c# - .Net and Bitmap not automatically disposed by GC when there is no memory left -

i'm wondering how allocation , disposal of memory allocated bitmaps work in .net.

when lot of bitmap creations in loops in function , call in succession work until @ point bitmap wont able allocate memory giving exception "invalid parameter" size specified.

if call garbage collector while while works.

with following code able repoduce error:

class bitmapobject {     public bool visible {         { return enb; }         set { enb = value; }     }     private bool enb;     private bitmap bmp; public bitmapobject(int i, bool en) {     enb = en;     bmp = new bitmap(i, i);      } }  class pool<t> t : bitmapobject {     list<t> preallocatedbitmaps = new list<t>(); public void fill() {     random r = new random();     (int = 0; < 500; i++) {         bitmapobject item = new bitmapobject(500, r.nextdouble() > 0.5);         preallocatedbitmaps.add(item t);     } }  public ienumerable<t> objects {         {         foreach (t component in this.preallocatedbitmaps)         {             if (component.visible)             {                 yield return (t)component;             }         }        }     } }  static class program {     /// <summary>     /// main entry point application.     /// </summary>     [stathread]     static void main() {     (int = 0; < 10; i++ )     {         test();              // without breaks             //gc.collect();             //gc.waitforpendingfinalizers();         }          console.readkey();     }      private static void test() {         pool<bitmapobject> pool = new pool<bitmapobject>();         pool.fill();          (int = 0; < 100; i++)         {             var visbitmaps = pool.objects;             //         }             } } 

the .net bitmap class "encapsulates gdi+ bitmap", means should call dispose on bitmap when finished it,

"always call dispose before release last reference image. otherwise, resources using not freed until garbage collector calls image object's finalize method."