gnome-shell/src/shell-drawing.c

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/* -*- mode: C; c-file-style: "gnu"; indent-tabs-mode: nil; -*- */
#include "shell-drawing.h"
#include <math.h>
/**
* shell_create_vertical_gradient:
* @top: the color at the top
* @bottom: the color at the bottom
*
* Creates a vertical gradient actor.
*
* Return value: (transfer none): a #ClutterCairoTexture actor with the
* gradient. The texture actor is floating, hence (transfer none).
*/
ClutterCairoTexture *
shell_create_vertical_gradient (ClutterColor *top,
ClutterColor *bottom)
{
ClutterCairoTexture *texture;
cairo_t *cr;
cairo_pattern_t *pattern;
/* Draw the gradient on an 8x8 pixel texture. Because the gradient is drawn
* from the uppermost to the lowermost row, after stretching 1/16 of the
* texture height has the top color and 1/16 has the bottom color. The 8
* pixel width is chosen for reasons related to graphics hardware internals.
*/
texture = CLUTTER_CAIRO_TEXTURE (clutter_cairo_texture_new (8, 8));
cr = clutter_cairo_texture_create (texture);
pattern = cairo_pattern_create_linear (0, 0, 0, 8);
cairo_pattern_add_color_stop_rgba (pattern, 0,
top->red / 255.,
top->green / 255.,
top->blue / 255.,
top->alpha / 255.);
cairo_pattern_add_color_stop_rgba (pattern, 1,
bottom->red / 255.,
bottom->green / 255.,
bottom->blue / 255.,
bottom->alpha / 255.);
cairo_set_source (cr, pattern);
cairo_paint (cr);
cairo_pattern_destroy (pattern);
cairo_destroy (cr);
return texture;
}
/**
* shell_create_horizontal_gradient:
* @left: the color on the left
* @right: the color on the right
*
* Creates a horizontal gradient actor.
*
* Return value: (transfer none): a #ClutterCairoTexture actor with the
* gradient. The texture actor is floating, hence (transfer none).
*/
ClutterCairoTexture *
shell_create_horizontal_gradient (ClutterColor *left,
ClutterColor *right)
{
ClutterCairoTexture *texture;
cairo_t *cr;
cairo_pattern_t *pattern;
/* Draw the gradient on an 8x1 pixel texture. Because the gradient is drawn
* from the left to the right column, after stretching 1/16 of the
* texture width has the left side color and 1/16 has the right side color.
* There is no reason to use the 8 pixel height that would be similar to the
* reason we are using the 8 pixel width for the vertical gradient, so we
* are just using the 1 pixel height instead.
*/
texture = CLUTTER_CAIRO_TEXTURE (clutter_cairo_texture_new (8, 1));
cr = clutter_cairo_texture_create (texture);
pattern = cairo_pattern_create_linear (0, 0, 8, 0);
cairo_pattern_add_color_stop_rgba (pattern, 0,
left->red / 255.,
left->green / 255.,
left->blue / 255.,
left->alpha / 255.);
cairo_pattern_add_color_stop_rgba (pattern, 1,
right->red / 255.,
right->green / 255.,
right->blue / 255.,
right->alpha / 255.);
cairo_set_source (cr, pattern);
cairo_paint (cr);
cairo_pattern_destroy (pattern);
cairo_destroy (cr);
return texture;
}
void
shell_draw_clock (ClutterCairoTexture *texture,
int hour,
int minute)
{
cairo_t *cr;
guint width, height;
double xc, yc, radius, hour_radius, minute_radius;
double angle;
clutter_cairo_texture_get_surface_size (texture, &width, &height);
xc = (double)width / 2;
yc = (double)height / 2;
radius = (double)(MIN(width, height)) / 2 - 2;
minute_radius = radius - 3;
hour_radius = radius / 2;
clutter_cairo_texture_clear (texture);
cr = clutter_cairo_texture_create (texture);
cairo_set_line_width (cr, 1.0);
/* Outline */
cairo_arc (cr, xc, yc, radius, 0.0, 2.0 * M_PI);
cairo_stroke (cr);
/* Hour hand. (We add a fraction to @hour for the minutes, then
* convert to radians, and then subtract pi/2 because cairo's origin
* is at 3:00, not 12:00.)
*/
angle = ((hour + minute / 60.0) / 12.0) * 2.0 * M_PI - M_PI / 2.0;
cairo_move_to (cr, xc, yc);
cairo_line_to (cr,
xc + hour_radius * cos (angle),
yc + hour_radius * sin (angle));
cairo_stroke (cr);
/* Minute hand */
angle = (minute / 60.0) * 2.0 * M_PI - M_PI / 2.0;
cairo_move_to (cr, xc, yc);
cairo_line_to (cr,
xc + minute_radius * cos (angle),
yc + minute_radius * sin (angle));
cairo_stroke (cr);
cairo_destroy (cr);
}
void
shell_draw_glow (ClutterCairoTexture *texture,
double red,
double green,
double blue,
double alpha)
{
cairo_t *cr;
guint width, height;
cairo_pattern_t *gradient;
clutter_cairo_texture_get_surface_size (texture, &width, &height);
clutter_cairo_texture_clear (texture);
cr = clutter_cairo_texture_create (texture);
cairo_save (cr);
cairo_translate (cr, width / 2.0, height / 2.0);
cairo_scale (cr, width / 2.0, height / 2.0);
gradient = cairo_pattern_create_radial (0.0, 0.0, 0.0, 0.0, 0.0, 1.0);
cairo_pattern_add_color_stop_rgba (gradient, 0.0, red, green, blue, alpha);
cairo_pattern_add_color_stop_rgba (gradient, 0.7, red, green, blue, alpha * 0.7);
cairo_pattern_add_color_stop_rgba (gradient, 1.0, red, green, blue, alpha * 0.3);
cairo_set_source (cr, gradient);
cairo_arc (cr, 0.0, 0.0, 1.0, 0.0, 2.0 * M_PI);
cairo_fill (cr);
cairo_restore (cr);
cairo_pattern_destroy (gradient);
cairo_destroy (cr);
}