--- /dev/null
+/*
+ * art_render_gradient.c: Gradient image source for modular rendering.
+ *
+ * Libart_LGPL - library of basic graphic primitives
+ * Copyright (C) 2000 Raph Levien
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ *
+ * Authors: Raph Levien <raph@acm.org>
+ * Alexander Larsson <alla@lysator.liu.se>
+ */
+
+#include <math.h>
+
+#include "art_misc.h"
+#include "art_alphagamma.h"
+#include "art_filterlevel.h"
+
+#include "art_render.h"
+#include "art_render_gradient.h"
+
+typedef struct _ArtImageSourceGradLin ArtImageSourceGradLin;
+typedef struct _ArtImageSourceGradRad ArtImageSourceGradRad;
+
+struct _ArtImageSourceGradLin {
+ ArtImageSource super;
+ const ArtGradientLinear *gradient;
+};
+
+struct _ArtImageSourceGradRad {
+ ArtImageSource super;
+ const ArtGradientRadial *gradient;
+ double a;
+};
+
+#define EPSILON 1e-6
+
+/**
+ * art_render_gradient_setpix: Set a gradient pixel.
+ * @render: The render object.
+ * @dst: Pointer to destination (where to store pixel).
+ * @n_stops: Number of stops in @stops.
+ * @stops: The stops for the gradient.
+ * @offset: The offset.
+ *
+ * @n_stops must be > 0.
+ *
+ * Sets a gradient pixel, storing it at @dst.
+ **/
+static void
+art_render_gradient_setpix (ArtRender *render,
+ art_u8 *dst,
+ int n_stops, ArtGradientStop *stops,
+ double offset)
+{
+ int ix;
+ int j;
+ double off0, off1;
+ int n_ch = render->n_chan + 1;
+
+ for (ix = 0; ix < n_stops; ix++)
+ if (stops[ix].offset > offset)
+ break;
+ /* stops[ix - 1].offset < offset < stops[ix].offset */
+ if (ix > 0 && ix < n_stops)
+ {
+ off0 = stops[ix - 1].offset;
+ off1 = stops[ix].offset;
+ if (fabs (off1 - off0) > EPSILON)
+ {
+ double interp;
+
+ interp = (offset - off0) / (off1 - off0);
+ for (j = 0; j < n_ch; j++)
+ {
+ int z0, z1;
+ int z;
+ z0 = stops[ix - 1].color[j];
+ z1 = stops[ix].color[j];
+ z = floor (z0 + (z1 - z0) * interp + 0.5);
+ if (render->buf_depth == 8)
+ dst[j] = ART_PIX_8_FROM_MAX (z);
+ else /* (render->buf_depth == 16) */
+ ((art_u16 *)dst)[j] = z;
+ }
+ return;
+ }
+ }
+ else if (ix == n_stops)
+ ix--;
+
+ for (j = 0; j < n_ch; j++)
+ {
+ int z;
+ z = stops[ix].color[j];
+ if (render->buf_depth == 8)
+ dst[j] = ART_PIX_8_FROM_MAX (z);
+ else /* (render->buf_depth == 16) */
+ ((art_u16 *)dst)[j] = z;
+ }
+}
+
+static void
+art_render_gradient_linear_done (ArtRenderCallback *self, ArtRender *render)
+{
+ art_free (self);
+}
+
+static void
+art_render_gradient_linear_render (ArtRenderCallback *self, ArtRender *render,
+ art_u8 *dest, int y)
+{
+ ArtImageSourceGradLin *z = (ArtImageSourceGradLin *)self;
+ const ArtGradientLinear *gradient = z->gradient;
+ int pixstride = (render->n_chan + 1) * (render->depth >> 3);
+ int x;
+ int width = render->x1 - render->x0;
+ double offset, d_offset;
+ double actual_offset;
+ int n_stops = gradient->n_stops;
+ ArtGradientStop *stops = gradient->stops;
+ art_u8 *bufp = render->image_buf;
+ ArtGradientSpread spread = gradient->spread;
+
+ offset = render->x0 * gradient->a + y * gradient->b + gradient->c;
+ d_offset = gradient->a;
+
+ for (x = 0; x < width; x++)
+ {
+ if (spread == ART_GRADIENT_PAD)
+ actual_offset = offset;
+ else if (spread == ART_GRADIENT_REPEAT)
+ actual_offset = offset - floor (offset);
+ else /* (spread == ART_GRADIENT_REFLECT) */
+ {
+ double tmp;
+
+ tmp = offset - 2 * floor (0.5 * offset);
+ actual_offset = tmp > 1 ? 2 - tmp : tmp;
+ }
+ art_render_gradient_setpix (render, bufp, n_stops, stops, actual_offset);
+ offset += d_offset;
+ bufp += pixstride;
+ }
+}
+
+static void
+art_render_gradient_linear_negotiate (ArtImageSource *self, ArtRender *render,
+ ArtImageSourceFlags *p_flags,
+ int *p_buf_depth, ArtAlphaType *p_alpha)
+{
+ self->super.render = art_render_gradient_linear_render;
+ *p_flags = 0;
+ *p_buf_depth = render->depth;
+ *p_alpha = ART_ALPHA_PREMUL;
+}
+
+/**
+ * art_render_gradient_linear: Add a linear gradient image source.
