图片收缩

在使用一款手机软件时，难免会用到图片的放大或缩小，以下博客就是跟大家简单介绍一下怎么设置图片的放缩

在这里我们主要用到的写好的一个工具类

首先布局文件简单

<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" >    <com.example.pic.TouchImageView        android:id="@+id/image"        android:layout_width="200dp"        android:layout_height="200dp"        android:src="@drawable/ic_launcher" /></RelativeLayout>

主界面代码

package com.example.pic;import android.app.Activity;import android.os.Bundle;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.widget.ImageView;public class MainActivity extends Activity {    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        TouchImageView image = (TouchImageView) findViewById(R.id.image);//      image.setImageBitmap(bm)    }}

下面这个就是所引用的TouchImageView

/* * TouchImageView.java * By: Michael Ortiz * Updated By: Patrick Lackemacher * Updated By: Babay88 * Updated By: @ipsilondev * Updated By: hank-cp * Updated By: singpolyma * ------------------- * Extends Android ImageView to include pinch zooming, panning, fling and double tap zoom. */package com.example.pic;import android.annotation.TargetApi;import android.content.Context;import android.content.res.Configuration;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Matrix;import android.graphics.PointF;import android.graphics.RectF;import android.graphics.drawable.Drawable;import android.net.Uri;import android.os.Build;import android.os.Build.VERSION;import android.os.Build.VERSION_CODES;import android.os.Bundle;import android.os.Parcelable;import android.util.AttributeSet;import android.util.Log;import android.view.GestureDetector;import android.view.MotionEvent;import android.view.ScaleGestureDetector;import android.view.View;import android.view.animation.AccelerateDecelerateInterpolator;import android.widget.ImageView;import android.widget.OverScroller;import android.widget.Scroller;public class TouchImageView extends ImageView {    private static final String DEBUG = "DEBUG";    //    // SuperMin and SuperMax multipliers. Determine how much the image can be    // zoomed below or above the zoom boundaries, before animating back to the    // min/max zoom boundary.    //    private static final float SUPER_MIN_MULTIPLIER = .75f;    private static final float SUPER_MAX_MULTIPLIER = 1.25f;    //    // Scale of image ranges from minScale to maxScale, where minScale == 1    // when the image is stretched to fit view.    //    private float normalizedScale;    //    // Matrix applied to image. MSCALE_X and MSCALE_Y should always be equal.    // MTRANS_X and MTRANS_Y are the other values used. prevMatrix is the matrix    // saved prior to the screen rotating.    //    private Matrix matrix, prevMatrix;    private static enum State {        NONE, DRAG, ZOOM, FLING, ANIMATE_ZOOM    };    private State state;    private float minScale;    private float maxScale;    private float superMinScale;    private float superMaxScale;    private float[] m;    private Context context;    private Fling fling;    private ScaleType mScaleType;    private boolean imageRenderedAtLeastOnce;    private boolean onDrawReady;    private ZoomVariables delayedZoomVariables;    //    // Size of view and previous view size (ie before rotation)    //    private int viewWidth, viewHeight, prevViewWidth, prevViewHeight;    //    // Size of image when it is stretched to fit view. Before and After    // rotation.    //    private float matchViewWidth, matchViewHeight, prevMatchViewWidth,            prevMatchViewHeight;    private ScaleGestureDetector mScaleDetector;    private GestureDetector mGestureDetector;    private GestureDetector.OnDoubleTapListener doubleTapListener = null;    private OnTouchListener userTouchListener = null;    private OnTouchImageViewListener touchImageViewListener = null;    public TouchImageView(Context context) {        super(context);        sharedConstructing(context);    }    public TouchImageView(Context context, AttributeSet attrs) {        super(context, attrs);        sharedConstructing(context);    }    public TouchImageView(Context context, AttributeSet attrs, int defStyle) {        super(context, attrs, defStyle);        sharedConstructing(context);    }    private void sharedConstructing(Context context) {        super.setClickable(true);        this.context = context;        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());        mGestureDetector = new GestureDetector(context, new GestureListener());        matrix = new Matrix();        prevMatrix = new Matrix();        m = new float[9];        normalizedScale = 1;        if (mScaleType == null) {            mScaleType = ScaleType.FIT_CENTER;        }        minScale = 1;        maxScale = 3;        superMinScale = SUPER_MIN_MULTIPLIER * minScale;        superMaxScale = SUPER_MAX_MULTIPLIER * maxScale;        setImageMatrix(matrix);        setScaleType(ScaleType.MATRIX);        setState(State.NONE);        onDrawReady = false;        super.setOnTouchListener(new PrivateOnTouchListener());    }    @Override    public void setOnTouchListener(View.OnTouchListener l) {        userTouchListener = l;    }    public void setOnTouchImageViewListener(OnTouchImageViewListener l) {        touchImageViewListener = l;    }    public void setOnDoubleTapListener(GestureDetector.OnDoubleTapListener l) {        doubleTapListener = l;    }    @Override    public void setImageResource(int resId) {        super.setImageResource(resId);        