use dark play/gif button as overlay when image is mostly light

art/play_gif_black.svg

@@ -64,5 +64,5 @@
      d="M11.5 9H13v6h-1.5zM9 9H6c-.6 0-1 .5-1 1v4c0 .5.4 1 1 1h3c.6 0 1-.5 1-1v-2H8.5v1.5h-2v-3H10V10c0-.5-.4-1-1-1zm10 1.5V9h-4.5v6H16v-2h2v-1.5h-2v-1z"
      clip-path="url(#b)"
      id="path10"
-     style="fill:#ffffff;fill-opacity:0.7019608" />
+     style="fill:#000000;fill-opacity:0.54" />
 </svg>

art/play_gif_white.svg

@@ -0,0 +1,68 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="24"
+   height="24"
+   viewBox="0 0 24 24"
+   id="svg2"
+   version="1.1"
+   inkscape:version="0.91 r13725"
+   sodipodi:docname="play_gif.svg">
+  <metadata
+     id="metadata14">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <sodipodi:namedview
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1"
+     objecttolerance="10"
+     gridtolerance="10"
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="1920"
+     inkscape:window-height="1200"
+     id="namedview12"
+     showgrid="false"
+     inkscape:zoom="9.8333333"
+     inkscape:cx="1.5762712"
+     inkscape:cy="11.084746"
+     inkscape:window-x="0"
+     inkscape:window-y="0"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="svg2" />
+  <defs
+     id="defs4">
+    <path
+       id="a"
+       d="M24 24H0V0h24v24z" />
+  </defs>
+  <clipPath
+     id="b">
+    <use
+       xlink:href="#a"
+       overflow="visible"
+       id="use8" />
+  </clipPath>
+  <path
+     d="M11.5 9H13v6h-1.5zM9 9H6c-.6 0-1 .5-1 1v4c0 .5.4 1 1 1h3c.6 0 1-.5 1-1v-2H8.5v1.5h-2v-3H10V10c0-.5-.4-1-1-1zm10 1.5V9h-4.5v6H16v-2h2v-1.5h-2v-1z"
+     clip-path="url(#b)"
+     id="path10"
+     style="fill:#ffffff;fill-opacity:0.70" />
+</svg>

art/play_video_black.svg

@@ -55,5 +55,5 @@
   <path
      d="M20 33l12-9-12-9v18zm4-29C12.95 4 4 12.95 4 24s8.95 20 20 20 20-8.95 20-20S35.05 4 24 4zm0 36c-8.82 0-16-7.18-16-16S15.18 8 24 8s16 7.18 16 16-7.18 16-16 16z"
      id="path6"
-     style="fill:#ffffff;fill-opacity:0.7019608;opacity:1;stroke:none;stroke-opacity:0.38039216" />
+     style="fill:#000000;fill-opacity:0.54;opacity:1;stroke:none;stroke-opacity:0.38039216" />
 </svg>

art/play_video_white.svg

@@ -0,0 +1,59 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<svg
+   xmlns:dc="http://purl.org/dc/elements/1.1/"
+   xmlns:cc="http://creativecommons.org/ns#"
+   xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
+   xmlns:svg="http://www.w3.org/2000/svg"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:sodipodi="http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd"
+   xmlns:inkscape="http://www.inkscape.org/namespaces/inkscape"
+   width="48"
+   height="48"
+   viewBox="0 0 48 48"
+   id="svg2"
+   version="1.1"
+   inkscape:version="0.91 r13725"
+   sodipodi:docname="play_video.svg">
+  <metadata
+     id="metadata12">
+    <rdf:RDF>
+      <cc:Work
+         rdf:about="">
+        <dc:format>image/svg+xml</dc:format>
+        <dc:type
+           rdf:resource="http://purl.org/dc/dcmitype/StillImage" />
+        <dc:title></dc:title>
+      </cc:Work>
+    </rdf:RDF>
+  </metadata>
+  <defs
+     id="defs10" />
+  <sodipodi:namedview
+     pagecolor="#ffffff"
+     bordercolor="#666666"
+     borderopacity="1"
+     objecttolerance="10"
+     gridtolerance="10"
+     guidetolerance="10"
+     inkscape:pageopacity="0"
+     inkscape:pageshadow="2"
+     inkscape:window-width="1916"
+     inkscape:window-height="1156"
+     id="namedview8"
+     showgrid="false"
+     inkscape:zoom="4.9166667"
+     inkscape:cx="0.91525424"
+     inkscape:cy="24"
+     inkscape:window-x="0"
+     inkscape:window-y="20"
+     inkscape:window-maximized="0"
+     inkscape:current-layer="svg2" />
+  <path
+     d="M0 0h48v48H0z"
+     fill="none"
+     id="path4" />
+  <path
+     d="M20 33l12-9-12-9v18zm4-29C12.95 4 4 12.95 4 24s8.95 20 20 20 20-8.95 20-20S35.05 4 24 4zm0 36c-8.82 0-16-7.18-16-16S15.18 8 24 8s16 7.18 16 16-7.18 16-16 16z"
+     id="path6"
+     style="fill:#ffffff;fill-opacity:0.70;opacity:1;stroke:none;stroke-opacity:0.38039216" />
+</svg>

