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diff --git a/hw/xfree86/ramdac/CURSOR.NOTES b/hw/xfree86/ramdac/CURSOR.NOTES new file mode 100644 index 000000000..3e901e380 --- /dev/null +++ b/hw/xfree86/ramdac/CURSOR.NOTES @@ -0,0 +1,191 @@ + CURSOR.NOTES + + This file describes how to add hardware cursor support to a chipset +driver. Though the cursor support itself is in the ramdac module, +cursor management is separate from the rest of the module. + + +1) CURSOR INITIALIZATION AND SHUTDOWN + + All relevant prototypes and defines are in xf86Cursor.h. + + To initialize the cursor, the driver should allocate an +xf86CursorInfoRec via xf86CreateCursorInfoRec(), fill it out as described +later in this document and pass it to xf86InitCursor(). xf86InitCursor() +must be called _after_ the software cursor initialization (usually +miDCInitialize). + + When shutting down, the driver should free the xf86CursorInfoRec +structure in its CloseScreen function via xf86DestroyCursorInfoRec(). + + +2) FILLING OUT THE xf86CursorInfoRec + + The driver informs the ramdac module of it's hardware cursor capablities by +filling out an xf86CursorInfoRec structure and passing it to xf86InitCursor(). +The xf86CursorInfoRec contains the following function pointers: + + +/**** These functions are required ****/ + +void ShowCursor(ScrnInfoPtr pScrn) + + ShowCursor should display the current cursor. + +void HideCursor(ScrnInfoPtr pScrn) + + HideCursor should hide the current cursor. + +void SetCursorPosition(ScrnInfoPtr pScrn, int x, int y) + + Set the cursor position to (x,y). X and/or y may be negative + indicating that the cursor image is partially offscreen on + the left and/or top edges of the screen. It is up to the + driver to trap for this and deal with that situation. + +void SetCursorColors(ScrnInfoPtr pScrn, int bg, int fg) + + Set the cursor foreground and background colors. In 8bpp, fg and + bg are indicies into the current colormap unless the + HARDWARE_CURSOR_TRUECOLOR_AT_8BPP flag is set. In that case + and in all other bpps the fg and bg are in 8-8-8 RGB format. + +void LoadCursorImage(ScrnInfoPtr pScrn, unsigned char *bits) + + LoadCursorImage is how the hardware cursor bits computed by the + RealizeCursor function will be passed to the driver when the cursor + shape needs to be changed. + + +/**** These functions are optional ****/ + + +unsigned char* RealizeCursor(xf86CursorInfoPtr infoPtr, CursorPtr pCurs) + + If RealizeCursor is not provided by the driver, one will be provided + for you based on the Flags field described below. The driver must + provide this function if the hardware cursor format is not one of + the common ones supported by this module. + + +Bool UseHWCursor(ScreenPtr pScreen, CursorPtr pCurs) + + If the driver is unable to use a hardware cursor for reasons + other than the cursor being larger than the maximum specified + in the MaxWidth or MaxHeight field below, it can supply the + UseHWCursor function. If UseHWCursor is provided by the driver, + it will be called whenever the cursor shape changes or the video + mode changes. This is useful for when the hardware cursor cannot + be used in interlaced or doublescan modes. + + +/**** The following fields are required ****/ + +MaxWidth +MaxHeight + + These indicate the largest sized cursor that can be a hardware + cursor. It will fall back to a software cursor when a cursor + exceeding this size needs to be used. + + +Flags + + /* Color related flags */ + + HARDWARE_CURSOR_TRUECOLOR_AT_8BPP + + This indicates that the colors passed to the SetCursorColors + function should not be in 8-8-8 RGB format in 8bpp but rather, + they should be the pixel values from the current colormap. + + + /* Cursor data loading flags */ + + HARDWARE_CURSOR_SHOW_TRANSPARENT + + The HideCursor entry will normally be called instead of displaying a + completely transparent cursor, or when a switch to a software cursor + needs to occur. This flag prevents this behaviour, thus causing the + LoadCursorImage entry to be called with transparent cursor data. + NOTE: If you use this flag and provide your own RealizeCursor() entry, + ensure this entry returns transparent cursor data when called + with a NULL pCurs parameter. + + HARDWARE_CURSOR_UPDATE_UNHIDDEN + + This flag prevents the HideCursor call that would normally occur just before + the LoadCursorImage entry is to be called to load a new hardware cursor + image. + + + /* Cursor data packing flags */ + + Hardware cursor data consists of two pieces, a source and a mask. + The mask is a bitmap indicating which parts of the cursor are + transparent and which parts are drawn. The source is a bitmap + indicating which parts of the non-transparent portion of the the + cursor should be painted in the foreground color and which should + be painted in the background color. + + HARDWARE_CURSOR_INVERT_MASK + + By default, set bits indicate the opaque part of the mask bitmap + and clear bits indicate the transparent part. If your hardware + wants this the opposite way, this flag will invert the mask. + + HARDWARE_CURSOR_SWAP_SOURCE_AND_MASK + + By default, RealizeCursor will store the source first and then + the mask. If the hardware needs this order reversed then this + flag should be set. + + HARDWARE_CURSOR_AND_SOURCE_WITH_MASK + + This flag will have the module logical AND the source with the mask to make + sure there are no source bits set if the corresponding mask bits + aren't set. Some hardware will not care if source bits are set where + there are supposed to be transparent areas, but some hardware will + interpret this as a third cursor color or similar. That type of + hardware will need this flag set. + + HARDWARE_CURSOR_BIT_ORDER_MSBFIRST + + By default, it is assumed that the least significant bit in each byte + corresponds to the leftmost pixel on the screen. If your hardware + has this reversed you should set this flag. + + HARDWARE_CURSOR_NIBBLE_SWAPPED + + If your hardware requires byte swapping of the hardware cursor, enable + this option. + + + /* Source-Mask interleaving flags */ + + By default the source and mask data are inlined (source first unless + the HARDWARE_CURSOR_SWAP_SOURCE_AND_MASK flag is set). Some hardware + will require the source and mask to be interleaved, that is, X number + of source bits should packed and then X number of mask bits repeating + until the entire pattern is stored. The following flags describe the + bit interleave. + + HARDWARE_CURSOR_SOURCE_MASK_NOT_INTERLEAVED + + This one is the default. + + The following are for interleaved cursors. + + HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_1 + HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_8 + HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_16 + HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_32 + HARDWARE_CURSOR_SOURCE_MASK_INTERLEAVE_64 + + And once again, if your hardware requires something different than + these packing styles, your driver can supply its own RealizeCursor + function. + + + +$XFree86: xc/programs/Xserver/hw/xfree86/ramdac/CURSOR.NOTES,v 1.5 2003/02/13 20:28:41 tsi Exp $ |