/* cairo - a vector graphics library with display and print output * * Copyright © 2011 Intel Corporation. * * This library is free software; you can redistribute it and/or * modify it either under the terms of the GNU Lesser General Public * License version 2.1 as published by the Free Software Foundation * (the "LGPL") or, at your option, under the terms of the Mozilla * Public License Version 1.1 (the "MPL"). If you do not alter this * notice, a recipient may use your version of this file under either * the MPL or the LGPL. * * You should have received a copy of the LGPL along with this library * in the file COPYING-LGPL-2.1; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA * You should have received a copy of the MPL along with this library * in the file COPYING-MPL-1.1 * * The contents of this file are subject to the Mozilla Public License * Version 1.1 (the "License"); you may not use this file except in * compliance with the License. You may obtain a copy of the License at * http://www.mozilla.og/MPL/ * * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY * OF ANY KIND, either express or implied. See the LGPL or the MPL for * the specific language governing rights and limitations. * * Contributor(s): * Robert Bragg */ //#include "cairoint.h" #include "cairo-cogl-private.h" #include "cairo-cogl-gradient-private.h" #include "cairo-image-surface-private.h" #include #include #define DUMP_GRADIENTS_TO_PNG static unsigned long _cairo_cogl_linear_gradient_hash (unsigned int n_stops, const cairo_gradient_stop_t *stops) { return _cairo_hash_bytes (n_stops, stops, sizeof (cairo_gradient_stop_t) * n_stops); } static cairo_cogl_linear_gradient_t * _cairo_cogl_linear_gradient_lookup (cairo_cogl_device_t *ctx, unsigned long hash, unsigned int n_stops, const cairo_gradient_stop_t *stops) { cairo_cogl_linear_gradient_t lookup; lookup.cache_entry.hash = hash, lookup.n_stops = n_stops; lookup.stops = stops; return _cairo_cache_lookup (&ctx->linear_cache, &lookup.cache_entry); } cairo_bool_t _cairo_cogl_linear_gradient_equal (const void *key_a, const void *key_b) { const cairo_cogl_linear_gradient_t *a = key_a; const cairo_cogl_linear_gradient_t *b = key_b; if (a->n_stops != b->n_stops) return FALSE; return memcmp (a->stops, b->stops, a->n_stops * sizeof (cairo_gradient_stop_t)) == 0; } cairo_cogl_linear_gradient_t * _cairo_cogl_linear_gradient_reference (cairo_cogl_linear_gradient_t *gradient) { assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count)); _cairo_reference_count_inc (&gradient->ref_count); return gradient; } void _cairo_cogl_linear_gradient_destroy (cairo_cogl_linear_gradient_t *gradient) { GList *l; assert (CAIRO_REFERENCE_COUNT_HAS_REFERENCE (&gradient->ref_count)); if (! _cairo_reference_count_dec_and_test (&gradient->ref_count)) return; for (l = gradient->textures; l; l = l->next) { cairo_cogl_linear_texture_entry_t *entry = l->data; cogl_object_unref (entry->texture); free (entry); } g_list_free (gradient->textures); free (gradient); } static int _cairo_cogl_util_next_p2 (int a) { int rval = 1; while (rval < a) rval <<= 1; return rval; } static float get_max_color_component_range (const cairo_color_stop_t *color0, const cairo_color_stop_t *color1) { float range; float max = 0; range = fabs (color0->red - color1->red); max = MAX (range, max); range = fabs (color0->green - color1->green); max = MAX (range, max); range = fabs (color0->blue - color1->blue); max = MAX (range, max); range = fabs (color0->alpha - color1->alpha); max = MAX (range, max); return max; } static int _cairo_cogl_linear_gradient_width_for_stops (cairo_extend_t extend, unsigned int n_stops, const cairo_gradient_stop_t *stops) { unsigned int n; float max_texels_per_unit_offset = 0; float total_offset_range; /* Find the stop pair