1 files changed, 174 insertions, 0 deletions
diff --git a/animism-align/frontend/common/upload.helpers.js b/animism-align/frontend/common/upload.helpers.js
new file mode 100644
index 0000000..f26e2cc
--- /dev/null
+++ b/animism-align/frontend/common/upload.helpers.js
@@ -0,0 +1,174 @@
+import ExifReader from 'exifreader'
+
+function base64ToUint8Array(string, start, finish) {
+  start = start || 0
+  finish = finish || string.length
+  // atob that shit
+  const binary = atob(string)
+  const buffer = new Uint8Array(binary.length)
+  for (let i = start; i < finish; i++) {
+    buffer[i] = binary.charCodeAt(i)
+  }
+  return buffer
+}
+
+function getOrientation(uri) {
+  // Split off the base64 data
+  const base64String = uri.split(',')[1]
+  // Read off first 128KB, which is all we need to
+  // get the EXIF data
+  const arr = base64ToUint8Array(base64String, 0, 2 ** 17)
+  try {
+    const tags = ExifReader.load(arr.buffer)
+    // console.log(tags)
+    if (typeof tags.Orientation == 'number') {
+      return tags.Orientation
+    }
+    return tags.Orientation.value
+  } catch (err) {
+    return 1
+  }
+}
+
+function applyRotation(canvas, ctx, deg) {
+  const radians = deg * (Math.PI / 180)
+  if (deg === 90) {
+    ctx.translate(canvas.width, 0)
+  } else if (deg === 180) {
+    ctx.translate(canvas.width, canvas.height)
+  } else if (deg === 270) {
+    ctx.translate(0, canvas.height)
+  }
+  ctx.rotate(radians)
+}
+
+/**
+ * Mapping from EXIF orientation values to data
+ * regarding the rotation and mirroring necessary to
+ * render the canvas correctly
+ * Derived from:
+ * http://www.daveperrett.com/articles/2012/07/28/exif-orientation-handling-is-a-ghetto/
+ */
+const orientationToTransform = {
+  1: { rotation: 0, mirror: false },
+  2: { rotation: 0, mirror: true },
+  3: { rotation: 180, mirror: false },
+  4: { rotation: 180, mirror: true },
+  5: { rotation: 90, mirror: true },
+  6: { rotation: 90, mirror: false },
+  7: { rotation: 270, mirror: true },
+  8: { rotation: 270, mirror: false }
+}
+
+function applyOrientationCorrection(canvas, ctx, uri) {
+  const orientation = getOrientation(uri)
+  // Only apply transform if there is some non-normal orientation
+  if (orientation && orientation !== 1) {
+    console.log(orientation)
+    const transform = orientationToTransform[orientation]
+    const { rotation } = transform
+    const flipAspect = rotation === 90 || rotation === 270
+    if (flipAspect) {
+      // Fancy schmancy swap algo
+      canvas.width = canvas.height + canvas.width
+      canvas.height = canvas.width - canvas.height
+      canvas.width -= canvas.height
+    }
+    if (rotation > 0) {
+      applyRotation(canvas, ctx, rotation)
+    }
+  }
+}
+
+function getScale(width, height, viewportWidth, viewportHeight, fillViewport) {
+  function fitHorizontal() {
+    return viewportWidth / width
+  }
+  function fitVertical() {
+    return viewportHeight / height
+  }
+  fillViewport = !!fillViewport
+  const landscape = (width / height) > (viewportWidth / viewportHeight)
+  if (landscape) {
+    if (fillViewport) {
+      return fitVertical()
+    }
+    if (width > viewportWidth) {
+      return fitHorizontal()
+    }
+  } else {
+    if (fillViewport) {
+      return fitHorizontal()
+    }
+    if (height > viewportHeight) {
+      return fitVertical()
+    }
+  }
+  return 1
+}
+
+export function renderToCanvas(img, options) {
+  if (!img) return null
+  options = options || {}
+
+  // Canvas max size for any side
+  const maxSide = options.maxSide || 0
+  const canvas = document.createElement('canvas')
+  const ctx = canvas.getContext('2d')
+  const initialScale = options.scale || 1
+  /*
+  // constrain
+  // Scale to needed to constrain canvas to max size
+  let scale = getScale(img.naturalWidth * initialScale, img.naturalHeight * initialScale, maxSide, maxSide, true)
+  // console.log(scale)
+  // Still need to apply the user defined scale
+  scale *= initialScale
+  canvas.width = Math.round(img.naturalWidth * scale)
+  canvas.height = Math.round(img.naturalHeight * scale)
+  */
+  const { naturalWidth, naturalHeight } = img
+  if (maxSide > 0) {
+    if (naturalWidth > naturalHeight) {
+      canvas.width = Math.min(maxSide, naturalWidth)
+      canvas.height = naturalHeight * canvas.width / naturalWidth
+    } else {
+      canvas.height = Math.min(maxSide, naturalHeight)
+      canvas.width = naturalWidth * canvas.height / naturalHeight
+    }
+  } else {
+    canvas.width = naturalWidth
+    canvas.height = naturalHeight
+  }
+  const { correctOrientation } = options
+  const jpeg = !!img.src.match(/data:image\/jpeg|\.jpeg$|\.jpg$/i)
+  const hasDataURI = !!img.src.match(/^data:/)
+
+  ctx.save()
+
+  // Can only correct orientation on JPEGs represented as dataURIs
+  // for the time being
+  if (correctOrientation && jpeg && hasDataURI) {
+    applyOrientationCorrection(canvas, ctx, img.src)
+  }
+  // Resize image if too large
+  // if (scale !== 1) {
+  //   ctx.scale(scale, scale)
+  // }
+
+  ctx.drawImage(img, 0, 0, canvas.width, canvas.height)
+  ctx.restore()
+
+  return canvas
+}
+
+export function renderThumbnail(img) {
+  const resized = renderToCanvas(img, { correctOrientation: true })
+  // const canvas = document.createElement('canvas') // document.querySelector('#user_photo_canvas')
+  // const ctx = canvas.getContext('2d')
+  // ctx.fillStyle = 'black'
+  // ctx.fillRect(0, 0, MAX_SIDE, MAX_SIDE)
+  // const xOffset = (MAX_SIDE - resized.width) / 2
+  // const yOffset = (MAX_SIDE - resized.height) / 2
+  // ctx.drawImage(resized, xOffset, yOffset, resized.width, resized.height)
+  return resized
+}