GetWMgrPort
GetWMgrPort Obtain a pointer to the Window Manager port GrafPtr *wPort; receives the pointer value value that may be used to find out about the Window Manager's
graphics environment.
Notes: We are warned against modifying fields of the Window Manager's GrafPort. However, as a read-only data area, it can be useful in finding out such facts
as the height and width of the primary screen. See the discussion of the
To simply get the size of the primary screen, access the global variable
screenBits. The global variable GrayRgn may be more useful; it is the
region below the menu bar, including all real estate on multiple screens.
In order to be MulitFinder compatible, applications shouldn't draw outside
their windows. MultiFinder documentation warns against drawing in
WMgrPort since the system "owns" the desktop and windows of other
applications are drawn within it. However, if you must draw outside your
window, you should follow these rules.
WMgrPort has its visRgn set to include all active screens. Its clipRgn is
initially set to the rectangle -32767, -32767, 32767, 32767. This
GrafPort should be treated as read-only, with global variable GrayRgn equal
to the WMgrPort's visRgn less the menu bar. You should use GrayRgn to
find the shape, size and coordinates of the screen. You should never have to
use the WMgrPort directly and you shouldn't call GetWMgrPort ever.
Rules
Only draw to the whole screen in a " modal" way. This could be an
animation across windows or visual feedback from dragging from one to
an other. It is important to know that no other application, including the
Finder, will draw until you have finished. In the case of an animation effect,
the drawing shouldn't take much time. In the case of a drag, you should only
draw while the mouse button is down.
All operations should end with nothing left drawn outside your windows.
Under MultiFinder it is alright not to call GetNextEvent, EventAvail or
WaitNextEvent while drawing outside your windows. Use the StillDown or
WaitMouseUp functions for loops that wait for the mouse button to go up.
Never draw something on the desktop and leave it there. There is no way to
tell the system that you have drawn on the desktop, so the Finder may draw
right over you.
Examples and How To
One famous animation effect is the ZoomRect routine. It is used by the
Finder to draw a series of nested rectangles around an icon that is being
opened. The rectangles zoom out to where the window for the icon will be.
Another example is when you drag something to another window. This
should be done with DragGrayRgn, which does the right thing and doesn't call
GetNextEvent, etc.
To make these examples happen, you should use a GrafPort, not a window
or WMgrPort, that covers all the screens. OpenPort will set up most of the
fields of the GrafPort correctly. You have to change the visRgn of your port
to a copy of GrayRgn and put the GrayRgn's rgnBox into your portRect.
Don't directly manipulate the visRgn of a window under MultiFinder!
Draw using srcXor mode; this will allow you to erase as you go, by drawing
each object a second time, also in srcXor mode. Remember to leave all areas
outside your window exactly as you found them.
WDEFs and MDEFs
Window and menu definition procedures draw in the current port, which is
set to the WMgrPort by the WindowManager and the Menu Manager. This
means you don't ever have to call GetWMgrPort. You shouldn't ever draw into
it except from one of these procedures!