如何获得图像的缩放功能？

Question

是否有一种常见的方法来显示大图像并允许用户放大、缩小和平移图像？

到目前为止，我找到了两种方法：

1. 覆盖ImageView，对于这样一个常见问题来说，这似乎有点太多了。
2. 使用 webview 但对整体布局等的控制较少。

Answer 1

更新

我刚刚给了 TouchImageView 一个新的更新。除了平移和捏合缩放之外，它现在还包括双击缩放和滑动。下面的代码非常过时了。您可以查看github项目以获取最新代码。

用法

将 TouchImageView.java 放入您的项目中。然后可以像下面一样使用它
图像视图。示例：

TouchImageView img = (TouchImageView) findViewById(R.id.img);

如果您在 xml 中使用 TouchImageView，那么您必须提供完整的包
名称，因为它是自定义视图。示例：

<com.example.touch.TouchImageView
    android:id="@+id/img”
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

注意：我删除了之前的答案，其中包括一些非常旧的代码，现在直接链接到 github 上最新的代码。

ViewPager

如果您有兴趣将 TouchImageView 放入 ViewPager，请参阅此答案.

Answer 2

我修改了一些代码来创建支持多点触控（>2.1）的 TouchImageView。
它的灵感来自于你好，Android！ （第3版）

它包含在以下3个文件中
TouchImageView.java
WrapMotionEvent.java
EclairMotionEvent.java

TouchImageView.java

import se.robertfoss.ChanImageBrowser.Viewer;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.util.FloatMath;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

    private static final String TAG = "Touch";
    // These matrices will be used to move and zoom image
    Matrix matrix = new Matrix();
    Matrix savedMatrix = new Matrix();

    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // Remember some things for zooming
    PointF start = new PointF();
    PointF mid = new PointF();
    float oldDist = 1f;

    Context context;


    public TouchImageView(Context context) {
        super(context);
        super.setClickable(true);
        this.context = context;

        matrix.setTranslate(1f, 1f);
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);

        setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent rawEvent) {
                WrapMotionEvent event = WrapMotionEvent.wrap(rawEvent);

                // Dump touch event to log
                if (Viewer.isDebug == true){
                    dumpEvent(event);
                }

                // Handle touch events here...
                switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    savedMatrix.set(matrix);
                    start.set(event.getX(), event.getY());
                    Log.d(TAG, "mode=DRAG");
                    mode = DRAG;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    oldDist = spacing(event);
                    Log.d(TAG, "oldDist=" + oldDist);
                    if (oldDist > 10f) {
                        savedMatrix.set(matrix);
                        midPoint(mid, event);
                        mode = ZOOM;
                        Log.d(TAG, "mode=ZOOM");
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    int xDiff = (int) Math.abs(event.getX() - start.x);
                    int yDiff = (int) Math.abs(event.getY() - start.y);
                    if (xDiff < 8 && yDiff < 8){
                        performClick();
                    }
                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                    Log.d(TAG, "mode=NONE");
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        // ...
                        matrix.set(savedMatrix);
                        matrix.postTranslate(event.getX() - start.x, event.getY() - start.y);
                    } else if (mode == ZOOM) {
                        float newDist = spacing(event);
                        Log.d(TAG, "newDist=" + newDist);
                        if (newDist > 10f) {
                            matrix.set(savedMatrix);
                            float scale = newDist / oldDist;
                            matrix.postScale(scale, scale, mid.x, mid.y);
                        }
                    }
                    break;
                }

                setImageMatrix(matrix);
                return true; // indicate event was handled
            }

        });
    }


    public void setImage(Bitmap bm, int displayWidth, int displayHeight) { 
        super.setImageBitmap(bm);

        //Fit to screen.
        float scale;
        if ((displayHeight / bm.getHeight()) >= (displayWidth / bm.getWidth())){
            scale =  (float)displayWidth / (float)bm.getWidth();
        } else {
            scale = (float)displayHeight / (float)bm.getHeight();
        }

        savedMatrix.set(matrix);
        matrix.set(savedMatrix);
        matrix.postScale(scale, scale, mid.x, mid.y);
        setImageMatrix(matrix);


