src/com/android/camera/ImageViewTouchBase.java

package com.android.camera;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.drawable.Drawable;
import android.os.Handler;
import android.os.SystemClock;
import android.util.AttributeSet;
import android.util.Config;
import android.util.Log;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.view.KeyEvent;
import android.widget.ImageView;

abstract public class ImageViewTouchBase extends ImageView {
    private static final String TAG = "ImageViewTouchBase";
    
    // if we're animating these images, it may be faster to cache the image
    // at its target size first. to do this set this variable to true.
    // currently we're not animating images, so we don't need to do this
    // extra work.
    private final boolean USE_PERFECT_FIT_OPTIMIZATION = false;
    
    // This is the base transformation which is used to show the image
    // initially.  The current computation for this shows the image in
    // it's entirety, letterboxing as needed.  One could chose to
    // show the image as cropped instead.  
    //
    // This matrix is recomputed when we go from the thumbnail image to
    // the full size image.
    protected Matrix mBaseMatrix = new Matrix();

    // This is the supplementary transformation which reflects what 
    // the user has done in terms of zooming and panning.
    //
    // This matrix remains the same when we go from the thumbnail image
    // to the full size image.
    protected Matrix mSuppMatrix = new Matrix();

    // This is the final matrix which is computed as the concatentation
    // of the base matrix and the supplementary matrix.
    private Matrix mDisplayMatrix = new Matrix();

    // Temporary buffer used for getting the values out of a matrix.
    private float[] mMatrixValues = new float[9];

    // The current bitmap being displayed.
    protected Bitmap mBitmapDisplayed;

    // The thumbnail bitmap.
    protected Bitmap mThumbBitmap;
    
    // The full size bitmap which should be used once we start zooming.
    private Bitmap mFullBitmap;

    // The bitmap which is exactly sized to what we need.  The decoded bitmap is
    // drawn into the mPerfectFitBitmap so that animation is faster.
    protected Bitmap mPerfectFitBitmap;

    // True if the image is the thumbnail.
    protected boolean mBitmapIsThumbnail;

    // True if the user is zooming -- use the full size image
    protected boolean mIsZooming;

    // Paint to use to clear the "mPerfectFitBitmap"
    protected Paint mPaint = new Paint();
    
    static boolean sNewZoomControl = false;
    
    int mThisWidth = -1, mThisHeight = -1;
    
    float mMaxZoom;
    
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        mThisWidth = right - left;
        mThisHeight = bottom - top;
        Runnable r = mOnLayoutRunnable;
        if (r != null) {
            mOnLayoutRunnable = null;
            r.run();
        }
        if (mBitmapDisplayed != null) {
            setBaseMatrix(mBitmapDisplayed, mBaseMatrix);
            setImageMatrix(getImageViewMatrix());
        }
    }

    @Override
    public boolean onKeyDown(int keyCode, KeyEvent event) {
        if (keyCode == KeyEvent.KEYCODE_BACK && getScale() > 1.0f) {
            // If we're zoomed in, pressing Back jumps out to show the entire image, otherwise Back
            // returns the user to the gallery.
            zoomTo(1.0f);
            return true;
        }
        return super.onKeyDown(keyCode, event);
    }

    protected Handler mHandler = new Handler();
    
    protected int mLastXTouchPos;
    protected int mLastYTouchPos;
    
    protected boolean doesScrolling() {
        return true;
    }

    // Translate a given point through a given matrix.
    static private void translatePoint(Matrix matrix, float [] xy) {
        matrix.mapPoints(xy);
    }

    // Return the mapped x coordinate through the matrix.
    static int mapXPoint(Matrix matrix, int point) {
        // Matrix's mapPoints takes an array of x/y coordinates.
        // That's why we have to allocte an array of length two
        // even though we don't use the y coordinate.
        float [] xy = new float[2];
        xy[0] = point;
        xy[1] = 0F;
        matrix.mapPoints(xy);
        return (int) xy[0];
    }
    
    @Override
    public void setImageBitmap(Bitmap bitmap) {
        throw new NullPointerException();
    }

    public void setImageBitmap(Bitmap bitmap, boolean isThumbnail) {
        super.setImageBitmap(bitmap);
        Drawable d = getDrawable();
        if (d != null) 
            d.setDither(true);
        mBitmapDisplayed = bitmap;
        mBitmapIsThumbnail = isThumbnail;
    }
    
    protected boolean usePerfectFitBitmap() {
        return USE_PERFECT_FIT_OPTIMIZATION && !mIsZooming;
    }
    
    public void recycleBitmaps() {
        if (mFullBitmap != null) {
            if (Config.LOGV)
                Log.v(TAG, "recycling mFullBitmap " + mFullBitmap + "; this == " + this.hashCode());
            mFullBitmap.recycle();
            mFullBitmap = null;
        }
        if (mThumbBitmap != null) {
            if (Config.LOGV)
                Log.v(TAG, "recycling mThumbBitmap" + mThumbBitmap + "; this == " + this.hashCode());
            mThumbBitmap.recycle();
            mThumbBitmap = null;
        }

