diff options
Diffstat (limited to 'pixman/pixman/pixman-gradient-walker.c')
| -rw-r--r-- | pixman/pixman/pixman-gradient-walker.c | 106 |
1 files changed, 68 insertions, 38 deletions
diff --git a/pixman/pixman/pixman-gradient-walker.c b/pixman/pixman/pixman-gradient-walker.c index e7e724fa6..5944a559a 100644 --- a/pixman/pixman/pixman-gradient-walker.c +++ b/pixman/pixman/pixman-gradient-walker.c @@ -37,11 +37,14 @@ _pixman_gradient_walker_init (pixman_gradient_walker_t *walker, walker->stops = gradient->stops; walker->left_x = 0; walker->right_x = 0x10000; - walker->stepper = 0; - walker->left_ag = 0; - walker->left_rb = 0; - walker->right_ag = 0; - walker->right_rb = 0; + 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; @@ -55,6 +58,9 @@ gradient_walker_reset (pixman_gradient_walker_t *walker, 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) { @@ -116,24 +122,49 @@ gradient_walker_reset (pixman_gradient_walker_t *walker, left_c = right_c; } - walker->left_x = left_x; - walker->right_x = right_x; - walker->left_ag = ((left_c->alpha >> 8) << 16) | (left_c->green >> 8); - walker->left_rb = ((left_c->red & 0xff00) << 8) | (left_c->blue >> 8); - walker->right_ag = ((right_c->alpha >> 8) << 16) | (right_c->green >> 8); - walker->right_rb = ((right_c->red & 0xff00) << 8) | (right_c->blue >> 8); - - if (walker->left_x == walker->right_x || - (walker->left_ag == walker->right_ag && - walker->left_rb == walker->right_rb)) + /* 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->stepper = 0; + 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 { - int32_t width = right_x - left_x; - walker->stepper = ((1 << 24) + width / 2) / width; + 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; } @@ -142,31 +173,30 @@ uint32_t _pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker, pixman_fixed_48_16_t x) { - int dist, idist; - uint32_t t1, t2, a, color; + 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); - - dist = ((int)(x - walker->left_x) * walker->stepper) >> 16; - idist = 256 - dist; + gradient_walker_reset (walker, x); - /* combined INTERPOLATE and premultiply */ - t1 = walker->left_rb * idist + walker->right_rb * dist; - t1 = (t1 >> 8) & 0xff00ff; + y = x * (1.0f / 65536.0f); - t2 = walker->left_ag * idist + walker->right_ag * dist; - t2 &= 0xff00ff00; + 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); - color = t2 & 0xff000000; - a = t2 >> 24; + a8 = a + 0.5f; + r8 = r + 0.5f; + g8 = g + 0.5f; + b8 = b + 0.5f; - t1 = t1 * a + 0x800080; - t1 = (t1 + ((t1 >> 8) & 0xff00ff)) >> 8; + v = ((a8 << 24) & 0xff000000) | + ((r8 << 16) & 0x00ff0000) | + ((g8 << 8) & 0x0000ff00) | + ((b8 >> 0) & 0x000000ff); - t2 = (t2 >> 8) * a + 0x800080; - t2 = (t2 + ((t2 >> 8) & 0xff00ff)); - - return (color | (t1 & 0xff00ff) | (t2 & 0xff00)); + return v; } - |