The Be Book - System Overview - The Application Kit
You can use a
BCursor to represent a mouse cursor as
an object instead of as a block of pixel data; this can be more convenient
in some situations. Also, if you want to call BApplication::SetCursor()
without forcing an immediate sync of the Application Server,
you have to use a BCursor.
The default BCursors are
B_CURSOR_SYSTEM_DEFAULT
for the hand cursor and
B_CURSOR_I_BEAM
for the I-beam
text editing cursor.
The first four bytes of cursor data give information about the cursor:
Byte 1 | Size in pixels-per-side. Cursors are always square; currently, only 16-by-16 cursors are allowed. |
Byte 2 | Color depth in bits-per-pixel. Currently, only one-bit monochrome is allowed. |
Bytes 3 & 4 | Hot spot coordinates. Given in "cursor coordinates" where (0,0) is the upper left corner of the cursor grid, byte 3 is the hot spot's y coordinate, and byte 4 is its x coordinate. The hot spot is a single pixel that's "activated" when the user clicks the mouse. To push a button, for example, the hot spot must be within the button's bounds. |
Next comes an array of pixel color data. Pixels are specified from left to right in rows starting at the top of the image and working downward. The size of an array element is the depth of the image. In one-bit depth…
the 16x16 array fits in 32 bytes. 1 is black and 0 is white.
Then comes the pixel transparency bitmask, given left-to-right and top-to-bottom. 1 is opaque, 0 is transparent. Transparency only applies to white pixels, black pixels are always opaque.
