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/* ----------------------------------------------------------------------------
*
* Double buffering code, courtesy of Stephan Zachwieja
* Some modifications to suit particular needs by Mark Stern (Summer 1990)
*
* ----------------------------------------------------------------------------
*/
#include "dbl.h"
struct {
unsigned short red;
unsigned short green;
unsigned short blue;
} color[] = {
{ 65280, 65280, 65280 }, /* white */
{ 0, 0, 65280 }, /* blue */
{ 0, 65280, 0 }, /* green */
{ 65280, 0, 0 }, /* red */
{ 42240, 10752, 10752 }, /* brown */
{ 65280, 32512, 0 }, /* orange */
{ 32512, 32512, 32512 }, /* gray */
{ 0, 0, 0 } /* black */
};
/* ------------------------------------------------------------------------- */
DoubleBuffer *
DBLcreate_double_buffer (display, window, backing_store, colors, num_colors)
Display *display;
Window window;
int backing_store;
XColor *colors;
int num_colors;
{
int i, j, k, l, m, offset, mask, size;
int max_planes;
char *string;
Surface *surface;
DoubleBuffer *db;
XGCValues xgcv;
unsigned long xgcvmask;
/* allocate the double buffer structure, and then open the display */
if ((db = (DoubleBuffer *)calloc(1, sizeof(DoubleBuffer))) == 0) {
printf("DBLopen_double_buffer : memory allocation error\n");
return (NULL);
}
/* note the display */
db->display = display;
/* first some information about our display */
db->screen = DefaultScreenOfDisplay(db->display);
db->window = window;
/* now get some information on color resources */
db->visual = DefaultVisualOfScreen(db->screen);
db->depth = DefaultDepthOfScreen(db->screen);
db->colormap = DefaultColormapOfScreen(db->screen);
/* set up colors */
for (i = 0 ; i < num_colors; i++) {
color[i].red = colors[i].red;
color[i].green = colors[i].green;
color[i].blue = colors[i].blue;
}
/* see if the user wanted to limit the number of planes used
then see how many are available, make it a multiple of 2 */
if ((string = getenv("DBL_MAX_PLANES")) == NULL)
max_planes = DBL_MAX_PLANES;
else {
max_planes = atoi(string);
}
if ((db->num_planes = PlanesOfScreen(db->screen)) > max_planes) {
db->num_planes = max_planes;
}
db->num_planes = (db->num_planes >> 1) << 1;
/* otherwise allocate contiguous planes to do double buffering */
while (db->num_planes >= DBL_MIN_PLANES) {
if (XAllocColorCells (db->display, db->colormap, 1, db->planes,
db->num_planes, db->pixels, 1)) {
break;
}
db->num_planes -= 2;
}
/* if we have at least minimum planes, then we can do double
buffering and we want to setup our surfaces and colormaps */
if (db->num_planes < DBL_MIN_PLANES)
db->num_surfaces = 0;
else {
db->num_colors = 1 << (db->num_planes >> 1);
db->num_surfaces = DBL_MAX_SURFACES;
/* if the number of colors is less than DBL_MAX_COLORS,
then we want to make sure black is the last color */
for (i = db->num_colors - 1; i < DBL_MAX_COLORS; i++) {
color[i].red = color[DBL_MAX_COLORS - 1].red;
color[i].green = color[DBL_MAX_COLORS - 1].green;
color[i].blue = color[DBL_MAX_COLORS - 1].blue;
}
/* we have a set of contiguous planes. compute a mask for
the planes, and figure out the offset in the hardware */
for (i = 0; i < db->num_planes; i++) {
db->mask |= db->planes[i];
}
mask = db->mask;
offset = 0;
while ((mask & 1) == 0) {
mask = mask >> 1;
offset = offset + 1;
}
mask = (1 << (db->num_planes >> 1)) - 1;
/* now create the surfaces that will contain plane mask and
colormap information that we use to do double buffering */
for (i = 0; i < db->num_surfaces; i++) {
size = sizeof(Surface) + sizeof(XColor) * (1 << db->num_planes);
if ((surface = (Surface *)malloc(size)) != NULL)
db->surface[i] = surface;
else {
printf("DBLcreate_double_buffer : memory allocation error\n");
DBLdelete_double_buffer(db);
return(NULL);
}
surface->offset = offset + i * (db->num_planes >> 1);
surface->mask = mask << surface->offset;
surface->num_colors = 1 << db->num_planes;
/* compute our pixel values by taking every permutation
of the pixel and planes returned by XAllocColorCells */
for (j = 0; j < (surface->num_colors); j++) {
surface->color[j].pixel = db->pixels[0];
}
for (j = 0; j < db->num_planes; j++) {
for (k = (1 << j); k < (surface->num_colors); k += (2 << j)) {
for (l = k; l < (k + (1 << j)); l++) {
surface->color[l].pixel |= db->planes[j];
}
}
}
/* now populate those pixels with the proper colors so
that we can do animation by banging in a new colormap */
for (j = 0; j < surface->num_colors; j++) {
