Merge pull request #91 from svgdotjs/pr/jonenst/86

Pr/jonenst/86

readme.md

@@ -77,7 +77,7 @@ You can override the default options by passing an object in to the `.panZoom({o
 | wheelZoom | true | Enable mouse wheel zoom |
 | panButton | 0 | Which mouse button to use for pan ([info](https://developer.mozilla.org/en-US/docs/Web/API/MouseEvent/button)) |
 | oneFingerPan | false | Enables the ability to pan with only one finger instead of two for touchdevices |
-| margins | false | An object {top, left, right, bottom} to restrict the pan area so that at least x px are still visible  |
+| margins | false | An object {top, left, right, bottom} to restrict the pan area towards this side so that at least x user units of the opposite side are still visible |
 | zoomFactor | 2 | How quickly to zoom when using `wheelZoom` |
 | zoomMin | Number.MIN_VALUE | The minimum zoom level |
 | zoomMax | Number.MAX_VALUE | The maximum zoom level |

src/svg.panzoom.js

@@ -27,20 +27,103 @@ extend(Svg, {
  let lastTouches
  let zoomInProgress = false
 
+ const viewbox = this.viewbox()
+
  const restrictToMargins = box => {
  if (!margins) return box
  const { top, left, bottom, right } = margins
- const zoom = this.width() / box.width
 
  const { width, height } = this.attr(['width', 'height'])
+ const preserveAspectRatio = this.node.preserveAspectRatio.baseVal
+
+ // The current viewport (exactly what is shown on the screen, what we ultimately want to restrict)
+ // is not always exactly the same as current viewbox. They are different when the viewbox aspectRatio and the svg aspectRatio
+ // are different and preserveAspectRatio is not "none". These offsets represent the difference in user coordinates
+ // between the side of the viewbox and the side of the viewport.
+ let viewportLeftOffset = 0
+ let viewportRightOffset = 0
+ let viewportTopOffset = 0
+ let viewportBottomOffset = 0
+
+ // preserveAspectRatio none has no offsets
+ if (preserveAspectRatio.align !== preserveAspectRatio.SVG_PRESERVEASPECTRATIO_NONE) {
+ const svgAspectRatio = width / height
+ const viewboxAspectRatio = viewbox.width / viewbox.height
+ // when aspectRatios are the same, there are no offsets
+ if (viewboxAspectRatio !== svgAspectRatio) {
+ // aspectRatio unknown is like meet because that's the default
+ const isMeet = preserveAspectRatio.meetOrSlice !== preserveAspectRatio.SVG_MEETORSLICE_SLICE
+ const changedAxis = svgAspectRatio > viewboxAspectRatio ? 'width' : 'height'
+ const isWidth = changedAxis === 'width'
+ const changeHorizontal = (isMeet && isWidth) || (!isMeet && !isWidth)
+ const ratio = changeHorizontal
+ ? svgAspectRatio / viewboxAspectRatio
+ : viewboxAspectRatio / svgAspectRatio
+
+ const offset = box[changedAxis] - box[changedAxis] * ratio
+ if (changeHorizontal) {
+ if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMIN ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMID ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMAX) {
+ viewportLeftOffset = offset / 2
+ viewportRightOffset = -offset / 2
+ } else if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMIN ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMID ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMAX) {
+ viewportRightOffset = -offset
+ } else if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMIN ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMID ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMAX) {
+ viewportLeftOffset = offset
+ }
+ } else {
+ if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMID ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMID ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMID) {
+ viewportTopOffset = offset / 2
+ viewportBottomOffset = -offset / 2
+ } else if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMIN ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMIN ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMIN) {
+ viewportBottomOffset = -offset
+ } else if (
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMINYMAX ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMIDYMAX ||
+ preserveAspectRatio.align === preserveAspectRatio.SVG_PRESERVEASPECTRATIO_XMAXYMAX) {
+ viewportTopOffset = offset
+ }
+ }
 
- const leftLimit = width - left / zoom
- const rightLimit = (right - width) / zoom
- const topLimit = height - top / zoom
- const bottomLimit = (bottom - height) / zoom
+ }
+ }
 
- box.x = Math.min(leftLimit, Math.max(rightLimit, box.x))
- box.y = Math.min(topLimit, Math.max(bottomLimit, box.y))
+ // when box.x == leftLimit, the image is panned to the left,
+ // i.e the current box is to the right of the initial viewbox,
+ // and only the right part of the initial image is visible, i.e.
+ // the right side of the initial viewbox minus left margin (viewbox.x+viewbox.width-left)
+ // is aligned with the left side of the viewport (box.x + viewportLeftOffset):
+ // viewbox.width + viewbox.x - left = box.x + viewportLeftOffset
+ // viewbox.width + viewbox.x - left - viewportLeftOffset = box.x (= leftLimit)
+ const leftLimit = viewbox.width + viewbox.x - left - viewportLeftOffset
+ // when box.x == rightLimit, the image is panned to the right,
+ // i.e the current box is to the left of the initial viewbox
+ // and only the left part of the initial image is visible, i.e
+ // the left side of the initial viewbox plus right margin (viewbox.x + right)
+ // is aligned with the right side of the viewport (box.x + box.width + viewportRightOffset)
+ // viewbox.x + right = box.x + box.width + viewportRightOffset
+ // viewbox.x + right - box.width - viewportRightOffset = box.x (= rightLimit)
+ const rightLimit = viewbox.x + right - box.width - viewportRightOffset
+ // same with top and bottom
+ const topLimit = viewbox.height + viewbox.y - top - viewportTopOffset
+ const bottomLimit = viewbox.y + bottom - box.height - viewportBottomOffset
+
+ box.x = Math.min(leftLimit, Math.max(rightLimit, box.x)) // enforce rightLimit <= box.x <= leftLimit
+ box.y = Math.min(topLimit, Math.max(bottomLimit, box.y)) // enforce bottomLimit <= box.y <= topLimit
  return box
  }