A method needs cleanup. Removed test code and added an explanation:
private static PathEffect createPathEffect2(float pathLength, float
phase) {
//I modified the original approach using phase, to use only
path instead because later I want to animate also the starting point and
phase alone is not enough for this
float full = phase * pathLength;
return new DashPathEffect(new float[] {full, Float.MAX_VALUE},
//on, off
0);
}
Am Mittwoch, 16. Juli 2014 23:27:48 UTC+2 schrieb user123:
>
> I'm trying to make a path animation with DashPathEffect. Have to be able
> to replay it multiple times, using a button. Targeting KitKat.
>
> Based on
> http://www.curious-creature.org/2013/12/21/android-recipe-4-path-tracing/
>
> My problem is, the animation works well the first 10 times or so, then the
> path goes crazy and it starts flickering, going in the reverse order or
> finishes where it doesn't have to.
>
> I logged the values of the animation and the values passed to the path and
> they look correct, no jumps or anything weird. I have no idea what is
> causing the issues.
>
> *This is the code:*
>
> public class Test extends View {
>
> private float mDrag;
>
> private MyPath path1;
>
> private int mDuration;
>
> //just some shape
> private static Path makeDragPath(int radius) {
> Path p = new Path();
> RectF oval = new RectF(10.0f, 10.0f, radius * 2.0f, radius *
> 2.0f);
>
> float cx = oval.centerX();
> float cy = oval.centerY();
> float rx = oval.width() / 2.0f;
> float ry = oval.height() / 2.0f;
>
> final float TAN_PI_OVER_8 = 0.414213562f;
> final float ROOT_2_OVER_2 = 0.707106781f;
>
> float sx = rx * TAN_PI_OVER_8;
> float sy = ry * TAN_PI_OVER_8;
> float mx = rx * ROOT_2_OVER_2;
> float my = ry * ROOT_2_OVER_2;
>
> float L = oval.left;
> float T = oval.top;
> float R = oval.right;
> float B = oval.bottom;
>
> p.moveTo(R, cy);
> p.quadTo( R, cy + sy, cx + mx, cy + my);
> p.quadTo(cx + sx, B, cx, B);
> p.quadTo(cx - sx, B, cx - mx, cy + my);
> p.quadTo(L, cy + sy, L, cy);
> p.quadTo( L, cy - sy, cx - mx, cy - my);
> p.quadTo(cx - sx, T, cx, T);
>
>
> return p;
> }
>
>
>
>
> public Test(Context context, AttributeSet attrs) {
> super(context, attrs);
>
> init();
> }
>
>
>
>
> public static class MyPath {
> private static final Region sRegion = new Region();
> private static final Region sMaxClip = new Region(
> Integer.MIN_VALUE, Integer.MIN_VALUE,
> Integer.MAX_VALUE, Integer.MAX_VALUE);
>
> final Path path;
> final Paint paint;
> final float length;
> final Rect bounds;
>
> MyPath(Path path, Paint paint) {
> this.path = path;
> this.paint = paint;
>
> PathMeasure measure = new PathMeasure(path, false);
> this.length = measure.getLength();
>
> sRegion.setPath(path, sMaxClip);
> bounds = sRegion.getBounds();
> }
>
>
> }
>
>
> private static PathEffect createPathEffect2(float pathLength,
> float phase) {
>
> int startOffset = 200;
>
> float empty = Math.min(phase * pathLength, startOffset);
>
> float full = phase * pathLength;
> float rest = pathLength - empty - full;
>
> return new DashPathEffect(new float[] {full, Float.MAX_VALUE},
> //on, off
> 0);
> }
>
> ObjectAnimator current;
>
>
> public void startAnim() {
> if (current != null) {
> current.cancel();
> }
>
> current = ObjectAnimator.ofFloat(Test.this, "drag", 0.0f,
> 1.0f).setDuration(mDuration);
> current.start();
> }
>
> private void scalePath(Path path, float scale) {
> Matrix scaleMatrix = new Matrix();
> scaleMatrix.setScale(scale, scale);
> path.transform(scaleMatrix);
> }
>
> private void init() {
>
> Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
> paint.setStyle(Paint.Style.STROKE);
>
> paint.setStrokeWidth(8.0f);
> paint.setColor(0xffffffff);
>
> mDuration = 3000;
>
> Path p1 = makeDragPath(40);
> scalePath(p1, 3);
>
> path1 = new MyPath(p1, paint);
>
>
> startAnim();
> }
>
> public float getDrag() {
> return mDrag;
> }
>
> public void setDrag(float drag) {
>
> mDrag = drag;
>
> path1.paint.setPathEffect(createPathEffect2(path1.length,
> mDrag));
>
> invalidate();
> }
>
> @Override
> protected void onDraw(Canvas canvas) {
> super.onDraw(canvas);
>
> canvas.drawColor(Color.BLACK); //doesn't help
>
> canvas.drawPath(path1.path, path1.paint);
> }
>
> }
>
>
> *In my activity:*
>
>
> @Override
> protected void onCreate(Bundle savedInstanceState) {
> super.onCreate(savedInstanceState);
> setContentView(R.layout.activity_my);
>
> final Test test = (Test)findViewById(R.id.test);
>
> Button button = (Button)findViewById(R.id.startTest);
> button.setOnClickListener(new View.OnClickListener() {
> @Override
> public void onClick(View v) {
> test.startAnim();
> }
> });
> }
>
>
> *xml:*
>
> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android";
> xmlns:tools="http://schemas.android.com/tools";
> android:layout_width="match_parent"
> android:layout_height="match_parent"
> android:paddingLeft="@dimen/activity_horizontal_margin"
> android:paddingRight="@dimen/activity_horizontal_margin"
> android:paddingTop="@dimen/activity_vertical_margin"
> android:paddingBottom="@dimen/activity_vertical_margin"
> tools:context=".MyActivity">
>
>
> <Button
> android:id="@+id/startTest"
> android:layout_width="200dp"
> android:layout_alignParentBottom="true"
> android:layout_alignParentLeft="true"
> android:layout_height="60dp" />
>
> <com.example.ivanschuetzd.myapplication.Test
> android:id="@+id/test"
> android:layout_width="100dp"
> android:layout_height="100dp"
> android:layout_alignParentBottom="true"
> android:layout_alignParentRight="true"
> android:background="#000000"
> />
>
> </RelativeLayout>
>
>
>
> Any idea? Or maybe a different approach to make this kind of animation
> with an arbitrary path? Thanks!
>
>
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