4;
x += offset;
CalcBoundingBox(x0, y0);
CalcBoundingBox(x0 + width0, y0 + height);
}
+
+
+void wxDCBase::DoGradientFillLinear(const wxRect& rect,
+ const wxColour& initialColour,
+ const wxColour& destColour,
+ wxDirection nDirection)
+{
+ // save old pen
+ wxPen oldPen = m_pen;
+
+ wxUint8 nR1 = destColour.Red();
+ wxUint8 nG1 = destColour.Green();
+ wxUint8 nB1 = destColour.Blue();
+ wxUint8 nR2 = initialColour.Red();
+ wxUint8 nG2 = initialColour.Green();
+ wxUint8 nB2 = initialColour.Blue();
+ wxUint8 nR, nG, nB;
+
+ if ( nDirection == wxEAST || nDirection == wxWEST )
+ {
+ wxInt32 x = rect.GetWidth();
+ wxInt32 w = x; // width of area to shade
+ wxInt32 xDelta = w/256; // height of one shade bend
+ if (xDelta < 1)
+ xDelta = 1;
+
+ while (x >= xDelta)
+ {
+ x -= xDelta;
+ if (nR1 > nR2)
+ nR = nR1 - (nR1-nR2)*(w-x)/w;
+ else
+ nR = nR1 + (nR2-nR1)*(w-x)/w;
+
+ if (nG1 > nG2)
+ nG = nG1 - (nG1-nG2)*(w-x)/w;
+ else
+ nG = nG1 + (nG2-nG1)*(w-x)/w;
+
+ if (nB1 > nB2)
+ nB = nB1 - (nB1-nB2)*(w-x)/w;
+ else
+ nB = nB1 + (nB2-nB1)*(w-x)/w;
+
+ SetPen(wxPen(wxColour(nR, nG, nB), 1, wxSOLID));
+ if(nDirection == wxEAST)
+ DrawRectangle(rect.GetLeft()+x, rect.GetTop(),
+ xDelta, rect.GetHeight());
+ else //nDirection == wxWEST
+ DrawRectangle(rect.GetRight()-x-xDelta, rect.GetTop(),
+ xDelta, rect.GetHeight());
+ }
+ }
+ else // nDirection == wxNORTH || nDirection == wxSOUTH
+ {
+ wxInt32 y = rect.GetHeight();
+ wxInt32 w = y; // height of area to shade
+ wxInt32 yDelta = w/255; // height of one shade bend
+ if (yDelta < 1)
+ yDelta = 1;
+
+ while (y > 0)
+ {
+ y -= yDelta;
+ if (nR1 > nR2)
+ nR = nR1 - (nR1-nR2)*(w-y)/w;
+ else
+ nR = nR1 + (nR2-nR1)*(w-y)/w;
+
+ if (nG1 > nG2)
+ nG = nG1 - (nG1-nG2)*(w-y)/w;
+ else
+ nG = nG1 + (nG2-nG1)*(w-y)/w;
+
+ if (nB1 > nB2)
+ nB = nB1 - (nB1-nB2)*(w-y)/w;
+ else
+ nB = nB1 + (nB2-nB1)*(w-y)/w;
+
+ SetPen(wxPen(wxColour(nR, nG, nB), 1, wxSOLID));
+ if(nDirection == wxNORTH)
+ DrawRectangle(rect.GetLeft(), rect.GetTop()+y,
+ rect.GetWidth(), yDelta);
+ else //nDirection == wxSOUTH
+ DrawRectangle(rect.GetLeft(), rect.GetBottom()-y-yDelta,
+ rect.GetWidth(), yDelta);
+ }
+ }
+
+ SetPen(oldPen);
+}
+
+void wxDCBase::GradientFillConcentric(const wxRect& rect,
+ const wxColour& initialColour,
+ const wxColour& destColour,
+ const wxPoint& circleCenter)
+{
+ //save the old pen color
+ wxColour oldPenColour = m_pen.GetColour();
+
+ wxUint8 nR1 = destColour.Red();
+ wxUint8 nG1 = destColour.Green();
+ wxUint8 nB1 = destColour.Blue();
+ wxUint8 nR2 = initialColour.Red();
+ wxUint8 nG2 = initialColour.Green();
+ wxUint8 nB2 = initialColour.Blue();
+ wxUint8 nR, nG, nB;
+
+
+ //Radius
+ wxInt32 cx = rect.GetWidth() / 2;
+ wxInt32 cy = rect.GetHeight() / 2;
