samples/devbytes/graphics/FoldingLayout/src/com/example/android/foldinglayout/FoldingLayoutActivity.java

/*
 * Copyright (C) 2013 The Android Open Source Project
 *
 * 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.example.android.foldinglayout;

import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.app.Activity;
import android.graphics.Color;
import android.graphics.ColorMatrix;
import android.graphics.ColorMatrixColorFilter;
import android.graphics.Paint;
import android.graphics.SurfaceTexture;
import android.hardware.Camera;
import android.os.Build;
import android.os.Bundle;
import android.view.GestureDetector;
import android.view.Menu;
import android.view.MenuItem;
import android.view.MotionEvent;
import android.view.TextureView;
import android.view.View;
import android.view.ViewConfiguration;
import android.view.ViewGroup;
import android.view.animation.AccelerateInterpolator;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.Spinner;

import com.example.android.foldinglayout.FoldingLayout.Orientation;

import java.io.IOException;

/**
 * This application creates  a paper like folding effect of some view.
 * The number of folds, orientation (vertical or horizontal) of the fold, and the
 * anchor point about which the view will fold can be set to achieve different
 * folding effects.
 *
 * Using bitmap and canvas scaling techniques, the foldingLayout can be scaled so as
 * to depict a paper-like folding effect. The addition of shadows on the separate folds
 * adds a sense of realism to the visual effect.
 *
 * This application shows folding of a TextureView containing a live camera feed,
 * as well as the folding of an ImageView with a static image. The TextureView experiences
 * jagged edges as a result of scaling operations on rectangles. The ImageView however
 * contains a 1 pixel transparent border around its contents which can be used to avoid
 * this unwanted artifact.
 */
public class FoldingLayoutActivity extends Activity {

    private final int ANTIALIAS_PADDING = 1;

    private final int FOLD_ANIMATION_DURATION = 1000;

    /* A bug was introduced in Android 4.3 that ignores changes to the Canvas state
     * between multiple calls to super.dispatchDraw() when running with hardware acceleration.
     * To account for this bug, a slightly different approach was taken to fold a
     * static image whereby a bitmap of the original contents is captured and drawn
     * in segments onto the canvas. However, this method does not permit the folding
     * of a TextureView hosting a live camera feed which continuously updates.
     * Furthermore, the sepia effect was removed from the bitmap variation of the
     * demo to simplify the logic when running with this workaround."
     */
    static final boolean IS_JBMR2 = Build.VERSION.SDK_INT == Build.VERSION_CODES.JELLY_BEAN_MR2;

    private FoldingLayout mFoldLayout;
    private SeekBar mAnchorSeekBar;
    private Orientation mOrientation = Orientation.HORIZONTAL;

    private int mTranslation = 0;
    private int mNumberOfFolds = 2;
    private int mParentPositionY = -1;
    private int mTouchSlop = -1;

    private float mAnchorFactor = 0;

    private boolean mDidLoadSpinner = true;
    private boolean mDidNotStartScroll = true;

    private boolean mIsCameraFeed = false;
    private boolean mIsSepiaOn = true;

    private GestureDetector mScrollGestureDetector;
    private ItemSelectedListener mItemSelectedListener;

    private Camera mCamera;
    private TextureView mTextureView;
    private ImageView mImageView;

    private Paint mSepiaPaint;
    private Paint mDefaultPaint;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_fold);

        mImageView = (ImageView)findViewById(R.id.image_view);
        mImageView.setPadding(ANTIALIAS_PADDING, ANTIALIAS_PADDING, ANTIALIAS_PADDING,
                ANTIALIAS_PADDING);
        mImageView.setScaleType(ImageView.ScaleType.FIT_XY);
        mImageView.setImageDrawable(getResources().getDrawable(R.drawable.image));

        mTextureView = new TextureView(this);
        mTextureView.setSurfaceTextureListener(mSurfaceTextureListener);

        mAnchorSeekBar = (SeekBar)findViewById(R.id.anchor_seek_bar);
        mFoldLayout = (FoldingLayout)findViewById(R.id.fold_view);
        mFoldLayout.setBackgroundColor(Color.BLACK);
        mFoldLayout.setFoldListener(mOnFoldListener);

        mTouchSlop = ViewConfiguration.get(this).getScaledTouchSlop();

        mAnchorSeekBar.setOnSeekBarChangeListener(mSeekBarChangeListener);

        mScrollGestureDetector = new GestureDetector(this, new ScrollGestureDetector());
        mItemSelectedListener = new ItemSelectedListener();

        mDefaultPaint = new Paint();
        mSepiaPaint = new Paint();

        ColorMatrix m1 = new ColorMatrix();
        ColorMatrix m2 = new ColorMatrix();
        m1.setSaturation(0);
        m2.setScale(1f, .95f, .82f, 1.0f);
        m1.setConcat(m2, m1);
        mSepiaPaint.setColorFilter(new ColorMatrixColorFilter(m1));
    }

