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Add the names of the main widgets as keywords to our demos, but also things like "game". This helps finding relevant demos in our growing list. You can now for example type "label", and find the "error states" and "links" demos showing GtkLabel features.
382 lines
10 KiB
C
382 lines
10 KiB
C
/* Drawing Area
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* #Keywords: GtkDrawingArea
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*
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* GtkDrawingArea is a blank area where you can draw custom displays
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* of various kinds.
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*
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* This demo has two drawing areas. The checkerboard area shows
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* how you can just draw something; all you have to do is set a function
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* via gtk_drawing_area_set_draw_func(), as shown here.
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*
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* The "scribble" area is a bit more advanced, and shows how to handle
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* events such as button presses and mouse motion. Click the mouse
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* and drag in the scribble area to draw squiggles. Resize the window
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* to clear the area.
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*/
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#include <gtk/gtk.h>
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static GtkWidget *window = NULL;
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/* Pixmap for scribble area, to store current scribbles */
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static cairo_surface_t *surface = NULL;
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/* Create a new surface of the appropriate size to store our scribbles */
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static void
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create_surface (GtkWidget *widget)
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{
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cairo_t *cr;
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if (surface)
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cairo_surface_destroy (surface);
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surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
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gtk_widget_get_width (widget),
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gtk_widget_get_height (widget));
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/* Initialize the surface to white */
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cr = cairo_create (surface);
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cairo_set_source_rgb (cr, 1, 1, 1);
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cairo_paint (cr);
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cairo_destroy (cr);
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}
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static void
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scribble_resize (GtkWidget *widget,
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int width,
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int height)
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{
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create_surface (widget);
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}
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/* Redraw the screen from the surface */
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static void
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scribble_draw (GtkDrawingArea *da,
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cairo_t *cr,
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int width,
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int height,
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gpointer data)
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{
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cairo_set_source_surface (cr, surface, 0, 0);
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cairo_paint (cr);
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}
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/* Draw a rectangle on the screen */
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static void
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draw_brush (GtkWidget *widget,
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double x,
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double y)
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{
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GdkRectangle update_rect;
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cairo_t *cr;
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if (surface == NULL ||
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cairo_image_surface_get_width (surface) != gtk_widget_get_width (widget) ||
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cairo_image_surface_get_height (surface) != gtk_widget_get_height (widget))
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create_surface (widget);
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update_rect.x = x - 3;
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update_rect.y = y - 3;
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update_rect.width = 6;
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update_rect.height = 6;
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/* Paint to the surface, where we store our state */
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cr = cairo_create (surface);
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gdk_cairo_rectangle (cr, &update_rect);
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cairo_fill (cr);
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cairo_destroy (cr);
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gtk_widget_queue_draw (widget);
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}
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static double start_x;
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static double start_y;
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static void
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drag_begin (GtkGestureDrag *gesture,
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double x,
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double y,
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GtkWidget *area)
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{
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start_x = x;
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start_y = y;
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draw_brush (area, x, y);
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}
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static void
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drag_update (GtkGestureDrag *gesture,
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double x,
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double y,
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GtkWidget *area)
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{
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draw_brush (area, start_x + x, start_y + y);
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}
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static void
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drag_end (GtkGestureDrag *gesture,
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double x,
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double y,
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GtkWidget *area)
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{
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draw_brush (area, start_x + x, start_y + y);
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}
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static void
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oval_path (cairo_t *cr,
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double xc, double yc,
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double xr, double yr)
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{
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cairo_save (cr);
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cairo_translate (cr, xc, yc);
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cairo_scale (cr, 1.0, yr / xr);
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cairo_move_to (cr, xr, 0.0);
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cairo_arc (cr,
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0, 0,
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xr,
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0, 2 * G_PI);
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cairo_close_path (cr);
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cairo_restore (cr);
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}
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/* Fill the given area with checks in the standard style
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* for showing compositing effects.
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*
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* It would make sense to do this as a repeating surface,
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* but most implementations of RENDER currently have broken
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* implementations of repeat + transform, even when the
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* transform is a translation.
