Discuss: rubber banding - erase a line
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I try to draw a line with mouse moves, similar to line-tool of MS Paint-Brush - see my previous post any idea to draw this line for more. http://www.codeproject.com/script/comments/forums.asp?forumid=1647&fr=151[^] I have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?). //--- my MFC code is bellow, //--- I only copy key code for idea. CPoint ptStart,ptEnd; BOOL bDraw=0; OnLButtonDown(UINT nFlags, CPoint pt) { bDraw=1; ptStart=ptEnd=pt; } void OnPaint() { CPaintDC dc(this); if(bDraw) { CPen penB(PS_SOLID,10,RGB(0,0,0)); CPen*pPenOld=dc.SelectObject(&penB); dc.MoveTo(ptStart); dc.LineTo(ptEnd); dc.SelectObject(pPenOld); } } void OnMouseMove(UINT nFlags, CPoint pt) { if(bDraw) { CPoint ptT=ptEnd; ptEnd=pt; //erase RenewLine(ptT); //display RenewLine(pt); } } RenewLine(CPoint pt) { CDC*pDC=GetDC(); CPen penNull(PS_NULL,10,RGB(0,0,0)); CPen*pPenOld=pDC->SelectObject(&penNull); UINT u=R2_NOT; // UINT u=R2_XORPEN; int iROP=pDC->SetROP2(u); pDC->MoveTo(ptStart); pDC->LineTo(pt); pDC->SetROP2(iROP); pDC->SelectObject(pPenOld); ReleaseDC(pDC); } //ignore mouse up and capure etc. Result is none of lines can be seen, what is wrong?
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I try to draw a line with mouse moves, similar to line-tool of MS Paint-Brush - see my previous post any idea to draw this line for more. http://www.codeproject.com/script/comments/forums.asp?forumid=1647&fr=151[^] I have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?). //--- my MFC code is bellow, //--- I only copy key code for idea. CPoint ptStart,ptEnd; BOOL bDraw=0; OnLButtonDown(UINT nFlags, CPoint pt) { bDraw=1; ptStart=ptEnd=pt; } void OnPaint() { CPaintDC dc(this); if(bDraw) { CPen penB(PS_SOLID,10,RGB(0,0,0)); CPen*pPenOld=dc.SelectObject(&penB); dc.MoveTo(ptStart); dc.LineTo(ptEnd); dc.SelectObject(pPenOld); } } void OnMouseMove(UINT nFlags, CPoint pt) { if(bDraw) { CPoint ptT=ptEnd; ptEnd=pt; //erase RenewLine(ptT); //display RenewLine(pt); } } RenewLine(CPoint pt) { CDC*pDC=GetDC(); CPen penNull(PS_NULL,10,RGB(0,0,0)); CPen*pPenOld=pDC->SelectObject(&penNull); UINT u=R2_NOT; // UINT u=R2_XORPEN; int iROP=pDC->SetROP2(u); pDC->MoveTo(ptStart); pDC->LineTo(pt); pDC->SetROP2(iROP); pDC->SelectObject(pPenOld); ReleaseDC(pDC); } //ignore mouse up and capure etc. Result is none of lines can be seen, what is wrong?
Hi includeh10
includeh10 wrote:
have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?).
I wrote an application that displays multiple models (as boxes) and treats connections between them as rubber bands. I used InvalidateRect(), and although I acknowledge that the technique redraws more of the image than is necessary, I wouldn't go so far as to call it incorrect in concept. It does the job and is plenty fast enough to keep pace with mouse moves, even when there are many connections to redraw. It also seems to be the 'windows way'. I'm not sure how to get parts of the view updated without using invalidation. I had some problems with flickering background rectangles in early versions, but solved this by using a memory device context and blitting to the view's device context. Best Regards Cliff
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Hi includeh10
includeh10 wrote:
have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?).
I wrote an application that displays multiple models (as boxes) and treats connections between them as rubber bands. I used InvalidateRect(), and although I acknowledge that the technique redraws more of the image than is necessary, I wouldn't go so far as to call it incorrect in concept. It does the job and is plenty fast enough to keep pace with mouse moves, even when there are many connections to redraw. It also seems to be the 'windows way'. I'm not sure how to get parts of the view updated without using invalidation. I had some problems with flickering background rectangles in early versions, but solved this by using a memory device context and blitting to the view's device context. Best Regards Cliff
if u have an image in size of 2000x2000 pixels at background, you will know what happends by calling InvaliadateRect(0) - even 0 is set as a small rect. incorrect! definitely.
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Hi includeh10
includeh10 wrote:
have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?).
I wrote an application that displays multiple models (as boxes) and treats connections between them as rubber bands. I used InvalidateRect(), and although I acknowledge that the technique redraws more of the image than is necessary, I wouldn't go so far as to call it incorrect in concept. It does the job and is plenty fast enough to keep pace with mouse moves, even when there are many connections to redraw. It also seems to be the 'windows way'. I'm not sure how to get parts of the view updated without using invalidation. I had some problems with flickering background rectangles in early versions, but solved this by using a memory device context and blitting to the view's device context. Best Regards Cliff
I have got it work! you are 100% incorrect!
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I have got it work! you are 100% incorrect!
Oh well, it's good to score 100% now and again - it's normally just an aspirational target. :doh: I'm sorry that my reply was unhelpful and glad you have solved the problem. What's the key to updating the view without invalidation? Best Regards Cliff
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I try to draw a line with mouse moves, similar to line-tool of MS Paint-Brush - see my previous post any idea to draw this line for more. http://www.codeproject.com/script/comments/forums.asp?forumid=1647&fr=151[^] I have downloaded several samples, but all of them are incorrect in basic concept, because they all call update function InvalidateRect(0), RedrawWindow(0) etc - if so, there is no neccessary to use Rubber band tech, as my understanding, rubber banding should only update requied pixels (such as a line) and without touching others (right?). //--- my MFC code is bellow, //--- I only copy key code for idea. CPoint ptStart,ptEnd; BOOL bDraw=0; OnLButtonDown(UINT nFlags, CPoint pt) { bDraw=1; ptStart=ptEnd=pt; } void OnPaint() { CPaintDC dc(this); if(bDraw) { CPen penB(PS_SOLID,10,RGB(0,0,0)); CPen*pPenOld=dc.SelectObject(&penB); dc.MoveTo(ptStart); dc.LineTo(ptEnd); dc.SelectObject(pPenOld); } } void OnMouseMove(UINT nFlags, CPoint pt) { if(bDraw) { CPoint ptT=ptEnd; ptEnd=pt; //erase RenewLine(ptT); //display RenewLine(pt); } } RenewLine(CPoint pt) { CDC*pDC=GetDC(); CPen penNull(PS_NULL,10,RGB(0,0,0)); CPen*pPenOld=pDC->SelectObject(&penNull); UINT u=R2_NOT; // UINT u=R2_XORPEN; int iROP=pDC->SetROP2(u); pDC->MoveTo(ptStart); pDC->LineTo(pt); pDC->SetROP2(iROP); pDC->SelectObject(pPenOld); ReleaseDC(pDC); } //ignore mouse up and capure etc. Result is none of lines can be seen, what is wrong?
didn't i ever already asked you to post your code sample within
<pre></pre>tags when you ask or answer something ? :suss:
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