demanding the most precision because we are * interpolating the largest color-component range. * * From that we can define the relative sizes of all the other * stop pairs within our texture and thus the overall size. * * To determine the maximum number of texels for a given gap we * look at the range of colors we are expected to interpolate (so * long as the stop offsets are not degenerate) and we simply * assume we want one texel for each unique color value possible * for a one byte-per-component representation. * XXX: maybe this is overkill and just allowing 128 levels * instead of 256 would be enough and then we'd rely on the * bilinear filtering to give the full range. * * XXX: potentially we could try and map offsets to pixels to come * up with a more precise mapping, but we are aiming to cache * the gradients so we can't make assumptions about how it will be * scaled in the future. */ for (n = 1; n < n_stops; n++) { float color_range; float offset_range; float texels; float texels_per_unit_offset; /* note: degenerate stops don't need to be represented in the * texture but we want to be sure that solid gaps get at least * one texel and all other gaps get at least 2 texels. */ if (stops[n].offset == stops[n-1].offset) continue; color_range = get_max_color_component_range (&stops[n].color, &stops[n-1].color); if (color_range == 0) texels = 1; else texels = MAX (2, 256.0f * color_range); /* So how many texels would we need to map over the full [0,1] * gradient range so this gap would have enough texels? ... */ offset_range = stops[n].offset - stops[n - 1].offset; texels_per_unit_offset = texels / offset_range; if (texels_per_unit_offset > max_texels_per_unit_offset) max_texels_per_unit_offset = texels_per_unit_offset; } total_offset_range = fabs (stops[n_stops - 1].offset - stops[0].offset); return max_texels_per_unit_offset * total_offset_range; } /* Aim to create gradient textures without an alpha component so we can avoid * needing to use blending... */ static CoglPixelFormat _cairo_cogl_linear_gradient_format_for_stops (cairo_extend_t extend, unsigned int n_stops, const cairo_gradient_stop_t *stops) { unsigned int n; /* We have to add extra transparent texels to the end of the gradient to * handle CAIRO_EXTEND_NONE... */ if (extend == CAIRO_EXTEND_NONE) return COGL_PIXEL_FORMAT_BGRA_8888_PRE; for (n = 1; n < n_stops; n++) { if (stops[n].color.alpha != 1.0) return COGL_PIXEL_FORMAT_BGRA_8888_PRE; } return COGL_PIXEL_FORMAT_BGR_888; } static cairo_cogl_gradient_compatibility_t _cairo_cogl_compatibility_from_extend_mode (cairo_extend_t extend_mode) { switch (extend_mode) { case CAIRO_EXTEND_NONE: return CAIRO_COGL_GRADIENT_CAN_EXTEND_NONE; case CAIRO_EXTEND_PAD: return CAIRO_COGL_GRADIENT_CAN_EXTEND_PAD; case CAIRO_EXTEND_REPEAT: return CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT; case CAIRO_EXTEND_REFLECT: return CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT; } assert (0); /* not reached */ return CAIRO_EXTEND_NONE; } cairo_cogl_linear_texture_entry_t * _cairo_cogl_linear_gradient_texture_for_extend (cairo_cogl_linear_gradient_t *gradient, cairo_extend_t extend_mode) { GList *l; cairo_cogl_gradient_compatibility_t compatibility = _cairo_cogl_compatibility_from_extend_mode (extend_mode); for (l = gradient->textures; l; l = l->next) { cairo_cogl_linear_texture_entry_t *entry = l->data; if (entry->compatibility & compatibility) return entry; } return NULL; } static void color_stop_lerp (const cairo_color_stop_t *c0, const cairo_color_stop_t *c1, float factor, cairo_color_stop_t *dest) { /* NB: we always ignore the short members in this file so we don't need to * worry about initializing them here. */ dest->red = c0->red * (1.0f-factor) + c1->red * factor; dest->green = c0->green * (1.0f-factor) + c1->green * factor; dest->blue = c0->blue * (1.0f-factor) + c1->blue * factor; dest->alpha = c0->alpha * (1.0f-factor) + c1->alpha * factor; } static size_t _cairo_cogl_linear_gradient_size (cairo_cogl_linear_gradient_t *gradient) { GList *l; size_t size = 0; for (l = gradient->textures; l; l = l->next) { cairo_cogl_linear_texture_entry_t *entry = l->data; size += cogl_texture_get_width (entry->texture) * 4; } return size; } static void emit_stop (CoglVertexP2C4 **position, float left, float right, const cairo_color_stop_t *left_color, const cairo_color_stop_t *right_color) { CoglVertexP2C4 *p = *position; guint8 lr = left_color->red * 255; guint8 lg = left_color->green * 255; guint8 lb = left_color->blue * 255; guint8 la = left_color->alpha * 255; guint8 rr = right_color->red * 255; guint8 rg = right_color->green * 255; guint8 rb = right_color->blue * 255; guint8 ra = right_color->alpha * 255; p[0].x = left; p[0].y = 0; p[0].r = lr; p[0].g = lg; p[0].b = lb; p[0].a = la; p[1].x = left; p[1].y = 1; p[1].r = lr; p[1].g = lg; p[1].b = lb; p[1].a = la; p[2].x = right; p[2].y = 1; p[2].r = rr; p[2].g = rg; p[2].b = rb; p[2].a = ra; p[3].x = left; p[3].y = 0; p[3].r = lr; p[3].g = lg; p[3].b = lb; p[3].a = la; p[4].x = right; p[4].y = 1; p[4].r = rr; p[4].g = rg; p[4].b = rb; p[4].a = ra; p[5].x = right; p[5].y = 0; p[5].r = rr; p[5].g = rg; p[5].b = rb; p[5].a = ra; *position = &p[6]; } #ifdef DUMP_GRADIENTS_TO_PNG static void dump_gradient_to_png (CoglTexture *texture) { cairo_image_surface_t *image = (cairo_image_surface_t *) cairo_image_surface_create (CAIRO_FORMAT_ARGB32, cogl_texture_get_width (texture), cogl_texture_get_height (texture)); CoglPixelFormat format; static int gradient_id = 0; char *gradient_name; if (image->base.status) return; #if G_BYTE_ORDER == G_LITTLE_ENDIAN format = COGL_PIXEL_FORMAT_BGRA_8888_PRE; #else format = COGL_PIXEL_FORMAT_ARGB_8888_PRE; #endif cogl_texture_get_data (texture, format, 0, image->data); gradient_name = g_strdup_printf ("./gradient%d.png", gradient_id++); g_print ("writing gradient: %s\n", gradient_name); cairo_surface_write_to_png ((cairo_surface_t *)image, gradient_name); g_free (gradient_name); } #endif cairo_int_status_t _cairo_cogl_get_linear_gradient (cairo_cogl_device_t *device, cairo_extend_t extend_mode, int n_stops, const cairo_gradient_stop_t *stops, cairo_cogl_linear_gradient_t **gradient_out) { unsigned long hash; cairo_cogl_linear_gradient_t *gradient; cairo_cogl_linear_texture_entry_t *entry; cairo_gradient_stop_t *internal_stops; int stop_offset; int n_internal_stops; int n; cairo_cogl_gradient_compatibility_t compatibilities; int width; int left_padding = 0; cairo_color_stop_t left_padding_color; int right_padding = 0; cairo_color_stop_t right_padding_color; CoglPixelFormat format; CoglTexture2D *tex; GError *error = NULL; int un_padded_width; CoglHandle offscreen; cairo_int_status_t status; int n_quads; int n_vertices; float prev; float right; CoglVertexP2C4 *vertices; CoglVertexP2C4 *p; CoglPrimitive *prim; hash = _cairo_cogl_linear_gradient_hash (n_stops, stops); gradient = _cairo_cogl_linear_gradient_lookup (device, hash, n_stops, stops); if (gradient) { cairo_cogl_linear_texture_entry_t *entry = _cairo_cogl_linear_gradient_texture_for_extend (gradient, extend_mode); if (entry) { *gradient_out = _cairo_cogl_linear_gradient_reference (gradient); return CAIRO_INT_STATUS_SUCCESS; } } if (!gradient) { gradient = _cairo_malloc (sizeof (cairo_cogl_linear_gradient_t) + sizeof (cairo_gradient_stop_t) * (n_stops - 1)); if (!gradient) return CAIRO_INT_STATUS_NO_MEMORY; CAIRO_REFERENCE_COUNT_INIT (&gradient->ref_count, 1); /* NB: we update the cache_entry size at the end before * [re]adding it to the cache. */ gradient->cache_entry.hash = hash; gradient->textures = NULL; gradient->n_stops = n_stops; gradient->stops = gradient->stops_embedded; memcpy (gradient->stops_embedded, stops, sizeof (cairo_gradient_stop_t) * n_stops); } else _cairo_cogl_linear_gradient_reference (gradient); entry = _cairo_malloc (sizeof (cairo_cogl_linear_texture_entry_t)); if (!entry) { status = CAIRO_INT_STATUS_NO_MEMORY; goto BAIL; } compatibilities = _cairo_cogl_compatibility_from_extend_mode (extend_mode); n_internal_stops = n_stops; stop_offset = 0; /* We really need stops covering the full [0,1] range for repeat/reflect * if we want to use sampler REPEAT/MIRROR wrap modes so we may need * to add some extra stops... */ if (extend_mode == CAIRO_EXTEND_REPEAT || extend_mode == CAIRO_EXTEND_REFLECT) { /* If we don't need any extra stops then actually the texture * will be shareable for repeat and reflect... */ compatibilities = (CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT | CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT); if (stops[0].offset != 0) { n_internal_stops++; stop_offset++; } if (stops[n_stops - 1].offset != 1) n_internal_stops++; } internal_stops = alloca (n_internal_stops * sizeof (cairo_gradient_stop_t)); memcpy (&internal_stops[stop_offset], stops, sizeof (cairo_gradient_stop_t) * n_stops); /* cairo_color_stop_t values are all unpremultiplied but we need to * interpolate premultiplied colors so we premultiply all the double * components now. (skipping any extra stops added for repeat/reflect) * * Anothing thing to note is that by premultiplying the colors * early we'll also reduce the range of colors to interpolate * which can result in smaller gradient textures. */ for (n = stop_offset; n < n_stops; n++) { cairo_color_stop_t *color = &internal_stops[n].color; color->red *= color->alpha; color->green *= color->alpha; color->blue *= color->alpha; } if (n_internal_stops != n_stops) { if (extend_mode == CAIRO_EXTEND_REPEAT) { compatibilities &= ~CAIRO_COGL_GRADIENT_CAN_EXTEND_REFLECT; if (stops[0].offset != 0) { /* what's the wrap-around distance between the user's end-stops? */ double dx = (1.0 - stops[n_stops - 1].offset) + stops[0].offset; internal_stops[0].offset = 0; color_stop_lerp (&stops[0].color, &stops[n_stops - 1].color, stops[0].offset / dx, &internal_stops[0].color); } if (stops[n_stops - 1].offset != 1) { internal_stops[n_internal_stops - 1].offset = 1; internal_stops[n_internal_stops - 1].color = internal_stops[0].color; } } else if (extend_mode == CAIRO_EXTEND_REFLECT) { compatibilities &= ~CAIRO_COGL_GRADIENT_CAN_EXTEND_REPEAT; if (stops[0].offset != 0) { internal_stops[0].offset = 0; internal_stops[0].color = stops[n_stops - 1].color; } if (stops[n_stops - 1].offset != 1) { internal_stops[n_internal_stops - 1].offset = 1; internal_stops[n_internal_stops - 1].color = stops[0].color; } } } stops = internal_stops; n_stops = n_internal_stops; width = _cairo_cogl_linear_gradient_width_for_stops (extend_mode, n_stops, stops); if (extend_mode == CAIRO_EXTEND_PAD) { /* Here we need to guarantee that the edge texels of our * texture correspond to the desired padding color so we * can use CLAMP_TO_EDGE. * * For short stop-gaps and especially for degenerate stops * it's possible that without special consideration the * user's end stop colors would not be present in our final * texture. * * To handle this we forcibly add two extra padding texels * at the edges which extend beyond the [0,1] range of the * gradient itself and we will later report a translate and * scale transform to compensate for this. */ /* XXX: If we consider generating a mipmap for our 1d texture * at some point then we also need to consider how much * padding to add to be sure lower mipmap levels still have * the desired edge color (as opposed to a linear blend with * other colors of the gradient). */ left_padding = 1; left_padding_color = stops[0].color; right_padding = 1; right_padding_color = stops[n_stops - 1].color; } else if (extend_mode == CAIRO_EXTEND_NONE) { /* We handle EXTEND_NONE by adding two extra, transparent, texels at * the ends of the texture and use CLAMP_TO_EDGE. * * We add a scale and translate transform so to account for our texels * extending beyond the [0,1] range. */ left_padding = 1; left_padding_color.red = 0; left_padding_color.green = 0; left_padding_color.blue = 0; left_padding_color.alpha = 0; right_padding = 1; right_padding_color = left_padding_color; } /* If we still have stops that don't cover the full [0,1] range * then we need to define a texture-coordinate scale + translate * transform to account for that... */ if (stops[n_stops - 1].offset - stops[0].offset < 1) { float range = stops[n_stops - 1].offset - stops[0].offset; entry->scale_x = 1.0 / range; entry->translate_x = -(stops[0].offset * entry->scale_x); } width += left_padding + right_padding; width = _cairo_cogl_util_next_p2 (width); width = MIN (4096, width); /* lets not go too stupidly big! */ format = _cairo_cogl_linear_gradient_format_for_stops (extend_mode, n_stops, stops); do { tex = cogl_texture_2d_new_with_size (device->cogl_context, width, 1, format, &error); if (!tex) g_error_free (error); } while (tex == NULL && width >> 1); if (!tex) { status = CAIRO_INT_STATUS_NO_MEMORY; goto BAIL; } entry->texture = COGL_TEXTURE (tex); entry->compatibility = compatibilities; un_padded_width = width - left_padding - right_padding; /* XXX: only when we know the final texture width can we calculate the * scale and translate factors needed to account for padding... */ if (un_padded_width != width) entry->scale_x *= (float)un_padded_width / (float)width; if (left_padding) entry->translate_x += (entry->scale_x / (float)un_padded_width) * (float)left_padding; offscreen = cogl_offscreen_new_to_texture (tex); cogl_push_framebuffer (COGL_FRAMEBUFFER (offscreen)); cogl_ortho (0, width, 1, 0, -1, 100); cogl_framebuffer_clear4f (COGL_FRAMEBUFFER (offscreen), COGL_BUFFER_BIT_COLOR, 0, 0, 0, 0); n_quads = n_stops - 1 + !!left_padding + !!right_padding; n_vertices = 6 * n_quads; vertices = alloca (sizeof (CoglVertexP2C4) * n_vertices); p = vertices; if (left_padding) emit_stop (&p, 0, left_padding, &left_padding_color, &left_padding_color); prev = (float)left_padding; for (n = 1; n < n_stops; n++) { right = (float)left_padding + (float)un_padded_width * stops[n].offset; emit_stop (&p, prev, right, &stops[n-1].color, &stops[n].color); prev = right; } if (right_padding) emit_stop (&p, prev, width, &right_padding_color, &right_padding_color); prim = cogl_primitive_new_p2c4 (COGL_VERTICES_MODE_TRIANGLES, n_vertices, vertices); /* Just use this as the simplest way to setup a default pipeline... */ cogl_set_source_color4f (0, 0, 0, 0); cogl_primitive_draw (prim); cogl_object_unref (prim); cogl_pop_framebuffer (); cogl_object_unref (offscreen); gradient->textures = g_list_prepend (gradient->textures, entry); gradient->cache_entry.size = _cairo_cogl_linear_gradient_size (gradient); #ifdef DUMP_GRADIENTS_TO_PNG dump_gradient_to_png (COGL_TEXTURE (tex)); #endif #warning "FIXME:" /* XXX: it seems the documentation of _cairo_cache_insert isn't true - it * doesn't handle re-adding the same entry gracefully - the cache will * just keep on growing and then it will start randomly evicting things * pointlessly */ /* we ignore errors here and just return an uncached gradient */ if (likely (! _cairo_cache_insert (&device->linear_cache, &gradient->cache_entry))) _cairo_cogl_linear_gradient_reference (gradient); *gradient_out = gradient; return CAIRO_INT_STATUS_SUCCESS; BAIL: free (entry); if (gradient) _cairo_cogl_linear_gradient_destroy (gradient); return status; }