docs/develop/servers/app_server/BitmapManager.htm

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  20 <P class="Body" style="margin: 0px"><span class="OBOS-Title">BitmapManager class</span><span style="color: rgb(0,0,0); font-size: 24pt"></span></P>
  21 <P class="Body" style="margin: 0px"><BR>
  22 </P>
  23 <P class="Body" style="margin: 0px">The BitmapManager object handles all ServerBitmap allocation and deallocation. The rest of the server uses CreateBitmap and DeleteBitmap instead of new and delete. It utilizes the outside pool manager BGET.</P>
  24 <P class="Body" style="margin: 0px"><BR>
  25 <BR>
  26 <HR>
  27 </P>
  28 <P class="Body" style="margin: 0px"><BR>
  29 Member Functions</P>
  30 <P class="Body" style="margin: 0px"><BR>
  31 </P>
  32 <TABLE WIDTH=621 HEIGHT=105 BORDER=1 CELLPADDING=1 CELLSPACING=2>
  33         <TR>
  34                 <TD WIDTH=238 HEIGHT=17>
  35                         <P class="Body" style="margin: 0px">BitmapManager(void)</P>
  36                         </TD>
  37                 <TD WIDTH=228 HEIGHT=17>
  38                         <P class="Body" style="margin: 0px">~BitmapManager(void)</P>
  39                         </TD>
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  41         <TR>
  42                 <TD WIDTH=238 HEIGHT=62>
  43                         <P class="Body" style="margin: 0px">ServerBitmap *CreateBitmap(BRect bounds, color_space space, int32 flags, int32 bytes_per_row=-1, screen_id screen=B_MAIN_SCREEN_ID)</P>
  44                         </TD>
  45                 <TD WIDTH=228 HEIGHT=62>
  46                         <P class="Body" style="margin: 0px">void DeleteBitmap(ServerBitmap *bitmap)</P>
  47                         </TD>
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  49 </TABLE>
  50 <P class="Body" style="margin: 0px"><BR>
  51 <BR>
  52 Global Functions</P>
  53 <P class="Body" style="margin: 0px"><BR>
  54 extern "C" void set_area_buffer_management(void);</P>
  55 <P class="Body" style="margin: 0px">void * expand_area_storage(long size)</P>
  56 <P class="Body" style="margin: 0px">void contract_area_storage(void *buffer)</P>
  57 <P class="Body" style="margin: 0px"><BR>
  58 <HR>
  59 </P>
  60 <P class="Body" style="margin: 0px"><span class="OBOS-Function-Def">BitmapManager(void)</span></P>
  61 <P class="Body" style="margin: 0px"><BR>
  62 1) Create the bitmap list</P>
  63 <P class="Body" style="margin: 0px">2) Create the bitmap area</P>
  64 <P class="Body" style="margin: 0px">3) Allocate the access semaphore</P>
  65 <P class="Body" style="margin: 0px">4) Call set_buffer_area_management</P>
  66 <P class="Body" style="margin: 0px">5) Set up the buffer pool via bpool</P>
  67 <P class="Body" style="margin: 0px"><BR>
  68 <span class="OBOS-Function-Def">~BitmapManager(void)</span></P>
  69 <P class="Body" style="margin: 0px"><BR>
  70 1) Iterate over each item in the bitmap list, removing each item, calling brel() on its buffer, and deleting it.</P>
  71 <P class="Body" style="margin: 0px">2) Delete the bitmap list</P>
  72 <P class="Body" style="margin: 0px">3) Delete the bitmap area</P>
  73 <P class="Body" style="margin: 0px">4) Free the access semaphore</P>
  74 <P class="Body" style="margin: 0px"><BR>
  75 <span class="OBOS-Function-Def">ServerBitmap *CreateBitmap(BRect bounds, color_space space, int32 flags, int32 bytes_per_row=-1, screen_id screen=B_MAIN_SCREEN_ID)</span></P>
  76 <P class="Body" style="margin: 0px"><BR>
  77 CreateBitmap is called by outside objects to allocate a ServerBitmap object. If a problem occurs, it returns NULL.</P>
  78 <P class="Body" style="margin: 0px"><BR>
  79 1) Acquire the access semaphore</P>