savePreviousImageValues();        fitImageToView();    }    @Override    public void setImageBitmap(Bitmap bm) {        super.setImageBitmap(bm);        savePreviousImageValues();        fitImageToView();    }    @Override    public void setImageDrawable(Drawable drawable) {        super.setImageDrawable(drawable);        savePreviousImageValues();        fitImageToView();    }    @Override    public void setImageURI(Uri uri) {        super.setImageURI(uri);        savePreviousImageValues();        fitImageToView();    }    @Override    public void setScaleType(ScaleType type) {        if (type == ScaleType.FIT_START || type == ScaleType.FIT_END) {            throw new UnsupportedOperationException(                    "TouchImageView does not support FIT_START or FIT_END");        }        if (type == ScaleType.MATRIX) {            super.setScaleType(ScaleType.MATRIX);        } else {            mScaleType = type;            if (onDrawReady) {                //                // If the image is already rendered, scaleType has been called                // programmatically                // and the TouchImageView should be updated with the new                // scaleType.                //                setZoom(this);            }        }    }    @Override    public ScaleType getScaleType() {        return mScaleType;    }    /**     * Returns false if image is in initial, unzoomed state. False, otherwise.     *      * @return true if image is zoomed     */    public boolean isZoomed() {        return normalizedScale != 1;    }    /**     * Return a Rect representing the zoomed image.     *      * @return rect representing zoomed image     */    public RectF getZoomedRect() {        if (mScaleType == ScaleType.FIT_XY) {            throw new UnsupportedOperationException(                    "getZoomedRect() not supported with FIT_XY");        }        PointF topLeft = transformCoordTouchToBitmap(0, 0, true);        PointF bottomRight = transformCoordTouchToBitmap(viewWidth, viewHeight,                true);        float w = getDrawable().getIntrinsicWidth();        float h = getDrawable().getIntrinsicHeight();        return new RectF(topLeft.x / w, topLeft.y / h, bottomRight.x / w,                bottomRight.y / h);    }    /**     * Save the current matrix and view dimensions in the prevMatrix and     * prevView variables.     */    private void savePreviousImageValues() {        if (matrix != null && viewHeight != 0 && viewWidth != 0) {            matrix.getValues(m);            prevMatrix.setValues(m);            prevMatchViewHeight = matchViewHeight;            prevMatchViewWidth = matchViewWidth;            prevViewHeight = viewHeight;            prevViewWidth = viewWidth;        }    }    @Override    public Parcelable onSaveInstanceState() {        Bundle bundle = new Bundle();        bundle.putParcelable("instanceState", super.onSaveInstanceState());        bundle.putFloat("saveScale", normalizedScale);        bundle.putFloat("matchViewHeight", matchViewHeight);        bundle.putFloat("matchViewWidth", matchViewWidth);        bundle.putInt("viewWidth", viewWidth);        bundle.putInt("viewHeight", viewHeight);        matrix.getValues(m);        bundle.putFloatArray("matrix", m);        bundle.putBoolean("imageRendered", imageRenderedAtLeastOnce);        return bundle;    }    @Override    public void onRestoreInstanceState(Parcelable state) {        if (state instanceof Bundle) {            Bundle bundle = (Bundle) state;            normalizedScale = bundle.getFloat("saveScale");            m = bundle.getFloatArray("matrix");            prevMatrix.setValues(m);            prevMatchViewHeight = bundle.getFloat("matchViewHeight");            prevMatchViewWidth = bundle.getFloat("matchViewWidth");            prevViewHeight = bundle.getInt("viewHeight");            prevViewWidth = bundle.getInt("viewWidth");            imageRenderedAtLeastOnce = bundle.getBoolean("imageRendered");            super.onRestoreInstanceState(bundle.getParcelable("instanceState"));            return;        }        super.onRestoreInstanceState(state);    }    @Override    protected void onDraw(Canvas canvas) {        onDrawReady = true;        imageRenderedAtLeastOnce = true;        if (delayedZoomVariables != null) {            setZoom(delayedZoomVariables.scale, delayedZoomVariables.focusX,                    delayedZoomVariables.focusY, delayedZoomVariables.scaleType);            delayedZoomVariables = null;        }        super.onDraw(canvas);    }    @Override    public void onConfigurationChanged(Configuration newConfig) {        super.onConfigurationChanged(newConfig);        savePreviousImageValues();    }    /**     * Get the max zoom multiplier.     *      * @return max zoom multiplier.     */    public float getMaxZoom() {        return maxScale;    }    /**     * Set the max zoom multiplier. Default value: 3.     *      * @param max     *            max zoom multiplier.     */    public void setMaxZoom(float max) {        maxScale = max;        superMaxScale = SUPER_MAX_MULTIPLIER * maxScale;    }    /**     * Get the min zoom multiplier.     *      * @return min zoom multiplier.     */    public float getMinZoom() {        return minScale;    }    /**     * Get the current zoom. This is the zoom relative to the initial scale, not     * the original resource.     *      * @return current zoom multiplier.     */    public float getCurrentZoom() {        return normalizedScale;    }    /**     * Set the min zoom multiplier. Default value: 1.     *      * @param min     *            min zoom multiplier.     */    public void setMinZoom(float min) {        minScale = min;        superMinScale = SUPER_MIN_MULTIPLIER * minScale;    }    /**     * Reset zoom and translation to initial state.     */    public void resetZoom() {        normalizedScale = 1;        fitImageToView();    }    /**     * Set zoom to the specified scale. Image will be centered by default.     *      * @param scale     */    public void setZoom(float scale) {        setZoom(scale, 0.5f, 0.5f);    }    /**     * Set zoom to the specified scale. Image will be centered around the point     * (focusX, focusY). These floats range from 0 to 1 and denote the focus     * point as a fraction from the left and top of the view. For example, the     * top left corner of the image would be (0, 0). And the bottom right corner     * would be (1, 1).     *      * @param scale     * @param focusX     * @param focusY     */    public void setZoom(float scale, float focusX, float focusY) {        setZoom(scale, focusX, focusY, mScaleType);    }    /**     * Set zoom to the specified scale. Image will be centered around the point     * (focusX, focusY). These floats range from 0 to 1 and denote the focus     * point as a fraction from the left and top of the view. For example, the     * top left corner of the image would be (0, 0). And the bottom right corner     * would be (1, 1).     *      * @param scale     * @param focusX     * @param focusY     * @param scaleType     */    public void setZoom(float scale, float focusX, float focusY,            ScaleType scaleType) {        //        // setZoom can be called before the image is on the screen, but at this        // point,        // image and view sizes have not yet been calculated in onMeasure. Thus,        // we should        // delay calling setZoom until the view has been measured.        //        if (!onDrawReady) {            delayedZoomVariables = new ZoomVariables(scale, focusX, focusY,                    scaleType);            return;        }        if (scaleType != mScaleType) {            setScaleType(scaleType);        }        resetZoom();        scaleImage(scale, viewWidth / 2, viewHeight / 2, true);        matrix.getValues(m);        m[Matrix.MTRANS_X] = -((focusX * getImageWidth()) - (viewWidth * 0.5f));        m[Matrix.MTRANS_Y] = -((focusY * getImageHeight()) - (viewHeight * 0.5f));        matrix.setValues(m);        fixTrans();        setImageMatrix(matrix);    }    /**     * Set zoom parameters equal to another TouchImageView. Including scale,     * position, and ScaleType.     *      * @param TouchImageView     */    public void setZoom(TouchImageView img) {        PointF center = img.getScrollPosition();        setZoom(img.getCurrentZoom(), center.x, center.y, img.getScaleType());    }    /**     * Return the point at the center of the zoomed image. The PointF     * coordinates range in value between 0 and 1 and the focus point is denoted     * as a fraction from the left and top of the view. For example, the top     * left corner of the image would be (0, 0). And the bottom right corner     * would be (1, 1).     *      * @return PointF representing the scroll position of the zoomed image.     */    public PointF getScrollPosition() {        Drawable drawable = getDrawable();        if (drawable == null) {            return null;        }        int drawableWidth = drawable.getIntrinsicWidth();        int drawableHeight = drawable.getIntrinsicHeight();        PointF point = transformCoordTouchToBitmap(viewWidth / 2,                viewHeight / 2, true);        point.x /= drawableWidth;        point.y /= drawableHeight;        return point;    }    /**     * Set the focus point of the zoomed image. The focus points are denoted as     * a fraction from the left and top of the view. The focus points can range     * in value between 0 and 1.     *      * @param focusX     * @param focusY     */    public void setScrollPosition(float focusX, float focusY) {        setZoom(normalizedScale, focusX, focusY);    }    /**     * Performs boundary checking and fixes the image matrix if it is out of     * bounds.     */    private void fixTrans() {        matrix.getValues(m);        float transX = m[Matrix.MTRANS_X];        float transY = m[Matrix.MTRANS_Y];        float fixTransX = getFixTrans(transX, viewWidth, getImageWidth());        float fixTransY = getFixTrans(transY, viewHeight, getImageHeight());        if (fixTransX != 0 || fixTransY != 0) {            matrix.postTranslate(fixTransX, fixTransY);        }    }    /**     * When transitioning from zooming from focus to zoom from center (or vice     * versa) the image can become unaligned within the view. This is apparent     * when zooming quickly. When the content size is less than the view size,     * the content will often be centered incorrectly within the view.     * fixScaleTrans first calls fixTrans() and then makes sure the image is     * centered correctly within the view.     */    private void fixScaleTrans() {        fixTrans();        matrix.getValues(m);        if (getImageWidth() < viewWidth) {            m[Matrix.MTRANS_X] = (viewWidth - getImageWidth()) / 2;        }        if (getImageHeight() < viewHeight) {            m[Matrix.MTRANS_Y] = (viewHeight - getImageHeight()) / 2;        }        matrix.setValues(m);    }    private float getFixTrans(float trans, float viewSize, float contentSize) {        float minTrans, maxTrans;        if (contentSize <= viewSize) {            minTrans = 0;            maxTrans = viewSize - contentSize;        } else {            minTrans = viewSize - contentSize;            maxTrans = 0;        }        if (trans < minTrans)            return -trans + minTrans;        if (trans > maxTrans)            return -trans + maxTrans;        return 0;    }    private float getFixDragTrans(float delta, float viewSize, float contentSize) {        if (contentSize <= viewSize) {            return 0;        }        return delta;    }    private float getImageWidth() {        return matchViewWidth * normalizedScale;    }    private float getImageHeight() {        return matchViewHeight * normalizedScale;    }    @Override    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {        Drawable drawable = getDrawable();        if (drawable == null || drawable.getIntrinsicWidth() == 0                || drawable.getIntrinsicHeight() == 0) {            setMeasuredDimension(0, 0);            return;        }        int drawableWidth = drawable.getIntrinsicWidth();        int drawableHeight = drawable.getIntrinsicHeight();        int widthSize = MeasureSpec.getSize(widthMeasureSpec);        int widthMode = MeasureSpec.getMode(widthMeasureSpec);        int heightSize = MeasureSpec.getSize(heightMeasureSpec);        int heightMode = MeasureSpec.getMode(heightMeasureSpec);        viewWidth = setViewSize(widthMode, widthSize, drawableWidth);        viewHeight = setViewSize(heightMode, heightSize, drawableHeight);        //        // Set view dimensions        //        setMeasuredDimension(viewWidth, viewHeight);        //        // Fit content within view        //        fitImageToView();    }    /**     * If the normalizedScale is equal to 1, then the image is made to fit the     * screen. Otherwise, it is made to fit the screen according to the     * dimensions of the previous image matrix. This allows the image to     * maintain its zoom after rotation.     */    private void fitImageToView() {        Drawable drawable = getDrawable();        if (drawable == null || drawable.getIntrinsicWidth() == 0                || drawable.getIntrinsicHeight() == 0) {            return;        }        if (matrix == null || prevMatrix == null) {            return;        }        int drawableWidth = drawable.getIntrinsicWidth();        int drawableHeight = drawable.getIntrinsicHeight();        //        // Scale image for view        //        float scaleX = (float) viewWidth / drawableWidth;        float scaleY = (float) viewHeight / drawableHeight;        switch (mScaleType) {        case CENTER:            scaleX = scaleY = 1;            break;        case CENTER_CROP:            scaleX = scaleY = Math.max(scaleX, scaleY);            break;        case CENTER_INSIDE:            scaleX = scaleY = Math.min(1, Math.min(scaleX, scaleY));        case FIT_CENTER:            scaleX = scaleY = Math.min(scaleX, scaleY);            break;        case FIT_XY:            break;        default:            //            // FIT_START and FIT_END not supported            //            throw new UnsupportedOperationException(                    "TouchImageView does not support FIT_START or FIT_END");        }        //        // Center the image        //        float redundantXSpace = viewWidth - (scaleX * drawableWidth);        float redundantYSpace = viewHeight - (scaleY * drawableHeight);        matchViewWidth = viewWidth - redundantXSpace;        matchViewHeight = viewHeight - redundantYSpace;        if (!isZoomed() && !imageRenderedAtLeastOnce) {            //            // Stretch and center image to fit view            //            matrix.setScale(scaleX, scaleY);            matrix.postTranslate(redundantXSpace / 2, redundantYSpace / 2);            normalizedScale = 1;        } else {            //            // These values should never be 0 or we will set viewWidth and            // viewHeight            // to NaN in translateMatrixAfterRotate. To avoid this, call            // savePreviousImageValues            // to set them equal to the current values.            //            if (prevMatchViewWidth == 0 || prevMatchViewHeight == 0) {                savePreviousImageValues();            }            prevMatrix.getValues(m);            //            // Rescale Matrix after rotation            //            m[Matrix.MSCALE_X] = matchViewWidth / drawableWidth                    * normalizedScale;            m[Matrix.MSCALE_Y] = matchViewHeight / drawableHeight                    * normalizedScale;            //            // TransX and TransY from previous matrix            //            float transX = m[Matrix.MTRANS_X];            float transY = m[Matrix.MTRANS_Y];            //            // Width            //            float prevActualWidth = prevMatchViewWidth * normalizedScale;            float actualWidth = getImageWidth();            translateMatrixAfterRotate(Matrix.MTRANS_X, transX,                    prevActualWidth, actualWidth, prevViewWidth, viewWidth,                    drawableWidth);            //            // Height            //            float prevActualHeight = prevMatchViewHeight * normalizedScale;            float actualHeight = getImageHeight();            translateMatrixAfterRotate(Matrix.MTRANS_Y, transY,                    prevActualHeight, actualHeight, prevViewHeight, viewHeight,                    drawableHeight);            //            // Set the matrix to the adjusted scale and translate values.            //            matrix.setValues(m);        }        fixTrans();        setImageMatrix(matrix);    }    /**     * Set view dimensions based on layout params     *      * @param mode     * @param size     * @param drawableWidth     * @return     */    private int setViewSize(int mode, int size, int drawableWidth) {        int viewSize;        switch (mode) {        case MeasureSpec.EXACTLY:            viewSize = size;            break;        case MeasureSpec.AT_MOST:            viewSize = Math.min(drawableWidth, size);            break;        case MeasureSpec.UNSPECIFIED:            viewSize = drawableWidth;            break;        default:            viewSize = size;            break;        }        return viewSize;    }    /**     * After rotating, the matrix needs to be translated. This function finds     * the area of image which was previously centered and adjusts translations     * so that is again the center, post-rotation.     *      * @param axis     *            Matrix.MTRANS_X or Matrix.MTRANS_Y     * @param trans     *            the value of trans in that axis before the rotation     * @param prevImageSize     *            the width/height of the image before the rotation     * @param imageSize     *            width/height of the image after rotation     * @param prevViewSize     *            width/height of view before rotation     * @param viewSize     *            width/height of view after rotation     * @param drawableSize     *            width/height of drawable     */    private void translateMatrixAfterRotate(int axis, float trans,            float prevImageSize, float imageSize, int prevViewSize,            int viewSize, int drawableSize) {        if (imageSize < viewSize) {            //            // The width/height of image is less than the view's width/height.            // Center it.            //            m[axis] = (viewSize - (drawableSize * m[Matrix.MSCALE_X])) * 0.5f;        } else if (trans > 0) {            //            // The image is larger than the view, but was not before rotation.            // Center it.            //            m[axis] = -((imageSize - viewSize) * 0.5f);        } else {            //            // Find the area of the image which was previously centered in the            // view. Determine its distance            // from the left/top side of the view as a fraction of the entire            // image's width/height. Use that percentage            // to calculate the trans in the new view width/height.            //            float percentage = (Math.abs(trans) + (0.5f * prevViewSize))                    / prevImageSize;            m[axis] = -((percentage * imageSize) - (viewSize * 0.5f));        }    }    private void setState(State state) {        this.state = state;    }    public boolean canScrollHorizontallyFroyo(int direction) {        return canScrollHorizontally(direction);    }    @Override    public boolean canScrollHorizontally(int direction) {        matrix.getValues(m);        float x = m[Matrix.MTRANS_X];        if (getImageWidth() < viewWidth) {            return false;        } else if (x >= -1 && direction < 0) {            return false;        } else if (Math.abs(x) + viewWidth + 1 >= getImageWidth()                && direction > 0) {            return false;        }        return true;    }    /**     * Gesture Listener detects a single click or long click and passes that on     * to the view's listener.     *      * @author Ortiz     *      */    private class GestureListener extends            GestureDetector.SimpleOnGestureListener {        @Override        public boolean onSingleTapConfirmed(MotionEvent e) {            if (doubleTapListener != null) {                return doubleTapListener.onSingleTapConfirmed(e);            }            return performClick();        }        @Override        public void onLongPress(MotionEvent e) {            performLongClick();        }        @Override        public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,                float velocityY) {            if (fling != null) {                //                // If a previous fling is still active, it should be cancelled                // so that two flings                // are not run simultaenously.                //                fling.cancelFling();            }            fling = new Fling((int) velocityX, (int) velocityY);            compatPostOnAnimation(fling);            return super.onFling(e1, e2, velocityX, velocityY);        }        @Override        public boolean onDoubleTap(MotionEvent e) {            boolean consumed = false;            if (doubleTapListener != null) {                consumed = doubleTapListener.onDoubleTap(e);            }            if (state == State.NONE) {                float targetZoom = (normalizedScale == minScale) ? maxScale                        : minScale;                DoubleTapZoom doubleTap = new DoubleTapZoom(targetZoom,                        e.getX(), e.getY(), false);                compatPostOnAnimation(doubleTap);                consumed = true;            }            return consumed;        }        @Override        public boolean onDoubleTapEvent(MotionEvent e) {            if (doubleTapListener != null) {                return doubleTapListener.onDoubleTapEvent(e);            }            return false;        }    }    public interface OnTouchImageViewListener {        public void onMove();    }    /**     * Responsible for all touch events. Handles the heavy lifting of drag and     * also sends touch events to Scale Detector and Gesture Detector.     *      * @author Ortiz     *      */    private class PrivateOnTouchListener implements OnTouchListener {        //        // Remember last point position for dragging        //        private PointF last = new PointF();        @Override        public boolean onTouch(View v, MotionEvent event) {            mScaleDetector.onTouchEvent(event);            mGestureDetector.onTouchEvent(event);            PointF curr = new PointF(event.getX(), event.getY());            if (state == State.NONE || state == State.DRAG                    || state == State.FLING) {                switch (event.getAction()) {                case MotionEvent.ACTION_DOWN:                    last.set(curr);                    if (fling != null)                        fling.cancelFling();                    setState(State.DRAG);                    break;                case MotionEvent.ACTION_MOVE:                    if (state == State.DRAG) {                        float deltaX = curr.x - last.x;                        float deltaY = curr.y - last.y;                        float fixTransX = getFixDragTrans(deltaX, viewWidth,                                getImageWidth());                        float fixTransY = getFixDragTrans(deltaY, viewHeight,                                getImageHeight());                        matrix.postTranslate(fixTransX, fixTransY);                        fixTrans();                        last.set(curr.x, curr.y);                    }                    break;                case MotionEvent.ACTION_UP:                case MotionEvent.ACTION_POINTER_UP:                    setState(State.NONE);                    break;                }            }            setImageMatrix(matrix);            //            // User-defined OnTouchListener            //            if (userTouchListener != null) {                userTouchListener.onTouch(v, event);            }            //            // OnTouchImageViewListener is set: TouchImageView dragged by user.            //            if (touchImageViewListener != null) {                touchImageViewListener.onMove();            }            //            // indicate event was handled            //            return true;        }    }    /**     * ScaleListener detects user two finger scaling and scales image.     *      * @author Ortiz     *      */    private class ScaleListener extends            ScaleGestureDetector.SimpleOnScaleGestureListener {        @Override        public boolean onScaleBegin(ScaleGestureDetector detector) {            setState(State.ZOOM);            return true;        }        @Override        public boolean onScale(ScaleGestureDetector detector) {            scaleImage(detector.getScaleFactor(), detector.getFocusX(),                    detector.getFocusY(), true);            //            // OnTouchImageViewListener is set: TouchImageView pinch zoomed by            // user.            //            if (touchImageViewListener != null) {                touchImageViewListener.onMove();            }            return true;        }        @Override        public void onScaleEnd(ScaleGestureDetector detector) {            super.onScaleEnd(detector);            setState(State.NONE);            boolean animateToZoomBoundary = false;            float targetZoom = normalizedScale;            if (normalizedScale > maxScale) {                targetZoom = maxScale;                animateToZoomBoundary = true;            } else if (normalizedScale < minScale) {                targetZoom = minScale;                animateToZoomBoundary = true;            }            if (animateToZoomBoundary) {                DoubleTapZoom doubleTap = new DoubleTapZoom(targetZoom,                        viewWidth / 2, viewHeight / 2, true);                compatPostOnAnimation(doubleTap);            }        }    }    private void scaleImage(double deltaScale, float focusX, float focusY,            boolean stretchImageToSuper) {        float lowerScale, upperScale;        if (stretchImageToSuper) {            lowerScale = superMinScale;            upperScale = superMaxScale;        } else {            lowerScale = minScale;            upperScale = maxScale;        }        float origScale = normalizedScale;        normalizedScale *= deltaScale;        if (normalizedScale > upperScale) {            normalizedScale = upperScale;            deltaScale = upperScale / origScale;        } else if (normalizedScale < lowerScale) {            normalizedScale = lowerScale;            deltaScale = lowerScale / origScale;        }        matrix.postScale((float) deltaScale, (float) deltaScale, focusX, focusY);        fixScaleTrans();    }    /**     * DoubleTapZoom calls a series of runnables which apply an animated zoom     * in/out graphic to the image.     *      * @author Ortiz     *      */    private class DoubleTapZoom implements Runnable {        private long startTime;        private static final float ZOOM_TIME = 300;        private float startZoom, targetZoom;        private float bitmapX, bitmapY;        private boolean stretchImageToSuper;        private AccelerateDecelerateInterpolator interpolator = new AccelerateDecelerateInterpolator();        private PointF startTouch;        private PointF endTouch;        DoubleTapZoom(float targetZoom, float focusX, float focusY,                boolean stretchImageToSuper) {            setState(State.ANIMATE_ZOOM);            startTime = System.currentTimeMillis();            this.startZoom = normalizedScale;            this.targetZoom = targetZoom;            this.stretchImageToSuper = stretchImageToSuper;            PointF bitmapPoint = transformCoordTouchToBitmap(focusX, focusY,                    false);            this.bitmapX = bitmapPoint.x;            this.bitmapY = bitmapPoint.y;            //            // Used for translating image during scaling            //            startTouch = transformCoordBitmapToTouch(bitmapX, bitmapY);            endTouch = new PointF(viewWidth / 2, viewHeight / 2);        }        @Override        public void run() {            float t = interpolate();            double deltaScale = calculateDeltaScale(t);            scaleImage(deltaScale, bitmapX, bitmapY, stretchImageToSuper);            translateImageToCenterTouchPosition(t);            fixScaleTrans();            setImageMatrix(matrix);            //            // OnTouchImageViewListener is set: double tap runnable updates            // listener            // with every frame.            //            if (touchImageViewListener != null) {                touchImageViewListener.onMove();            }            if (t < 1f) {                //                // We haven't finished zooming                //                compatPostOnAnimation(this);            } else {                //                // Finished zooming                //                setState(State.NONE);            }        }        /**         * Interpolate between where the image should start and end in order to         * translate the image so that the point that is touched is what ends up         * centered at the end of the zoom.         *          * @param t         */        private void translateImageToCenterTouchPosition(float t) {            float targetX = startTouch.x + t * (endTouch.x - startTouch.x);            float targetY = startTouch.y + t * (endTouch.y - startTouch.y);            PointF curr = transformCoordBitmapToTouch(bitmapX, bitmapY);            matrix.postTranslate(targetX - curr.x, targetY - curr.y);        }        /**         * Use interpolator to get t         *          * @return         */        private float interpolate() {            long currTime = System.currentTimeMillis();            float elapsed = (currTime - startTime) / ZOOM_TIME;            elapsed = Math.min(1f, elapsed);            return interpolator.getInterpolation(elapsed);        }        /**         * Interpolate the current targeted zoom and get the delta from the         * current zoom.         *          * @param t         * @return         */        private double calculateDeltaScale(float t) {            double zoom = startZoom + t * (targetZoom - startZoom);            return zoom / normalizedScale;        }    }    /**     * This function will transform the coordinates in the touch event to the     * coordinate system of the drawable that the imageview contain     *      * @param x     *            x-coordinate of touch event     * @param y     *            y-coordinate of touch event     * @param clipToBitmap     *            Touch event may occur within view, but outside image content.     *            True, to clip return value to the bounds of the bitmap size.     * @return Coordinates of the point touched, in the coordinate system of the     *         original drawable.     */    private PointF transformCoordTouchToBitmap(float x, float y,            boolean clipToBitmap) {        matrix.getValues(m);        float origW = getDrawable().getIntrinsicWidth();        float origH = getDrawable().getIntrinsicHeight();        float transX = m[Matrix.MTRANS_X];        float transY = m[Matrix.MTRANS_Y];        float finalX = ((x - transX) * origW) / getImageWidth();        float finalY = ((y - transY) * origH) / getImageHeight();        if (clipToBitmap) {            finalX = Math.min(Math.max(finalX, 0), origW);            finalY = Math.min(Math.max(finalY, 0), origH);        }        return new PointF(finalX, finalY);    }    /**     * Inverse of transformCoordTouchToBitmap. This function will transform the     * coordinates in the drawable's coordinate system to the view's coordinate     * system.     *      * @param bx     *            x-coordinate in original bitmap coordinate system     * @param by     *            y-coordinate in original bitmap coordinate system     * @return Coordinates of the point in the view's coordinate system.     */    private PointF transformCoordBitmapToTouch(float bx, float by) {        matrix.getValues(m);        float origW = getDrawable().getIntrinsicWidth();        float origH = getDrawable().getIntrinsicHeight();        float px = bx / origW;        float py = by / origH;        float finalX = m[Matrix.MTRANS_X] + getImageWidth() * px;        float finalY = m[Matrix.MTRANS_Y] + getImageHeight() * py;        return new PointF(finalX, finalY);    }    /**     * Fling launches sequential runnables which apply the fling graphic to the     * image. The values for the translation are interpolated by the Scroller.     *      * @author Ortiz     *      */    private class Fling implements Runnable {        CompatScroller scroller;        int currX, currY;        Fling(int velocityX, int velocityY) {            setState(State.FLING);            scroller = new CompatScroller(context);            matrix.getValues(m);            int startX = (int) m[Matrix.MTRANS_X];            int startY = (int) m[Matrix.MTRANS_Y];            int minX, maxX, minY, maxY;            if (getImageWidth() > viewWidth) {                minX = viewWidth - (int) getImageWidth();                maxX = 0;            } else {                minX = maxX = startX;            }            if (getImageHeight() > viewHeight) {                minY = viewHeight - (int) getImageHeight();                maxY = 0;            } else {                minY = maxY = startY;            }            scroller.fling(startX, startY, (int) velocityX, (int) velocityY,                    minX, maxX, minY, maxY);            currX = startX;            currY = startY;        }        public void cancelFling() {            if (scroller != null) {                setState(State.NONE);                scroller.forceFinished(true);            }        }        @Override        public void run() {            //            // OnTouchImageViewListener is set: TouchImageView listener has been            // flung by user.            // Listener runnable updated with each frame of fling animation.            //            if (touchImageViewListener != null) {                touchImageViewListener.onMove();            }            if (scroller.isFinished()) {                scroller = null;                return;            }            if (scroller.computeScrollOffset()) {                int newX = scroller.getCurrX();                int newY = scroller.getCurrY();                int transX = newX - currX;                int transY = newY - currY;                currX = newX;                currY = newY;                matrix.postTranslate(transX, transY);                fixTrans();                setImageMatrix(matrix);                compatPostOnAnimation(this);            }        }    }    @TargetApi(Build.VERSION_CODES.GINGERBREAD)    private class CompatScroller {        Scroller scroller;        OverScroller overScroller;        boolean isPreGingerbread;        public CompatScroller(Context context) {            if (VERSION.SDK_INT < VERSION_CODES.GINGERBREAD) {                isPreGingerbread = true;                scroller = new Scroller(context);            } else {                isPreGingerbread = false;                overScroller = new OverScroller(context);            }        }        public void fling(int startX, int startY, int velocityX, int velocityY,                int minX, int maxX, int minY, int maxY) {            if (isPreGingerbread) {                scroller.fling(startX, startY, velocityX, velocityY, minX,                        maxX, minY, maxY);            } else {                overScroller.fling(startX, startY, velocityX, velocityY, minX,                        maxX, minY, maxY);            }        }        public void forceFinished(boolean finished) {            if (isPreGingerbread) {                scroller.forceFinished(finished);            } else {                overScroller.forceFinished(finished);            }        }        public boolean isFinished() {            if (isPreGingerbread) {                return scroller.isFinished();            } else {                return overScroller.isFinished();            }        }        public boolean computeScrollOffset() {            if (isPreGingerbread) {                return scroller.computeScrollOffset();            } else {                overScroller.computeScrollOffset();                return overScroller.computeScrollOffset();            }        }        public int getCurrX() {            if (isPreGingerbread) {                return scroller.getCurrX();            } else {                return overScroller.getCurrX();            }        }        public int getCurrY() {            if (isPreGingerbread) {                return scroller.getCurrY();            } else {                return overScroller.getCurrY();            }        }    }    @TargetApi(Build.VERSION_CODES.JELLY_BEAN)    private void compatPostOnAnimation(Runnable runnable) {        if (VERSION.SDK_INT >= VERSION_CODES.JELLY_BEAN) {            postOnAnimation(runnable);        } else {            postDelayed(runnable, 1000 / 60);        }    }    private class ZoomVariables {        public float scale;        public float focusX;        public float focusY;        public ScaleType scaleType;        public ZoomVariables(float scale, float focusX, float focusY,                ScaleType scaleType) {            this.scale = scale;            this.focusX = focusX;            this.focusY = focusY;            this.scaleType = scaleType;        }    }    private void printMatrixInfo() {        float[] n = new float[9];        matrix.getValues(n);        Log.d(DEBUG, "Scale: " + n[Matrix.MSCALE_X] + " TransX: "                + n[Matrix.MTRANS_X] + " TransY: " + n[Matrix.MTRANS_Y]);    }}

以上就是一个简单的图片缩放的功能，具体怎么缩放，我们可以自己修改工具类的方法！