    /**
     * This listener, along with the setSepiaLayer method below, show a possible use case
     * of the OnFoldListener provided with the FoldingLayout. This is a fun extra addition
     * to the demo showing what kind of visual effects can be applied to the child of the
     * FoldingLayout by setting the layer type to hardware. With a hardware layer type
     * applied to the child, a paint object can also be applied to the same layer. Using
     * the concatenation of two different color matrices (above), a color filter was created
     * which simulates a sepia effect on the layer.*/
    private OnFoldListener mOnFoldListener =
            new OnFoldListener() {
        @Override
        public void onStartFold() {
            if (mIsSepiaOn) {
                setSepiaLayer(mFoldLayout.getChildAt(0), true);
            }
        }

        @Override
        public void onEndFold() {
            setSepiaLayer(mFoldLayout.getChildAt(0), false);
        }
    };

    private void setSepiaLayer (View view, boolean isSepiaLayerOn) {
        if (!IS_JBMR2) {
            if (isSepiaLayerOn) {
                view.setLayerType(View.LAYER_TYPE_HARDWARE, null);
                view.setLayerPaint(mSepiaPaint);
            } else {
                view.setLayerPaint(mDefaultPaint);
            }
        }
    }

    /**
     * Creates a SurfaceTextureListener in order to prepare a TextureView
     * which displays a live, and continuously updated, feed from the Camera.
     */
    private TextureView.SurfaceTextureListener mSurfaceTextureListener = new TextureView
            .SurfaceTextureListener() {
        @Override
        public void onSurfaceTextureAvailable(SurfaceTexture surfaceTexture, int i, int i2) {
            mCamera = Camera.open();

            if (mCamera == null && Camera.getNumberOfCameras() > 1) {
                mCamera = mCamera.open(Camera.CameraInfo.CAMERA_FACING_FRONT);
            }

            if (mCamera == null) {
                return;
            }

            try {
                mCamera.setPreviewTexture(surfaceTexture);
                mCamera.setDisplayOrientation(90);
                mCamera.startPreview();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        @Override
        public void onSurfaceTextureSizeChanged(SurfaceTexture surfaceTexture, int i, int i2) {
            // Ignored, Camera does all the work for us
        }

        @Override
        public boolean onSurfaceTextureDestroyed(SurfaceTexture surfaceTexture) {
            if (mCamera != null) {
                mCamera.stopPreview();
                mCamera.release();
            }
            return true;
        }

        @Override
        public void onSurfaceTextureUpdated(SurfaceTexture surfaceTexture) {
            // Invoked every time there's a new Camera preview frame
        }
    };

    /**
     * A listener for scrolling changes in the seekbar. The anchor point of the folding
     * view is updated every time the seekbar stops tracking touch events. Every time the
     * anchor point is updated, the folding view is restored to a default unfolded state.
     */
    private SeekBar.OnSeekBarChangeListener mSeekBarChangeListener = new SeekBar
            .OnSeekBarChangeListener() {
        @Override
        public void onProgressChanged(SeekBar seekBar, int i, boolean b) {
        }

        @Override
        public void onStartTrackingTouch(SeekBar seekBar) {
        }

        @Override
        public void onStopTrackingTouch(SeekBar seekBar) {
            mTranslation = 0;
            mAnchorFactor = ((float)mAnchorSeekBar.getProgress())/100.0f;
            mFoldLayout.setAnchorFactor(mAnchorFactor);
        }
    };

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        if (IS_JBMR2) {
            getMenuInflater().inflate(R.menu.fold_with_bug, menu);
        } else {
            getMenuInflater().inflate(R.menu.fold, menu);
        }
        Spinner s = (Spinner) menu.findItem(R.id.num_of_folds).getActionView();
        s.setOnItemSelectedListener(mItemSelectedListener);
        return true;
    }

    @Override
    public void onWindowFocusChanged (boolean hasFocus) {
        super.onWindowFocusChanged(hasFocus);

        int[] loc = new int[2];
        mFoldLayout.getLocationOnScreen(loc);
        mParentPositionY = loc[1];
    }

    @Override
    public boolean onTouchEvent(MotionEvent me) {
        return mScrollGestureDetector.onTouchEvent(me);
    }

