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.NET Forum / Windows Forms / WinForm General / July 2006Slow drawing speed of WinForms (esp via COM interop)
Hi, Has anybody experienced severe slow-down with the drawing speed of WinForms? It's not fast at the best of time, but the particular scenario I am having problems with is via COM interop and Excel. The structure is: Excel VBA macro | V instantiate and call a COM wrapper class exposed by my assembly using ComVisible(true) | V Wrapper class instantiates the WinForm and displays it The forms don't do anything special, they contain maybe 10-20 controls, including one or two grids, but you can sit there and watch them paint themselves control-by-control. I am using data binding, if that helps. Any help to fix this will be very gratefully received, but even if you have experienced something similar please reply so that I know I am not alone! -- Phil COM Interop is slow. I would minimize the number of calls (what is the source you databind ?, do you have a single call to the .NET application ?). I made something the other way round i..e uisng Excel from Windows. I's much quicker : - to copy data to Excel using a single cell (as an array) instead of copying all separately - to have the winform to create an Excel macro that is then transmitted and executed in Excel (quicker than performing the layout from the Winforms with the associated overhead for each call).  SignaturePatrice > Hi, > [quoted text clipped - 26 lines] > -- > Phil >COM Interop is slow. I would minimize the number of calls (what is the >source you databind ?, do you have a single call to the .NET application ?). Patrice, Yes, just essentially a call to ShowDialog(). I am gonna try it from other applications eg a VB6 and see if that makes a difference, it might be an Excel-specific problem. -- Phil What I don't understand for now is if Excel is involved in the picture. Does Excel just launch the form and the rest of the whole process is internal. What is the source of the bindings ? If 2.0 you can try Joris's suggestion with the "Shown" event... SignaturePatrice >>COM Interop is slow. I would minimize the number of calls (what is the >>source you databind ?, do you have a single call to the .NET application [quoted text clipped - 8 lines] > -- > Phil >What I don't understand for now is if Excel is involved in the picture. Does >Excel just launch the form and the rest of the whole process is internal. Yes, exactly. There are 2 lines of VBA behind a button in Excel. >What is the source of the bindings ? A typed DataSet - which has been loaded before the form is shown. I have basically written an overload of ShowDialog() that does this: public void ShowDialog(string SalesOrderNum) { load the dataset with 1 order for SalesOrderNum initialise data bindings set form caption to "New Order" or "Edit Order" ShowDialog(); // call standard form ShowDialog to display the window } So I am doing the majority of my work *before* I call ShowDialog, so I am surprised at the slow painting, everything should be there by then. It may be that I should use the events....perhaps doing it the way I am is non-standard and is causing the problem. >If 2.0 you can try Joris's suggestion with the "Shown" event... -- Phil Hi Phil, In cases like that, I often display the form first, without the "databinding". In the Form_LOad event, I activate a Forms Timer with an interval of maybe 20 ms, and then when the timer elapses I fill in all the controls (and disable the timer to make sure it only elapses once). This speeds up the loading of the form and the painting, so the user sees an empty screen much faster. Then the data is loaded with a small delay, ususally not disturbing for the user. This doesn't make it faster, but it looks faster and certainly much nicer, and it is a much better experienc for the user. Hope this helps, Joris > Hi, > [quoted text clipped - 26 lines] > -- > Phil >Hi Phil, > [quoted text clipped - 12 lines] > >Joris Joris, I'll try it later this week (have to get ready for a demo now....) Thanks for the suggestion. -- Phil Free MagazinesGet these publications absolutely FREE for up to 12 months. There are no hidden fees and no obligation. Simply choose a title, complete the application form and submit it. Read more ...
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