Ruby 使用 Cairo 的 Gtk3 内存泄漏

Question

我正在尝试在 Linux 的 Ruby Gtk3 中制作一个简单的框图编辑器原型。在我看来，我对 Gtk/Cairo 的使用不够充分，或者我遇到了内存泄漏。

症状如下：当我创建一个图形对象（矩形）并移动它时，我的内存使用量迅速增加，如下所示。

问题是Gtk3::DrawingArea.queue_draw.

的使用

我错过了什么？

我的版本如下：

ruby 2.4.0p0（2016-12-24 修订版 57164）[x86_64-linux]
gtk3 (3.2.7)

require 'gtk3'

BLUE = [0.1,0.0,0.7]

class Rectangle
 attr_accessor :x,:y,:w,:h
 attr_accessor :color
 def initialize x,y,w,h
  @x,@y,@w,@h= x,y,w,h
  @color=BLUE
 end

 def draw ctx
  ctx.set_source_rgb *color
  ctx.rectangle x,y,w,h
  ctx.fill
 end
end

class Drawer

 def initialize
  init_gui
  @grobs=[]
  @on_rect=nil
 end

 def init_gui
  builder = Gtk::Builder.new
  builder.add_from_file('drawing.glade')
  @window = builder['applicationwindow2']
  @window.signal_connect('destroy'){Gtk.main_quit}

  @drawingArea = builder['drawingarea']
  init_event_handlers
  @window.present
 end

 def init_event_handlers

  @drawingArea.signal_connect "draw" do
   ctx=@drawingArea.window.create_cairo_context
   redraw
  end

  @drawingArea.signal_connect("button-press-event") do |widget, event|
   puts "mouse pressed"
   if @on_rect
    @moving=true
   else
    @grobs << Rectangle.new(event.x,event.y,50,50)
    redraw
   end
  end

  @drawingArea.signal_connect("motion-notify-event") do |widget, event|
   puts "moving rect" if @moving
   if @moving
    @on_rect.x=event.x+@dx
    @on_rect.y=event.y+@dy
    @drawingArea.queue_draw
   else
    if @on_rect=on_rect?(event)
     @dx,@dy=@on_rect.x-event.x,@on_rect.y-event.y
     w,h=@on_rect.w,@on_rect.h
     @drawingArea.queue_draw
    end
   end
  end

  @drawingArea.signal_connect("button-release-event") do |widget, event|
   puts "mouse released"
   @moving=false
   @on_rect=nil
   redraw
  end

  def on_rect? event
   for rect in @grobs
    if event.x>rect.x && event.x < rect.x+rect.w
     if event.y>rect.y && event.y < rect.y+rect.h
      return rect
     end
    end
   end
   nil
  end
 end

 def redraw
  ctx=@drawingArea.window.create_cairo_context
  @grobs.each{|grob| grob.draw(ctx)}
 end

end #class

Drawer.new
Gtk.main

<?xml version="1.0" encoding="UTF-8"?>
<!-- Generated with glade 3.18.3 -->
<interface>
  <requires lib="gtk+" version="3.12"/>
  <object class="GtkApplicationWindow" id="applicationwindow2">
    <property name="name">app_window</property>
    <property name="can_focus">False</property>
    <property name="title" translatable="yes">drawing_2</property>
    <property name="has_resize_grip">True</property>
    <child>
      <object class="GtkBox" id="box1">
        <property name="visible">True</property>
        <property name="can_focus">False</property>
        <property name="orientation">vertical</property>
        <child>
          <object class="GtkMenuBar" id="menubar1">
            <property name="visible">True</property>
            <property name="can_focus">False</property>
            <child>
              <object class="GtkMenuItem" id="menuitem1">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_File</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu1">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem1">
                        <property name="label">gtk-new</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem2">
                        <property name="label">gtk-open</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem3">
                        <property name="label">gtk-save</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem4">
                        <property name="label">gtk-save-as</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkSeparatorMenuItem" id="separatormenuitem1">
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem5">
                        <property name="label">gtk-quit</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem2">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Edit</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu2">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem6">
                        <property name="label">gtk-cut</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem7">
                        <property name="label">gtk-copy</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem8">
                        <property name="label">gtk-paste</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem9">
                        <property name="label">gtk-delete</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem3">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_View</property>
                <property name="use_underline">True</property>
              </object>
            </child>
            <child>
              <object class="GtkMenuItem" id="menuitem4">
                <property name="visible">True</property>
                <property name="can_focus">False</property>
                <property name="label" translatable="yes">_Help</property>
                <property name="use_underline">True</property>
                <child type="submenu">
                  <object class="GtkMenu" id="menu3">
                    <property name="visible">True</property>
                    <property name="can_focus">False</property>
                    <child>
                      <object class="GtkImageMenuItem" id="imagemenuitem10">
                        <property name="label">gtk-about</property>
                        <property name="visible">True</property>
                        <property name="can_focus">False</property>
                        <property name="use_underline">True</property>
                        <property name="use_stock">True</property>
                      </object>
                    </child>
                  </object>
                </child>
              </object>
            </child>
          </object>
          <packing>
            <property name="expand">False</property>
            <property name="fill">True</property>
            <property name="position">0</property>
          </packing>
        </child>
        <child>
          <object class="GtkDrawingArea" id="drawingarea">
            <property name="name">drawing_area</property>
            <property name="width_request">1000</property>
            <property name="height_request">600</property>
            <property name="visible">True</property>
            <property name="app_paintable">True</property>
            <property name="can_focus">True</property>
            <property name="events">GDK_POINTER_MOTION_MASK | GDK_BUTTON_PRESS_MASK | GDK_BUTTON_RELEASE_MASK</property>
            <property name="margin_left">9</property>
            <property name="margin_right">10</property>
            <property name="margin_top">10</property>
            <property name="margin_bottom">10</property>
            <signal name="drag-begin" handler="drag" swapped="no"/>
            <signal name="drag-motion" handler="drag" swapped="no"/>
            <signal name="scroll-event" handler="scroll" swapped="no"/>
          </object>
          <packing>
            <property name="expand">True</property>
            <property name="fill">True</property>
            <property name="padding">7</property>
            <property name="pack_type">end</property>
            <property name="position">1</property>
          </packing>
        </child>
      </object>
    </child>
  </object>
</interface>

Answer 1

我不知道 Ruby 内存管理，但我建议您使用 Gtk 提供的 Cairo 上下文，而不是创建您自己的上下文：

--- test.rb.orig    2018-07-28 08:04:24.958448613 +0200
+++ test.rb 2018-07-28 08:05:11.889968403 +0200
@@ -38,9 +38,8 @@ class Drawer

    def init_event_handlers

-       @drawingArea.signal_connect "draw" do
-           ctx=@drawingArea.window.create_cairo_context
-           redraw
+       @drawingArea.signal_connect "draw" do |widget, ctx|
+           @grobs.each{|grob| grob.draw(ctx)}
        end

        @drawingArea.signal_connect("button-press-event") do |widget, event|

Answer 2

我已将此问题报告给维护者 (kou)。线程是 here. This is really a bug (unnecessary object copies). Thanks to him, it is now fixed. The bug fix is here。此修复需要 cairo >=1.15.14.

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