PolyLine and autoscrolling canvas
in [MFC]
|
From: Luigino on 18 Feb 2010 06:47 Hi again, I was trying some testing and I figured also if I set Y interval to 32766 or 65534 after BitBlt it shows as like a little line instead to fill the whole client, in fact if I do, after assigning to memory dc the mapping: CRect memdc_rect; memDC.GetClipBox(&memdc_rect); I get something like: top=65534 bottom=0 left=613 right=0 when the top should be 380 and 65534 is only the scale... plus the grid goes left to right instead to be right to left... any hint?... Thanks a lot Ciao Luigi
From: Stephen Myers on 19 Feb 2010 11:31 Luigino wrote: > HI Joe, > > I figured to draw correctly horizontal scrolling having origin point > at right bottom so the graphic starts from right to left but it > flickers. > So I created a memory DC with CreateCompatibleDC but looks like memory > dc doesn't behave really the same about mapping as you can see in this > code: > > void CMyDLL::PrepareDC(CDC & dc, CRect rc) > { > dc.SetMapMode(MM_ANISOTROPIC); > > switch (iGraphType) > { > case GRAPH_BARS: > { > //dc.Rectangle() > } > break; > > case GRAPH_LINES: > { > dc.SetWindowExt(-rc.Width(), iYMaxInterval); > dc.SetViewportExt(rc.Width(), -rc.Height()); > dc.SetWindowOrg(rc.Width(), 0); > dc.SetViewportOrg(0, rc.Height()); > } > break; > > default: > break; > } > } > > void CMyDLL::DoDrawing(CDC & dc, CRect rc) > { > // *********** graphic component *********** > // based on choice of graph type > CPen qPolylinePen(PS_SOLID, 1, RGB(0, 255, 0)); > > switch (iGraphType) > { > case GRAPH_BARS: > { > //dc.Rectangle() > } > break; > > case GRAPH_LINES: > { > if (vtPoints.capacity() == 1) > { > > for (int i=vtPoints[0].size()-1;i>=0;i--) { > vtToDraw[0].at(i).x = vtPoints[0].at(i).x; > vtToDraw[0].at(i).y = ( (vtPoints[0].at(i).y > 0) ? > vtPoints[0].at(i).y : 86 ); > } > > dc.SelectObject(qPolylinePen); > vectfPoints* pointsline = &vtToDraw[0]; > dc.Polyline(&(*pointsline)[0], (int)pointsline->size()); > //dc.PolyPolyline() > } > } > break; > > default: > break; > } > GDI_FLUSH(); > } > > void CNyDLL::OnPaint() > { > CPaintDC dc(this); // device context for painting > > CRect r; > dc.GetClipBox(&r); > dc.SetBkColor(RGB(0,0,0)); > > int saveobject = dc.SaveDC(); > > if(bSetDraw) > { > // ********** Background *********** > // Grid > if (firstTime) { > PrepareDC(dc, r); > firstTime = FALSE; > } > > CDC memDC; > CBitmap bBitmap; // Offscreen bitmap > CBitmap* bOldBitmap; // bitmap originally found > > memDC.CreateCompatibleDC(&dc); > bBitmap.CreateCompatibleBitmap(&dc, r.Width(), r.Height()); > bOldBitmap = memDC.SelectObject(&bBitmap); > > memDC.FillSolidRect(r, dc.GetBkColor()); > memDC.SetMapMode(dc.GetMapMode()); > memDC.SetWindowExt(dc.GetWindowExt()); > memDC.SetViewportExt(dc.GetViewportExt()); > memDC.SetWindowOrg(dc.GetWindowOrg()); > memDC.SetViewportOrg(dc.GetViewportOrg()); > > if (bActivateGrid) > { > CPen qLinePen(PS_SOLID, 0, RGB(0,139,0)); > memDC.SelectObject(qLinePen); > > // Grid - Horizontal lines > for(int y = 0; y < r.bottom; y += (int)12) { > /* scan y */ > memDC.MoveTo(r.left, y); > memDC.LineTo(r.right, y); > } /* scan y */ > > // Grid - Vertical lines > for(int x = 0 - (int)gridOffset; x <= r.right - (int)gridOffset; x > += (int)12 ) { > /* scan x */ > memDC.MoveTo(x, r.top); > memDC.LineTo(x, r.bottom); > } /* scan x */ > } > > DoDrawing(memDC, r); > > // Copy the offscreen bitmap onto the screen. > dc.BitBlt(r.left, r.top, r.Width(), r.Height(), > &memDC, r.left, r.top, SRCCOPY); > > //Swap back the original bitmap. > memDC.SelectObject(bOldBitmap); > } > //} > dc.RestoreDC(saveobject); > } > > > because the PolyLine now starts from left to rigtht and on the other > hand it looks like it doesn't apply correctly the Y interval... > Did I maybe forgot something or is there a possible alternative to > avoid flickering if CreateCompatibleDC isn't the right solution for > this?... > > Thanks, > Ciao > Luigi Luigi, Assume that anytime a DC is created or passed as a parameter, that it is in MM_TEXT. Your mapping is only valid for the life of the object. In particular, your OnPaint() assumes (incorrectly) that the mapping done in PrepareDC is only required one time. Each time you create a DC you must do the mappings. Having said that, why bother changing the mapping of DC at all? The CDC that you want to map is memDC. So call PrepareDC(memDC, r) each time through. You will then want to memDC.SetMapMode(MM_TEXT) immediately prior to doing the bitblt. Steve