        // Center the image
        float redundantYSpace = (float)displayHeight - (scale * (float)bm.getHeight()) ;
        float redundantXSpace = (float)displayWidth - (scale * (float)bm.getWidth());

        redundantYSpace /= (float)2;
        redundantXSpace /= (float)2;


        savedMatrix.set(matrix);
        matrix.set(savedMatrix);
        matrix.postTranslate(redundantXSpace, redundantYSpace);
        setImageMatrix(matrix);
    }


    /** Show an event in the LogCat view, for debugging */
    private void dumpEvent(WrapMotionEvent event) {
        // ...
        String names[] = { "DOWN", "UP", "MOVE", "CANCEL", "OUTSIDE",
            "POINTER_DOWN", "POINTER_UP", "7?", "8?", "9?" };
        StringBuilder sb = new StringBuilder();
        int action = event.getAction();
        int actionCode = action & MotionEvent.ACTION_MASK;
        sb.append("event ACTION_").append(names[actionCode]);
        if (actionCode == MotionEvent.ACTION_POINTER_DOWN
                || actionCode == MotionEvent.ACTION_POINTER_UP) {
            sb.append("(pid ").append(
                    action >> MotionEvent.ACTION_POINTER_ID_SHIFT);
            sb.append(")");
        }
        sb.append("[");
        for (int i = 0; i < event.getPointerCount(); i++) {
            sb.append("#").append(i);
            sb.append("(pid ").append(event.getPointerId(i));
            sb.append(")=").append((int) event.getX(i));
            sb.append(",").append((int) event.getY(i));
            if (i + 1 < event.getPointerCount())
            sb.append(";");
        }
        sb.append("]");
        Log.d(TAG, sb.toString());
    }

    /** Determine the space between the first two fingers */
    private float spacing(WrapMotionEvent event) {
        // ...
        float x = event.getX(0) - event.getX(1);
        float y = event.getY(0) - event.getY(1);
        return FloatMath.sqrt(x * x + y * y);
    }

    /** Calculate the mid point of the first two fingers */
    private void midPoint(PointF point, WrapMotionEvent event) {
        // ...
        float x = event.getX(0) + event.getX(1);
        float y = event.getY(0) + event.getY(1);
        point.set(x / 2, y / 2);
    }
}

WrapMotionEvent.java

import android.view.MotionEvent;

public class WrapMotionEvent {
protected MotionEvent event;




    protected WrapMotionEvent(MotionEvent event) {
        this.event = event;
    }

    static public WrapMotionEvent wrap(MotionEvent event) {
            try {
                return new EclairMotionEvent(event);
            } catch (VerifyError e) {
                return new WrapMotionEvent(event);
            }
    }



    public int getAction() {
            return event.getAction();
    }

    public float getX() {
            return event.getX();
    }

    public float getX(int pointerIndex) {
            verifyPointerIndex(pointerIndex);
            return getX();
    }

    public float getY() {
            return event.getY();
    }

    public float getY(int pointerIndex) {
            verifyPointerIndex(pointerIndex);
            return getY();
    }

    public int getPointerCount() {
            return 1;
    }

    public int getPointerId(int pointerIndex) {
            verifyPointerIndex(pointerIndex);
            return 0;
    }

    private void verifyPointerIndex(int pointerIndex) {
            if (pointerIndex > 0) {
                throw new IllegalArgumentException(
                    "Invalid pointer index for Donut/Cupcake");
            }
    }

}

EclairMotionEvent.java

import android.view.MotionEvent;

public class EclairMotionEvent extends WrapMotionEvent {

    protected EclairMotionEvent(MotionEvent event) {
            super(event);
    }

    public float getX(int pointerIndex) {
            return event.getX(pointerIndex);
    }

    public float getY(int pointerIndex) {
            return event.getY(pointerIndex);
    }

    public int getPointerCount() {
            return event.getPointerCount();
    }

    public int getPointerId(int pointerIndex) {
            return event.getPointerId(pointerIndex);
    }
}

Answer 3

从内存加载图像

webview.loadUrl("file://...")

