gtk2/demos/gtk-demo/transparent.c
2017-01-20 21:37:04 +01:00

242 lines
6.6 KiB
C

/* Overlay/Transparency
*
* Use transparent background on GdkWindows to create a shadow effect on a GtkOverlay widget.
*/
#include <gtk/gtk.h>
#define SHADOW_OFFSET_X 7
#define SHADOW_OFFSET_Y 7
#define SHADOW_RADIUS 5
static void
draw_shadow_box (cairo_t *cr,
GdkRectangle rect,
double radius,
double transparency)
{
cairo_pattern_t *pattern;
double x0, x1, x2, x3;
double y0, y1, y2, y3;
x0 = rect.x;
x1 = rect.x + radius;
x2 = rect.x + rect.width - radius;
x3 = rect.x + rect.width;
y0 = rect.y;
y1 = rect.y + radius;
y2 = rect.y + rect.height - radius;
y3 = rect.y + rect.height;
/* Fill non-border part */
cairo_set_source_rgba (cr, 0, 0, 0, transparency);
cairo_rectangle (cr,
x1, y1, x2 - x1, y2 - y1);
cairo_fill (cr);
/* Upper border */
pattern = cairo_pattern_create_linear (0, y0, 0, y1);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, 0.0);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, transparency);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x1, y0,
x2 - x1, y1 - y0);
cairo_fill (cr);
/* Bottom border */
pattern = cairo_pattern_create_linear (0, y2, 0, y3);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x1, y2,
x2 - x1, y3 - y2);
cairo_fill (cr);
/* Left border */
pattern = cairo_pattern_create_linear (x0, 0, x1, 0);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, 0.0);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, transparency);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x0, y1,
x1 - x0, y2 - y1);
cairo_fill (cr);
/* Right border */
pattern = cairo_pattern_create_linear (x2, 0, x3, 0);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x2, y1,
x3 - x2, y2 - y1);
cairo_fill (cr);
/* NW corner */
pattern = cairo_pattern_create_radial (x1, y1, 0,
x1, y1, radius);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x0, y0,
x1 - x0, y1 - y0);
cairo_fill (cr);
/* NE corner */
pattern = cairo_pattern_create_radial (x2, y1, 0,
x2, y1, radius);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x2, y0,
x3 - x2, y1 - y0);
cairo_fill (cr);
/* SW corner */
pattern = cairo_pattern_create_radial (x1, y2, 0,
x1, y2, radius);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x0, y2,
x1 - x0, y3 - y2);
cairo_fill (cr);
/* SE corner */
pattern = cairo_pattern_create_radial (x2, y2, 0,
x2, y2, radius);
cairo_pattern_add_color_stop_rgba (pattern, 0.0, 0.0, 0, 0, transparency);
cairo_pattern_add_color_stop_rgba (pattern, 1.0, 0.0, 0, 0, 0.0);
cairo_set_source (cr, pattern);
cairo_pattern_destroy (pattern);
cairo_rectangle (cr,
x2, y2,
x3 - x2, y3 - y2);
cairo_fill (cr);
}
static gboolean
draw_callback (GtkWidget *widget,
cairo_t *cr,
gpointer data)
{
GdkRectangle rect;
gtk_widget_get_allocation (widget, &rect);
rect.x += SHADOW_OFFSET_X;
rect.y += SHADOW_OFFSET_Y;
rect.width -= SHADOW_OFFSET_X;
rect.height -= SHADOW_OFFSET_Y;
draw_shadow_box (cr,
rect, SHADOW_RADIUS, 0.4);
return FALSE;
}
GtkWidget *
do_transparent (GtkWidget *do_widget)
{
static GtkWidget *window = NULL;
if (!window)
{
GtkWidget *view;
GtkWidget *sw;
GtkWidget *overlay;
GtkWidget *entry;
GtkCssProvider *provider;
gchar *css;
window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
gtk_window_set_screen (GTK_WINDOW (window),
gtk_widget_get_screen (do_widget));
gtk_window_set_default_size (GTK_WINDOW (window), 450, 450);
g_signal_connect (window, "destroy",
G_CALLBACK (gtk_widget_destroyed), &window);
gtk_window_set_title (GTK_WINDOW (window), "Transparency");
view = gtk_text_view_new ();
sw = gtk_scrolled_window_new (NULL, NULL);
gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (sw),
GTK_POLICY_AUTOMATIC,
GTK_POLICY_AUTOMATIC);
gtk_container_add (GTK_CONTAINER (sw), view);
overlay = gtk_overlay_new ();
gtk_container_add (GTK_CONTAINER (overlay), sw);
gtk_container_add (GTK_CONTAINER (window), overlay);
entry = gtk_entry_new ();
provider = gtk_css_provider_new ();
css = g_strdup_printf ("* { border-width: 0px %dpx %dpx 0px; }",
SHADOW_OFFSET_X, SHADOW_OFFSET_Y);
gtk_css_provider_load_from_data (provider, css, -1);
g_free (css);
gtk_style_context_add_provider (gtk_widget_get_style_context (entry),
GTK_STYLE_PROVIDER (provider),
GTK_STYLE_PROVIDER_PRIORITY_APPLICATION);
g_signal_connect (entry, "draw", G_CALLBACK (draw_callback), NULL);
gtk_overlay_add_overlay (GTK_OVERLAY (overlay), entry);
gtk_widget_set_halign (entry, GTK_ALIGN_CENTER);
gtk_widget_set_valign (entry, GTK_ALIGN_START);
gtk_widget_show (overlay);
}
if (!gtk_widget_get_visible (window))
gtk_widget_show (window);
else
gtk_widget_destroy (window);
return window;
}