Add support for OTA emoji download.

app/src/main/java/org/thoughtcrime/securesms/util/ScreenDensity.java

@@ -0,0 +1,82 @@
+package org.thoughtcrime.securesms.util;
+
+import android.content.Context;
+import android.util.DisplayMetrics;
+
+import androidx.annotation.NonNull;
+
+import java.util.LinkedHashMap;
+import java.util.Map;
+
+/**
+ * Helper class to get density information about a device's display
+ */
+public final class ScreenDensity {
+
+  private static final String UNKNOWN = "unknown";
+
+  private static final float XHDPI_TO_LDPI = 0.25f;
+  private static final float XHDPI_TO_MDPI = 0.5f;
+  private static final float XHDPI_TO_HDPI = 0.75f;
+
+  private static final LinkedHashMap<Integer, String> LEVELS = new LinkedHashMap<Integer, String>() {{
+    put(DisplayMetrics.DENSITY_LOW, "ldpi");
+    put(DisplayMetrics.DENSITY_MEDIUM, "mdpi");
+    put(DisplayMetrics.DENSITY_HIGH, "hdpi");
+    put(DisplayMetrics.DENSITY_XHIGH, "xhdpi");
+    put(DisplayMetrics.DENSITY_XXHIGH, "xxhdpi");
+    put(DisplayMetrics.DENSITY_XXXHIGH, "xxxhdpi");
+  }};
+
+  private final String bucket;
+  private final int    density;
+
+  public ScreenDensity(String bucket, int density) {
+    this.bucket  = bucket;
+    this.density = density;
+  }
+
+  public static @NonNull ScreenDensity get(@NonNull Context context) {
+    int density = context.getResources().getDisplayMetrics().densityDpi;
+
+    String bucket = UNKNOWN;
+
+    for (Map.Entry<Integer, String> entry : LEVELS.entrySet()) {
+      bucket = entry.getValue();
+      if (entry.getKey() > density) {
+        break;
+      }
+    }
+
+    return new ScreenDensity(bucket, density);
+  }
+
+  public String getBucket() {
+    return bucket;
+  }
+
+  public boolean isKnownDensity() {
+    return !bucket.equals(UNKNOWN);
+  }
+
+  @Override
+  public @NonNull String toString() {
+    return bucket + " (" + density + ")";
+  }
+
+  public static float xhdpiRelativeDensityScaleFactor(@NonNull String density) {
+    switch (density) {
+      case "ldpi":
+        return XHDPI_TO_LDPI;
+      case "mdpi":
+        return XHDPI_TO_MDPI;
+      case "hdpi":
+        return XHDPI_TO_HDPI;
+      case "xhdpi":
+        return 1f;
+      default:
+        throw new IllegalStateException("Unsupported density: " + density);
+    }
+
+  }
+}