Android 如何获得图像的缩放功能？

How can I get zoom functionality for images?

提问by Janusz

Is there a common way to show a big image and enable the user to zoom in and out and pan the image?

有没有一种通用的方法来显示大图像并使用户能够放大、缩小和平移图像？

Until now I found two ways:

到目前为止，我发现了两种方法：

1. overwriting ImageView, that seems a little bit too much for such a common problem.
2. using a webview but with less control over the overall layout etc.

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。

采纳答案by Janusz

I used a WebView and loaded the image from the memory via

我使用了 WebView 并通过以下方式从内存中加载了图像

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

The WebView handles all the panning zooming and scrolling. If you use wrap_content the webview won't be bigger then the image and no white areas are shown. The WebView is the better ImageView ;)

WebView 处理所有平移缩放和滚动。如果您使用 wrap_content，则 webview 不会比图像更大，并且不会显示白色区域。WebView 是更好的 ImageView ;)

回答by Mike Ortiz

UPDATE

更新

I've just given TouchImageView a new update. It now includes Double Tap Zoom and Fling in addition to Panning and Pinch Zoom. The code below is verydated. You can check out the github projectto get the latest code.

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甩动。下面的代码非常过时。可以查看github项目获取最新代码。

USAGE

用法

Place TouchImageView.java in your project. It can then be used the same as ImageView. Example:

将 TouchImageView.java 放在您的项目中。然后可以像 ImageView 一样使用它。例子：

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

If you are using TouchImageView in xml, then you must provide the full package name, because it is a custom view. Example:

如果您在 xml 中使用 TouchImageView，那么您必须提供完整的包名称，因为它是一个自定义视图。例子：

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

Note: I've removed my prior answer, which included some very old code and now link straight to the most updated code on github.

注意：我已经删除了我之前的答案，其中包含一些非常旧的代码，现在直接链接到 github 上最新的代码。

ViewPager

浏览器

If you are interested in putting TouchImageView in a ViewPager, refer to this answer.

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

回答by Robert Foss

I adapted some code to create a TouchImageView that supports multitouch (>2.1). It is inspired by the book Hello, Android! (3rd edition)

我修改了一些代码来创建一个支持多点触控 (>2.1) 的 TouchImageView。它的灵感来自这本书你好，Android！（第三版）

It is contained within the following 3 files TouchImageView.java WrapMotionEvent.java EclairMotionEvent.java

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

TouchImageView.java

触摸图像视图.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

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

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);
    }
}

回答by digiphd

In Response to Janusz original question, there are several ways to achieve this all of which vary in their difficulty level and have been stated below. Using a web view is good, but it is very limited in terms of look and feel and controllability. If you are drawing a bitmap from a canvas, the most versatile solutions that have been proposed seems to be MikeOrtiz's, Robert Foss's and/or what Jacob Nordfalk suggested. There is a great example for incorporating the android-multitouch-controller by PaulBourke, and is great for having the multi-touch support and alltypes of custom views.

在对 Janusz 原始问题的回应中，有几种方法可以实现这一点，所有这些方法的难度级别各不相同，如下所述。使用 Web 视图是好的，但它在外观和感觉和可控性方面非常有限。如果您正在从画布上绘制位图，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。PaulBourke有一个结合 android-multitouch-controller 的很好的例子，它非常适合多点触控支持和所有类型的自定义视图。

Personally, if you are simply drawing a canvas to a bitmap and then displaying it inside and ImageView and want to be able to zoom into and move around using multi touch, I find MikeOrtiz's solution as the easiest. However, for my purposes the code from the Gitthat he has provided seems to only work when his TouchImageView custom ImageView class is the only child or provide the layout params as:

就个人而言，如果您只是将画布绘制到位图，然后在内部和 ImageView 中显示它，并且希望能够使用多点触控放大和移动，我发现 MikeOrtiz 的解决方案是最简单的。但是，出于我的目的，他提供的来自Git的代码似乎仅在他的 TouchImageView 自定义 ImageView 类是唯一的子类或提供布局参数时才有效：

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

Unfortunately due to my layout design, I needed "wrap_content" for "layout_height". When I changed it to this the image was cropped at the bottom and I couldn't scroll or zoom to the cropped region. So I took a look at the Sourcefor ImageView just to see how Android implemented "onMeasure" and changed MikeOrtiz's to suit.

不幸的是，由于我的布局设计，“layout_height”需要“wrap_content”。当我将其更改为此图像时，图像在底部被裁剪，我无法滚动或缩放到裁剪区域。因此，我查看了 ImageView的源代码，以了解 Android 如何实现“onMeasure”并更改 MikeOrtiz 以适应。

   @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);
}

Here resolveSize(int,int) is a "Utility to reconcile a desired size with constraints imposed by a MeasureSpec, where :

这里 resolveSize(int,int) 是一个“实用程序，用于协调所需大小与 MeasureSpec 强加的约束，其中：

Parameters:

参数：

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

Returns:

返回：

 - The size this view should be."

So essentially providing a behaviour a little more similar to the original ImageView class when the image is loaded. Some more changes could be made to support a greater variety of screens which modify the aspect ratio. But for now I Hope this helps. Thanks to MikeOrtiz for his original code, great work.

因此，本质上在加载图像时提供与原始 ImageView 类更相似的行为。可以进行更多更改以支持更多种修改纵横比的屏幕。但现在我希望这会有所帮助。感谢 MikeOrtiz 的原始代码，很棒的工作。

回答by zontar

I just integrated Robert Foss's TouchImageView: it worked perfectly out of the box! Thanks!

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

I just modified a bit the code so I could be able to instantiate it from my layout.xml.

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。

Just add two constructors

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);
}

and transform the old constructor into an init method:

并将旧的构造函数转换为 init 方法：

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

回答by Jacob Nordfalk

You could also try out http://code.google.com/p/android-multitouch-controller/

你也可以试试http://code.google.com/p/android-multitouch-controller/

The library is really great, although initially a little hard to grasp.

图书馆真的很棒，虽然最初有点难以理解。

回答by Roman Truba

@Robert Foss, @Mike Ortiz, thank you very much for your work. I merged your work, and completed Robert classes for android > 2.0 with Mike additional work.

@Robert Foss、@Mike Ortiz，非常感谢您的工作。我合并了您的工作，并完成了适用于 android > 2.0 的 Robert 课程以及 Mike 的其他工作。

As result of my work I present Android Touch Gallery, based on ViewPager and used modificated TouchImageView. Images loading by URL and you can zoom and drag them. You can find it here https://github.com/Dreddik/AndroidTouchGallery

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

回答by Dave Morrissey

This is a very late addition to this thread but I've been working on an image view that supports zoom and pan and has a couple of features I haven't found elsewhere. This started out as a way of displaying very large images without causing OutOfMemoryErrors, by subsampling the image when zoomed out and loading higher resolution tiles when zoomed in. It now supports use in a ViewPager, rotation manually or using EXIF information (90° stops), override of selected touch events using OnClickListeneror your own GestureDetectoror OnTouchListener, subclassing to add overlays, pan while zooming, and fling momentum.

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找不到的功能。这最初是作为一种显示非常大的图像而不引起OutOfMemoryErrors 的方式，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 中使用ViewPager，手动旋转或使用 EXIF 信息（90° 停止），使用OnClickListener或 您自己的GestureDetectoror覆盖选定的触摸事件OnTouchListener，子类化以添加叠加层、缩放时平移和抛掷动量。

It's not intended as a general use replacement for ImageViewso doesn't extend it, and doesn't support display of images from resources, only assets and external files. It requires SDK 10.

它不打算作为一般用途的替代品，ImageView因此不扩展它，也不支持显示来自资源的图像，仅支持资产和外部文件。它需要 SDK 10。

Source is on GitHub, and there's a sample that illustrates use in a ViewPager.

源代码在 GitHub 上，有一个示例说明在ViewPager.

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

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

回答by karooolek

Try using ZoomViewfor zooming any other view.

尝试ZoomView用于缩放任何其他视图。

http://code.google.com/p/android-zoom-view/it's easy, free and fun to use!

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

回答by Terence

Adding to @Mike's answer. I also needed double tap to restore the image to the original dimensions when first viewed. So I added a whole heap of "orig..." instance variables and added the SimpleOnGestureListener which did the trick.

添加到@Mike 的答案中。我还需要双击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，它起到了作用。

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);
    }

}