icimage.c

按照官方的说法：Cairo is a vector graphics library with cross-device output support. 翻译过来

/*
 * Copyright © 2000 SuSE, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of SuSE not be used in advertising or
 * publicity pertaining to distribution of the software without specific,
 * written prior permission.  SuSE makes no representations about the
 * suitability of this software for any purpose.  It is provided "as is"
 * without express or implied warranty.
 *
 * SuSE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL SuSE
 * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
 * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
 * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * Author:  Keith Packard, SuSE, Inc.
 */

#include "pixman-xserver-compat.h"

pixman_image_t *
pixman_image_create (pixman_format_t	*format,
	       int	width,
	       int	height)
{
    pixman_image_t	*image;
    FbPixels	*pixels;

    pixels = FbPixelsCreate (width, height, format->depth);
    if (pixels == NULL)
	return NULL;

    image = pixman_image_createForPixels (pixels, format);
    if (image == NULL) {
	FbPixelsDestroy (pixels);
	return NULL;
    }

    image->owns_pixels = 1;

    return image;
}
slim_hidden_def(pixman_image_create);

pixman_image_t *
pixman_image_create_for_data (FbBits *data, pixman_format_t *format, int width, int height, int bpp, int stride)
{
    pixman_image_t	*image;
    FbPixels	*pixels;

    pixels = FbPixelsCreateForData (data, width, height, format->depth, bpp, stride);
    if (pixels == NULL)
	return NULL;

    image = pixman_image_createForPixels (pixels, format);
    if (image == NULL) {
	FbPixelsDestroy (pixels);
	return NULL;
    }

    image->owns_pixels = 1;

    return image;
}

pixman_image_t *
pixman_image_createForPixels (FbPixels	*pixels,
			pixman_format_t	*format)
{
    pixman_image_t		*image;

    image = malloc (sizeof (pixman_image_t));
    if (!image)
    {
	return NULL;
    }

    image->pixels = pixels;
    image->image_format = *format;
    image->format_code = format->format_code;
/* XXX: What's all this about?
    if (pDrawable->type == DRAWABLE_PIXMAP)
    {
	++((PixmapPtr)pDrawable)->refcnt;
	image->pNext = 0;
    }
    else
    {
	image->pNext = GetPictureWindow(((WindowPtr) pDrawable));
	SetPictureWindow(((WindowPtr) pDrawable), image);
    }
*/

    pixman_image_init (image);

    return image;
}

static CARD32 xRenderColorToCard32(pixman_color_t c)
{
    return
        (c.alpha >> 8 << 24) |
        (c.red >> 8 << 16) |
        (c.green & 0xff00) |
        (c.blue >> 8);
}

static uint32_t premultiply(uint32_t x)
{
    uint32_t a = x >> 24;
    uint32_t t = (x & 0xff00ff) * a + 0x800080;
    t = (t + ((t >> 8) & 0xff00ff)) >> 8;
    t &= 0xff00ff;

    x = ((x >> 8) & 0xff) * a + 0x80;
    x = (x + ((x >> 8) & 0xff));
    x &= 0xff00;
    x |= t | (a << 24);
    return x;
}

static uint32_t INTERPOLATE_PIXEL_256(uint32_t x, uint32_t a, uint32_t y, uint32_t b)
{
    CARD32 t = (x & 0xff00ff) * a + (y & 0xff00ff) * b;
    t >>= 8;
    t &= 0xff00ff;

    x = ((x >> 8) & 0xff00ff) * a + ((y >> 8) & 0xff00ff) * b;
    x &= 0xff00ff00;
    x |= t;
    return x;
}

uint32_t
pixman_gradient_color (pixman_gradient_stop_t *stop1,
		       pixman_gradient_stop_t *stop2,
		       uint32_t		      x)
{
    uint32_t current_color, next_color;
    int	     dist, idist;

    current_color = xRenderColorToCard32 (stop1->color);
    next_color    = xRenderColorToCard32 (stop2->color);

    dist  = (int) (256 * (x - stop1->x) / (stop2->x - stop1->x));
    idist = 256 - dist;

