如何使用qtruby让表的模型/视图工作？

Question

我正在尝试找出如何在使用TableView的模型中使用qtruby。在http://doc.qt.io/qt-5/modelview.html的教程中，我尝试改编C++中的示例，并编写了如下所示的代码。

问题出在AbstractTableModel的data方法的实现中:只有角色Qt::DisplayRole才能按预期工作。角色Qt::FontRole和Qt::BackgroundRole不会导致错误，但似乎也不会做任何事情。更糟糕的是，如果启用，角色Qt::TextAlignmentRole和Qt::CheckStateRole会导致分段错误。谁能告诉我我是不是做错了什么？

#!/usr/bin/env ruby
require 'Qt'
include Qt

class MyModel < AbstractTableModel
  def initialize(p)
    super
  end

  def rowCount(p)
    2
  end

  def columnCount(p)
    3
  end

  def data(index, role)
    row = index.row
    col = index.column

    case role
    when Qt::DisplayRole
      return Variant.new "Row#{row + 1}, Column#{col + 1}"
    when Qt::FontRole
      # this doesn't result in an error, but doesn't seem to do anything either
      if (row == 0 && col == 0)
        boldFont = Font.new
        boldFont.setBold(true)
        return boldFont
      end
    when Qt::BackgroundRole
      # this doesn't result in an error, but doesn't seem to do anything either
      if (row == 1 && col == 2)
        redBackground = Brush.new(Qt::red)
        return redBackground
      end
    when Qt::TextAlignmentRole
      # # the following causes a segmentation fault if uncommented
      # if (row == 1 && col == 1)
      #   return Qt::AlignRight + Qt::AlignVCenter
      # end
    when Qt::CheckStateRole
      # # the following causes a segmentation fault if uncommented
      # if (row == 1 && col == 0)
      #   return Qt::Checked
      # end
    end
    Variant.new
  end
end

app = Application.new ARGV
tableView = TableView.new
myModel = MyModel.new(nil)
tableView.setModel(myModel)
tableView.show
app.exec

Answer 1

这是因为对于DisplayRole，您将按照预期创建一个新的Qt::Variant。

对于其他返回值，您应该使用：

return Qt::Variant.fromValue(boldFont)

return Qt::Variant.fromValue(redBackground)

return Qt::Variant.fromValue(Qt::AlignRight + Qt::AlignVCenter)

return Qt::Variant.fromValue(Qt::Checked)