+ wxInt32 nRadius;
+ if (cx < cy)
+ nRadius = cx;
+ else
+ nRadius = cy;
+
+ //Offset of circle
+ wxInt32 nCircleOffX = circleCenter.x - (rect.GetWidth() / 2);
+ wxInt32 nCircleOffY = circleCenter.y - (rect.GetHeight() / 2);
+
+ for ( wxInt32 x = 0; x < rect.GetWidth(); x++ )
+ {
+ for ( wxInt32 y = 0; y < rect.GetHeight(); y++ )
+ {
+ //get color difference
+ wxInt32 nGradient = ((nRadius -
+ (wxInt32)sqrt(
+ pow((double)(x - cx - nCircleOffX), 2) +
+ pow((double)(y - cy - nCircleOffY), 2)
+ )) * 100) / nRadius;
+
+ //normalize Gradient
+ if (nGradient < 0 )
+ nGradient = 0;
+
+ //get dest colors
+ nR = nR1 + ((nR2 - nR1) * nGradient / 100);
+ nG = nG1 + ((nG2 - nG1) * nGradient / 100);
+ nB = nB1 + ((nB2 - nB1) * nGradient / 100);
+
+ //set the pixel
+ m_pen.SetColour(wxColour(nR,nG,nB));
+ DrawPoint(wxPoint(x + rect.GetLeft(), y + rect.GetTop()));
+ }
+ }
+ //return old pen color
+ m_pen.SetColour(oldPenColour);
+}
+
+/*
+Notes for wxWidgets DrawEllipticArcRot(...)
+
+wxDCBase::DrawEllipticArcRot(...) draws a rotated elliptic arc or an ellipse.
+It uses wxDCBase::CalculateEllipticPoints(...) and wxDCBase::Rotate(...),
+which are also new.
+
+All methods are generic, so they can be implemented in wxDCBase.
+DoDrawEllipticArcRot(...) is virtual, so it can be called from deeper
+methods like (WinCE) wxDC::DoDrawArc(...).
+
+CalculateEllipticPoints(...) fills a given list of wxPoints with some points
+of an elliptic arc. The algorithm is pixel-based: In every row (in flat
+parts) or every column (in steep parts) only one pixel is calculated.
+Trigonometric calculation (sin, cos, tan, atan) is only done if the
+starting angle is not equal to the ending angle. The calculation of the
+pixels is done using simple arithmetic only and should perform not too
+bad even on devices without floating point processor. I didn't test this yet.
+
+Rotate(...) rotates a list of point pixel-based, you will see rounding errors.
+For instance: an ellipse rotated 180 degrees is drawn
+slightly different from the original.
+
+The points are then moved to an array and used to draw a polyline and/or polygon
+(with center added, the pie).
+The result looks quite similar to the native ellipse, only e few pixels differ.
+
+The performance on a desktop system (Athlon 1800, WinXP) is about 7 times
+slower as DrawEllipse(...), which calls the native API.
+An rotated ellipse outside the clipping region takes nearly the same time,
+while an native ellipse outside takes nearly no time to draw.
+
+If you draw an arc with this new method, you will see the starting and ending angles
+are calculated properly.
+If you use DrawEllipticArc(...), you will see they are only correct for circles
+and not properly calculated for ellipses.
