frames/tests/cypress/support/leaflet.js

/**
 * Allows dragging a Leaflet map by the given amounts. A factor of 1 means the map
 * will be dragged the whole width of the map canvas in X direction and the whole
 * height of the map canvas in Y direction.
 *
 * ex: cy.get('#map-canvas').dragMapFromCenter({ xMoveFactor: 0.25, yMoveFactor: -0.5 })
 */
Cypress.Commands.add(
  'dragMapFromCenter',
  { prevSubject: 'element' },
  (element, { xMoveFactor, yMoveFactor }) => {
    // Get the raw HTML element from jQuery wrapper
    const canvas = element.get(0)
    const rect = canvas.getBoundingClientRect()
    const center = {
      x: rect.left + rect.width / 2,
      y: rect.top + rect.height / 2
    }

    // Start dragging from the center of the map
    cy.log('mousedown', {
      clientX: center.x,
      clientY: center.y
    })
    canvas.dispatchEvent(
      new MouseEvent('mousedown', {
        clientX: center.x,
        clientY: center.y
      })
    )

    // Let Leaflet know the mouse has started to move. The diff between
    // mousedown and mousemove event needs to be large enough so that Leaflet
    // will really think the mouse is moving and not that it was a click where
    // the mouse moved just a tiny amount.
    cy.log('mousemove', {
      clientX: center.x,
      clientY: center.y + 5
    })
    canvas.dispatchEvent(
      new MouseEvent('mousemove', {
        clientX: center.x,
        clientY: center.y + 5,
        bubbles: true
      })
    )

    // After Leaflet knows mouse is moving, we move the mouse as depicted by the options.
    cy.log('mousemove', {
      clientX: center.x + rect.width * xMoveFactor,
      clientY: center.y + rect.height * yMoveFactor
    })
    canvas.dispatchEvent(
      new MouseEvent('mousemove', {
        clientX: center.x + rect.width * xMoveFactor,
        clientY: center.y + rect.height * yMoveFactor,
        bubbles: true
      })
    )

    // Now when we "release" the mouse, Leaflet will fire a "dragend" event and
    // the search should register that the drag has stopped and run callbacks.
    cy.log('mouseup', {
      clientX: center.x + rect.width * xMoveFactor,
      clientY: center.y + rect.height * yMoveFactor
    })
    requestAnimationFrame(() => {
      canvas.dispatchEvent(
        new MouseEvent('mouseup', {
          clientX: center.x + rect.width * xMoveFactor,
          clientY: center.y + rect.height * yMoveFactor,
          bubbles: true
        })
      )
    })
  }
)