C# Discussion Boards - CodeProject

Luc Pattyn15-Dec-08 9:45

Luc Pattyn

15-Dec-08 9:45

Hi,

so you are creating one million pens and wondering why it is sooo slow?

furthermore, your PictureBox is not serving a real purpose, you can draw your map on top of any kind of Control, e.g. a Form itself, a Panel (that is what I prefer), etc.

Now why can't you turn the whole map into a real Bitmap; say you do something like this:

int w=1000;
int h=1000;
Bitmap bm=new Bitmap(w,h);
for (int y=0; y< h; y++) {
    for (int x=0; x< w; x++) {
        bm.SetPixel(x, y, someColor);
    }
}

this will take a while, but has to happen only once. After that you can paint this image over and over, either yourself (e.g. in a Panel's paint handler), or automatically by setting myPictureBox.Image=bm;

BTW: you can speed up the above bitmap creation by using "unsafe" code and pointers; a little Google action will inform you about the details.

FYI: all the objects you create need to be disposed of if their class provides a Dispose() method;
this applies to pens, brushes, fonts, and many more; disposing will free unmanaged resources much sooner, improving the memory situation and the overall performance.

Smile | :)

Luc Pattyn [Forum Guidelines] [My Articles]

Fixturized forever. Confused | :confused:

DaveyM6915-Dec-08 10:20

DaveyM69

15-Dec-08 10:20

Luc Pattyn wrote:
a little Google action

Haven't had any of that for a while Wink | ;)

Dave
BTW, in software, hope and pray is not a viable strategy. (Luc Pattyn)
Visual Basic is not used by normal people so we're not covering it here. (Uncyclopedia)

Re: Displaying Graphics in Windows Form [modified]

Dave Kreskowiak15-Dec-08 10:49

Dave Kreskowiak

15-Dec-08 10:49

Luc Pattyn wrote:
so you are creating one million pens and wondering why it is sooo slow?

Not only that, he's not Disposing them either. Well, from the limited code sample he provided anyway.

A guide to posting questions on CodeProject[^]

Dave Kreskowiak
Microsoft MVP
Visual Developer - Visual Basic
2006, 2007, 2008

Think-A-Tron15-Dec-08 23:31

Think-A-Tron

15-Dec-08 23:31

Using SetPixel is dog slow. If more than a few pixels are modified, it's next to worthless. I know of two efficient ways to modify a bitmap on a pixel-by-pixel basis. Both methods have advantages.

First, lock the bitmap, access it with pointers in unsafe mode, then unlock it. Here's a link to a very nice article using this approach:

Code Project Article

Second, lock the bitmap, copy it to a regular array, and unlock it. Modify the data in the array, and when done, lock the bitmap, copy the data back, then unlock the bitmap. If you only want to initialize the bitmap, you can simplify the process, since there's no need to copy from the bitmap. Just write the regular array and copy it to the (locked) bitmap. This idea is also useful if you only want to individually modify pixels, and don't need to use any of the bitmap features, such as line drawing. Use the pixel array as the "master" version, and copy it into the bitmap to display it. Here's an example of this method:

