Mscomm and draw chart

[Dave Kreskowiak]

First, you're doing some drawing in a Timer event. Don't! Any drawing you do to the screen should be done only in the Paint event. Second, you're using a Timer out of the ToolBox?? This passes its Timer Tick as an event, which is routed through the app's message pump. This means that other events can pile up VERY rapidly before the Timer Tick event, such as moving the form. Using an event based Timer isn't really a good idea. Also, 100ms doesn't leave your code very much time to do anything. Painting can take an eternity (>100ms) if not done correctly. While you're collecting data, draw to a Bitmap. Then you don't have to worry about painting, and repainting, old data continously. You paint your data once on the Bitmap and it'll be persisted between Paint events. Dave Kreskowiak Microsoft MVP - Visual Basic

[codeadair]

Thank you for your reply heartly! Well.i will try to do some changes as follow: 1> take the drawing action out of timer event 2> I havn't drawn graphics to bitmap before.but i will try. By the way.what does this sentence mean?

Dave Kreskowiak wrote:

you're using a Timer out of the ToolBox??

I am using the timer control from toolbox.it is a system.timer but windows.forms.timer. ICQ:258-235-734 MSN:msnadair@hotmail.com

[Dave Kreskowiak]

codeadair wrote:

I am using the timer control from toolbox.it is a system.timer but windows.forms.timer.

This is the Timer I was asking about. It's not the most accurate and it's event can be bogged down by other events the form has to process. Dave Kreskowiak Microsoft MVP - Visual Basic

[codeadair]

I agree with you. And now i am using doublebuffer method.It is really very useful . But it is going on.and now i have to work off. I believe i could do well to resolve the problem with your help. Thank you very much for you help.Please follow the problem. By the way.what's your time now? ICQ:258-235-734 MSN:msnadair@hotmail.com

[Dave Kreskowiak]

codeadair wrote:

By the way.what's your time now?

To you, it's comming up on Saturday. I'm still on Friday morning. Dave Kreskowiak Microsoft MVP - Visual Basic -- modified at 9:51 Friday 30th June, 2006

[codeadair]

Dave Kreskowiak wrote:

Draw to a Bitmap object that same size as the panel. Set the BackgroundImage property of the panel to the Bitmap. now, when you draw on the Bitmap, just call Refresh on the Panel.

Yes.I just do as you day. But i find a problem.when i use g.ScaleTransform(xscaletran, yscaletran) method.And then refresh the panel:me.panel1.refresh. it will take no effect.why?Have i need to redraw all datas? ICQ:258-235-734 MSN:msnadair@hotmail.com

[Dave Kreskowiak]

Where did the Graphics object (g) come from?? Dave Kreskowiak Microsoft MVP - Visual Basic

[codeadair]

Dave Kreskowiak wrote:

Where did the Graphics object (g) come from??

Graphics object (g) is a form variant.look here: dim bmp as bitmap=new bitmap(800,600) dim g as graphics=graphics.fromimage(bmp) Maybe you could read my another forum question named "graphics.scaletransform() method".it describes the question clearly. Thank you for you reply heartly! ICQ:258-235-734 MSN:msnadair@hotmail.com -- modified at 23:47 Monday 3rd July, 2006

[Dave Kreskowiak]

ScaleTransform doesn't do anything until you draw something. It sets up a transform for any drawing done to the surface after the call the ScaleTransform. Dave Kreskowiak Microsoft MVP - Visual Basic

[codeadair]

Dave Kreskowiak wrote:

ScaleTransform doesn't do anything until you draw something. It sets up a transform for any drawing done to the surface after the call the ScaleTransform.

Yes.I think so. And i have to redraw bitmap if i want to transform the graphic.So bitmap doesn't look very useful this time. ICQ:258-235-734 MSN:msnadair@hotmail.com