Merge pull request #100 from caleb-mabry/webp-support

WebAO Partial Image Fixes

5 files changed, 92 insertions, 0 deletions

diff --git a/webAO/utils/calculateGifLength.js b/webAO/utils/calculateGifLength.js
new file mode 100644
index 0000000..1df0ba9
--- /dev/null
+++ b/webAO/utils/calculateGifLength.js
@@ -0,0 +1,27 @@
+/**
+	 * Adds up the frame delays to find out how long a GIF is
+	 * I totally didn't steal this
+	 * @param {data} gifFile the GIF data
+	 */
+const calculateGifLength = (gifFile) => {
+  const d = new Uint8Array(gifFile);
+  // Thanks to http://justinsomnia.org/2006/10/gif-animation-duration-calculation/
+  // And http://www.w3.org/Graphics/GIF/spec-gif89a.txt
+  let duration = 0;
+  for (let i = 0; i < d.length; i++) {
+    // Find a Graphic Control Extension hex(21F904__ ____ __00)
+    if (d[i] === 0x21
+				&& d[i + 1] === 0xF9
+				&& d[i + 2] === 0x04
+				&& d[i + 7] === 0x00) {
+      // Swap 5th and 6th bytes to get the delay per frame
+      const delay = (d[i + 5] << 8) | (d[i + 4] & 0xFF);
+
+      // Should be aware browsers have a minimum frame delay
+      // e.g. 6ms for IE, 2ms modern browsers (50fps)
+      duration += delay < 2 ? 10 : delay;
+    }
+  }
+  return duration * 10;
+};
+export default calculateGifLength;
diff --git a/webAO/utils/calculateWebpLength.js b/webAO/utils/calculateWebpLength.js
new file mode 100644
index 0000000..1b422a0
--- /dev/null
+++ b/webAO/utils/calculateWebpLength.js
@@ -0,0 +1,22 @@
+const calculateWebpLength = (webpFile) => {
+  const d = new Uint8Array(webpFile);
+  // https://developers.google.com/speed/webp/docs/riff_container#animation
+  let duration = 0;
+  for (let i = 0; i < d.length; i++) {
+    // Find ANMF header (41 4E 4D 46)
+    if (d[i] === 0x41
+      && d[i + 1] === 0x4E
+      && d[i + 2] === 0x4D
+      && d[i + 3] === 0x46) {
+      // Swap 5th and 6th bytes to get the delay per frame
+      const delay = (d[i + 21] << 8) | (d[i + 20] & 0xFF);
+
+      // Should be aware browsers have a minimum frame delay
+      // e.g. 6ms for IE, 2ms modern browsers (50fps)
+      duration += delay < 2 ? 10 : delay;
+    }
+  }
+  return duration;
+};
+
+export default calculateWebpLength;
diff --git a/webAO/utils/calculatorHandler.js b/webAO/utils/calculatorHandler.js
new file mode 100644
index 0000000..7686573
--- /dev/null
+++ b/webAO/utils/calculatorHandler.js
@@ -0,0 +1,7 @@
+import calculateGifLength from './calculateGifLength';
+import calculateWebpLength from './calculateWebpLength';
+
+export default {
+  '.gif': calculateGifLength,
+  '.webp': calculateWebpLength,
+};
diff --git a/webAO/utils/getCookie.js b/webAO/utils/getCookie.js
new file mode 100644
index 0000000..3be0733
--- /dev/null
+++ b/webAO/utils/getCookie.js
@@ -0,0 +1,26 @@
+/**
+ * read a cookie from storage
+ * got this from w3schools
+ * https://www.w3schools.com/js/js_cookies.asp
+ * @param {String} cname The name of the cookie to return
+ */
+const getCookie = (cname) => {
+  try {
+    const name = `${cname}=`;
+    const decodedCookie = decodeURIComponent(document.cookie);
+    const ca = decodedCookie.split(';');
+    for (let i = 0; i < ca.length; i++) {
+      let c = ca[i];
+      while (c.charAt(0) === ' ') {
+        c = c.substring(1);
+      }
+      if (c.indexOf(name) === 0) {
+        return c.substring(name.length, c.length);
+      }
+    }
+    return '';
+  } catch (error) {
+    return '';
+  }
+};
+export default getCookie;
diff --git a/webAO/utils/setCookie.js b/webAO/utils/setCookie.js
new file mode 100644
index 0000000..9734eae
--- /dev/null
+++ b/webAO/utils/setCookie.js
@@ -0,0 +1,10 @@
+/**
+ * set a cookie
+ * the version from w3schools expects these to expire
+ * @param {String} cname The name of the cookie to return
+ * @param {String} value The value of that cookie option
+ */
+const setCookie = (cname, value) => {
+  document.cookie = `${cname}=${value}`;
+};
+export default setCookie;