Add option to config max width of scalebar.

app/src/androidTest/java/com/mapbox/mapboxsdk/plugins/scalebar/ScaleBarTest.java

@@ -247,4 +247,25 @@ public void testMetrics() {
       assertFalse(scaleBarWidget.isMetricUnit());
     });
   }
+
+  @Test
+  public void testRatio() {
+    validateTestSetup();
+    setupScaleBar();
+    assertEquals(0.5f,scaleBarWidget.getRatio(), 0f);
+    invoke(mapboxMap, (uiController, mapboxMap) -> {
+      ScaleBarOptions option = new ScaleBarOptions(activity);
+      option.setMaxWidthRatio(0.1f);
+      scaleBarWidget = scaleBarPlugin.create(option);
+      assertNotNull(scaleBarWidget);
+      assertEquals(0.1f, scaleBarWidget.getRatio(), 0f);
+    });
+    invoke(mapboxMap, (uiController, mapboxMap) -> {
+      ScaleBarOptions option = new ScaleBarOptions(activity);
+      option.setMaxWidthRatio(1.0f);
+      scaleBarWidget = scaleBarPlugin.create(option);
+      assertNotNull(scaleBarWidget);
+      assertEquals(1.0f, scaleBarWidget.getRatio(), 0f);
+    });
+  }
 }

app/src/main/java/com/mapbox/mapboxsdk/plugins/testapp/activity/scalebar/ScalebarActivity.kt

@@ -46,6 +46,7 @@ class ScalebarActivity : AppCompatActivity() {
                 .setMarginTop(15f)
                 .setMarginLeft(16f)
                 .setTextBarMargin(15f)
+                .setMaxWidthRatio(0.5f)
 
         scaleBarPlugin.create(scaleBarOptions)
         fabScaleWidget.setOnClickListener {

plugin-scalebar/src/main/java/com/mapbox/pluginscalebar/ScaleBarOptions.java

@@ -4,6 +4,7 @@
 
 import androidx.annotation.ColorRes;
 import androidx.annotation.DimenRes;
+import androidx.annotation.FloatRange;
 import androidx.annotation.NonNull;
 import androidx.annotation.VisibleForTesting;
 import androidx.core.content.ContextCompat;
@@ -28,6 +29,7 @@ public class ScaleBarOptions {
   private float borderWidth;
   private float textSize;
   private boolean isMetricUnit;
+  private float ratio;
 
   public ScaleBarOptions(@NonNull Context context) {
     this.context = context;
@@ -42,6 +44,7 @@ public ScaleBarOptions(@NonNull Context context) {
     setTextColor(android.R.color.black);
     setPrimaryColor(android.R.color.black);
     setSecondaryColor(android.R.color.white);
+    setMaxWidthRatio(0.5f);
   }
 
   /**
@@ -62,6 +65,7 @@ ScaleBarWidget build() {
     scaleBarWidget.setSecondaryColor(secondaryColor);
     scaleBarWidget.setTextColor(textColor);
     scaleBarWidget.setTextSize(textSize);
+    scaleBarWidget.setRatio(ratio);
     return scaleBarWidget;
   }
 
@@ -256,6 +260,16 @@ public ScaleBarOptions setTextBarMargin(@DimenRes int textBarMargin) {
     return this;
   }
 
+  /**
+   * Set the ratio of scale bar max width compared with MapView width.
+   *
+   * @param ratio the ratio scale bar will use, must be in the range from 0.1f to 1.0f.
+   */
+  public ScaleBarOptions setMaxWidthRatio(@FloatRange(from = 0.1f, to = 1.0f) float ratio) {
+    this.ratio = ratio;
+    return this;
+  }
+
   /**
    * Helper class to determine the user measuring system.
    * <p>

plugin-scalebar/src/main/java/com/mapbox/pluginscalebar/ScaleBarWidget.java

@@ -41,6 +41,7 @@ public class ScaleBarWidget extends View {
   private float textSize;
   private double distancePerPixel;
   private boolean isMetricUnit;
+  private float ratio;
   private ArrayList<Pair<Integer, Integer>> scaleTable;
   private String unit;
   private final RefreshHandler refreshHandler;
@@ -59,7 +60,7 @@ protected void onDraw(Canvas canvas) {
     if (distancePerPixel <= 0) {
       return;
     }
-    double maxDistance = mapViewWidth * distancePerPixel / 2;
+    double maxDistance = mapViewWidth * distancePerPixel * ratio;
     Pair<Integer, Integer> pair = scaleTable.get(0);
     for (int i = 1; i < scaleTable.size(); i++) {
       pair = scaleTable.get(i);
@@ -71,7 +72,7 @@ protected void onDraw(Canvas canvas) {
     }
 
     int unitDistance = pair.first / pair.second;
-    float unitBarWidth = maxBarWidth / 2f;
+    float unitBarWidth = maxBarWidth / pair.second;
     if (unitDistance == 0) {
       unitDistance = 1;
     } else {
@@ -179,7 +180,7 @@ public float getMarginLeft() {
    */
   public void setMarginLeft(float marginLeft) {
     this.marginLeft = marginLeft;
-    maxBarWidth = mapViewWidth / 2f - marginLeft;
+    maxBarWidth = mapViewWidth * ratio - marginLeft;
   }
 
   /**
@@ -346,7 +347,7 @@ public int getMapViewWidth() {
    */
   void setMapViewWidth(int mapViewWidth) {
     this.mapViewWidth = mapViewWidth;
-    maxBarWidth = mapViewWidth / 2f - marginLeft;
+    maxBarWidth = mapViewWidth * ratio - marginLeft;
   }
 
   /**
@@ -364,6 +365,22 @@ private String getDistanceText(int distance) {
     }
   }
 
+  /**
+   * Set the ratio of scale bar max width compared with MapView width.
+   * @param ratio the ratio scale bar will use.
+   */
+  public void setRatio(float ratio) {
+    this.ratio = ratio;
+  }
+
+  /**
+   * Get the current ratio of scale bar.
+   * @return current ratio.
+   */
+  public float getRatio() {
+    return this.ratio;
+  }
+
   /**
    * Handler class to limit the refresh frequent.
    */