haiku/docs/develop/servers/app_server/BitmapManager.htm

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<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>
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<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>
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Member Functions</P>
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<P class="Body" style="margin: 0px">BitmapManager(void)</P>
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<P class="Body" style="margin: 0px">~BitmapManager(void)</P>
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<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>
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<P class="Body" style="margin: 0px">void DeleteBitmap(ServerBitmap *bitmap)</P>
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Global Functions</P>
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extern "C" void set_area_buffer_management(void);</P>
<P class="Body" style="margin: 0px">void * expand_area_storage(long size)</P>
<P class="Body" style="margin: 0px">void contract_area_storage(void *buffer)</P>
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<P class="Body" style="margin: 0px"><span class="OBOS-Function-Def">BitmapManager(void)</span></P>
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1) Create the bitmap list</P>
<P class="Body" style="margin: 0px">2) Create the bitmap area</P>
<P class="Body" style="margin: 0px">3) Allocate the access semaphore</P>
<P class="Body" style="margin: 0px">4) Call set_buffer_area_management</P>
<P class="Body" style="margin: 0px">5) Set up the buffer pool via bpool</P>
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<span class="OBOS-Function-Def">~BitmapManager(void)</span></P>
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1) Iterate over each item in the bitmap list, removing each item, calling brel() on its buffer, and deleting it.</P>
<P class="Body" style="margin: 0px">2) Delete the bitmap list</P>
<P class="Body" style="margin: 0px">3) Delete the bitmap area</P>
<P class="Body" style="margin: 0px">4) Free the access semaphore</P>
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<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>
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CreateBitmap is called by outside objects to allocate a ServerBitmap object. If a problem occurs, it returns NULL.</P>
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1) Acquire the access semaphore</P>
<P class="Body" style="margin: 0px">2) Verify parameters and if any are invalid, spew an error to stderr and return NULL</P>
<P class="Body" style="margin: 0px">3) Allocate a new ServerBitmap</P>
<P class="Body" style="margin: 0px">4) Allocate a buffer for the bitmap via bget() with the bitmap's theoretical buffer length</P>
<P class="Body" style="margin: 0px">5) If NULL, delete the bitmap and return NULL</P>
<P class="Body" style="margin: 0px">6) Set the bitmap's area and buffer to the appropriate values (area_for buffer and buffer)</P>
<P class="Body" style="margin: 0px">7) Add the bitmap to the bitmap list</P>
<P class="Body" style="margin: 0px">8) Release the access semaphore</P>
<P class="Body" style="margin: 0px">9) Return the bitmap</P>
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<span class="OBOS-Function-Def">void DeleteBitmap(ServerBitmap *bitmap)</span></P>
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Frees a ServerBitmap allocated by CreateBitmap()</span></P>
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1) Acquire the access semaphore</span></P>
<P class="Body" style="margin: 0px"><span class="Default">2) Find the bitmap in the list</span></P>
<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>
<P class="Body" style="margin: 0px"><span class="Default">4) call brel() on the bitmap's buffer if it is non-NULL</span></P>
<P class="Body" style="margin: 0px"><span class="Default">5) delete the bitmap</span></P>
<P class="Body" style="margin: 0px"><span class="Default">6) Release the access semaphore</span></P>
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</span><span class="OBOS-Function-Def">extern "C" void set_area_buffer_management(void)</span></P>
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C function defined externally to point the BGET manager to our homegrown area allocation and deallocation functions.</span></P>
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</span><span class="OBOS-Function-Def">void * expand_area_storage(long size)</span></P>
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"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>
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1) If size is less than B_PAGE_SIZE, set the area size to B_PAGE_SIZE</P>
<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>
<P class="Body" style="margin: 0px">3) Call create_area with the area size.</P>
<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>
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<span class="OBOS-Function-Def">void contract_area_storage(void *buffer)</span></P>
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</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>
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1) Call area_for on the buffer</span></P>
<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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