+
+Peter Lenhard
+p.lenhard@t-online.de
+*/
+
+#ifdef __WXWINCE__
+void wxDCBase::DoDrawEllipticArcRot( wxCoord x, wxCoord y,
+ wxCoord w, wxCoord h,
+ double sa, double ea, double angle )
+{
+ wxList list;
+
+ CalculateEllipticPoints( &list, x, y, w, h, sa, ea );
+ Rotate( &list, angle, wxPoint( x+w/2, y+h/2 ) );
+
+ // Add center (for polygon/pie)
+ list.Append( (wxObject*) new wxPoint( x+w/2, y+h/2 ) );
+
+ // copy list into array and delete list elements
+ int n = list.Number();
+ wxPoint *points = new wxPoint[n];
+ int i = 0;
+ wxNode* node = 0;
+ for ( node = list.First(); node; node = node->Next(), i++ )
+ {
+ wxPoint *point = (wxPoint *)node->Data();
+ points[i].x = point->x;
+ points[i].y = point->y;
+ delete point;
+ }
+
+ // first draw the pie without pen, if necessary
+ if( GetBrush() != *wxTRANSPARENT_BRUSH )
+ {
+ wxPen tempPen( GetPen() );
+ SetPen( *wxTRANSPARENT_PEN );
+ DoDrawPolygon( n, points, 0, 0 );
+ SetPen( tempPen );
+ }
+
+ // then draw the arc without brush, if necessary
+ if( GetPen() != *wxTRANSPARENT_PEN )
+ {
+ // without center
+ DoDrawLines( n-1, points, 0, 0 );
+ }
+
+ delete [] points;
+
+} // DrawEllipticArcRot
+
+void wxDCBase::Rotate( wxList* points, double angle, wxPoint center )
+{
+ if( angle != 0.0 )
+ {
+ double pi(M_PI);
+ double dSinA = -sin(angle*2.0*pi/360.0);
+ double dCosA = cos(angle*2.0*pi/360.0);
+ for ( wxNode* node = points->First(); node; node = node->Next() )
+ {
+ wxPoint* point = (wxPoint*)node->Data();
+
+ // transform coordinates, if necessary
+ if( center.x ) point->x -= center.x;
+ if( center.y ) point->y -= center.y;
+
+ // calculate rotation, rounding simply by implicit cast to integer
+ int xTemp = point->x * dCosA - point->y * dSinA;
+ point->y = point->x * dSinA + point->y * dCosA;
+ point->x = xTemp;
+
+ // back transform coordinates, if necessary
+ if( center.x ) point->x += center.x;
+ if( center.y ) point->y += center.y;
+ }
+ }
+}
+
+void wxDCBase::CalculateEllipticPoints( wxList* points,
+ wxCoord xStart, wxCoord yStart,
+ wxCoord w, wxCoord h,
+ double sa, double ea )
+{
+ double pi = M_PI;
+ double sar = 0;
+ double ear = 0;
+ int xsa = 0;
+ int ysa = 0;
+ int xea = 0;
+ int yea = 0;
+ int sq = 0;
+ int eq = 0;
+ bool bUseAngles = false;
+ if( w<0 ) w = -w;
+ if( h<0 ) h = -h;
+ // half-axes
+ wxCoord a = w/2;
+ wxCoord b = h/2;
+ // decrement 1 pixel if ellipse is smaller than 2*a, 2*b
+ int decrX = 0;
+ if( 2*a == w ) decrX = 1;
+ int decrY = 0;
+ if( 2*b == h ) decrY = 1;
+ // center
+ wxCoord xCenter = xStart + a;
+ wxCoord yCenter = yStart + b;
+ // calculate data for start and end, if necessary
+ if( sa != ea )
+ {
+ bUseAngles = true;
+ // normalisation of angles
+ while( sa<0 ) sa += 360;
+ while( ea<0 ) ea += 360;
+ while( sa>=360 ) sa -= 360;
+ while( ea>=360 ) ea -= 360;
+ // calculate quadrant numbers
+ if( sa > 270 ) sq = 3;
+ else if( sa > 180 ) sq = 2;
+ else if( sa > 90 ) sq = 1;
+ if( ea > 270 ) eq = 3;
+ else if( ea > 180 ) eq = 2;
+ else if( ea > 90 ) eq = 1;
+ sar = sa * pi / 180.0;
+ ear = ea * pi / 180.0;
+ // correct angle circle -> ellipse
+ sar = atan( -a/(double)b * tan( sar ) );
+ if ( sq == 1 || sq == 2 ) sar += pi;
+ ear = atan( -a/(double)b * tan( ear ) );
+ if ( eq == 1 || eq == 2 ) ear += pi;
+ // coordinates of points
+ xsa = xCenter + a * cos( sar );
+ if( sq == 0 || sq == 3 ) xsa -= decrX;
+ ysa = yCenter + b * sin( sar );
+ if( sq == 2 || sq == 3 ) ysa -= decrY;
+ xea = xCenter + a * cos( ear );
+ if( eq == 0 || eq == 3 ) xea -= decrX;
+ yea = yCenter + b * sin( ear );
+ if( eq == 2 || eq == 3 ) yea -= decrY;
