Add snap option to CircleFlowIndicator

like ViewPagerIndicator's. It makes the active indicator jump to the
next position instead of following the scroll offsets. I've also
documentated it in the README.

Author: orac

README.md

@@ -66,8 +66,15 @@ And then you'll need to connect your `ViewFlow` with the `FlowIndicator`:
 
 	CircleFlowIndicator indic = (CircleFlowIndicator) findViewById(R.id.viewflowindic);
 	viewFlow.setFlowIndicator(indic);
-	
-The following attributes are supported: `activeColor`, `inactiveColor`, `activeType` (either fill or stroke), `inactiveType` (either fill or stroke), `fadeOut` (time in ms until indicator fades out, 0 = never), `radius`.
+
+By default, the 'active' indicator moves smoothly from one 'inactive' indicator
+to the next, as the user scrolls. If you set the `snap` attribute to `true`, it
+will instead jump to the next position when the flow settles at the next page.
+
+The following attributes are supported: `activeColor`, `inactiveColor`,
+`activeType` (either fill or stroke), `inactiveType` (either fill or stroke),
+`fadeOut` (time in ms until indicator fades out, 0 = never), `radius`, `sync`
+(see above).
 
 #### Title Flow Indicator ####
 This indicator presents the title of the previous, current and next `View` in the adapter (see screenshot below).

viewflow/res/values/attrs.xml

@@ -33,6 +33,7 @@
 			<flag name="stroke" value="0" />
 			<flag name="fill" value="1" />
 		</attr>
+		<attr name="snap" format="boolean" />
     </declare-styleable>    
     <declare-styleable name="TitleFlowIndicator">
         <attr name="titlePadding" format="dimension" />
@@ -48,4 +49,4 @@
         <attr name="footerTriangleHeight" format="dimension" />
         <attr name="customTypeface" format="string" />
     </declare-styleable>    
-</resources>
+</resources>

viewflow/src/org/taptwo/android/widget/CircleFlowIndicator.java

@@ -54,6 +54,9 @@
  * <li>
  * spacing: Define the circle spacing (default to 4.0)
  * </li>
+ * <li>
+ * snap: If true, the 'active' indicator snaps from one page to the next; otherwise, it moves smoothly.
+ * </li>
  * </ul>
  */
 public class CircleFlowIndicator extends View implements FlowIndicator,
@@ -70,11 +73,13 @@ public class CircleFlowIndicator extends View implements FlowIndicator,
 	private final Paint mPaintActive = new Paint(Paint.ANTI_ALIAS_FLAG);
 	private ViewFlow viewFlow;
 	private int currentScroll = 0;
+	private int currentPosition = 0;
 	private int flowWidth = 0;
 	private FadeTimer timer;
 	public AnimationListener animationListener = this;
 	private Animation animation;
 	private boolean mCentered = false;
+	private boolean mSnap = false;
 
 	/**
 	 * Default constructor
@@ -133,6 +138,8 @@ public CircleFlowIndicator(Context context, AttributeSet attrs) {
 		fadeOutTime = a.getInt(R.styleable.CircleFlowIndicator_fadeOut, 0);
 
 		mCentered = a.getBoolean(R.styleable.CircleFlowIndicator_centered, false);
+
+		mSnap = a.getBoolean(R.styleable.CircleFlowIndicator_snap, false);
 
 		initColors(activeColor, inactiveColor, activeType, inactiveType);
 	}
@@ -197,11 +204,15 @@ protected void onDraw(Canvas canvas) {
 					getPaddingTop() + mRadius, mRadiusInactive, mPaintInactive);
 		}
 		float cx = 0;
-		if (flowWidth != 0) {
-			// Draw the filled circle according to the current scroll
-			cx = (currentScroll * spacing) / flowWidth;
+		if (mSnap) {
+			cx = currentPosition * spacing;
+		} else {
+			if (flowWidth != 0) {
+				// Draw the filled circle according to the current scroll
+				cx = (currentScroll * spacing) / flowWidth;
+			}
+			// else, the flow width hasn't been updated yet. Draw the default position.
 		}
-		// The flow width has been upadated yet. Draw the default position
 		canvas.drawCircle(leftPadding + mRadius + cx+centeringOffset, getPaddingTop()
 				+ mRadius, mRadiusActive, mPaintActive);
 	}
@@ -215,6 +226,12 @@ protected void onDraw(Canvas canvas) {
 	 */
 	@Override
 	public void onSwitched(View view, int position) {
+		currentPosition = position;
+		if (mSnap) {
+			setVisibility(View.VISIBLE);
+			resetTimer();
+			invalidate();
+		}
 	}
 
 	/*
@@ -240,11 +257,13 @@ public void setViewFlow(ViewFlow view) {
 	 */
 	@Override
 	public void onScrolled(int h, int v, int oldh, int oldv) {
-		setVisibility(View.VISIBLE);
-		resetTimer();
 		currentScroll = h;
 		flowWidth = viewFlow.getChildWidth();
-		invalidate();
+		if (!mSnap) {
+			setVisibility(View.VISIBLE);
+			resetTimer();
+			invalidate();
+		}
 	}
 
 	/*