Add foundational UX and state support for Group Calling.

app/src/main/java/org/thoughtcrime/securesms/animation/ResizeAnimation.java

@@ -0,0 +1,50 @@
+package org.thoughtcrime.securesms.animation;
+
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.animation.Animation;
+import android.view.animation.Transformation;
+
+import androidx.annotation.NonNull;
+
+public class ResizeAnimation extends Animation {
+
+  private final View target;
+  private final int  targetWidthPx;
+  private final int  targetHeightPx;
+
+  private int startWidth;
+  private int startHeight;
+
+  public ResizeAnimation(@NonNull View target, int targetWidthPx, int targetHeightPx) {
+    this.target         = target;
+    this.targetWidthPx  = targetWidthPx;
+    this.targetHeightPx = targetHeightPx;
+  }
+
+  @Override
+  protected void applyTransformation(float interpolatedTime, Transformation t) {
+    int newWidth  = (int) (startWidth + (targetWidthPx - startWidth) * interpolatedTime);
+    int newHeight = (int) (startHeight + (targetHeightPx - startHeight) * interpolatedTime);
+
+    ViewGroup.LayoutParams params = target.getLayoutParams();
+
+    params.width  = newWidth;
+    params.height = newHeight;
+
+    target.setLayoutParams(params);
+  }
+
+  @Override
+  public void initialize(int width, int height, int parentWidth, int parentHeight) {
+    super.initialize(width, height, parentWidth, parentHeight);
+
+    this.startWidth  = width;
+    this.startHeight = height;
+  }
+
+  @Override
+  public boolean willChangeBounds() {
+    return true;
+  }
+}