    return premultiply (INTERPOLATE_PIXEL_256 (current_color, idist,
					       next_color, dist));
}

static int
_pixman_init_gradient (pixman_gradient_image_t	    *gradient,
		       const pixman_gradient_stop_t *stops,
		       int			    n_stops)
{
    pixman_fixed16_16_t dpos;
    int			i;

    if (n_stops <= 0)
	return 1;

    dpos = -1;
    for (i = 0; i < n_stops; i++)
    {
	if (stops[i].x < dpos || stops[i].x > (1 << 16))
	    return 1;

	dpos = stops[i].x;
    }

    gradient->class	     = SourcePictClassUnknown;
    gradient->stopRange	     = 0xffff;
    gradient->colorTable     = NULL;
    gradient->colorTableSize = 0;

    return 0;
}

static pixman_image_t *
_pixman_create_source_image (void)
{
    pixman_image_t *image;

    image = (pixman_image_t *) malloc (sizeof (pixman_image_t));
    image->pDrawable   = 0;
    image->pixels      = 0;
    image->format_code = PICT_a8r8g8b8;

    pixman_image_init (image);

    return image;
}

pixman_image_t *
pixman_image_create_linear_gradient (const pixman_linear_gradient_t *gradient,
				     const pixman_gradient_stop_t   *stops,
				     int			    n_stops)
{
    pixman_linear_gradient_image_t *linear;
    pixman_image_t		   *image;

    if (n_stops < 2)
	return 0;

    image = _pixman_create_source_image ();
    if (!image)
	return 0;

    linear = malloc (sizeof (pixman_linear_gradient_image_t) +
		     sizeof (pixman_gradient_stop_t) * n_stops);
    if (!linear)
    {
	free (image);
	return 0;
    }

    linear->stops  = (pixman_gradient_stop_t *) (linear + 1);
    linear->nstops = n_stops;

    memcpy (linear->stops, stops, sizeof (pixman_gradient_stop_t) * n_stops);

    linear->type = SourcePictTypeLinear;
    linear->p1   = gradient->p1;
    linear->p2   = gradient->p2;

    image->pSourcePict = (pixman_source_image_t *) linear;

    if (_pixman_init_gradient (&image->pSourcePict->gradient, stops, n_stops))
    {
	free (image);
	return 0;
    }

    return image;
}

pixman_image_t *
pixman_image_create_radial_gradient (const pixman_radial_gradient_t *gradient,
				     const pixman_gradient_stop_t   *stops,
				     int			    n_stops)
{
    pixman_radial_gradient_image_t *radial;
    pixman_image_t		   *image;
    double			   x;

    if (n_stops < 2)
	return 0;

    image = _pixman_create_source_image ();
    if (!image)
	return 0;

    radial = malloc (sizeof (pixman_radial_gradient_image_t) +
		     sizeof (pixman_gradient_stop_t) * n_stops);
    if (!radial)
    {
	free (image);
	return 0;
    }

    radial->stops  = (pixman_gradient_stop_t *) (radial + 1);
    radial->nstops = n_stops;

    memcpy (radial->stops, stops, sizeof (pixman_gradient_stop_t) * n_stops);

    radial->type = SourcePictTypeRadial;
    x = (double) gradient->inner.radius / (double) gradient->outer.radius;
    radial->dx = (gradient->outer.x - gradient->inner.x);
    radial->dy = (gradient->outer.y - gradient->inner.y);
    radial->fx = (gradient->inner.x) - x * radial->dx;
    radial->fy = (gradient->inner.y) - x * radial->dy;
    radial->m = 1. / (1 + x);
    radial->b = -x * radial->m;
    radial->dx /= 65536.;
    radial->dy /= 65536.;
    radial->fx /= 65536.;
    radial->fy /= 65536.;
    x = gradient->outer.radius / 65536.;
    radial->a = x * x - radial->dx * radial->dx - radial->dy * radial->dy;

    image->pSourcePict = (pixman_source_image_t *) radial;

    if (_pixman_init_gradient (&image->pSourcePict->gradient, stops, n_stops))
    {
	free (image);
	return 0;
    }