        // mBitmapDisplayed is either mPerfectFitBitmap or mFullBitmap (in the case of zooming)
        setImageBitmap(null, true);
    }
    
    public void clear() {
        mBitmapDisplayed = null;
        recycleBitmaps();
    }
    
    private Runnable mOnLayoutRunnable = null;
    
    public void setImageBitmapResetBase(final Bitmap bitmap, final boolean resetSupp, final boolean isThumb) {
        if ((bitmap != null) && (bitmap == mPerfectFitBitmap)) {
            // TODO: this should be removed in production
            throw new IllegalArgumentException("bitmap must not be mPerfectFitBitmap");
        }

        final int viewWidth = getWidth();
        final int viewHeight = getHeight();

        if (viewWidth <= 0)  {
            mOnLayoutRunnable = new Runnable() {
                public void run() {
                    setImageBitmapResetBase(bitmap, resetSupp, isThumb);
                }
            };
            return;
        }
        
        if (isThumb && mThumbBitmap != bitmap) {
            if (mThumbBitmap != null) {
                mThumbBitmap.recycle();
            }
            mThumbBitmap = bitmap;
        } else if (!isThumb && mFullBitmap != bitmap) {
            if (mFullBitmap != null) {
                mFullBitmap.recycle();
            }
            mFullBitmap = bitmap;
        }
        mBitmapIsThumbnail = isThumb;
        
        if (bitmap != null) {
            if (!usePerfectFitBitmap()) {
                setScaleType(ImageView.ScaleType.MATRIX);
                setBaseMatrix(bitmap, mBaseMatrix);
                setImageBitmap(bitmap, isThumb);
            } else {
                Matrix matrix = new Matrix();
                setBaseMatrix(bitmap, matrix);
                if ((mPerfectFitBitmap == null) || 
                        mPerfectFitBitmap.getWidth() != mThisWidth || 
                        mPerfectFitBitmap.getHeight() != mThisHeight) {
                    if (mPerfectFitBitmap != null) {
                        if (Config.LOGV)
                            Log.v(TAG, "recycling mPerfectFitBitmap " + mPerfectFitBitmap.hashCode());
                        mPerfectFitBitmap.recycle();
                    }
                    mPerfectFitBitmap = Bitmap.createBitmap(mThisWidth, mThisHeight, Bitmap.Config.RGB_565);
                }
                Canvas canvas = new Canvas(mPerfectFitBitmap);
                // clear the bitmap which may be bigger than the image and
                // contain the the previous image.
                canvas.drawColor(0xFF000000);

                final int bw = bitmap.getWidth();
                final int bh = bitmap.getHeight();
                final float widthScale  = Math.min(viewWidth / (float)bw, 1.0f);
                final float heightScale = Math.min(viewHeight/ (float)bh, 1.0f);
                int translateX, translateY;
                if (widthScale > heightScale) {
                    translateX = (int)((viewWidth -(float)bw*heightScale)*0.5f);
                    translateY = (int)((viewHeight-(float)bh*heightScale)*0.5f);
                } else {
                    translateX = (int)((viewWidth -(float)bw*widthScale)*0.5f);
                    translateY = (int)((viewHeight-(float)bh*widthScale)*0.5f);
                }

                android.graphics.Rect src = new android.graphics.Rect(0, 0, bw, bh);
                android.graphics.Rect dst = new android.graphics.Rect(
                        translateX, translateY,  
                        mThisWidth - translateX, mThisHeight - translateY);
                canvas.drawBitmap(bitmap, src, dst, mPaint);
                
                setImageBitmap(mPerfectFitBitmap, isThumb);
                setScaleType(ImageView.ScaleType.MATRIX);
                setImageMatrix(null);
            }
        } else {
            mBaseMatrix.reset();
            setImageBitmap(null, isThumb);
        }

        if (resetSupp)
            mSuppMatrix.reset();
        setImageMatrix(getImageViewMatrix());
        mMaxZoom = maxZoom();
    }

    // Center as much as possible in one or both axis.  Centering is
    // defined as follows:  if the image is scaled down below the 
    // view's dimensions then center it (literally).  If the image
    // is scaled larger than the view and is translated out of view
    // then translate it back into view (i.e. eliminate black bars).
    protected void center(boolean vertical, boolean horizontal, boolean animate) {
        if (mBitmapDisplayed == null)
            return;