<br />
// (Some of these may not be necessary.)<br />
using System;<br />
using System.Collections.Generic;<br />
using System.ComponentModel;<br />
using System.Data;<br />
using System.Drawing;<br />
using System.Text;<br />
using System.Windows.Forms;<br />
using System.Runtime.InteropServices;<br />
using System.Drawing.Imaging;<br />
<br />
    // Could use enumeration here.<br />
    const int bmB = 0;<br />
    const int bmG = 1;<br />
    const int bmR = 2;<br />
    const int bmA = 3;<br />
   <br />
    //<br />
    // Allocate a pixel array to match the bitmap.<br />
    //<br />
    int bitsPerPixel;<br />
    bool hasAlpha;<br />
    switch (bitmap.PixelFormat)<br />
    {<br />
        case PixelFormat.Format24bppRgb:<br />
	    bitsPerPixel = 24;<br />
            hasAlpha = false;<br />
	    break;<br />
        case PixelFormat.Format32bppRgb:<br />
            bitsPerPixel = 32;<br />
            hasAlpha = false;<br />
        case PixelFormat.Format32bppArgb:<br />
        case PixelFormat.Format32bppPArgb:<br />
            bitsPerPixel = 32;<br />
            hasAlpha = true;<br />
            break;<br />
        default:<br />
            throw new ArgumentException("Unsupported pixel format.");<br />
    }<br />
<br />
    // (Stride is available in the BitmapData structure.)<br />
    int bytesPerPixel = bitsPerPixel >> 3;<br />
    int stride = ((bitmap.Width * bitsPerPixel + 31) & ~31) >> 3;<br />
    int bitmapBytes = stride * bitmap.Height;<br />
    byte[] pixels = new byte[bitmapBytes];<br />
<br />
...<br />
    //<br />
    // Copy the bitmap into the pixel array.<br />
    //<br />
<br />
    // Lock the bitmap's bits.<br />
    BitmapData bmpData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadWrite, bitmap.PixelFormat);<br />
<br />
    // Copy the bitmap pixels into the array.<br />
    Marshal.Copy(bmpData.Scan0, pixels, 0, bitmapBytes);<br />
<br />
    // Unlock the bits.<br />
    bitmap.UnlockBits(bmpData);<br />
<br />
...<br />
    //<br />
    // Copy the pixel array into the bitmap.<br />
    //<br />
<br />
    // Lock the bitmap's bits.  <br />
    BitmapData bmpData = bitmap.LockBits(new Rectangle(0, 0, bitmap.Width, bitmap.Height), ImageLockMode.ReadWrite, bitmap.PixelFormat);<br />
<br />
    // Copy the array back into the bitmap.<br />
    Marshal.Copy(pixels, 0, bmpData.Scan0, bitmapBytes);<br />
<br />
    // Unlock the bits.<br />
    bitmap.UnlockBits(bmpData);<br />
	<br />

Note this only works for direct (non-indexed) bitmaps. For 24 bit pixels, the pixels are stored in B, G, R order; for 32 bit pixels, the order is B, G, R, A. For example, to access the green component of a 24 bit pixel at (x, y), use pixels[(bytesPerPixel * x + stride * y) + bmG].

modified on Tuesday, December 16, 2008 6:20 PM

User 665815-Dec-08 9:45

getting a file type's icon location (SHGetFileInfo??)

15-Dec-08 9:45

Is this going to be a game? If yes, you may want to take a look at the XNA Framework[^].

Drawing a million rectangles per frame is going to be very slow. With XNA you could take advantage of your GPU - additionally XNA would put the the million objects into one batch and draw them at once as one large triangle list, which would only take a few milliseconds utilizing the GPU.

regards

modified 12-Sep-18 21:01pm.

mirko8615-Dec-08 8:30

mirko86

15-Dec-08 8:30

good day people

so i want to get the location for every file type (both dll and index) and i tried using SHGetFileInfo api (ICONLOCATION flag) but for some reason it only works for either the desktop or a folder, regular fyletipes like .txt, .pdf, .xml dont work

is there another way i can get the dll and index for every file type?? i tried searching in the registry and it works for me but two specific file types still give me problems (cant find their icon's dll and index) when i run my program in another computer (my OS is windows vista x32, i have problems running it in vista (x86)

i'll repeat my main question: How can i get the dll and index for every file type??

thanks in advance for your help

Re: getting a file type's icon location (SHGetFileInfo??)

