Add files

app/src/main/java/com/hippo/view/ViewTransition.java

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+/*
+ * Copyright (C) 2015 Hippo Seven
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.hippo.view;
+
+import android.animation.Animator;
+import android.animation.ObjectAnimator;
+import android.view.View;
+
+import com.hippo.anani.SimpleAnimatorListener;
+
+public class ViewTransition {
+
+    private static long ANIMATE_TIME = 300L;
+
+    private final View[] mViews;
+
+    private int mShownView = -1;
+
+    private Animator mAnimator1;
+    private Animator mAnimator2;
+
+    public ViewTransition(View... views) {
+        if (views.length < 2) {
+            throw new IllegalStateException("You must pass view to ViewTransition");
+        }
+        for (View v : views) {
+            if (v == null) {
+                throw new IllegalStateException("Any View pass to ViewTransition must not be null");
+            }
+        }
+
+        mViews = views;
+        showView(0, false);
+    }
+
+    public int getShownViewIndex() {
+        return mShownView;
+    }
+
+    public boolean showView(int shownView) {
+        return showView(shownView, true);
+    }
+
+    public boolean showView(int shownView, boolean animation) {
+        View[] views = mViews;
+        int length = views.length;
+        if (shownView >= length || shownView < 0) {
+            throw new IndexOutOfBoundsException("Only " + length + " view(s) in " +
+                    "the ViewTransition, but attempt to show " + shownView);
+        }
+
+        if (mShownView != shownView) {
+            int oldShownView = mShownView;
+            mShownView = shownView;
+
+            // Cancel animation
+            if (mAnimator1 != null) {
+                mAnimator1.cancel();
+            }
+            if (mAnimator2 != null) {
+                mAnimator2.cancel();
+            }
+
+            if (animation) {
+                for (int i = 0; i < length; i++) {
+                    if (i != oldShownView && i != shownView) {
+                        View v = views[i];
+                        v.setAlpha(0f);
+                        v.setVisibility(View.GONE);
+                    }
+                }
+                startAnimations(views[oldShownView], views[shownView]);
+            } else {
+                for (int i = 0; i < length; i++) {
+                    View v = views[i];
+                    if (i == shownView) {
+                        v.setAlpha(1f);
+                        v.setVisibility(View.VISIBLE);
+                    } else {
+                        v.setAlpha(0f);
+                        v.setVisibility(View.GONE);
+                    }
+                }
+            }
+
+            return true;
+        } else {
+            return false;
+        }
+    }
+
+    private void startAnimations(final View hiddenView, final View shownView) {
+        ObjectAnimator oa1 = ObjectAnimator.ofFloat(hiddenView, "alpha", 0f);
+        oa1.setDuration(ANIMATE_TIME);
+        oa1.addListener(new SimpleAnimatorListener() {
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                hiddenView.setVisibility(View.GONE);
+                mAnimator1 = null;
+            }
+        });
+        oa1.start();
+        mAnimator1 = oa1;
+
+        shownView.setVisibility(View.VISIBLE);
+        ObjectAnimator oa2 = ObjectAnimator.ofFloat(shownView, "alpha", 1f);
+        oa2.setDuration(ANIMATE_TIME);
+        oa2.addListener(new SimpleAnimatorListener() {
+            @Override
+            public void onAnimationEnd(Animator animation) {
+                mAnimator2 = null;
+            }
+        });
+        oa2.start();
+        mAnimator2 = oa2;
+    }
+}