    return image;
}

void
pixman_image_init (pixman_image_t *image)
{
    image->refcnt = 1;
    image->repeat = PIXMAN_REPEAT_NONE;
    image->graphicsExposures = 0;
    image->subWindowMode = ClipByChildren;
    image->polyEdge = PolyEdgeSharp;
    image->polyMode = PolyModePrecise;
    /*
     * In the server this was 0 because the composite clip list
     * can be referenced from a window (and often is)
     */
    image->freeCompClip = 0;
    image->freeSourceClip = 0;
    image->clientClipType = CT_NONE;
    image->componentAlpha = 0;
    image->compositeClipSource = 0;

    image->alphaMap = NULL;
    image->alphaOrigin.x = 0;
    image->alphaOrigin.y = 0;

    image->clipOrigin.x = 0;
    image->clipOrigin.y = 0;
    image->clientClip = NULL;

    image->dither = 0L;

    image->stateChanges = (1 << (CPLastBit+1)) - 1;
/* XXX: What to lodge here?
    image->serialNumber = GC_CHANGE_SERIAL_BIT;
*/

    if (image->pixels)
    {
	image->pCompositeClip = pixman_region_create();
	pixman_region_union_rect (image->pCompositeClip, image->pCompositeClip,
				  0, 0, image->pixels->width,
				  image->pixels->height);
	image->freeCompClip = 1;

	image->pSourceClip = pixman_region_create ();
	pixman_region_union_rect (image->pSourceClip, image->pSourceClip,
				  0, 0, image->pixels->width,
				  image->pixels->height);
	image->freeSourceClip = 1;
    }
    else
    {
	image->pCompositeClip = NULL;
	image->pSourceClip    = NULL;
    }

    image->transform = NULL;

    image->filter = PIXMAN_FILTER_NEAREST;
    image->filter_params = NULL;
    image->filter_nparams = 0;

    image->owns_pixels = 0;

    image->pSourcePict = NULL;
}

void
pixman_image_set_component_alpha (pixman_image_t	*image,
				  int		component_alpha)
{
    if (image)
	image->componentAlpha = component_alpha;
}
slim_hidden_def(pixman_image_set_component_alpha);

int
pixman_image_set_transform (pixman_image_t		*image,
		     pixman_transform_t	*transform)
{
    static const pixman_transform_t	identity = { {
	{ xFixed1, 0x00000, 0x00000 },
	{ 0x00000, xFixed1, 0x00000 },
	{ 0x00000, 0x00000, xFixed1 },
    } };

    if (transform && memcmp (transform, &identity, sizeof (pixman_transform_t)) == 0)
	transform = NULL;

    if (transform)
    {
	if (!image->transform)
	{
	    image->transform = malloc (sizeof (pixman_transform_t));
	    if (!image->transform)
		return 1;
	}
	*image->transform = *transform;
    }
    else
    {
	if (image->transform)
	{
	    free (image->transform);
	    image->transform = NULL;
	}
    }
    return 0;
}

void
pixman_image_set_repeat (pixman_image_t		*image,
			 pixman_repeat_t	repeat)
{
    if (image)
	image->repeat = repeat;
}
slim_hidden_def(pixman_image_set_repeat);

void
pixman_image_set_filter (pixman_image_t	*image,
		  pixman_filter_t	filter)
{
    if (image)
	image->filter = filter;
}

int
pixman_image_get_width (pixman_image_t	*image)
{
    if (image->pixels)
	return image->pixels->width;

    return 0;
}

int
pixman_image_get_height (pixman_image_t	*image)
{
    if (image->pixels)
	return image->pixels->height;

    return 0;
}

int
pixman_image_get_depth (pixman_image_t	*image)
{
    if (image->pixels)
	return image->pixels->depth;

    return 0;
}

int
pixman_image_get_stride (pixman_image_t	*image)
{
    if (image->pixels)
	return image->pixels->stride;

    return 0;
}

pixman_format_t *
pixman_image_get_format (pixman_image_t	*image)
{
    return &image->image_format;
}

FbBits *
pixman_image_get_data (pixman_image_t	*image)
{
    if (image->pixels)
	return image->pixels->data;

    return 0;
}