Issue #212: Add possibility to configure alpha of description text.

taptargetview/src/main/java/com/getkeepsafe/taptargetview/TapTarget.java

@@ -82,6 +82,8 @@ public class TapTarget {
   boolean cancelable = true;
   boolean tintTarget = true;
   boolean transparentTarget = false;
+  // This variable is used for configuring alpha of description text.
+  float descriptionTextAlpha = 0;
 
   /**
    * Return a tap target for the overflow button from the given toolbar
@@ -414,6 +416,17 @@ public TapTarget targetRadius(int targetRadius) {
     return this;
   }
 
+  /**
+  * @param descriptionTextAlpha is used to define alpha of description text, should be [0..255].
+  * @return TapTarget object with defined alpha for description text.
+  */
+  public TapTarget descriptionTextAlpha(float descriptionTextAlpha) {
+    if (descriptionTextAlpha < 0 || descriptionTextAlpha > 255) {
+      throw new IllegalArgumentException("Alpha is out of allowed bounds");
+    }
+    this.descriptionTextAlpha = descriptionTextAlpha;
+    return this;
+  }
 
   /** Return the id associated with this tap target **/
   public int id() {

taptargetview/src/main/java/com/getkeepsafe/taptargetview/TapTargetView.java

@@ -665,7 +665,11 @@ protected void onDraw(Canvas c) {
 
       if (descriptionLayout != null && titleLayout != null) {
         c.translate(0, titleLayout.getHeight() + TEXT_SPACING);
-        descriptionPaint.setAlpha((int) (0.54f * textAlpha));
+        if (target.descriptionTextAlpha != 0) {
+            descriptionPaint.setAlpha((int) target.descriptionTextAlpha);
+        } else {
+            descriptionPaint.setAlpha((int) (0.54f * textAlpha));
+        }
         descriptionLayout.draw(c);
       }
     }