art/render.rb

@@ -18,8 +18,10 @@ images = {
     'ic_search_white.svg' => ['ic_search_background_white', 144],
     'ic_no_results_white.svg' => ['ic_no_results_background_white', 144],
     'ic_no_results_black.svg' => ['ic_no_results_background_black', 144],
-	'play_video.svg' => ['play_video', 128],
-	'play_gif.svg' => ['play_gif', 128],
+	'play_video_white.svg' => ['play_video_white', 128],
+	'play_gif_white.svg' => ['play_gif_white', 128],
+    'play_video_black.svg' => ['play_video_black', 128],
+    'play_gif_black.svg' => ['play_gif_black', 128],
 	'conversations_mono.svg' => ['ic_notification', 24],
 	'ic_received_indicator.svg' => ['ic_received_indicator', 12],
 	'ic_send_text_offline.svg' => ['ic_send_text_offline', 36],

src/main/java/eu/siacs/conversations/persistance/FileBackend.java

@@ -26,7 +26,6 @@ import android.util.Base64;
 import android.util.Base64OutputStream;
 import android.util.Log;
 import android.util.LruCache;
-import android.webkit.MimeTypeMap;
 
 import java.io.ByteArrayOutputStream;
 import java.io.Closeable;
@@ -44,7 +43,6 @@ import java.security.DigestOutputStream;
 import java.security.MessageDigest;
 import java.security.NoSuchAlgorithmException;
 import java.text.SimpleDateFormat;
-import java.util.Arrays;
 import java.util.Date;
 import java.util.List;
 import java.util.Locale;
@@ -675,7 +673,7 @@ public class FileBackend {
                     thumbnail = rotate(thumbnail, getRotation(file));
                     if (mime.equals("image/gif")) {
                         Bitmap withGifOverlay = thumbnail.copy(Bitmap.Config.ARGB_8888, true);
-						drawOverlay(withGifOverlay, R.drawable.play_gif, 1.0f);
+                        drawOverlay(withGifOverlay, paintOverlayBlack(withGifOverlay) ? R.drawable.play_gif_black : R.drawable.play_gif_white, 1.0f);
                         thumbnail.recycle();
                         thumbnail = withGifOverlay;
                     }
@@ -708,6 +706,24 @@ public class FileBackend {
         canvas.drawBitmap(overlay, null, dst, createAntiAliasingPaint());
     }
 
+    /**
+     * https://stackoverflow.com/a/3943023/210897
+     */
+    private boolean paintOverlayBlack(final Bitmap bitmap) {
+        int record = 0;
+        for (int y = 0; y < bitmap.getHeight(); ++y) {
+            for (int x = 0; x < bitmap.getWidth(); ++x) {
+                int pixel = bitmap.getPixel(x, y);
+                if ((Color.red(pixel) * 0.299 + Color.green(pixel) * 0.587 + Color.blue(pixel) * 0.114) > 186) {
+                    --record;
+                } else {
+                    ++record;
+                }
+            }
+        }
+        return record < 0;
+    }
+
     private Bitmap getVideoPreview(File file, int size) {
         MediaMetadataRetriever metadataRetriever = new MediaMetadataRetriever();
         Bitmap frame;
@@ -720,7 +736,7 @@ public class FileBackend {
             frame = Bitmap.createBitmap(size, size, Bitmap.Config.ARGB_8888);
             frame.eraseColor(0xff000000);
         }
-		drawOverlay(frame, R.drawable.play_video, 0.75f);
+        drawOverlay(frame, paintOverlayBlack(frame) ? R.drawable.play_video_black : R.drawable.play_video_white, 0.75f);
         return frame;
     }