C / C++ / MFC

31-Oct-06 5:59

Hi everyone,
I made a program which can draw some graphs using memory device, now I wanna print the graph. Unfortunately what I did doesnt work! In print preview, the graph is reversed and the size can't be controled which means the graph is not magnified proportionally.
could you please tell me how can I make it? Thank you very much and look forward to hearing from you!

In OnDraw function, I coded as follow:

void CMyView::OnDraw(CDC* pDC)<br />
{<br />
<pre><br />
        CMyDoc* pDoc = GetDocument();<br />
	ASSERT_VALID(pDoc);<br />
	// TODO: add draw code for native data here<br />
	CBitmap* pOldBitmap = m_pMemDC->SelectObject(m_pBitmap);<br />
<br />
	if(pDC->IsPrinting())<br />
	{<br />
		pDC->SetMapMode(MM_LOENGLISH);<br />
		pDC->StretchBlt(0,-950,pDC->GetDeviceCaps(LOGPIXELSX),pDC->GetDeviceCaps <br />
                       (LOGPIXELSY),m_pMemDC, 0,0, 6*m_nMaxX/5,m_nMaxY,SRCCOPY);<br />
<br />
	}<br />
	else<br />
		pDC->BitBlt(0,0,m_nMaxX,m_nMaxY, m_pMemDC,0,0,SRCCOPY);<br />
<br />
	m_pMemDC->SelectObject(pOldBitmap);<br />
</pre>	}<br />

where,

m_nMaxX = GetSystemMetrics(SM_CXSCREEN);
m_nMaxY = GetSystemMetrics(SM_CYSCREEN);

used for defining the boudary of drawing

bob1697231-Oct-06 6:52

An old post of mine. hope it helps[^]

31-Oct-06 6:52

hongmuer31-Oct-06 7:50

31-Oct-06 7:50

thanks for your help.
Acutally, my program wants to show the graph without scrollview, so I get the m_nMaxX and m_nMaxY and try to draw the graph dynamically according to the resolution of the computer. On the other hand, I use the memory device to draw the graph, so in "OnDraw" function, the function "StretchBlt" and "BitBlt" are used seperately for printing and screen view. I think that is the point, and that is what confuses me for a long time. How can I get the correct porporation when I use "StretchBlt" function for print preview?
Hope you can help me on this issue. thanks again!

bob1697231-Oct-06 8:31

31-Oct-06 8:31

My intent was to demonstrate MM_ISOTROPIC which allows your document to be defined in some arbitrary world coordinate system. (i.e 100x200, 1200x2000, 3000x3000, etc...). Your graphics don't have to be shuffled around or resized when printing to different devices or viewed via the screen. Instead you adjust the ViewPort extent to adjust the output to fit the device you are rendering to. Remove the scrollview stuff if you need.

Your blit's should work just fine. Don't lock yourself into a mapping mode like MM_LOENGLISH, MM_HIMETRIC, etc... since your going to have to adjust your output anyway to fit different devices in a proportional manner. MM_ISOTROPIC will preserve your aspect ratio when MM_ANISOTRIPC will allow you to have any aspect ratio you want. However, MM_ANISOTROPIC will distort output at any ratio than the original so it is of little practical value in production apps unless your intent is to distort the output.

Try this, make a document that is 1000x1000. Do your blitting so your image is at some location in this grid and try the sample. You will see that the image is always in the same relative position to the document and any other drawing output in OnDraw. You don't need to change the position of the items being drawn. The sample will ensure it is adjusted for you.

I hope I'm understanding the problem correctly. If not, I apologize

bob1697231-Oct-06 10:56

31-Oct-06 10:56

A simpler sample would be to first create an app with the sample code in the appropriate places. In the OnDraw, draw a simple line, rectangle, or some drawing primitive with coordinates that fall within the documents bounding box that is defined in the sample.

Resize the window, do a print preview in portrait, landscape, set different paper sizes before the print preview, change the screen resolution. You'll see how the document always fits itself.

Then once you see what it's doing, then try putting the blitting code in the OnDraw. All the code that determines if your printing or not is in the OnPrepareDC method so you only need the code for the blitting in the OnDraw.

hongmuer1-Nov-06 15:50

1-Nov-06 15:50

Thank you very much
I will try to understand what you taught me and then more questions Smile | :)

hongmuer1-Nov-06 16:30

1-Nov-06 16:30

I added following codes in OnDraw function

	if(pDC->IsPrinting())<br />
	{<br />
<pre>pDC->SetMapMode(MM_ISOTROPIC);<br />
pDC->StretchBlt(100,-100,pDC->GetDeviceCaps(HORZRES),-pDC->GetDeviceCaps(VERTRES),<br />
		m_pMemDC,0,0, 6*m_nMaxX/5,m_nMaxY,SRCCOPY);<br />
</pre>}

and in OnPrepareDC function, codes has been added as follow:

	if(pDC->IsPrinting())<br />
	{<br />
<pre>pDC->SetMapMode(MM_ISOTROPIC);<br />
		<br />
int nPageWidth = pDC->GetDeviceCaps(PHYSICALWIDTH); <br />
int nPageHeight = pDC->GetDeviceCaps(PHYSICALHEIGHT); <br />
		<br />
CSize size = CSize(nPageWidth, nPageHeight); <br />
pDC->SetWindowExt(size);<br />
		<br />
pDC->SetViewportExt(pDC->GetDeviceCaps(HORZRES),-pDC->GetDeviceCaps(VERTRES));</pre><br />
}

Now, I can get the correct view in print preview!
Thank you very much!
By the way, I think I am still confused in print issue, such as mapping, the difference between the window and view, etc. Could you please recommend some literatures for me?

bob1697210-Nov-06 19:26