diff options
Diffstat (limited to 'src/pixman/pixman/pixman-gradient-walker.c')
| -rw-r--r-- | src/pixman/pixman/pixman-gradient-walker.c | 202 |
1 files changed, 202 insertions, 0 deletions
diff --git a/src/pixman/pixman/pixman-gradient-walker.c b/src/pixman/pixman/pixman-gradient-walker.c new file mode 100644 index 0000000..5944a55 --- /dev/null +++ b/src/pixman/pixman/pixman-gradient-walker.c @@ -0,0 +1,202 @@ +/* + * + * Copyright © 2000 Keith Packard, member of The XFree86 Project, Inc. + * 2005 Lars Knoll & Zack Rusin, Trolltech + * + * 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 Keith Packard not be used in + * advertising or publicity pertaining to distribution of the software without + * specific, written prior permission. Keith Packard makes no + * representations about the suitability of this software for any purpose. It + * is provided "as is" without express or implied warranty. + * + * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS + * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND + * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS 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. + */ + +#ifdef HAVE_CONFIG_H +#include <config.h> +#endif +#include "pixman-private.h" + +void +_pixman_gradient_walker_init (pixman_gradient_walker_t *walker, + gradient_t * gradient, + pixman_repeat_t repeat) +{ + walker->num_stops = gradient->n_stops; + walker->stops = gradient->stops; + walker->left_x = 0; + walker->right_x = 0x10000; + walker->a_s = 0.0f; + walker->a_b = 0.0f; + walker->r_s = 0.0f; + walker->r_b = 0.0f; + walker->g_s = 0.0f; + walker->g_b = 0.0f; + walker->b_s = 0.0f; + walker->b_b = 0.0f; + walker->repeat = repeat; + + walker->need_reset = TRUE; +} + +static void +gradient_walker_reset (pixman_gradient_walker_t *walker, + pixman_fixed_48_16_t pos) +{ + int32_t x, left_x, right_x; + pixman_color_t *left_c, *right_c; + int n, count = walker->num_stops; + pixman_gradient_stop_t *stops = walker->stops; + float la, lr, lg, lb; + float ra, rr, rg, rb; + float lx, rx; + + if (walker->repeat == PIXMAN_REPEAT_NORMAL) + { + x = (int32_t)pos & 0xffff; + } + else if (walker->repeat == PIXMAN_REPEAT_REFLECT) + { + x = (int32_t)pos & 0xffff; + if ((int32_t)pos & 0x10000) + x = 0x10000 - x; + } + else + { + x = pos; + } + + for (n = 0; n < count; n++) + { + if (x < stops[n].x) + break; + } + + left_x = stops[n - 1].x; + left_c = &stops[n - 1].color; + + right_x = stops[n].x; + right_c = &stops[n].color; + + if (walker->repeat == PIXMAN_REPEAT_NORMAL) + { + left_x += (pos - x); + right_x += (pos - x); + } + else if (walker->repeat == PIXMAN_REPEAT_REFLECT) + { + if ((int32_t)pos & 0x10000) + { + pixman_color_t *tmp_c; + int32_t tmp_x; + + tmp_x = 0x10000 - right_x; + right_x = 0x10000 - left_x; + left_x = tmp_x; + + tmp_c = right_c; + right_c = left_c; + left_c = tmp_c; + + x = 0x10000 - x; + } + left_x += (pos - x); + right_x += (pos - x); + } + else if (walker->repeat == PIXMAN_REPEAT_NONE) + { + if (n == 0) + right_c = left_c; + else if (n == count) + left_c = right_c; + } + + /* The alpha channel is scaled to be in the [0, 255] interval, + * and the red/green/blue channels are scaled to be in [0, 1]. + * This ensures that after premultiplication all channels will + * be in the [0, 255] interval. + */ + la = (left_c->alpha * (1.0f/257.0f)); + lr = (left_c->red * (1.0f/257.0f)); + lg = (left_c->green * (1.0f/257.0f)); + lb = (left_c->blue * (1.0f/257.0f)); + + ra = (right_c->alpha * (1.0f/257.0f)); + rr = (right_c->red * (1.0f/257.0f)); + rg = (right_c->green * (1.0f/257.0f)); + rb = (right_c->blue * (1.0f/257.0f)); + + lx = left_x * (1.0f/65536.0f); + rx = right_x * (1.0f/65536.0f); + + if (FLOAT_IS_ZERO (rx - lx) || left_x == INT32_MIN || right_x == INT32_MAX) + { + walker->a_s = walker->r_s = walker->g_s = walker->b_s = 0.0f; + walker->a_b = (la + ra) / 2.0f; + walker->r_b = (lr + rr) / 510.0f; + walker->g_b = (lg + rg) / 510.0f; + walker->b_b = (lb + rb) / 510.0f; + } + else + { + float w_rec = 1.0f / (rx - lx); + + walker->a_b = (la * rx - ra * lx) * w_rec; + walker->r_b = (lr * rx - rr * lx) * w_rec * (1.0f/255.0f); + walker->g_b = (lg * rx - rg * lx) * w_rec * (1.0f/255.0f); + walker->b_b = (lb * rx - rb * lx) * w_rec * (1.0f/255.0f); + + walker->a_s = (ra - la) * w_rec; + walker->r_s = (rr - lr) * w_rec * (1.0f/255.0f); + walker->g_s = (rg - lg) * w_rec * (1.0f/255.0f); + walker->b_s = (rb - lb) * w_rec * (1.0f/255.0f); + } + + walker->left_x = left_x; + walker->right_x = right_x; + + walker->need_reset = FALSE; +} + +uint32_t +_pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker, + pixman_fixed_48_16_t x) +{ + float a, r, g, b; + uint8_t a8, r8, g8, b8; + uint32_t v; + float y; + + if (walker->need_reset || x < walker->left_x || x >= walker->right_x) + gradient_walker_reset (walker, x); + + y = x * (1.0f / 65536.0f); + + a = walker->a_s * y + walker->a_b; + r = a * (walker->r_s * y + walker->r_b); + g = a * (walker->g_s * y + walker->g_b); + b = a * (walker->b_s * y + walker->b_b); + + a8 = a + 0.5f; + r8 = r + 0.5f; + g8 = g + 0.5f; + b8 = b + 0.5f; + + v = ((a8 << 24) & 0xff000000) | + ((r8 << 16) & 0x00ff0000) | + ((g8 << 8) & 0x0000ff00) | + ((b8 >> 0) & 0x000000ff); + + return v; +} |
