QML：即使drag属性处于活动状态，也不会调用onDragStarted / finish [英] QML: onDragStarted / finished not called even though the drag property is active

问题描述

在下面的示例中，我希望拖动一个矩形时调用 onDragStarted / onDragFinished 。但是，仅 drag.onActiveChanged 和（矩形的） Drag.onActiveChanged 被调用。将 Drag.dragType 设置为 Drag.Automatic 时，我得到了预期的输出，但是我再也看不到矩形了。我在Mac（El Capitan）上使用Qt 5.5。

In the following example I would expect that onDragStarted / onDragFinished are called when one rectangle is dragged. However only drag.onActiveChanged (of the mouseArea) and Drag.onActiveChanged (of the rectangle are called). I get the expected output when setting Drag.dragType to Drag.Automatic but then I don't see the rectangle anymore. I am using Qt 5.5 on a Mac (El Capitan).

import QtQuick 2.5
import QtQuick.Window 2.2

Window {
  visible: true

  width: 100
  height: 200

  ListModel {
    id: testModel
    ListElement { name: "red";   value: "#f00" }
    ListElement { name: "green"; value: "#0f0" }
    ListElement { name: "blue";  value: "#00f" }
  }

  Component {
    id: rect
    Rectangle {

      Drag.active: mouseArea.drag.active
      Drag.hotSpot.x: width / 2
      Drag.hotSpot.y: height / 2
      //Drag.dragType: Drag.Automatic

      Drag.onActiveChanged: {
        console.log("Active changed..")
      }

      Drag.onDragStarted: {
        console.log("Drag started..")
      }

      Drag.onDragFinished: {
        console.log("Drag finished!")
      }

      MouseArea {
        id: mouseArea

        anchors.fill: parent
        hoverEnabled: true
        drag.target: parent

        drag.onActiveChanged: {
          console.log("Drag prop became active..")
        }

        onClicked: {
          colorButtonClicked(buttonName, buttonColor);
        }
      }

      width: 80
      height: 20
      radius: 6
      color: model.value
    }
  }

  Column {
    spacing: 3
    anchors.centerIn: parent
    Repeater {
      model: testModel
      delegate: rect
    }
  }
}

推荐答案

基于信号名称的假设，我对相同的问题感到困惑，但请查看文档显示，只有在使用 Drag.Automatic 或显式调用 startDrag 。

I was puzzled about the same problem based on my assumptions from the signal names, but a look at the documentation showed that the signals will only work when using Drag.Automatic or explicitly calling startDrag.

dragStarted（）

在拖动时发出此信号

dragStarted()

This signal is emitted when a drag is started with the startDrag() method or when it is started automatically using the dragType property.

此信号在发出该信号时发出拖动完成，并且拖动使用startDrag（）方法启动，或者使用dragType属性自动开始。

This signal is emitted when a drag finishes and the drag was started with the startDrag() method or started automatically using the dragType property.

使用<$ c时出现的另一个问题$ c> Drag.Automatic 在Qt 5.6.1中似乎已修复

The other issue seen when using Drag.Automatic appears to be fixed in Qt 5.6.1

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