文本添加到文本缓冲区时 GTK TextView 自动滚动

Question

我正在尝试创建一个非常简单的类似日志的 GUI 应用程序，它仅动态和异步地显示日志文件中的文本。问题是，当更新日志文件时，GUI 中的文本视图会滚动回第 1 行。每次修复此问题的尝试都失败了，我想知道我是否偶然发现了 GTK 中的错误。这是我的代码摘要：

using Cairo;
using Gtk;

namespace ServerManager {
    public class ServerManager : Window {
        public TextView text_view;
        public TextIter myIter;
        public TextMark myMark;

        public async void read_something_async (File file) {
            var text = new StringBuilder ();
            var dis = new DataInputStream (file.read ());
            string line;

            while ((line = yield dis.read_line_async (Priority.DEFAULT)) != null) {
                text.append (line);
                text.append_c('\n');
            }
            this.text_view.buffer.text = text.str;
            text_view.buffer.get_end_iter(out myIter);
            text_view.scroll_to_iter(myIter, 0, false, 0, 0);
        }

        public static int main (string[] args) {
        Gtk.init (ref args);


        var window = new ServerManager ();

        // The read-only TextView
        window.text_view = new TextView ();
        window.text_view.editable = false;
        window.text_view.cursor_visible = false;
        window.text_view.wrap_mode = Gtk.WrapMode.WORD;

        // Add scrolling functionality to the TextView
        var scroll = new ScrolledWindow (null, null);
        scroll.set_policy (PolicyType.AUTOMATIC, PolicyType.AUTOMATIC);
        scroll.add (window.text_view);

        // Vbox so that our TextView has someplace to live
        var vbox = new Box (Orientation.VERTICAL, 0);
        vbox.pack_start (scroll, true, true, 0);
        window.add (vbox);

        window.set_border_width (12);
        window.set_position (Gtk.WindowPosition.CENTER);
        window.set_default_size (800, 600);
        window.destroy.connect (Gtk.main_quit);
        window.show_all ();

        File file = File.new_for_path ("/home/user/temp.log");
        FileMonitor monitor = file.monitor (FileMonitorFlags.NONE, null);
        stdout.printf ("Monitoring: %s\n", file.get_path ());

        monitor.changed.connect (() => {
            window.read_something_async(file);
        });

        Gtk.main ();
        return 0;
        }
    }
}

我也尝试过使用 TextMarks 而不是 Iters，但这没有任何影响。

Answer 1

滚动到第一行是因为 read_something_async() 删除缓冲区的当前内容然后写入新内容（这就是设置文本属性所做的）。也许这就是您想要的，但除非您跟踪滚动位置，否则您将丢失它。

您的 scroll_to_iter() 未按预期工作的原因可能是：

Note that this function uses the currently-computed height of the lines in the text buffer. Line heights are computed in an idle handler; so this function may not have the desired effect if it’s called before the height computations. To avoid oddness, consider using gtk_text_view_scroll_to_mark() which saves a point to be scrolled to after line validation.

使用 "right gravity" TextMark 调用 TextView.ScrollToMark() 应该适合您。

文本添加到文本缓冲区时 GTK TextView 自动滚动

GTK TextView auto scroll when text is added to text buffer

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