Java tutorial
/* * Copyright (C) 2011 The Android Open Source Project * Copyright 2014 Manabu Shimobe * * 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.findme.views; import android.annotation.TargetApi; import android.content.Context; import android.content.res.TypedArray; import android.graphics.drawable.Drawable; import android.os.Build; import android.support.v4.content.res.ResourcesCompat; import android.text.TextUtils; import android.util.AttributeSet; import android.util.SparseBooleanArray; import android.view.MotionEvent; import android.view.View; import android.view.ViewGroup; import android.view.animation.AlphaAnimation; import android.view.animation.Animation; import android.view.animation.Transformation; import android.widget.ImageButton; import android.widget.LinearLayout; import android.widget.TextView; import com.findme.R; public class ExpandableTextView extends LinearLayout implements View.OnClickListener { public static final String TAG = ExpandableTextView.class.getSimpleName(); /* The default number of lines */ private static final int MAX_COLLAPSED_LINES = 8; /* The default animation duration */ private static final int DEFAULT_ANIM_DURATION = 300; /* The default alpha value when the animation starts */ private static final float DEFAULT_ANIM_ALPHA_START = 0.7f; protected TextView mTv; protected ImageButton mButton; // Button to expand/collapse private boolean mRelayout; private boolean mCollapsed = true; // Show short version as default. private int mCollapsedHeight; private int mTextHeightWithMaxLines; private int mMaxCollapsedLines; private int mMarginBetweenTxtAndBottom; private Drawable mExpandDrawable; private Drawable mCollapseDrawable; private int mAnimationDuration; private float mAnimAlphaStart; private boolean mAnimating; /* For saving collapsed status when used in ListView */ private SparseBooleanArray mCollapsedStatus; private int mPosition; public ExpandableTextView(Context context) { super(context); } public ExpandableTextView(Context context, AttributeSet attrs) { super(context, attrs); init(attrs); } @TargetApi(Build.VERSION_CODES.HONEYCOMB) public ExpandableTextView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); init(attrs); } @Override public void onClick(View view) { if (mButton.getVisibility() != View.VISIBLE) { return; } mCollapsed = !mCollapsed; mButton.setImageDrawable(mCollapsed ? mExpandDrawable : mCollapseDrawable); if (mCollapsedStatus != null) { mCollapsedStatus.put(mPosition, mCollapsed); } // mark that the animation is in progress mAnimating = true; Animation animation; if (mCollapsed) { animation = new ExpandCollapseAnimation(this, getHeight(), mCollapsedHeight); } else { animation = new ExpandCollapseAnimation(this, getHeight(), getHeight() + mTextHeightWithMaxLines - mTv.getHeight()); } animation.setFillAfter(true); animation.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { applyAlphaAnimation(mTv, mAnimAlphaStart); } @Override public void onAnimationEnd(Animation animation) { // clear animation here to avoid repeated applyTransformation() // calls clearAnimation(); // clear the animation flag mAnimating = false; } @Override public void onAnimationRepeat(Animation animation) { } }); clearAnimation(); startAnimation(animation); } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { // while an animation is in progress, intercept all the touch events to // children to // prevent extra clicks during the animation return mAnimating; } @Override protected void onFinishInflate() { findViews(); } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { // If no change, measure and return if (!mRelayout || getVisibility() == View.GONE) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); return; } mRelayout = false; // Setup with optimistic case // i.e. Everything fits. No button needed mButton.setVisibility(View.GONE); mTv.setMaxLines(Integer.MAX_VALUE); // Measure super.onMeasure(widthMeasureSpec, heightMeasureSpec); // If the text fits in collapsed mode, we are done. if (mTv.getLineCount() <= mMaxCollapsedLines) { return; } // Saves the text height w/ max lines mTextHeightWithMaxLines = getRealTextViewHeight(mTv); // Doesn't