k = (j & surface->mask) >> surface->offset;
surface->color[j].red = color[k].red;
surface->color[j].green = color[k].green;
surface->color[j].blue = color[k].blue;
surface->color[j].flags = DoRed | DoGreen | DoBlue;
}
}
db->current_surface = 0;
}
/* now figure out what pixel values we will use to draw with
and store them in the double buffer structure */
if (db->num_surfaces == 0) {
db->num_colors = DBL_MAX_COLORS;
db->colors[0] = WhitePixelOfScreen(db->screen);
for (i = 1; i < db->num_colors; i++) {
db->colors[i] = BlackPixelOfScreen(db->screen);
}
}
else {
for (i = 0; i < db->num_colors; i++) {
j = (i << (db->num_planes >> 1)) + i;
db->colors[i] = db->surface[0]->color[j].pixel;
}
}
/* fill out the remaining colors with the last color */
for (; i < DBL_MAX_COLORS; i++) {
db->colors[i] = db->colors[db->num_colors - 1];
}
db->width = WidthOfScreen(db->screen);
db->height = HeightOfScreen(db->screen);
/* if there are no surfaces then we are doing animation with
a frame buffer, so create a pixmap as our frame buffer */
if (db->num_surfaces > 0)
db->drawable = db->window;
else {
db->frame = XCreatePixmap(db->display, db->window,
db->width, db->height, db->depth);
db->drawable = db->frame;
}
/* if they have requested backing store, then create an extra
pixmap which we can use as backing store to handle exposures */
if (backing_store) {
db->backing = XCreatePixmap(db->display, db->window,
db->width, db->height, db->depth);
}
/* use the 0 pixel from one of the surfaces for the background */
xgcv.background = DBLinq_background(db);
xgcv.line_style = LineSolid;
xgcv.line_width = 0;
xgcv.cap_style = CapButt;
xgcv.join_style = JoinRound;
xgcvmask = GCBackground | GCLineStyle | GCLineWidth | GCCapStyle |
GCJoinStyle;
db->gc = XCreateGC(db->display, db->drawable, xgcvmask, &xgcv);
/* do an initial frame to setup the colormap, and return */
DBLbegin_frame(db);
DBLend_frame(db);
return (db);
}
/* ------------------------------------------------------------------------- */
void
DBLdelete_double_buffer (db)
DoubleBuffer *db;
{
int i;
/* remove and and all surfaces that are out there */
for (i = 0; i < DBL_MAX_SURFACES; i++) {
if (db->surface[i] != 0) {
free(db->surface[i]);
}
}
/* now clean up the various resources used for this double buffer */
if (db->frame != 0) {
XFreePixmap(db->display, db->frame);
}
if (db->backing != 0) {
XFreePixmap(db->display, db->backing);
}
/* if we created our own private colormap, then free the colormap */
if (db->colormap != DefaultColormapOfScreen(db->screen)) {
XFreeColormap(db->display, db->colormap);
}
free (db);
}
/* ------------------------------------------------------------------------- */
unsigned long
DBLinq_background(db)
DoubleBuffer *db;
{
if (db->num_surfaces > 0)
return(db->surface[0]->color[0].pixel);
else
return(WhitePixelOfScreen(db->screen));
}
/* ------------------------------------------------------------------------- */
DBLbegin_frame(db)
DoubleBuffer *db;
{
Surface *surface;
/* there will be at most two surfaces optimize with "&"*/
if (db->num_surfaces > 0) {
db->current_surface = (db->current_surface + 1) & 1;
surface = db->surface[db->current_surface];
}
/* clear the back surface of the window which may actually be a pixmap */
if (db->num_surfaces > 0)
XSetPlaneMask (db->display, db->gc, surface->mask);
/* clear out the back surface or frame buffer as appropriate */
XSetFunction(db->display, db->gc, GXclear);
XFillRectangle(db->display, db->drawable, db->gc,
0, 0, db->width, db->height);
/* set writing mode back to copy */
XSetFunction (db->display, db->gc, GXcopy);
XSync(db->display, False);
}
/* ------------------------------------------------------------------------- */
DBLend_frame(db)
DoubleBuffer *db;
{
Surface *surface;
/* if there are no drawing surfaces, then we are doing animation
with a frame buffer, copy the frame buffers to their viewports */
if (db->num_surfaces == 0) {
XCopyArea (db->display, db->frame, db->window,
db->gc, 0,0, db->width, db->height, 0,0);
} else {
/* otherwise, we can flip the surface by banging in the new colormap */
XSync(db->display, False);
surface = db->surface[db->current_surface];
XStoreColors (db->display, db->colormap,
surface->color, surface->num_colors);
}
if (db->backing != 0) {
XCopyArea (db->display, db->window, db->backing,
db->gc, 0,0, db->width, db->height, 0,0);
}
/* make sure this all goes off to the server, right away */
XSync(db->display, False);
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.