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simple graphics questionI used to do this Dim gfx As System.Drawing.Graphics = pic1.CreateGraphics gfx.FillEllipse blah blah blah to draw straight onto a form. but this is frowned up (slow). so what is the alternative? does this line make the new graphics in memory? Dim gfx As System.Drawing.Graphics = CreateGraphics() gfx.FillEllipse blah blah blah if so, how do I get the final image onto my form or picturebox? many thanks
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"Tim" <Citizen10Be***@gmail.com> wrote in message Calling CreateGraphics is pretty slow (or at least slower than using the news:1150986810.181813.13110@i40g2000cwc.googlegroups.com... > hi > > I used to do this > > Dim gfx As System.Drawing.Graphics = pic1.CreateGraphics > gfx.FillEllipse blah blah blah > > to draw straight onto a form. > but this is frowned up (slow). > > so what is the alternative? > > does this line make the new graphics in memory? > > Dim gfx As System.Drawing.Graphics = CreateGraphics() > gfx.FillEllipse blah blah blah > > if so, how do I get the final image onto my form or picturebox? > > many thanks > existing Graphics object that is already there, in the OnPaint method). So, override the OnPaint method and use the e.Graphics property :) Mythran interesting.
how do I limit when the onpaint gets called? say I want to click a button to draw something. also, I am drawing hundreds of circles on the form. I still think it would be better to draw them to something in memory, and then dump the finished thing to the form. any tips? Mythran wrote: Show quoteHide quote > "Tim" <Citizen10Be***@gmail.com> wrote in message > news:1150986810.181813.13110@i40g2000cwc.googlegroups.com... > > hi > > > > I used to do this > > > > Dim gfx As System.Drawing.Graphics = pic1.CreateGraphics > > gfx.FillEllipse blah blah blah > > > > to draw straight onto a form. > > but this is frowned up (slow). > > > > so what is the alternative? > > > > does this line make the new graphics in memory? > > > > Dim gfx As System.Drawing.Graphics = CreateGraphics() > > gfx.FillEllipse blah blah blah > > > > if so, how do I get the final image onto my form or picturebox? > > > > many thanks > > > > Calling CreateGraphics is pretty slow (or at least slower than using the > existing Graphics object that is already there, in the OnPaint method). So, > override the OnPaint method and use the e.Graphics property :) > > Mythran
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"Tim" <Citizen10Be***@gmail.com> wrote in message Ok, you really don't want to limit when onpaint gets called:news:1150995326.446477.165960@b68g2000cwa.googlegroups.com... > interesting. > > how do I limit when the onpaint gets called? > say I want to click a button to draw something. > > also, I am drawing hundreds of circles on the form. I still think it > would be better to draw them to something in memory, and then dump the > finished thing to the form. > > any tips? > > > Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) MyBase.OnPaint(e) ' This line will cause the form/control to paint ' itself. This also raised the Paint event for ' the form/control. ' Perform you custom paint functions here. End Sub What you can do, then, is to create a bitmap object and draw on that object (of course, you'll need to create your own Graphics class to do this) and then draw the bitmap onto the form/control using the Graphics object provided by the OnPaint method. I'm not sure if it is faster though, since you are creating another instance of the Graphics object on every call...maybe, instead, you can somehow prevent the actual rendering of the drawing until you have completed drawing the circles. You can force the OnPaint method to be called by invalidating the client area of the form (or just the region you want to repaint) by calling one of the Invalidate method overloads for the form/control. I'll check into it and get back to ya via ng. HTH, Mythran
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"Mythran" <kip_potter@hotmail.comREMOVETRAIL> wrote in message After checking, I believe what you want to do to prevent that actual news:OLFcu%23hlGHA.2304@TK2MSFTNGP02.phx.gbl... > > "Tim" <Citizen10Be***@gmail.com> wrote in message > news:1150995326.446477.165960@b68g2000cwa.googlegroups.com... >> interesting. >> >> how do I limit when the onpaint gets called? >> say I want to click a button to draw something. >> >> also, I am drawing hundreds of circles on the form. I still think it >> would be better to draw them to something in memory, and then dump the >> finished thing to the form. >> >> any tips? >> >> >> > > Ok, you really don't want to limit when onpaint gets called: > > Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) > MyBase.OnPaint(e) ' This line will cause the form/control to paint > ' itself. This also raised the Paint event for > ' the form/control. > > ' Perform you custom paint functions here. > End Sub > > What you can do, then, is to create a bitmap object and draw on that > object (of course, you'll need to create your own Graphics class to do > this) and then draw the bitmap onto the form/control using the Graphics > object provided by the OnPaint method. I'm not sure if it is faster > though, since you are creating another instance of the Graphics object on > every call...maybe, instead, you can somehow prevent the actual rendering > of the drawing until you have completed drawing the circles. > > You can force the OnPaint method to be called by invalidating the client > area of the form (or just the region you want to repaint) by calling one > of the Invalidate method overloads for the form/control. > > I'll check into it and get back to ya via ng. > > HTH, > Mythran > rendering of the control is to call SuspendLayout and then ResumeLayout when you want to render. HTH, Mythran I maintain a bitmap the same size as my control in memory then draw what I
want on the bitmap and when OnPaint is called, copy the bitmap to the graphics object using bitblt. This can be lightning fast if programmed correctly. -- Show quoteHide quoteDennis in Houston "Tim" wrote: > interesting. > > how do I limit when the onpaint gets called? > say I want to click a button to draw something. > > also, I am drawing hundreds of circles on the form. I still think it > would be better to draw them to something in memory, and then dump the > finished thing to the form. > > any tips? > > > > Mythran wrote: > > "Tim" <Citizen10Be***@gmail.com> wrote in message > > news:1150986810.181813.13110@i40g2000cwc.googlegroups.com... > > > hi > > > > > > I used to do this > > > > > > Dim gfx As System.Drawing.Graphics = pic1.CreateGraphics > > > gfx.FillEllipse blah blah blah > > > > > > to draw straight onto a form. > > > but this is frowned up (slow). > > > > > > so what is the alternative? > > > > > > does this line make the new graphics in memory? > > > > > > Dim gfx As System.Drawing.Graphics = CreateGraphics() > > > gfx.FillEllipse blah blah blah > > > > > > if so, how do I get the final image onto my form or picturebox? > > > > > > many thanks > > > > > > > Calling CreateGraphics is pretty slow (or at least slower than using the > > existing Graphics object that is already there, in the OnPaint method). So, > > override the OnPaint method and use the e.Graphics property :) > > > > Mythran > > |
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