我使用了 WebView 并通过WebView 处理所有平移、缩放和滚动 。如果您使用wrap_content，则网络视图不会比图像大，并且不会显示白色区域。
WebView 是更好的 ImageView ；）

Answer 4

在回答 Janusz 最初的问题时，有几种方法可以实现这一目标，所有这些方法的难度级别各不相同，如下所述。使用网页视图固然很好，但在观感和可控性方面却非常有限。如果您从画布上绘制位图，则已提出的最通用的解决方案似乎是 MikeOrtiz 的、Robert Foss 的和/或 Jacob Nordfalk 建议的解决方案。 PaulBourke，非常适合多点触控支持和所有类型的自定义视图。

就我个人而言，如果您只是将画布绘制为位图，然后将其显示在 ImageView 中，并且希望能够使用多点触控进行放大和移动，我发现 MikeOrtiz 的解决方案是最简单的。但是，出于我的目的，他提供的 Git 中的代码似乎仅在他的 TouchImageView 自定义 ImageView 类是唯一的子类时才有效或提供布局参数为：

android:layout_height="match_parent"
android:layout_height="match_parent"

不幸的是，由于我的布局设计，我需要“layout_height”的“wrap_content”。当我将其更改为此图像时，图像在底部被裁剪，并且我无法滚动或缩放到裁剪区域。
所以我看了一下 Source for ImageView 只是为了了解 Android 如何实现“onMeasure”并更改 MikeOrtiz 来适应。

   @Override
protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)
{
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);

  //**** ADDED THIS ********/////
      int  w = (int) bmWidth;
      int  h = (int) bmHeight;
     width = resolveSize(w, widthMeasureSpec);  
     height = resolveSize(h, heightMeasureSpec);
  //**** END ********///   

   // width = MeasureSpec.getSize(widthMeasureSpec);   // REMOVED
   // height = MeasureSpec.getSize(heightMeasureSpec); // REMOVED

    //Fit to screen.
    float scale;
    float scaleX =  (float)width / (float)bmWidth;
    float scaleY = (float)height / (float)bmHeight;

    scale = Math.min(scaleX, scaleY);
    matrix.setScale(scale, scale);
    setImageMatrix(matrix);
    saveScale = 1f;

    // Center the image
    redundantYSpace = (float)height - (scale * (float)bmHeight) ;
    redundantXSpace = (float)width - (scale * (float)bmWidth);
    redundantYSpace /= (float)2;
    redundantXSpace /= (float)2;

    matrix.postTranslate(redundantXSpace, redundantYSpace);

    origWidth = width - 2 * redundantXSpace;
    origHeight = height - 2 * redundantYSpace;
   // origHeight = bmHeight;
    right = width * saveScale - width - (2 * redundantXSpace * saveScale);
    bottom = height * saveScale - height - (2 * redundantYSpace * saveScale);

    setImageMatrix(matrix);
}

这里的resolveSize（int，int）是一个“使所需大小与MeasureSpec施加的约束相协调的实用程序，其中：

参数：

 - size How big the view wants to be
 - MeasureSpec Constraints imposed by the parent

返回：

 - The size this view should be."

因此本质上提供了一种行为与加载图像时的原始 ImageView 类更相似。可以进行更多更改以支持修改宽高比的更多种类的屏幕，但现在我希望这会有所帮助，感谢 MikeOrtiz 的原始代码。 。

Answer 5

您还可以尝试 http://code.google.com/p/android-multitouch -controller/

这个库真的很棒，尽管最初有点难以掌握。

Answer 6

我刚刚集成了 Robert Foss 的 TouchImageView：它开箱即用，完美运行！谢谢！

我只是修改了一些代码，这样我就可以从我的layout.xml 中实例化它。

只需添加两个构造函数

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

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

并将旧的构造函数转换为 init 方法即可：

private void init(Context context){
    //...old code ofconstructor of Robert Moss's code
}

Answer 7

@Robert Foss、@Mike Ortiz，非常感谢你们的工作。我合并了你的工作，并完成了 Android 的罗伯特课程 > 2.0 与迈克的额外工作。

作为我工作的成果，我展示了基于 ViewPager 并使用修改后的 TouchImageView 的 Android Touch Gallery。通过 URL 加载图像，您可以缩放和拖动它们。您可以在这里找到它 https://github.com/Dreddik/AndroidTouchGallery

Answer 8

尝试使用 ZoomView 缩放任何其他视图。

http://code.google.com/p/android-zoom-view/ 使用起来简单、免费且有趣！

Answer 9

添加到@Mike的答案。我还需要双击才能将图像恢复到第一次查看时的原始尺寸。所以我添加了一整堆“orig...”实例变量，并添加了 SimpleOnGestureListener 来实现这一点。

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

    Matrix matrix = new Matrix();

    // We can be in one of these 3 states
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;