        Matrix m = getImageViewMatrix();

        float [] topLeft  = new float[] { 0, 0 };
        float [] botRight = new float[] { mBitmapDisplayed.getWidth(), mBitmapDisplayed.getHeight() };

        translatePoint(m, topLeft);
        translatePoint(m, botRight);

        float height = botRight[1] - topLeft[1];
        float width  = botRight[0] - topLeft[0];

        float deltaX = 0, deltaY = 0;

        if (vertical) {
            int viewHeight = getHeight();
            if (height < viewHeight) {
                deltaY = (viewHeight - height)/2 - topLeft[1];
            } else if (topLeft[1] > 0) {
                deltaY = -topLeft[1];
            } else if (botRight[1] < viewHeight) {
                deltaY = getHeight() - botRight[1];
            }
        }

        if (horizontal) {
            int viewWidth = getWidth();
            if (width < viewWidth) {
                deltaX = (viewWidth - width)/2 - topLeft[0];
            } else if (topLeft[0] > 0) {
                deltaX = -topLeft[0];
            } else if (botRight[0] < viewWidth) {
                deltaX = viewWidth - botRight[0];
            }
        }

        postTranslate(deltaX, deltaY);
        if (animate) {
            Animation a = new TranslateAnimation(-deltaX, 0, -deltaY, 0);
            a.setStartTime(SystemClock.elapsedRealtime());
            a.setDuration(250);
            setAnimation(a);
        }
        setImageMatrix(getImageViewMatrix());
    }

    public void copyFrom(ImageViewTouchBase other) {
        mSuppMatrix.set(other.mSuppMatrix);
        mBaseMatrix.set(other.mBaseMatrix);
        
        if (mThumbBitmap != null)
            mThumbBitmap.recycle();
        
        if (mFullBitmap != null) 
            mFullBitmap.recycle();
        
        // copy the data
        mThumbBitmap       = other.mThumbBitmap;
        mFullBitmap        = null;
        
        if (other.mFullBitmap != null)
            other.mFullBitmap.recycle();
        
        // transfer "ownership"
        other.mThumbBitmap = null;
        other.mFullBitmap  = null;
        other.mBitmapIsThumbnail = true;

        setImageMatrix(other.getImageMatrix());
        setScaleType(other.getScaleType());
        
        setImageBitmapResetBase(mThumbBitmap, true, true);
    }
    
    @Override 
    public void setImageDrawable(android.graphics.drawable.Drawable d) {
        super.setImageDrawable(d);
    }

    public ImageViewTouchBase(Context context) {
        super(context);
        init();
    }

    public ImageViewTouchBase(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        setScaleType(ImageView.ScaleType.MATRIX);
        mPaint.setDither(true);
        mPaint.setFilterBitmap(true);
    }

    protected float getValue(Matrix matrix, int whichValue) {
        matrix.getValues(mMatrixValues);
        return mMatrixValues[whichValue];
    }
    
    // Get the scale factor out of the matrix.
    protected float getScale(Matrix matrix) {
        return getValue(matrix, Matrix.MSCALE_X);
    }

    protected float getScale() {
        return getScale(mSuppMatrix);
    }
    
    protected float getTranslateX() {
        return getValue(mSuppMatrix, Matrix.MTRANS_X);
    }

    protected float getTranslateY() {
        return getValue(mSuppMatrix, Matrix.MTRANS_Y);
    }

    // Setup the base matrix so that the image is centered and scaled properly.
    private void setBaseMatrix(Bitmap bitmap, Matrix matrix) {
        float viewWidth = getWidth();
        float viewHeight = getHeight();

        matrix.reset();
        float widthScale = Math.min(viewWidth / (float)bitmap.getWidth(), 1.0f);
        float heightScale = Math.min(viewHeight / (float)bitmap.getHeight(), 1.0f);
        float scale;
        if (widthScale > heightScale) {
            scale = heightScale;
        } else {
            scale = widthScale;
        }
        matrix.setScale(scale, scale);
        matrix.postTranslate(
                (viewWidth  - ((float)bitmap.getWidth()  * scale))/2F, 
                (viewHeight - ((float)bitmap.getHeight() * scale))/2F);
    }
    
