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Port drawing example to gestures

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Use a drag and a multi-press gesture.
This commit is contained in:
Matthias Clasen
2018-01-01 10:00:37 -05:00
parent bb568a51d4
commit c9267e70a9
1 changed files with 50 additions and 56 deletions
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106
examples/drawing.c
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@@ -77,64 +77,48 @@ draw_brush (GtkWidget *widget,
gtk_widget_queue_draw_area (widget, x - 3, y - 3, 6, 6);
}
/* Handle button press events by either drawing a rectangle
* or clearing the surface, depending on which button was pressed.
* The ::button-press signal handler receives a GdkEventButton
* struct which contains this information.
*/
static gboolean
button_press_event_cb (GtkWidget *widget,
GdkEventButton *event,
gpointer data)
static double start_x;
static double start_y;
static void
drag_begin (GtkGestureDrag *gesture,
double x,
double y,
GtkWidget *area)
{
guint button;
double x, y;
start_x = x;
start_y = y;
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
gdk_event_get_button ((GdkEvent *)event, &button);
gdk_event_get_coords ((GdkEvent *)event, &x, &y);
if (button == GDK_BUTTON_PRIMARY)
{
draw_brush (widget, x, y);
}
else if (button == GDK_BUTTON_SECONDARY)
{
clear_surface ();
gtk_widget_queue_draw (widget);
}
/* We've handled the event, stop processing */
return TRUE;
draw_brush (area, x, y);
}
/* Handle motion events by continuing to draw if button 1 is
* still held down. The ::motion-notify signal handler receives
* a GdkEventMotion struct which contains this information.
*/
static gboolean
motion_notify_event_cb (GtkWidget *widget,
GdkEventMotion *event,
gpointer data)
static void
drag_update (GtkGestureDrag *gesture,
double x,
double y,
GtkWidget *area)
{
double x, y;
GdkModifierType state;
draw_brush (area, start_x + x, start_y + y);
}
/* paranoia check, in case we haven't gotten a configure event */
if (surface == NULL)
return FALSE;
static void
drag_end (GtkGestureDrag *gesture,
double x,
double y,
GtkWidget *area)
{
draw_brush (area, start_x + x, start_y + y);
}
gdk_event_get_state ((GdkEvent *)event, &state);
gdk_event_get_coords ((GdkEvent *)event, &x, &y);
if (state & GDK_BUTTON1_MASK)
draw_brush (widget, x, y);
/* We've handled it, stop processing */
return TRUE;
static void
pressed (GtkGestureMultiPress *gesture,
int n_press,
double x,
double y,
GtkWidget *area)
{
clear_surface ();
gtk_widget_queue_draw (area);
}
static void
@@ -151,6 +135,8 @@ activate (GtkApplication *app,
GtkWidget *window;
GtkWidget *frame;
GtkWidget *drawing_area;
GtkGesture *drag;
GtkGesture *press;
window = gtk_application_window_new (app);
gtk_window_set_title (GTK_WINDOW (window), "Drawing Area");
@@ -172,11 +158,19 @@ activate (GtkApplication *app,
g_signal_connect_after (drawing_area, "size-allocate",
G_CALLBACK (size_allocate_cb), NULL);
/* Event signals */
g_signal_connect (drawing_area, "motion-notify-event",
G_CALLBACK (motion_notify_event_cb), NULL);
g_signal_connect (drawing_area, "button-press-event",
G_CALLBACK (button_press_event_cb), NULL);
drag = gtk_gesture_drag_new (drawing_area);
gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (drag), GDK_BUTTON_PRIMARY);
g_object_set_data_full (G_OBJECT (drawing_area), "drag", drag, g_object_unref);
g_signal_connect (drag, "drag-begin", G_CALLBACK (drag_begin), drawing_area);
g_signal_connect (drag, "drag-update", G_CALLBACK (drag_update), drawing_area);
g_signal_connect (drag, "drag-begin", G_CALLBACK (drag_end), drawing_area);
press = gtk_gesture_multi_press_new (drawing_area);
gtk_gesture_single_set_button (GTK_GESTURE_SINGLE (press), GDK_BUTTON_SECONDARY);
g_object_set_data_full (G_OBJECT (drawing_area), "press", press, g_object_unref);
g_signal_connect (press, "pressed", G_CALLBACK (pressed), drawing_area);
gtk_widget_show (window);
}