  80 <P class="Body" style="margin: 0px">2) Verify parameters and if any are invalid, spew an error to stderr and return NULL</P>
  81 <P class="Body" style="margin: 0px">3) Allocate a new ServerBitmap</P>
  82 <P class="Body" style="margin: 0px">4) Allocate a buffer for the bitmap via bget() with the bitmap's theoretical buffer length</P>
  83 <P class="Body" style="margin: 0px">5) If NULL, delete the bitmap and return NULL</P>
  84 <P class="Body" style="margin: 0px">6) Set the bitmap's area and buffer to the appropriate values (area_for buffer and buffer)</P>
  85 <P class="Body" style="margin: 0px">7) Add the bitmap to the bitmap list</P>
  86 <P class="Body" style="margin: 0px">8) Release the access semaphore</P>
  87 <P class="Body" style="margin: 0px">9) Return the bitmap</P>
  88 <P class="Body" style="margin: 0px"><BR>
  89 <span class="OBOS-Function-Def">void DeleteBitmap(ServerBitmap *bitmap)</span></P>
  90 <P class="Body" style="margin: 0px"><span class="Default"><BR>
  91 Frees a ServerBitmap allocated by CreateBitmap()</span></P>
  92 <P class="Body" style="margin: 0px"><span class="Default"><BR>
  93 1) Acquire the access semaphore</span></P>
  94 <P class="Body" style="margin: 0px"><span class="Default">2) Find the bitmap in the list</span></P>
  95 <P class="Body" style="margin: 0px"><span class="Default">3) Remove the bitmap from the list or release the semaphore and return if not found</span></P>
  96 <P class="Body" style="margin: 0px"><span class="Default">4) call brel() on the bitmap's buffer if it is non-NULL</span></P>
  97 <P class="Body" style="margin: 0px"><span class="Default">5) delete the bitmap</span></P>
  98 <P class="Body" style="margin: 0px"><span class="Default">6) Release the access semaphore</span></P>
  99 <P class="Body" style="margin: 0px"><span class="Default"><BR>
 100 </span><span class="OBOS-Function-Def">extern "C" void set_area_buffer_management(void)</span></P>
 101 <P class="Body" style="margin: 0px"><span class="Default"><BR>
 102 C function defined externally to point the BGET manager to our homegrown area allocation and deallocation functions.</span></P>
 103 <P class="Body" style="margin: 0px"><span class="Default"><BR>
 104 </span><span class="OBOS-Function-Def">void * expand_area_storage(long size)</span></P>
 105 <P class="Body" style="margin: 0px"><BR>
 106 "Internal" global function accessed only by set_area_buffer_management and BGET to handle the task of adding more area space to make room for more bitmaps.</P>
 107 <P class="Body" style="margin: 0px"><BR>
 108 1) If size is less than B_PAGE_SIZE, set the area size to B_PAGE_SIZE</P>
 109 <P class="Body" style="margin: 0px">2) If size % B_PAGE_SIZE, set area size to (size/B_PAGE_SIZE)+1)*B_PAGE_SIZE, otherwise setting it to the given size</P>
 110 <P class="Body" style="margin: 0px">3) Call create_area with the area size.</P>
 111 <P class="Body" style="margin: 0px">4) If it couldn't allocate an area, write a panic message to stderr and return NULL, otherwise, return the pointer to the area.</P>
 112 <P class="Body" style="margin: 0px"><BR>
 113 <span class="OBOS-Function-Def">void contract_area_storage(void *buffer)</span></P>
 114 <P class="Body" style="margin: 0px"><span class="Default"><BR>
 115 </span>"Internal" global function accessed only by set_area_buffer_management and BGET to <span class="Default">remove the area which was previously used for the bitmap pool</span></P>
 116 <P class="Body" style="margin: 0px"><span class="Default"><BR>
 117 1) Call area_for on the buffer</span></P>
 118 <P class="Body" style="margin: 0px"><span class="Default">2) If the area_id is not B_ERROR, call delete_area on its area_id.</span></P>
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