Merge pull request #430 from Valodim/certify

Revamp certify dialogue

OpenPGP-Keychain/src/main/java/org/sufficientlysecure/keychain/helper/OtherHelper.java

@@ -17,7 +17,12 @@
 
 package org.sufficientlysecure.keychain.helper;
 
+import android.graphics.Color;
 import android.os.Bundle;
+import android.text.Spannable;
+import android.text.SpannableStringBuilder;
+import android.text.style.ForegroundColorSpan;
+
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.util.Log;
 
@@ -60,6 +65,63 @@ public class OtherHelper {
         }
     }
 
+    public static SpannableStringBuilder colorizeFingerprint(String fingerprint) {
+        SpannableStringBuilder sb = new SpannableStringBuilder(fingerprint);
+        try {
+            // for each 4 characters of the fingerprint + 1 space
+            for (int i = 0; i < fingerprint.length(); i += 5) {
+                int spanEnd = Math.min(i + 4, fingerprint.length());
+                String fourChars = fingerprint.substring(i, spanEnd);
+
+                int raw = Integer.parseInt(fourChars, 16);
+                byte[] bytes = {(byte) ((raw >> 8) & 0xff - 128), (byte) (raw & 0xff - 128)};
+                int[] color = OtherHelper.getRgbForData(bytes);
+                int r = color[0];
+                int g = color[1];
+                int b = color[2];
+
+                // we cannot change black by multiplication, so adjust it to an almost-black grey,
+                // which will then be brightened to the minimal brightness level
+                if (r == 0 && g == 0 && b == 0) {
+                    r = 1;
+                    g = 1;
+                    b = 1;
+                }
+
+                // Convert rgb to brightness
+                double brightness = 0.2126 * r + 0.7152 * g + 0.0722 * b;
+
+                // If a color is too dark to be seen on black,
+                // then brighten it up to a minimal brightness.
+                if (brightness < 80) {
+                    double factor = 80.0 / brightness;
+                    r = Math.min(255, (int) (r * factor));
+                    g = Math.min(255, (int) (g * factor));
+                    b = Math.min(255, (int) (b * factor));
+
+                    // If it is too light, then darken it to a respective maximal brightness.
+                } else if (brightness > 180) {
+                    double factor = 180.0 / brightness;
+                    r = (int) (r * factor);
+                    g = (int) (g * factor);
+                    b = (int) (b * factor);
+                }
+
+                // Create a foreground color with the 3 digest integers as RGB
+                // and then converting that int to hex to use as a color
+                sb.setSpan(new ForegroundColorSpan(Color.rgb(r, g, b)),
+                        i, spanEnd, Spannable.SPAN_INCLUSIVE_INCLUSIVE);
+            }
+        } catch (Exception e) {
+            Log.e(Constants.TAG, "Colorization failed", e);
+            // if anything goes wrong, then just display the fingerprint without colour,
+            // instead of partially correct colour or wrong colours
+            return new SpannableStringBuilder(fingerprint);
+        }
+
+        return sb;
+    }
+
     /**
      * Converts the given bytes to a unique RGB color using SHA1 algorithm
      *