fix(map): make filter panel compact and scrollable

app/src/main/java/com/wytehat/btlogger/MapActivity.java

@@ -22,6 +22,7 @@ import android.widget.ArrayAdapter;
 import android.widget.Button;
 import android.widget.CheckBox;
 import android.widget.LinearLayout;
+import android.widget.ScrollView;
 import android.widget.Spinner;
 import android.widget.TextView;
 
@@ -48,6 +49,8 @@ implements SensorEventListener {
 
 	private LinearLayout filterPanel;  
 
+	private ScrollView filterScroll;
+
 	private Spinner categorySpinner;  
 	private Spinner deviceSpinner;  
 
@@ -207,7 +210,6 @@ implements SensorEventListener {
 			dp(4)  
 		);  
 
-		filterPanel.setVisibility(View.GONE);  
 
 		/*  
 		 * Category.  
@@ -387,11 +389,28 @@ implements SensorEventListener {
 
 		filterPanel.addView(showAll);  
 
-		root.addView(  
+		/*
+		 * Bounded to a third of the screen and scrollable, so every
+		 * control stays reachable on short screens.
+		 */
+		filterScroll = new ScrollView(this);
+
+		filterScroll.setVisibility(View.GONE);
+
+		filterScroll.addView(
 			filterPanel,
+			new android.widget.FrameLayout.LayoutParams(
+				android.widget.FrameLayout.LayoutParams.MATCH_PARENT,
+				android.widget.FrameLayout.LayoutParams.WRAP_CONTENT
+			)
+		);
+
+		root.addView(
+			filterScroll,
 			new LinearLayout.LayoutParams(
 				LinearLayout.LayoutParams.MATCH_PARENT,
-				LinearLayout.LayoutParams.WRAP_CONTENT  
+				0,
+				1
 			)
 		);
 
@@ -441,7 +460,7 @@ implements SensorEventListener {
 			new LinearLayout.LayoutParams(
 				LinearLayout.LayoutParams.MATCH_PARENT,
 				0,
-				1  
+				2
 			)
 		);  
 
@@ -476,19 +495,12 @@ implements SensorEventListener {
 				@Override  
 				public void onClick(View view) {  
 
-					if (filterPanel.getVisibility()  
-						== View.VISIBLE) {  
-
-						filterPanel.setVisibility(  
-							View.GONE  
+					filterScroll.setVisibility(
+						filterScroll.getVisibility()
+						== View.VISIBLE
+							? View.GONE
+							: View.VISIBLE
 					);  
-
-					} else {  
-
-						filterPanel.setVisibility(  
-							View.VISIBLE  
-						);  
-					}  
 				}  
 			}  
 		);  
@@ -646,7 +658,7 @@ implements SensorEventListener {
 					/*  
 					 * Collapse after applying.  
 					 */  
-					filterPanel.setVisibility(  
+					filterScroll.setVisibility(
 						View.GONE
 					);  
 				}  
@@ -698,7 +710,7 @@ implements SensorEventListener {
 
 		return new LinearLayout.LayoutParams(
 			LinearLayout.LayoutParams.MATCH_PARENT,
-			dp(42)  
+			dp(38)
 			);  
 	}