    @Override
    public boolean onOptionsItemSelected (MenuItem item) {
        switch(item.getItemId()) {
            case R.id.animate_fold:
                animateFold();
                break;
            case R.id.toggle_orientation:
                mOrientation = (mOrientation == Orientation.HORIZONTAL) ? Orientation.VERTICAL :
                        Orientation.HORIZONTAL;
                item.setTitle((mOrientation == Orientation.HORIZONTAL) ? R.string.vertical :
                R.string.horizontal);
                mTranslation = 0;
                mFoldLayout.setOrientation(mOrientation);
                break;
            case R.id.camera_feed:
                mIsCameraFeed = !mIsCameraFeed;
                item.setTitle(mIsCameraFeed ? R.string.static_image : R.string.camera_feed);
                item.setChecked(mIsCameraFeed);
                if (mIsCameraFeed) {
                    mFoldLayout.removeView(mImageView);
                    mFoldLayout.addView(mTextureView, new ViewGroup.LayoutParams(
                            mFoldLayout.getWidth(), mFoldLayout.getHeight()));
                } else {
                    mFoldLayout.removeView(mTextureView);
                    mFoldLayout.addView(mImageView, new ViewGroup.LayoutParams(
                            mFoldLayout.getWidth(), mFoldLayout.getHeight()));
                }
                mTranslation = 0;
                break;
            case R.id.sepia:
                mIsSepiaOn = !mIsSepiaOn;
                item.setChecked(!mIsSepiaOn);
                if (mIsSepiaOn && mFoldLayout.getFoldFactor() != 0) {
                    setSepiaLayer(mFoldLayout.getChildAt(0), true);
                } else {
                    setSepiaLayer(mFoldLayout.getChildAt(0), false);
                }
                break;
            default:
               break;

        }
        return super.onOptionsItemSelected(item);
    }

    /**
     * Animates the folding view inwards (to a completely folded state) from its
     * current state and then back out to its original state.
     */
    public void animateFold ()
    {
        float foldFactor = mFoldLayout.getFoldFactor();

        ObjectAnimator animator = ObjectAnimator.ofFloat(mFoldLayout, "foldFactor", foldFactor, 1);
        animator.setRepeatMode(ValueAnimator.REVERSE);
        animator.setRepeatCount(1);
        animator.setDuration(FOLD_ANIMATION_DURATION);
        animator.setInterpolator(new AccelerateInterpolator());
        animator.start();
    }

    /**
     * Listens for selection events of the spinner located on the action bar. Every
     * time a new value is selected, the number of folds in the folding view is updated
     * and is also restored to a default unfolded state.
     */
    private class ItemSelectedListener implements OnItemSelectedListener {
        @Override
        public void onItemSelected(AdapterView<?> parent, View view, int pos, long id) {
            mNumberOfFolds = Integer.parseInt(parent.getItemAtPosition(pos).toString());
            if (mDidLoadSpinner) {
                mDidLoadSpinner = false;
            } else {
                mTranslation = 0;
                mFoldLayout.setNumberOfFolds(mNumberOfFolds);
            }
        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
        }
    }

    /** This class uses user touch events to fold and unfold the folding view. */
    private class ScrollGestureDetector extends GestureDetector.SimpleOnGestureListener {
        @Override
        public boolean onDown (MotionEvent e) {
            mDidNotStartScroll = true;
            return true;
        }

        /**
         * All the logic here is used to determine by what factor the paper view should
         * be folded in response to the user's touch events. The logic here uses vertical
         * scrolling to fold a vertically oriented view and horizontal scrolling to fold
         * a horizontally oriented fold. Depending on where the anchor point of the fold is,
         * movements towards or away from the anchor point will either fold or unfold
         * the paper respectively.
         *
         * The translation logic here also accounts for the touch slop when a new user touch
         * begins, but before a scroll event is first invoked.
         */
        @Override
        public boolean onScroll(MotionEvent e1, MotionEvent e2, float distanceX, float distanceY) {
            int touchSlop = 0;
            float factor;
            if (mOrientation == Orientation.VERTICAL) {
                factor = Math.abs((float)(mTranslation) / (float)(mFoldLayout.getHeight()));

                if (e2.getY() - mParentPositionY <= mFoldLayout.getHeight()
                        && e2.getY() - mParentPositionY >= 0) {
                    if ((e2.getY() - mParentPositionY) > mFoldLayout.getHeight() * mAnchorFactor) {
                        mTranslation -= (int)distanceY;
                        touchSlop = distanceY < 0 ? -mTouchSlop : mTouchSlop;
                    } else {
                        mTranslation += (int)distanceY;
                        touchSlop = distanceY < 0 ? mTouchSlop : -mTouchSlop;
                    }
                    mTranslation = mDidNotStartScroll ? mTranslation + touchSlop : mTranslation;

                    if (mTranslation < -mFoldLayout.getHeight()) {
                        mTranslation = -mFoldLayout.getHeight();
                    }
                }
            } else {
                factor = Math.abs(((float)mTranslation) / ((float) mFoldLayout.getWidth()));

                if (e2.getRawX() > mFoldLayout.getWidth() * mAnchorFactor) {
                    mTranslation -= (int)distanceX;
                    touchSlop = distanceX < 0 ? -mTouchSlop : mTouchSlop;
                } else {
                    mTranslation += (int)distanceX;
                    touchSlop = distanceX < 0 ? mTouchSlop : -mTouchSlop;
                }
                mTranslation = mDidNotStartScroll ? mTranslation + touchSlop : mTranslation;

                if (mTranslation < -mFoldLayout.getWidth()) {
                    mTranslation = -mFoldLayout.getWidth();
                }
            }

            mDidNotStartScroll = false;

            if (mTranslation > 0) {
                mTranslation = 0;
            }

            mFoldLayout.setFoldFactor(factor);

            return true;
        }
    }
}