Giorgi Dalakishvili15-Dec-08 8:45

Giorgi Dalakishvili

15-Dec-08 8:45

See if this helps: IconHandler[^]

Giorgi Dalakishvili

#region signature
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Asynchronous Registry Notification Using Strongly-typed WMI Classes in .NET [^]

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Re: getting a file type's icon location (SHGetFileInfo??)

mirko8615-Dec-08 8:59

mirko86

15-Dec-08 8:59

actually i tried that already, that example gets the handle for the icon with SHGetFileInfo api, i need the dll path and the index, you know like for .exe files the dll is shell32.dll and the index is 2?

i tried using that same api with the flag ICONLOCATION and it did get the dll and index, but only for the desktop and folders, regular file types like .pdf or . txt wouldnt work

thanks anyway for your help

DateTime Parse.

postonoh15-Dec-08 6:21

postonoh

15-Dec-08 6:21

Unable to cast object of type 'System.DateTime' to type 'System.String'.

private void StudentsDataGridView_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
// Although we could have the SQL statement return a formatted date,
// this is really a User Interface issue and should be handled here.
//
// Display only Date part of datetime
if ((this.StudentsDataGridView.Columns[e.ColumnIndex].Name == this.TeachersDataSet.Students.BirthDateColumn.ColumnName))
{
if (!(e.Value == DBNull.Value))
{
e.Value = DateTime.Parse((string)e.Value).ToLongDateString(); e.FormattingApplied = true;
}
}

}

Learning to Code

Re: DateTime Parse.

Wendelius15-Dec-08 6:39

Wendelius

15-Dec-08 6:39

Mo John wrote:
Unable to cast object of type 'System.DateTime' to type 'System.String'

The exception says it all. You don't say what's the problem you're having, but if it is what I suspect, use the debugger and have a look at e.Value.

The need to optimize rises from a bad design.My articles[^]

Re: DateTime Parse. [modified]

postonoh15-Dec-08 6:47

postonoh

15-Dec-08 6:47

Oh yeah! The problem: When Iinter the birthdate in the field click save it update the database. When I query the database all the data is present. When I try to access the same field on a click button to get data on the persons it will not convert the field. I get the error message.

Trying format the field so only the date will show and not the time.

Learning to Code

modified on Monday, December 15, 2008 12:54 PM

Re: DateTime Parse.

Wendelius15-Dec-08 6:52

Wendelius

15-Dec-08 6:52

So have a look at the e.Value with the debugger. Especially, check the datatype.

The need to optimize rises from a bad design.My articles[^]

Sleep thread but not current

Xmen Real 15-Dec-08 6:00

Xmen Real

15-Dec-08 6:00

//Code
System.Threading.Thread.Sleep(1000);
//Code

the System.Threading.Thread.Sleep(1000); blocks the current thread for the timeperiod in param and dont let execute the next code to it, like MessageBox. But i want current thread keep running however the code blocked.

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Rs0~53%eYrd8mt^7Z6]iTF+(EWfJ9zaK-iTV.C\y<pjxsg-b$f4ia>
--------------------------------------------------------
128 bit encrypted signature, crack if you can

User 665815-Dec-08 6:38

15-Dec-08 6:38

Xmen wrote:
But i want current thread keep running however the code blocked.

Huh? How would that work?

modified 12-Sep-18 21:01pm.

Xmen Real 15-Dec-08 6:43

Xmen Real

15-Dec-08 6:43

//code
//code
//code
//
//Sleep 1000   <<stop here for 1000 ms but current thread keep running, mean if i want to move a form then it should
//
//next code
//next code
//

User 665815-Dec-08 6:48

15-Dec-08 6:48

There is no distinction between "Form moving code" and "other code" for the CPU, it's all the same.

If you have some code that needs to be paused, then you need to put it into a second thread and stop this one instead.

regards

modified 12-Sep-18 21:01pm.

Xmen Real 15-Dec-08 6:50

Xmen Real

15-Dec-08 6:50

Greeeg wrote:
There is no distinction between "Form moving code" and "other code" for the CPU, it's all the same.

dude, it was just an example

User 665815-Dec-08 6:52