+ } // if iUseAngles
+ // calculate c1 = b^2, c2 = b^2/a^2 with a = w/2, b = h/2
+ double c1 = b * b;
+ double c2 = 2.0 / w;
+ c2 *= c2;
+ c2 *= c1;
+ wxCoord x = 0;
+ wxCoord y = b;
+ long x2 = 1;
+ long y2 = y*y;
+ long y2_old = 0;
+ long y_old = 0;
+ // Lists for quadrant 1 to 4
+ wxList pointsarray[4];
+ // Calculate points for first quadrant and set in all quadrants
+ for( x = 0; x <= a; ++x )
+ {
+ x2 = x2+x+x-1;
+ y2_old = y2;
+ y_old = y;
+ bool bNewPoint = false;
+ while( y2 > c1 - c2 * x2 && y > 0 )
+ {
+ bNewPoint = true;
+ y2 = y2-y-y+1;
+ --y;
+ }
+ // old y now to big: set point with old y, old x
+ if( bNewPoint && x>1)
+ {
+ int x1 = x - 1;
+ // remove points on the same line
+ pointsarray[0].Insert( (wxObject*) new wxPoint( xCenter + x1 - decrX, yCenter - y_old ) );
+ pointsarray[1].Append( (wxObject*) new wxPoint( xCenter - x1, yCenter - y_old ) );
+ pointsarray[2].Insert( (wxObject*) new wxPoint( xCenter - x1, yCenter + y_old - decrY ) );
+ pointsarray[3].Append( (wxObject*) new wxPoint( xCenter + x1 - decrX, yCenter + y_old - decrY ) );
+ } // set point
+ } // calculate point
+
+ // Starting and/or ending points for the quadrants, first quadrant gets both.
+ pointsarray[0].Insert( (wxObject*) new wxPoint( xCenter + a - decrX, yCenter ) );
+ pointsarray[0].Append( (wxObject*) new wxPoint( xCenter, yCenter - b ) );
+ pointsarray[1].Append( (wxObject*) new wxPoint( xCenter - a, yCenter ) );
+ pointsarray[2].Append( (wxObject*) new wxPoint( xCenter, yCenter + b - decrY ) );
+ pointsarray[3].Append( (wxObject*) new wxPoint( xCenter + a - decrX, yCenter ) );
+
+ // copy quadrants in original list
+ if( bUseAngles )
+ {
+ // Copy the right part of the points in the lists
+ // and delete the wxPoints, because they do not leave this method.
+ points->Append( (wxObject*) new wxPoint( xsa, ysa ) );
+ int q = sq;
+ bool bStarted = false;
+ bool bReady = false;
+ bool bForceTurn = ( sq == eq && sa > ea );
+ while( !bReady )
+ {
+ for( wxNode *node = pointsarray[q].First(); node; node = node->Next() )
+ {
+ // once: go to starting point in start quadrant
+ if( !bStarted &&
+ (
+ ( (wxPoint*) node->Data() )->x < xsa+1 && q <= 1
+ ||
+ ( (wxPoint*) node->Data() )->x > xsa-1 && q >= 2
+ )
+ )
+ {
+ bStarted = true;
+ }
+
+ // copy point, if not at ending point
+ if( bStarted )
+ {
+ if( q != eq || bForceTurn
+ ||
+ ( (wxPoint*) node->Data() )->x > xea+1 && q <= 1
+ ||
+ ( (wxPoint*) node->Data() )->x < xea-1 && q >= 2
+ )
+ {
+ // copy point
+ wxPoint* pPoint = new wxPoint( *((wxPoint*) node->Data() ) );
+ points->Append( (wxObject*) pPoint );
+ }
+ else if( q == eq && !bForceTurn || ( (wxPoint*) node->Data() )->x == xea)
+ {
+ bReady = true;
+ }
+ }
+ } // for node
+ ++q;
+ if( q > 3 ) q = 0;
+ bForceTurn = false;
+ bStarted = true;
+ } // while not bReady
+ points->Append( (wxObject*) new wxPoint( xea, yea ) );
+
+ // delete points
+ for( q = 0; q < 4; ++q )
+ {
+ for( wxNode *node = pointsarray[q].First(); node; node = node->Next() )
+ {
+ wxPoint *p = (wxPoint *)node->Data();
+ delete p;
+ }
+ }
+ }
+ else
+ {
+ // copy whole ellipse, wxPoints will be deleted outside
+ for( wxNode *node = pointsarray[0].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[1].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[2].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ for( node = pointsarray[3].First(); node; node = node->Next() )
+ {
+ wxObject *p = node->Data();
+ points->Append( p );
+ }
+ } // not iUseAngles
+} // CalculateEllipticPoints
+
+#endif
+
projects / wxWidgets.git / blobdiff