Re: Appending one image to other
- From: "Garry Freemyer" <garryfre@xxxxxxxxxxxxxxxxxxx>
- Date: Thu, 2 Jun 2005 22:03:17 -0700
Never mind, I found the reason for the slowness.
I was using my own double-buffering, but so was the control too!! In effect,
I was quadruple buffering (Double-buffering twice!).
"Garry Freemyer" <garryfre@xxxxxxxxxxxxxxxxxxx> wrote in message
news:e3dpHgwZFHA.4068@xxxxxxxxxxxxxxxxxxxxxxx
> Hiya Sir, I have written a screensaver program and I noticed your FAQ
> where it says to do all painting in the paint routine and to Never ever
> "Steal" a graphics object to do painting outside of events. I just have a
> couple of questions for ye ...
>
> 1. The program as I have it written now, seems to work fine, however I
> decided to give your adivice in the GDI+ Faq a try, and have the
> SaverLoop, just draw to an offscreen bitmap, but then utilize the Paint
> event of the form to do the actual drawing on the form. This seems to work
> ok, albiet it is drastically slower! ....
>
> When saver loop is done with drawing to the bitmap, it calls invalidate
> and this triggers the Paint routine then calls Application.DoEvents();
> then repeats unless the user touched a key or moved or clicked the mouse.
>
> Here is the Paint event ...
>
> private void ScreenSaverForm_Paint(object sender,
> System.Windows.Forms.PaintEventArgs e)
>
> {
>
> if (this.SaverStarted == true) // Since saverLoop is a loop, don't call it
> twice.
>
> {
>
> e.Graphics.DrawImage(bm,0,0,bm.Width,bm.Height);
>
> }
>
> }
>
>
> 2. I wonder if this really applies when it comes to screensavers. I like
> the simplicity of this, it eliminates my having to create a timer to call
> SaverLoop which turns off the timer immediately, and it looks somewhat
> less complicated but still its dramatically slower. Does this rule really
> apply when you are using a screensaver, where you don't care if an object
> covers over the form because then you want to quit anyway.
>
> 3. My final concern is that most screensavers, including mine, write to
> the mini-preview box on the Display Properties dialog box. This is a clear
> example of "Stealing" a graphic's object in C# as far as how I do it in
> the program. I am unable to create a control via the handle, all I get
> back is a null control. The only thing I can get from this handle is a
> Graphics object, that appears to expose NO events. Obviously, something is
> either missing as far as knowledge, or this is an exception.
>
> Thoughts please?
>
> "Bob Powell [MVP]" <bob@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:OYOfVHIYFHA.712@xxxxxxxxxxxxxxxxxxxxxxx
>> Throw that lousy PictureBox out and write your own control to display the
>> image in its correct aspect ratio.
>>
>> See the GDI+ FAQ for code that you can adapt.
>>
>> --
>> Bob Powell [MVP]
>> Visual C#, System.Drawing
>>
>> Find great Windows Forms articles in Windows Forms Tips and Tricks
>> http://www.bobpowell.net/tipstricks.htm
>>
>> Answer those GDI+ questions with the GDI+ FAQ
>> http://www.bobpowell.net/faqmain.htm
>>
>> All new articles provide code in C# and VB.NET.
>> Subscribe to the RSS feeds provided and never miss a new article.
>>
>>
>>
>>
>>
>> "Saurabh" <saurabh@xxxxxxxxxxxx> wrote in message
>> news:O1o6OYHYFHA.1796@xxxxxxxxxxxxxxxxxxxxxxx
>>> Hello All,
>>>
>>> I am new to the image processing things, hence this question might be a
>>> bit silly but I could not find any obvious solution....
>>>
>>> I have an image object which is to be shown in a picturebox. The
>>> picturebox can actually change the size depending on the anchor /
>>> docking of the form. I do not want my image to lose its aspect ratio but
>>> still want to show it within the bounds of the picturebox. I was
>>> thinking of appending whitespaces (or transparent spaces) within the
>>> image itself so that my actual picture will maintain the aspect ratio
>>> but the image object will be of the same size as that of the picturebox.
>>> (Its a bit like the way 16:9 movies appear on a 4:3 TV screen with a
>>> black band appearing at top and bottom of the screen) Does anybody know
>>> how I can append such thing in the image object. Depending on the W : H
>>> ratio of the picturebox and the picture, sometimes I want the whitespace
>>> bands at top and bottom and sometimes at left and right.
>>>
>>> TIA,
>>>
>>> --Saurabh
>>>
>>
>>
>
>
.
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- From: Garry Freemyer
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