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*/
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static void
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fill_checks (cairo_t *cr,
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int x, int y,
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int width, int height)
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{
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int i, j;
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#define CHECK_SIZE 16
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cairo_rectangle (cr, x, y, width, height);
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cairo_set_source_rgb (cr, 0.4, 0.4, 0.4);
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cairo_fill (cr);
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/* Only works for CHECK_SIZE a power of 2 */
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j = x & (-CHECK_SIZE);
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for (; j < height; j += CHECK_SIZE)
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{
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i = y & (-CHECK_SIZE);
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for (; i < width; i += CHECK_SIZE)
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if ((i / CHECK_SIZE + j / CHECK_SIZE) % 2 == 0)
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cairo_rectangle (cr, i, j, CHECK_SIZE, CHECK_SIZE);
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}
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cairo_set_source_rgb (cr, 0.7, 0.7, 0.7);
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cairo_fill (cr);
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#undef CHECK_SIZE
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}
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/* Draw a red, green, and blue circle equally spaced inside
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* the larger circle of radius r at (xc, yc)
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*/
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static void
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draw_3circles (cairo_t *cr,
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double xc, double yc,
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double radius,
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double alpha)
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{
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double subradius = radius * (2 / 3. - 0.1);
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cairo_set_source_rgba (cr, 1., 0., 0., alpha);
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oval_path (cr,
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xc + radius / 3. * cos (G_PI * (0.5)),
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yc - radius / 3. * sin (G_PI * (0.5)),
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subradius, subradius);
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cairo_fill (cr);
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cairo_set_source_rgba (cr, 0., 1., 0., alpha);
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oval_path (cr,
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xc + radius / 3. * cos (G_PI * (0.5 + 2/.3)),
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yc - radius / 3. * sin (G_PI * (0.5 + 2/.3)),
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subradius, subradius);
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cairo_fill (cr);
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cairo_set_source_rgba (cr, 0., 0., 1., alpha);
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oval_path (cr,
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xc + radius / 3. * cos (G_PI * (0.5 + 4/.3)),
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yc - radius / 3. * sin (G_PI * (0.5 + 4/.3)),
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subradius, subradius);
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cairo_fill (cr);
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}
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static void
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groups_draw (GtkDrawingArea *darea,
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cairo_t *cr,
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int width,
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int height,
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gpointer data)
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{
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cairo_surface_t *overlay, *punch, *circles;
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cairo_t *overlay_cr, *punch_cr, *circles_cr;
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/* Fill the background */
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double radius = 0.5 * (width < height ? width : height) - 10;
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double xc = width / 2.;
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double yc = height / 2.;
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overlay = cairo_surface_create_similar (cairo_get_target (cr),
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CAIRO_CONTENT_COLOR_ALPHA,
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width, height);
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punch = cairo_surface_create_similar (cairo_get_target (cr),
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CAIRO_CONTENT_ALPHA,
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width, height);
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circles = cairo_surface_create_similar (cairo_get_target (cr),
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CAIRO_CONTENT_COLOR_ALPHA,
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width, height);
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fill_checks (cr, 0, 0, width, height);
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/* Draw a black circle on the overlay
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*/
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overlay_cr = cairo_create (overlay);
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cairo_set_source_rgb (overlay_cr, 0., 0., 0.);
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oval_path (overlay_cr, xc, yc, radius, radius);
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cairo_fill (overlay_cr);
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/* Draw 3 circles to the punch surface, then cut
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* that out of the main circle in the overlay
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*/
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punch_cr = cairo_create (punch);
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draw_3circles (punch_cr, xc, yc, radius, 1.0);
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cairo_destroy (punch_cr);
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cairo_set_operator (overlay_cr, CAIRO_OPERATOR_DEST_OUT);
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cairo_set_source_surface (overlay_cr, punch, 0, 0);
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cairo_paint (overlay_cr);
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/* Now draw the 3 circles in a subgroup again
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* at half intensity, and use OperatorAdd to join up
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* without seams.