    // Remember some things for zooming
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;

    float redundantXSpace, redundantYSpace, origRedundantXSpace, origRedundantYSpace;;

    float width, height;
    static final int CLICK = 3;
    static final float SAVE_SCALE = 1f;
    float saveScale = SAVE_SCALE;

    float right, bottom, origWidth, origHeight, bmWidth, bmHeight, origScale, origBottom,origRight;

    ScaleGestureDetector mScaleDetector;
    GestureDetector mGestureDetector;

    Context context;

    public TouchImageView(Context context) {
        super(context);
        super.setClickable(true);
        this.context = context;
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());

        matrix.setTranslate(1f, 1f);
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);

        setOnTouchListener(new OnTouchListener() {

            @Override
            public boolean onTouch(View v, MotionEvent event) {

                boolean onDoubleTapEvent = mGestureDetector.onTouchEvent(event);
                if (onDoubleTapEvent) {
                    // Reset Image to original scale values
                    mode = NONE;
                    bottom = origBottom;
                    right = origRight;
                    last = new PointF();
                    start = new PointF();
                    m = new float[9];
                    saveScale = SAVE_SCALE;
                    matrix = new Matrix();
                    matrix.setScale(origScale, origScale);
                    matrix.postTranslate(origRedundantXSpace, origRedundantYSpace);
                    setImageMatrix(matrix);
                    invalidate();
                    return true;
                } 


                mScaleDetector.onTouchEvent(event);

                matrix.getValues(m);
                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                PointF curr = new PointF(event.getX(), event.getY());

                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    last.set(event.getX(), event.getY());
                    start.set(last);
                    mode = DRAG;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        float deltaX = curr.x - last.x;
                        float deltaY = curr.y - last.y;
                        float scaleWidth = Math.round(origWidth * saveScale);
                        float scaleHeight = Math.round(origHeight * saveScale);
                        if (scaleWidth < width) {
                            deltaX = 0;
                            if (y + deltaY > 0)
                                deltaY = -y;
                            else if (y + deltaY < -bottom)
                                deltaY = -(y + bottom);
                        } else if (scaleHeight < height) {
                            deltaY = 0;
                            if (x + deltaX > 0)
                                deltaX = -x;
                            else if (x + deltaX < -right)
                                deltaX = -(x + right);
                        } else {
                            if (x + deltaX > 0)
                                deltaX = -x;
                            else if (x + deltaX < -right)
                                deltaX = -(x + right);

                            if (y + deltaY > 0)
                                deltaY = -y;
                            else if (y + deltaY < -bottom)
                                deltaY = -(y + bottom);
                        }
                        matrix.postTranslate(deltaX, deltaY);
                        last.set(curr.x, curr.y);
                    }
                    break;

                case MotionEvent.ACTION_UP:
                    mode = NONE;
                    int xDiff = (int) Math.abs(curr.x - start.x);
                    int yDiff = (int) Math.abs(curr.y - start.y);
                    if (xDiff < CLICK && yDiff < CLICK)
                        performClick();
                    break;

                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                    break;
                }

                setImageMatrix(matrix);
                invalidate();

                return true; // indicate event was handled
            }

        });

        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onDoubleTapEvent(MotionEvent e) {
                return true;
            }
        });
    }

    @Override
    public void setImageBitmap(Bitmap bm) {
        super.setImageBitmap(bm);
        bmWidth = bm.getWidth();
        bmHeight = bm.getHeight();
    }

    public void setMaxZoom(float x) {
        maxScale = x;
    }

    private class ScaleListener extends
            ScaleGestureDetector.SimpleOnScaleGestureListener {
        @Override
        public boolean onScaleBegin(ScaleGestureDetector detector) {
            mode = ZOOM;
            return true;
        }

