Pens and brushes..

[Borje Hagsten]

While playing around with the progressbar I recently made, I noticed
a drop in GDI resources for each created control. No leak, just a drop
while the control was loaded. Tracked it down to the fact I was storing
an array of pens during the control's life-time. Stupid thing to do, so
I will post a change in the code soon, with some other improvements
added to the control.

Anyway, this lead me to a small test. Seems like pens and brushes are
a big factor, when it comes to GDI resources. In case your program
stores many of them, do check and see if you can do it other way, like
create and delete them "on the fly".

(I noticed EZ_GUI made software stores a bunch of brushes - may be
worth looking into..)

Win NT and 2000 may handle this better, but the following little
test steals almost 15% of my GDI resources in Windows 98, and of
course returns them when the array of pens are deleted:

#COMPILE EXE
#INCLUDE "WIN32API.INC"
 
FUNCTION PBMAIN() AS LONG
  LOCAL I AS LONG
  REDIM hPen(255) AS LONG
 
  FOR I = 0 TO 255
     hPen(I) = CreatePen(%PS_SOLID, 1, RGB(I, I, I))
     'hPen(I) = CreateSolidBrush(RGB(I, I, I)) '<- even worse on resources..
  NEXT
  MSGBOX "255 pens created, check your GDI resources!"
 
  FOR I = 0 TO 255
     DeleteObject hPen(I)
  NEXT
  MSGBOX "255 pens deleted, check your GDI resources again!"
 
END FUNCTION

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[Edwin Knoppert]

255, way to much, you should see a drop on create is my guess.

Since you are using a memdc i recommend destroying pen by pen.
It's not slow.
I do it in all my functions, create brush, use it, destroy it..
And pens of course.

GDI is a difficult thing.

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[Ralph Berger]

Borje;

also had insufficient GDI Resource problem with my controls.
Maybe may Font/Brush cache can help. Pls look at the source code
forum.

Ralph

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[Chris Boss]

Borje;

In some instances it is impossible to keep the GDI resources down,
but the key is to try to conserve them as much as possible.

Loading a number of Bitmaps and Icons can use a lot of resources as well.

While, EZGUI 1.0 is quite effecient with resources (it only creates
32 default brushes at startup and uses System Fonts for default fonts),
EZGUI 2.0 does use a lot more Resources (it supports 3D brushes for
backgrounds).

If a large number of controls are used in an EZGUI app it is actually
more efficient since it uses Brushes and Fonts from a pool rather than
create a custom Font or Brush for each control. You can also Free
any GDI resources in an EZGUI app, if needed.

EZGUI doesn't create any Pens. It only creates Fonts and Brushes.

I will take a look at making EZGUI 2.0 more GDI Resource Efficient
as you suggested.



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[Edwin Knoppert]

Chris,
I believe you created the handles for standard qbcolors?
Windows has already created these brushes by default
See GetSysColorBrush..

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[Borje Hagsten]

thanks for the input, fellows. ralph, interesting idea with memory cache,
i'll have a closer look at it. also will have a look at the sample code
semen just posted and see if i can understand his way of getting gradient
colors. looks more advanced than what i currently use..

in the meantime - i have updated the progressbar sample with several new
features and changed code, so pens are created and deleted "on the fly".
better way, since windows handles these basic things so badly, imho..

updated test program at: http://www.powerbasic.com/support/pb...ad.php?t=22953

updated progessbar control include file at: http://www.powerbasic.com/support/pb...ad.php?t=22952


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[Semen Matusovski]

Borje --
All is enough simple.
"Internals" of memory hDC (exactly memory) are "internals" of bitmap, which is selected in it.
If to build 32-bit DIB section and to select it into hMemDC, array of pixels looks
Dim Pixels(pWidth - 1, 0 : pHeight - 1) As Long At Varptr(bm.bmBits) and you can operate with it directly.

Some notes:
1) lines are located from bottom to top (index 0 is last, bottom line)
2) colors - this is COLORREF (reverse order of bytes comparing with RGB).
3) I used &H020000000 + ... to stimulate selection from system pallete in 256-colors mode
(it will be clean color; of course, not gradient).

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