fit in collapsed mode. Collapse text view as needed. Show // button. if (mCollapsed) { mTv.setMaxLines(mMaxCollapsedLines); } mButton.setVisibility(View.VISIBLE); // Re-measure with new setup super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (mCollapsed) { // Gets the margin between the TextView's bottom and the ViewGroup's // bottom mTv.post(new Runnable() { @Override public void run() { mMarginBetweenTxtAndBottom = getHeight() - mTv.getHeight(); } }); // Saves the collapsed height of this ViewGroup mCollapsedHeight = getMeasuredHeight(); } } private void init(AttributeSet attrs) { TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.ExpandableTextView); mMaxCollapsedLines = typedArray.getInt(R.styleable.ExpandableTextView_maxCollapsedLines, MAX_COLLAPSED_LINES); mAnimationDuration = typedArray.getInt(R.styleable.ExpandableTextView_animDuration, DEFAULT_ANIM_DURATION); mAnimAlphaStart = typedArray.getFloat(R.styleable.ExpandableTextView_animAlphaStart, DEFAULT_ANIM_ALPHA_START); mExpandDrawable = typedArray.getDrawable(R.styleable.ExpandableTextView_expandDrawable); mCollapseDrawable = typedArray.getDrawable(R.styleable.ExpandableTextView_collapseDrawable); if (mExpandDrawable == null) { mExpandDrawable = ResourcesCompat.getDrawable(getResources(), R.drawable.ic_action_expand, null); } if (mCollapseDrawable == null) { mCollapseDrawable = ResourcesCompat.getDrawable(getResources(), R.drawable.ic_action_collapse, null); } typedArray.recycle(); } private static boolean isPostHoneycomb() { return Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB; } private void findViews() { mTv = (TextView) findViewById(R.id.expandable_text); mTv.setOnClickListener(this); mButton = (ImageButton) findViewById(R.id.expand_collapse); mButton.setImageDrawable(mCollapsed ? mExpandDrawable : mCollapseDrawable); mButton.setOnClickListener(this); } @TargetApi(Build.VERSION_CODES.HONEYCOMB) private static void applyAlphaAnimation(View view, float alpha) { if (isPostHoneycomb()) { view.setAlpha(alpha); } else { AlphaAnimation alphaAnimation = new AlphaAnimation(alpha, alpha); // make it instant alphaAnimation.setDuration(0); alphaAnimation.setFillAfter(true); view.startAnimation(alphaAnimation); } } public void setText(CharSequence text) { mRelayout = true; mTv.setText(text); setVisibility(TextUtils.isEmpty(text) ? View.GONE : View.VISIBLE); } public void setText(CharSequence text, SparseBooleanArray collapsedStatus, int position) { mCollapsedStatus = collapsedStatus; mPosition = position; boolean isCollapsed = collapsedStatus.get(position, true); clearAnimation(); mCollapsed = isCollapsed; mButton.setImageDrawable(mCollapsed ? mExpandDrawable : mCollapseDrawable); setText(text); getLayoutParams().height = ViewGroup.LayoutParams.WRAP_CONTENT; requestLayout(); } public CharSequence getText() { if (mTv == null) { return ""; } return mTv.getText(); } private static int getRealTextViewHeight(TextView textView) { int textHeight = textView.getLayout().getLineTop(textView.getLineCount()); int padding = textView.getCompoundPaddingTop() + textView.getCompoundPaddingBottom(); return textHeight + padding; } protected class ExpandCollapseAnimation extends Animation { private final View mTargetView; private final int mStartHeight; private final int mEndHeight; public ExpandCollapseAnimation(View view, int startHeight, int endHeight) { mTargetView = view; mStartHeight = startHeight; mEndHeight = endHeight; setDuration(mAnimationDuration); } @Override protected void applyTransformation(float interpolatedTime, Transformation t) { final int newHeight = (int) ((mEndHeight - mStartHeight) * interpolatedTime + mStartHeight); mTv.setMaxHeight(newHeight - mMarginBetweenTxtAndBottom); if (Float.compare(mAnimAlphaStart, 1.0f) != 0) { applyAlphaAnimation(mTv, mAnimAlphaStart + interpolatedTime * (1.0f - mAnimAlphaStart)); } mTargetView.getLayoutParams().height = newHeight; mTargetView.requestLayout(); } @Override public void initialize(int width, int height, int parentWidth, int parentHeight) { super.initialize(width, height, parentWidth, parentHeight); } @Override public boolean willChangeBounds() { return true; } }; }