        @Override
        public boolean onScale(ScaleGestureDetector detector) {
            float mScaleFactor = (float) Math.min(
                    Math.max(.95f, detector.getScaleFactor()), 1.05);
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale) {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            } else if (saveScale < minScale) {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            }
            right = width * saveScale - width
                    - (2 * redundantXSpace * saveScale);
            bottom = height * saveScale - height
                    - (2 * redundantYSpace * saveScale);
            if (origWidth * saveScale <= width
                    || origHeight * saveScale <= height) {
                matrix.postScale(mScaleFactor, mScaleFactor, width / 2,
                        height / 2);
                if (mScaleFactor < 1) {
                    matrix.getValues(m);
                    float x = m[Matrix.MTRANS_X];
                    float y = m[Matrix.MTRANS_Y];
                    if (mScaleFactor < 1) {
                        if (Math.round(origWidth * saveScale) < width) {
                            if (y < -bottom)
                                matrix.postTranslate(0, -(y + bottom));
                            else if (y > 0)
                                matrix.postTranslate(0, -y);
                        } else {
                            if (x < -right)
                                matrix.postTranslate(-(x + right), 0);
                            else if (x > 0)
                                matrix.postTranslate(-x, 0);
                        }
                    }
                }
            } else {
                matrix.postScale(mScaleFactor, mScaleFactor,
                        detector.getFocusX(), detector.getFocusY());
                matrix.getValues(m);
                float x = m[Matrix.MTRANS_X];
                float y = m[Matrix.MTRANS_Y];
                if (mScaleFactor < 1) {
                    if (x < -right)
                        matrix.postTranslate(-(x + right), 0);
                    else if (x > 0)
                        matrix.postTranslate(-x, 0);
                    if (y < -bottom)
                        matrix.postTranslate(0, -(y + bottom));
                    else if (y > 0)
                        matrix.postTranslate(0, -y);
                }
            }
            return true;

        }
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = MeasureSpec.getSize(widthMeasureSpec);
        height = MeasureSpec.getSize(heightMeasureSpec);
        // Fit to screen.
        float scale;
        float scaleX = (float) width / (float) bmWidth;
        float scaleY = (float) height / (float) bmHeight;
        scale = Math.min(scaleX, scaleY);
        matrix.setScale(scale, scale);
        setImageMatrix(matrix);
        saveScale = SAVE_SCALE;
        origScale = scale;

        // Center the image
        redundantYSpace = (float) height - (scale * (float) bmHeight);
        redundantXSpace = (float) width - (scale * (float) bmWidth);
        redundantYSpace /= (float) 2;
        redundantXSpace /= (float) 2;

        origRedundantXSpace = redundantXSpace;
        origRedundantYSpace = redundantYSpace;

        matrix.postTranslate(redundantXSpace, redundantYSpace);

        origWidth = width - 2 * redundantXSpace;
        origHeight = height - 2 * redundantYSpace;
        right = width * saveScale - width - (2 * redundantXSpace * saveScale);
        bottom = height * saveScale - height
                - (2 * redundantYSpace * saveScale);
        origRight = right;
        origBottom = bottom;
        setImageMatrix(matrix);
    }

}

Answer 10

这是这个线程的一个很晚的补充，但我一直在研究一个支持缩放和平移的图像视图，并且有一些我在其他地方没有找到的功能。这最初是一种显示非常大的图像而不导致 OutOfMemoryError 的方法，通过在缩小时对图像进行二次采样并在放大时加载更高分辨率的图块。它现在支持在 ViewPager< /code>，手动旋转或使用 EXIF 信息（90° 停止），使用 OnClickListener 或您自己的 GestureDetector 或 OnTouchListener 覆盖选定的触摸事件、子类化以添加叠加层、缩放时平移以及快速移动。

它并不是作为 ImageView 的通用替代品，因此不会扩展它，也不支持显示资源中的图像，仅支持资产和外部文件。它需要 SDK 10。

源代码位于 GitHub 上，并且有一个示例演示了在 ViewPager 中的使用。

https://github.com/davemorrissey/subsampling-scale-image-view

Answer 11

的 LayoutParams

public void zoom(boolean flag){
    if(flag){
        int width=40;
        int height=40;
    }
    else{
        int width=20;
        int height=20;
    }
    RelativeLayout.LayoutParams param=new RelativeLayout.LayoutParams(width,height); //use the parent layout of the ImageView;
    imageView.setLayoutParams(param); //imageView is the view which needs zooming.
}

您可以尝试使用此ZoomIn = Zoom(true);
缩小 = 缩放（假）；

Answer 12

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    imageDetail = (ImageView) findViewById(R.id.imageView1);
    imageDetail.setOnTouchListener(new View.OnTouchListener() {

