How to make faster WM_PAINT event

Question

0.00/5 (No votes)

See more:

Hi,

I have created a MFC application for drawing graphs. For this i had called Invalidate rect function for a particular region to repaint every 50ms(Written code in OnPaint event). In this after some time process get slowed due to frequent calling of InvalidateRect how to overcome this issue.

Code:

C++

// This is portion of drawing graph which i had returned in OnPaint event.
void CurveWindow1::OnPaint()
{
	if (m_Graph.m_bSetingFailed)
		return;

	global.UpdateDebugInfo(3);

	CPaintDC dc(this);

	CRect rect;
	GetClientRect(rect);

	m_Graph.BeginDraw(dc.m_hDC, rect);	
	m_Graph.RecalcRects(rect, 2);
	m_Graph.Axes(global.graph1LineColor, 2);
	m_Graph.DrawRealTimeLines(FALSE);
	//m_Graph.DrawBoundary(InitGraph1LineColor, 1);
	m_Graph.EndDraw(dc.m_hDC);	
}

//This will Call OnPaint message for the required area.
void CRealTime::Redraw(HWND hWnd)
{
	RECT rt;
	rt.left   = m_Rect.left - 1;
	rt.top    = m_Rect.top - 1;
	rt.right  = m_Rect.right - 1;
	rt.bottom = m_Rect.bottom - 1;
	::InvalidateRect(hWnd, &rt, FALSE);	
}

SQL

I had added time log for each function and find out that Polyline function is taking too much time. It takes nearly 80ms to plot 15000 points.
Is there some other function to make faster.

Posted 24-Dec-12 0:21am

sundarpalaniappan

Updated 26-Dec-12 2:33am

v3

Add a Solution

Comments

CPallini 24-Dec-12 6:41am

why do you need to repaint after 50 ms?

sundarpalaniappan 24-Dec-12 7:04am

I need to refresh the window every 50ms to show the updated graph, not after 50ms. So paint event will be called every 50ms when i call InvalidateRect function

CPallini 24-Dec-12 7:53am

That's not a graph, that's a movie!
InvalidateRect, itself doesn't slow down the system (UpdateWindow does). Could you please show us the relavant code?

sundarpalaniappan 24-Dec-12 8:02am

This is my coding for OnPaint and function for firing OnPaint event

// This is portion of drawing graph which i had returned in OnPaint event.
void CurveWindow1::OnPaint()
{
if (m_Graph.m_bSetingFailed)
return;

global.UpdateDebugInfo(3);

CPaintDC dc(this);

CRect rect;
GetClientRect(rect);

m_Graph.BeginDraw(dc.m_hDC, rect);
m_Graph.RecalcRects(rect, 2);
m_Graph.Axes(global.graph1LineColor, 2);
m_Graph.DrawRealTimeLines(FALSE);
//m_Graph.DrawBoundary(InitGraph1LineColor, 1);
m_Graph.EndDraw(dc.m_hDC);
}

//This will Call OnPaint message for the required area.
void CRealTime::Redraw(HWND hWnd)
{
RECT rt;
rt.left = m_Rect.left - 1;
rt.top = m_Rect.top - 1;
rt.right = m_Rect.right - 1;
rt.bottom = m_Rect.bottom - 1;
::InvalidateRect(hWnd, &rt, FALSE);
}

sundarpalaniappan 24-Dec-12 8:02am

I will call the above Redraw function for every 50ms

Richard MacCutchan 24-Dec-12 8:46am

If you are concerned about speed, then you should stop using MFC and code in the base Win32 functions. MFC tends to add a lot of extra processing just managing objects which is probably not necessary for fast drawing.

1 solution

Add a Solution

Add your solution here

Treat my content as plain text, not as HTML

Preview 0

…

Existing Members

Sign in to your account

...or Join us

Download, Vote, Comment, Publish.

Your Email
Password
Forgot your password?

Your Email
This email is in use. Do you need your password?
Optional Password

I have read and agree to the Terms of Service and Privacy Policy
Please subscribe me to the CodeProject newsletters

When answering a question please:

Read the question carefully.
Understand that English isn't everyone's first language so be lenient of bad spelling and grammar.
If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome.
Don't tell someone to read the manual. Chances are they have and don't get it. Provide an answer or move on to the next question.

Let's work to help developers, not make them feel stupid.

This content, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

CPallini · Answer 1 · 2012-12-24T02:17:00

I think you have the following options:

Make the drawing code faster (if you can, optimize it).
Update only the needed part of the graph (if you have this option).
Slow down the refresh time.

I guess the option (3) is the only one really viable. You may keep the correctness of the graphic representation (skipping 'intermediate' frames).

Option (2) could be viable if, for instance, your graph represents y=f(x) and x 'doesn't move too much' with each repaint. Then you may scroll left (this operation should be faster then recomputing and drawing) a big part of the graph and recompute (and draw) just a small part of it.