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*/
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circles_cr = cairo_create (circles);
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cairo_set_operator (circles_cr, CAIRO_OPERATOR_OVER);
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draw_3circles (circles_cr, xc, yc, radius, 0.5);
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cairo_destroy (circles_cr);
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cairo_set_operator (overlay_cr, CAIRO_OPERATOR_ADD);
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cairo_set_source_surface (overlay_cr, circles, 0, 0);
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cairo_paint (overlay_cr);
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cairo_destroy (overlay_cr);
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cairo_set_source_surface (cr, overlay, 0, 0);
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cairo_paint (cr);
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cairo_surface_destroy (overlay);
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cairo_surface_destroy (punch);
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cairo_surface_destroy (circles);
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}
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static void
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close_window (void)
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{
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window = NULL;
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if (surface)
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cairo_surface_destroy (surface);
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surface = NULL;
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}
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GtkWidget *
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do_drawingarea (GtkWidget *do_widget)
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{
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GtkWidget *frame;
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GtkWidget *vbox;
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GtkWidget *da;
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GtkWidget *label;
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GtkGesture *drag;
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if (!window)
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{
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window = gtk_window_new ();
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gtk_window_set_display (GTK_WINDOW (window),
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gtk_widget_get_display (do_widget));
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gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");
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g_signal_connect (window, "destroy",
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G_CALLBACK (close_window), NULL);
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vbox = gtk_box_new (GTK_ORIENTATION_VERTICAL, 8);
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gtk_widget_set_margin_start (vbox, 16);
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gtk_widget_set_margin_end (vbox, 16);
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gtk_widget_set_margin_top (vbox, 16);
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gtk_widget_set_margin_bottom (vbox, 16);
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gtk_window_set_child (GTK_WINDOW (window), vbox);
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/*
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* Create the groups area
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*/
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label = gtk_label_new (NULL);
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gtk_label_set_markup (GTK_LABEL (label),
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"<u>Knockout groups</u>");
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gtk_box_append (GTK_BOX (vbox), label);
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frame = gtk_frame_new (NULL);
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gtk_widget_set_vexpand (frame, TRUE);
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gtk_box_append (GTK_BOX (vbox), frame);
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da = gtk_drawing_area_new ();
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gtk_drawing_area_set_content_width (GTK_DRAWING_AREA (da), 100);
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gtk_drawing_area_set_content_height (GTK_DRAWING_AREA (da), 100);
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gtk_drawing_area_set_draw_func (GTK_DRAWING_AREA (da), groups_draw, NULL, NULL);
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gtk_frame_set_child (GTK_FRAME (frame), da);
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/*
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* Create the scribble area
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*/
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label = gtk_label_new (NULL);
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gtk_label_set_markup (GTK_LABEL (label),
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"<u>Scribble area</u>");
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gtk_box_append (GTK_BOX (vbox), label);
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frame = gtk_frame_new (NULL);
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gtk_widget_set_vexpand (frame, TRUE);
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gtk_box_append (GTK_BOX (vbox), frame);
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da = gtk_drawing_area_new ();
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gtk_drawing_area_set_content_width (GTK_DRAWING_AREA (da), 100);
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gtk_drawing_area_set_content_height (GTK_DRAWING_AREA (da), 100);
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gtk_drawing_area_set_draw_func (GTK_DRAWING_AREA (da), scribble_draw, NULL, NULL);
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gtk_frame_set_child (GTK_FRAME (frame), da);
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g_signal_connect (da, "resize",
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G_CALLBACK (scribble_resize), NULL);
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drag = gtk_gesture_drag_new ();
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gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (drag), GDK_BUTTON_PRIMARY);
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gtk_widget_add_controller (da, GTK_EVENT_CONTROLLER (drag));
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g_signal_connect (drag, "drag-begin", G_CALLBACK (drag_begin), da);
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g_signal_connect (drag, "drag-update", G_CALLBACK (drag_update), da);
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g_signal_connect (drag, "drag-end", G_CALLBACK (drag_end), da);
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}
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if (!gtk_widget_get_visible (window))
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gtk_widget_show (window);
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else
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gtk_window_destroy (GTK_WINDOW (window));
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return window;
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}
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