        @Override
        public boolean onTouch(View v, MotionEvent event) {
            ImageView view = (ImageView) v;
            System.out.println("matrix=" + savedMatrix.toString());
            switch (event.getAction() & MotionEvent.ACTION_MASK) {
                case MotionEvent.ACTION_DOWN:
                    savedMatrix.set(matrix);
                    startPoint.set(event.getX(), event.getY());
                    mode = DRAG;
                    break;
                case MotionEvent.ACTION_POINTER_DOWN:
                    oldDist = spacing(event);
                    if (oldDist > 10f) {
                        savedMatrix.set(matrix);
                        midPoint(midPoint, event);
                        mode = ZOOM;
                    }
                    break;
                case MotionEvent.ACTION_UP:
                case MotionEvent.ACTION_POINTER_UP:
                    mode = NONE;
                    break;
                case MotionEvent.ACTION_MOVE:
                    if (mode == DRAG) {
                        matrix.set(savedMatrix);
                        matrix.postTranslate(event.getX() - startPoint.x, event.getY() - startPoint.y);
                    } else if (mode == ZOOM) {
                        float newDist = spacing(event);
                        if (newDist > 10f) {
                            matrix.set(savedMatrix);
                            float scale = newDist / oldDist;
                            matrix.postScale(scale, scale, midPoint.x, midPoint.y);
                        }
                    }
                    break;
            }
            view.setImageMatrix(matrix);
            return true;

        }

        @SuppressLint("FloatMath")
        private float spacing(MotionEvent event) {
            float x = event.getX(0) - event.getX(1);
            float y = event.getY(0) - event.getY(1);
            return FloatMath.sqrt(x * x + y * y);
        }

        private void midPoint(PointF point, MotionEvent event) {
            float x = event.getX(0) + event.getX(1);
            float y = event.getY(0) + event.getY(1);
            point.set(x / 2, y / 2);
        }
    });
}

并且drawable文件夹应该有bticn图像文件。
完美运作:)

Answer 13

像下面这样的东西就可以做到。

@Override public boolean onTouch(View v,MotionEvent e)
{

    tap=tap2=drag=pinch=none;
    int mask=e.getActionMasked();
    posx=e.getX();posy=e.getY();

    float midx= img.getWidth()/2f;
    float midy=img.getHeight()/2f;
    int fingers=e.getPointerCount();

    switch(mask)
    {
        case MotionEvent.ACTION_POINTER_UP:
            tap2=1;break;

        case MotionEvent.ACTION_UP:
            tap=1;break;

        case MotionEvent.ACTION_MOVE:
            drag=1;
    }
    if(fingers==2){nowsp=Math.abs(e.getX(0)-e.getX(1));}
    if((fingers==2)&&(drag==0)){ tap2=1;tap=0;drag=0;}
    if((fingers==2)&&(drag==1)){ tap2=0;tap=0;drag=0;pinch=1;}

    if(pinch==1)

    {
        if(nowsp>oldsp)scale+=0.1;
        if(nowsp<oldsp)scale-=0.1;
        tap2=tap=drag=0;    
    }
    if(tap2==1)
        {
            scale-=0.1;
            tap=0;drag=0;
        }
    if(tap==1)
        {
            tap2=0;drag=0;
            scale+=0.1;
        }
    if(drag==1)
        {
            movx=posx-oldx;
            movy=posy-oldy;
            x+=movx;
            y+=movy;
            tap=0;tap2=0;
        }
    m.setTranslate(x,y);
    m.postScale(scale,scale,midx,midy);
    img.setImageMatrix(m);img.invalidate();
    tap=tap2=drag=none;
    oldx=posx;oldy=posy;
    oldsp=nowsp;
    return true;
}


public void onCreate(Bundle b)
{
        super.onCreate(b);

    img=new ImageView(this);
    img.setScaleType(ImageView.ScaleType.MATRIX);
    img.setOnTouchListener(this);

    path=Environment.getExternalStorageDirectory().getPath();   
    path=path+"/DCIM"+"/behala.jpg";
    byte[] bytes;
    bytes=null;
    try{
        FileInputStream fis;
        fis=new FileInputStream(path);
        BufferedInputStream bis;
        bis=new BufferedInputStream(fis);
        bytes=new byte[bis.available()];
        bis.read(bytes);
        if(bis!=null)bis.close();
        if(fis!=null)fis.close();

     }
    catch(Exception e)
        {
        ret="Nothing";
        }
    Bitmap bmp=BitmapFactory.decodeByteArray(bytes,0,bytes.length);

    img.setImageBitmap(bmp);

    setContentView(img);
}

要查看完整的程序，请参阅此处： 缩放图像的程序在安卓中