在ol.interaction.Draw中按住shift-click事件打開圖層

Question

我試圖使用ol.interaction.Draw將多邊形添加到openlayers地圖。我也有一個快照交互，並設置關閉，而我在按住Shift鍵。

const 
    snapInteraction = new ol.interaction.Snap({ 
    source: drawLayer.getSource() 
    }), 
    turnOnSnap = (evt) => { 
    if (!isShiftKey(evt)) { 
     return; 
    } 
    console.log('shift key is down, turning off snap'); 
    snapInteraction.setActive(false); 
    }, 
    turnOffSnap = (evt) => { 
    if (!isShiftKey(evt)) { 
     return; 
    } 
    console.log('shift key is up, turning on snap'); 
    snapInteraction.setActive(true); 
    }; 

document.addEventListener('keydown', turnOnSnap); 
document.addEventListener('keyup', turnOffSnap); 

這可以禁用捕捉。但是，當我按住Shift鍵時，我的Draw互動功能不起作用。我知道condition參數默認爲ol.events.condition.noModifierKeys，但是當我自定義condition時，它甚至不會被擊中！

const drawInteraction = new ol.interaction.Draw({ 
    source: drawLayer.getSource(), 
    type: 'Polygon', 
    condition: function (evt) { 
    console.log("yo, why isn't this hit when I hold down shift?", evt); 
    return (ol.events.condition.noModifierKeys(evt) || 
     ol.events.condition.shiftKeyOnly(evt)); 
    } 
}); 

爲什麼drawInteraction忽略shift + click事件？

Answer 1

freehandCondition的默認值爲捕捉shift + click事件，因此它們從未得到condition的評估。將其改爲其他內容，shift + click事件將觸發您的自定義條件功能。

const drawInteraction = new ol.interaction.Draw({ 
    source: drawLayer.getSource(), 
    type: 'Polygon', 
    condition: function (evt) { 
    return (ol.events.condition.noModifierKeys(evt) || 
     ol.events.condition.shiftKeyOnly(evt)); 
    }, 
    freehandCondition: ol.events.condition.never, // <-- add this line 
});