    // Combine the base matrix and the supp matrix to make the final matrix.
    protected Matrix getImageViewMatrix() {
        mDisplayMatrix.set(mBaseMatrix);
        mDisplayMatrix.postConcat(mSuppMatrix);
        return mDisplayMatrix;
    }

    private void onZoom() {
        mIsZooming = true;
        if (mFullBitmap != null && mFullBitmap != mBitmapDisplayed) {
            setImageBitmapResetBase(mFullBitmap, false, mBitmapIsThumbnail);
        }
    }
    
    private String describe(Bitmap b) {
        StringBuilder sb = new StringBuilder();
        if (b == null) {
            sb.append("NULL");
        } else if (b.isRecycled()) {
            sb.append(String.format("%08x: RECYCLED", b.hashCode()));
        } else {
            sb.append(String.format("%08x: LIVE", b.hashCode()));
            sb.append(String.format("%d x %d (size == %d)", b.getWidth(), b.getHeight(), b.getWidth()*b.getHeight()*2));
        }
        return sb.toString();
    }
    
    public void dump() {
        if (Config.LOGV) {
            Log.v(TAG, "dump ImageViewTouchBase " + this);
            Log.v(TAG, "... mBitmapDisplayed  = " + describe(mBitmapDisplayed));
            Log.v(TAG, "... mThumbBitmap      = " + describe(mThumbBitmap));
            Log.v(TAG, "... mFullBitmap       = " + describe(mFullBitmap));
            Log.v(TAG, "... mPerfectFitBitmap = " + describe(mPerfectFitBitmap));
            Log.v(TAG, "... mIsThumb          = " + mBitmapIsThumbnail);
        }
    }

    static final float sPanRate = 7;
    static final float sScaleRate = 1.05F;

    // Sets the maximum zoom, which is a scale relative to the base matrix. It is calculated to show
    // the image at 400% zoom regardless of screen or image orientation. If in the future we decode
    // the full 3 megapixel image, rather than the current 1024x768, this should be changed down to
    // 200%.
    protected float maxZoom() {
        if (mBitmapDisplayed == null)
            return 1F;
        
        float fw = (float) mBitmapDisplayed.getWidth()  / (float)mThisWidth;
        float fh = (float) mBitmapDisplayed.getHeight() / (float)mThisHeight;
        float max = Math.max(fw, fh) * 4;
//        Log.v(TAG, "Bitmap " + mBitmapDisplayed.getWidth() + "x" + mBitmapDisplayed.getHeight() +
//                " view " + mThisWidth + "x" + mThisHeight + " max zoom " + max);
        return max;
    }

    protected void zoomTo(float scale, float centerX, float centerY) {
        if (scale > mMaxZoom) {
            scale = mMaxZoom;
        }
        onZoom();
        
        float oldScale = getScale();
        float deltaScale = scale / oldScale;

        mSuppMatrix.postScale(deltaScale, deltaScale, centerX, centerY);
        setImageMatrix(getImageViewMatrix());
        center(true, true, false);
    }
    
    protected void zoomTo(final float scale, final float centerX, final float centerY, final float durationMs) {
        final float incrementPerMs = (scale - getScale()) / durationMs;
        final float oldScale = getScale();
        final long startTime = System.currentTimeMillis();
        
        mHandler.post(new Runnable() {
            public void run() {
                long now = System.currentTimeMillis();
                float currentMs = Math.min(durationMs, (float)(now - startTime));
                float target = oldScale + (incrementPerMs * currentMs);
                zoomTo(target, centerX, centerY);
                
                if (currentMs < durationMs) {
                    mHandler.post(this);
                }
            }
        }); 
    }

    protected void zoomTo(float scale) {
        float width = getWidth();
        float height = getHeight();
        
        zoomTo(scale, width/2F, height/2F);
    }
    
    protected void zoomIn() {
        zoomIn(sScaleRate);
    }
    
    protected void zoomOut() {
        zoomOut(sScaleRate);
    }

    protected void zoomIn(float rate) {
        if (getScale() >= mMaxZoom) {
            return;     // Don't let the user zoom into the molecular level.
        }
        if (mBitmapDisplayed == null) {
            return;
        }
        float width = getWidth();
        float height = getHeight();

        mSuppMatrix.postScale(rate, rate, width/2F, height/2F);
        setImageMatrix(getImageViewMatrix());

        onZoom();
    }

    protected void zoomOut(float rate) {
        if (mBitmapDisplayed == null) {
            return;
        }
        
        float width = getWidth();
        float height = getHeight();

        Matrix tmp = new Matrix(mSuppMatrix);
        tmp.postScale(1F/sScaleRate, 1F/sScaleRate, width/2F, height/2F);
        if (getScale(tmp) < 1F) {
            mSuppMatrix.setScale(1F, 1F, width/2F, height/2F);
        } else {
            mSuppMatrix.postScale(1F/rate, 1F/rate, width/2F, height/2F);
        }
        setImageMatrix(getImageViewMatrix());
        center(true, true, false);

        onZoom();
    }
    
    protected void postTranslate(float dx, float dy) {
        mSuppMatrix.postTranslate(dx, dy);
    }

    protected void panBy(float dx, float dy) {
        postTranslate(dx, dy);
        setImageMatrix(getImageViewMatrix());
    }
}