+ * @render: The render object.
+ * @gradient: The linear gradient.
+ *
+ * Adds the linear gradient @gradient as the image source for rendering
+ * in the render object @render.
+ **/
+void
+art_render_gradient_linear (ArtRender *render,
+ const ArtGradientLinear *gradient,
+ ArtFilterLevel level)
+{
+ ArtImageSourceGradLin *image_source = art_new (ArtImageSourceGradLin, 1);
+
+ image_source->super.super.render = NULL;
+ image_source->super.super.done = art_render_gradient_linear_done;
+ image_source->super.negotiate = art_render_gradient_linear_negotiate;
+
+ image_source->gradient = gradient;
+
+ art_render_add_image_source (render, &image_source->super);
+}
+
+static void
+art_render_gradient_radial_done (ArtRenderCallback *self, ArtRender *render)
+{
+ art_free (self);
+}
+
+static void
+art_render_gradient_radial_render (ArtRenderCallback *self, ArtRender *render,
+ art_u8 *dest, int y)
+{
+ ArtImageSourceGradRad *z = (ArtImageSourceGradRad *)self;
+ const ArtGradientRadial *gradient = z->gradient;
+ int pixstride = (render->n_chan + 1) * (render->depth >> 3);
+ int x;
+ int x0 = render->x0;
+ int width = render->x1 - x0;
+ int n_stops = gradient->n_stops;
+ ArtGradientStop *stops = gradient->stops;
+ art_u8 *bufp = render->image_buf;
+ double fx = gradient->fx;
+ double fy = gradient->fy;
+ double dx, dy;
+ double *affine = gradient->affine;
+ double aff0 = affine[0];
+ double aff1 = affine[1];
+ const double a = z->a;
+ const double arecip = 1.0 / a;
+ double b, db;
+ double c, dc, ddc;
+ double b_a, db_a;
+ double rad, drad, ddrad;
+
+ dx = x0 * aff0 + y * affine[2] + affine[4] - fx;
+ dy = x0 * aff1 + y * affine[3] + affine[5] - fy;
+ b = dx * fx + dy * fy;
+ db = aff0 * fx + aff1 * fy;
+ c = dx * dx + dy * dy;
+ dc = 2 * aff0 * dx + aff0 * aff0 + 2 * aff1 * dy + aff1 * aff1;
+ ddc = 2 * aff0 * aff0 + 2 * aff1 * aff1;
+
+ b_a = b * arecip;
+ db_a = db * arecip;
+
+ rad = b_a * b_a + c * arecip;
+ drad = 2 * b_a * db_a + db_a * db_a + dc * arecip;
+ ddrad = 2 * db_a * db_a + ddc * arecip;
+
+ for (x = 0; x < width; x++)
+ {
+ double z;
+
+ if (rad > 0)
+ z = b_a + sqrt (rad);
+ else
+ z = b_a;
+ art_render_gradient_setpix (render, bufp, n_stops, stops, z);
+ bufp += pixstride;
+ b_a += db_a;
+ rad += drad;
+ drad += ddrad;
+ }
+}
+
+static void
+art_render_gradient_radial_negotiate (ArtImageSource *self, ArtRender *render,
+ ArtImageSourceFlags *p_flags,
+ int *p_buf_depth, ArtAlphaType *p_alpha)
+{
+ self->super.render = art_render_gradient_radial_render;
+ *p_flags = 0;
+ *p_buf_depth = render->depth;
+ *p_alpha = ART_ALPHA_PREMUL;
+}
+
+/**
+ * art_render_gradient_radial: Add a radial gradient image source.
+ * @render: The render object.
+ * @gradient: The radial gradient.
+ *
+ * Adds the radial gradient @gradient as the image source for rendering
+ * in the render object @render.
+ **/
+void
+art_render_gradient_radial (ArtRender *render,
+ const ArtGradientRadial *gradient,
+ ArtFilterLevel level)
+{
+ ArtImageSourceGradRad *image_source = art_new (ArtImageSourceGradRad, 1);
+ double fx = gradient->fx;
+ double fy = gradient->fy;
+
+ image_source->super.super.render = NULL;
+ image_source->super.super.done = art_render_gradient_radial_done;
+ image_source->super.negotiate = art_render_gradient_radial_negotiate;
+
+ image_source->gradient = gradient;
+ /* todo: sanitycheck fx, fy? */
+ image_source->a = 1 - fx * fx - fy * fy;
+
+ art_render_add_image_source (render, &image_source->super);
+}
projects / rrdtool.git / blobdiff