From: Luigino on 19 Feb 2010 12:56 HI Steve! > Having said that, why bother changing the mapping of DC at all? The CDC > that you want to map is memDC. So call PrepareDC(memDC, r) each time > through. First, thanks for the answer...in fact mapping directly the memDC is like saving the operation of GetMapMode... > You will then want to memDC.SetMapMode(MM_TEXT) immediately prior to > doing the bitblt. This is completely new to me.... could you explain me a bit why I should map to MM_TEXT before to do BitBlt?... when I didn't used CreateCompatibleDC and drawn directly on DC I didn't needed for mappnig back to MM_TEXT and it drawn correctly as I wanted, in the specific graphic from right to left and stuff... Thanks again Ciao Luigi
From: Stephen Myers on 19 Feb 2010 13:39 Luigino wrote: > HI Steve! > >> Having said that, why bother changing the mapping of DC at all? The CDC >> that you want to map is memDC. So call PrepareDC(memDC, r) each time >> through. > > First, thanks for the answer...in fact mapping directly the memDC is > like saving the operation of GetMapMode... > >> You will then want to memDC.SetMapMode(MM_TEXT) immediately prior to >> doing the bitblt. > > This is completely new to me.... could you explain me a bit why I > should map to MM_TEXT before to do BitBlt?... > when I didn't used CreateCompatibleDC and drawn directly on DC I > didn't needed for mappnig back to MM_TEXT and it drawn correctly as I > wanted, in the specific graphic from right to left and stuff... > > Thanks again > Ciao > Luigi The default map mode for a CDC is MM_TEXT. The CDC you get when you do the CPaintDC is in this mode. The only drawing that you will do in the dc is the bitblt call at the very end. So long as the bitmaps are sized correctly (which is the case), your bitblt can be in raw pixels with no mapping modes involved. It is only for the bitblt that you would do the mapping back to MM_TEXT. The other way of accomplishing the same thing is to apply the scaling to both CDCs. The potential problem is calculating in logical units where to bitblt. If you use MM_TEXT the bitblt becomes trivial using 0,0 and r.width(),r.height() Steve
From: Joseph M. Newcomer on 20 Feb 2010 12:05
See below... On Mon, 15 Feb 2010 16:56:46 -0800 (PST), Luigino <npuleio(a)rocketmail.com> wrote: >HI Joe, > >> ***** >> As far as I know, custom controls can only be added as OCX controls. �I've never done >> this, because I don't develop OCX controls. >> >> Note that as an OCX control, there's a fair amount of power available; for example, you >> don't have to create a window because the control is its own window when you place it in >> the dialog editor. >> **** > >But also DLL can contains controls as far as I know... **** Any DLL can contain controls. But to add it to the "custom controls" library in VS, it has to be an OCX. So if you were asking about "custom controls" in general, any DLL works. But if you want to add "custom controls" that have first-class support in VS, they have to be OCXs. **** > >But I figured a thing: while I draw with MM_ANISOTROPIC first drawing >grid, then mapping the MM_ANISOTROPIC inverting coordinates, then >drawing the PolyLine it works, even if flickering... > >If I call CreateCompatibleDC and SelectObject **** SelectObject of what? Presumably, a compatible bitmap, or the DC has no value. **** >to have a memory dc copy >then mapping and drawing polyline doesn't work.... if a memory copy DC >is just a copy of the device, shouldn't just behave as like as on >CPaintDC device context?.... **** Only if it has a compatible bitmap of the same dimension selected in. joe **** > >Thanks >Ciao, >Luigi Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm |