Question

我正在使用 goocanvas 在 GTK 框架上绘制一个简单的图表，图表尺寸基于同一窗口上的值。当用户使用微调按钮更改界面上的值时，图表应实时更改其尺寸。

我成功设法在gtk window-＆gt; hbox-＆gt;框架之上渲染初始图表。

问题在于何时更改值。它在图纸上重新绘制。

goo canvas有没有“清晰”的功能？

还是有其他方法可以达到预期效果吗？

编辑：

当前代码：

<button data-bind="click: insideClick, clickBubble: false">
  Inside click.
</button>

当点击名为“measure”的按钮时，它的处理程序称为“ofruta” 在“ofruta”中它调用绘图函数。

这是一种正确的方法吗？

Answer 1

以下是基于https://developer.gnome.org/goocanvas/unstable/goocanvas-model-view-canvas.html的示例：

#include <stdlib.h>
#include <goocanvas.h>

static gboolean on_rect_button_press (GooCanvasItem  *view,
        GooCanvasItem  *target,
        GdkEventButton *event,
        gpointer        data);

static gboolean on_delete_event      (GtkWidget      *window,
        GdkEvent       *event,
        gpointer        unused_data);


GooCanvasItemModel *root, *rect_model, *text_model, *path;

int main (int argc, char *argv[]) {
    GtkWidget *window, *scrolled_win, *canvas;
    GooCanvasItem *rect_item;

    gtk_set_locale ();
    gtk_init (&argc, &argv);

    window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
    gtk_window_set_default_size (GTK_WINDOW (window), 640, 600);
    gtk_widget_show (window);
    g_signal_connect (window, "delete_event", (GtkSignalFunc) on_delete_event,
            NULL);

    scrolled_win = gtk_scrolled_window_new (NULL, NULL);
    gtk_scrolled_window_set_shadow_type (GTK_SCROLLED_WINDOW (scrolled_win),
            GTK_SHADOW_IN);
    gtk_widget_show (scrolled_win);
    gtk_container_add (GTK_CONTAINER (window), scrolled_win);

    canvas = goo_canvas_new ();
    gtk_widget_set_size_request (canvas, 600, 450);
    goo_canvas_set_bounds (GOO_CANVAS (canvas), 0, 0, 1000, 1000);
    gtk_widget_show (canvas);
    gtk_container_add (GTK_CONTAINER (scrolled_win), canvas);

    root = goo_canvas_group_model_new (NULL, NULL);

    rect_model = goo_canvas_rect_model_new (root, 100, 100, 400, 400,
            "line-width", 10.0,
            "radius-x", 20.0,
            "radius-y", 10.0,
            "stroke-color", "yellow",
            "fill-color", "red",
            NULL);

    text_model = goo_canvas_text_model_new (root, "Hello World", 300, 300, -1,
            GTK_ANCHOR_CENTER,
            "font", "Sans 24",
            NULL);
    goo_canvas_item_model_rotate (text_model, 45, 300, 300);

    goo_canvas_set_root_item_model (GOO_CANVAS (canvas), root);

    GooCanvasLineDash *dash = goo_canvas_line_dash_new (2, 5.0, 5.0);
    const char *buf = "M 0 128 L 1000 256";
    path = goo_canvas_path_model_new (root, buf,
            "stroke-color", "red",
            "line-dash", dash,
            NULL);

    rect_item = goo_canvas_get_item (GOO_CANVAS (canvas), rect_model);
    g_signal_connect (rect_item, "button_press_event",
            (GtkSignalFunc) on_rect_button_press, NULL);

    goo_canvas_line_dash_unref(dash);

    gtk_main ();

    return 0;
}


static gboolean on_rect_button_press (GooCanvasItem  *item,
        GooCanvasItem  *target,
        GdkEventButton *event,
        gpointer        data) {
    g_print ("rect item received button press event\n");

    static float a = 128, b = 256;
    a += 16, b += 16;

    char buf[64];
    snprintf(buf, sizeof(buf), "M 0 %f L 1000 %f", a, b);
    g_object_set(G_OBJECT(path), "data", buf, NULL);

    return TRUE;
}


static gboolean on_delete_event (GtkWidget *window,
        GdkEvent  *event,
        gpointer   unused_data) {
    exit (0);
}

通过使用data修改路径的g_object_set属性，当点击矩形时，它会移动。属性名称应取自文档，例如https://developer.gnome.org/goocanvas/unstable/GooCanvasPathModel.html

如何清除gtk，goocanvas表面？

编辑：

1 个答案: