fix: Speaker's color changes when searching (fossasia#2351)

* Add hashmap

* Revert "Add hashmap"

This reverts commit 3431a46.

* Fix color changing problem

* Use constant color from resources

* Set color to color primary dark

Author: leeyh20

android/app/src/main/java/org/fossasia/openevent/core/speaker/SpeakerViewHolder.java

@@ -8,6 +8,7 @@
 import android.graphics.drawable.Drawable;
 import android.os.Bundle;
 import android.support.annotation.Nullable;
+import android.support.v4.content.ContextCompat;
 import android.support.v7.graphics.Palette;
 import android.support.v7.widget.RecyclerView;
 import android.text.TextUtils;
@@ -95,8 +96,19 @@ public void bindSpeaker(Speaker speaker) {
 
         final Palette.PaletteAsyncListener paletteAsyncListener = palette -> {
             Palette.Swatch swatch = palette.getVibrantSwatch();
-            if (swatch != null && speakerTextualInfo != null) {
-                speakerTextualInfo.setBackgroundColor(swatch.getRgb());
+            if (speakerTextualInfo != null) {
+                if (swatch != null) {
+                    // bitmap has vibrant swatch profile
+                    speakerTextualInfo.setBackgroundColor(swatch.getRgb());
+                } else {
+                    Palette.Swatch swatch2 = palette.getDarkMutedSwatch();
+                    if (swatch2 != null) {
+                        // bitmap has dark muted swatch profile
+                        speakerTextualInfo.setBackgroundColor(swatch2.getRgb());
+                    } else {
+                        speakerTextualInfo.setBackgroundColor(ContextCompat.getColor(context, R.color.color_primary_dark));
+                    }
+                }
             }
         };