如何手动绘制GtkTreeView扩展器 [英] How to manually draw the GtkTreeView expander

问题描述

我正在使用GtkTreeView小部件，并且想要更改用于打开和关闭子行的"expander"图标的外观:我希望这些图标成为大家都熟悉的三角形，但是它们而是显示为带方框的"+"和-"符号.

I'm using a GtkTreeView widget and I want to change the appearance of the "expander" icon that opens and closes child rows: I want the icons to be the triangels that we're all familiar with, but they're appearing as boxed "+" and "-" symbols instead.

起初我以为必须要设置一个样式枚举，但是找不到.然后，我想也许可以在主题的gtkrc文件中设置一个样式属性，但我认为没有.最后，我采取了尝试像这样手动覆盖draw方法的方法:

At first I thought there must be a style enumeration that I can set, but I cannot find one. Then, I thought maybe there's a style property I can set in my theme's gtkrc file, but I don't think there is one. Finally, I resorted to trying to manually override the draw method like so:

GtkWidget *pTreeView = gtk_tree_view_new_with_model((GtkTreeModel *)pTreeModel);
(GTK_STYLE_GET_CLASS(pTreeView->style))->draw_expander = my_draw_expander_override;

但是my_draw_expander_override()从未被调用，并且扩展器仍然是带框的"+"和-"图标.

But my_draw_expander_override() never gets called and the expanders are still the boxed "+" and "-" icons.

有人知道如何更改GtkTreeView扩展器图标的外观或自己绘制吗?

Does anyone know how can I change the appearance of the GtkTreeView expander icons or just draw them myself?

预先感谢一堆！

推荐答案

此处是如何覆盖draw_expander的示例代码.您肯定需要阅读手册才能正确使用所有参数.

Here the sample code of how to overwrite draw_expander. You'll definetely have to take a look in the manual to get all the parameters right.

#include <gtk/gtk.h>
#include <cairo.h>


enum {
  COL_1,
  N_COLS
};

void draw_expander (GtkStyle        *style,
                    GdkWindow       *window,
                    GtkStateType         state_type,
                    GdkRectangle    *area,
                    GtkWidget       *widget,
                    const gchar     *detail,
                    gint         x,
                    gint         y,
                    GtkExpanderStyle     expander_style) {


  cairo_t *cr;

  cr = gdk_cairo_create (window);

  cairo_set_source_rgb(cr, 0, 0, 0);

  cairo_move_to (cr, 0, 0);
  cairo_line_to (cr, 0, 10);
  cairo_line_to (cr, 10, 5);
  cairo_close_path (cr);

  cairo_stroke  (cr);
}


GtkWidget *build_view (); /* just supply your own */


int main (int argc, char *argv[]) {
  gtk_init (&argc, &argv);

  GtkWidget *window;
  GtkWidget *view;

  window = g_object_new (GTK_TYPE_WINDOW, NULL);  
  view = build_view ();
  gtk_container_add (GTK_CONTAINER (window), view);

  GtkStyle *style = gtk_widget_get_style (view);
  GtkStyleClass *klass = GTK_STYLE_GET_CLASS (style);

  klass->draw_expander = draw_expander;

  gtk_widget_show_all (window);
  gtk_main ();

  return 0;
}

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