在Android中触摸图像缩放

Question

我在画廊中得到了一系列图像，并试图添加相同的缩放功能。我在Android中读了很多有关缩放的内容。制定了各种示例。最后，我可以通过从可绘制的文件夹中绘制特定图像而无需使用任何XML文件来创建一个项目来缩小图像。如下所示

我创建了一个名为Zooming.java

的Java类

public class Zooming extends ImageView {
    Matrix matrix;
    //3 states for zooming 
    static final int NONE = 0;
    static final int DRAG = 1;
    static final int ZOOM = 2;
    int mode = NONE;
    PointF last = new PointF();
    PointF start = new PointF();
    float minScale = 1f;
    float maxScale = 3f;
    float[] m;
    int viewWidth, viewHeight;
    static final int CLICK = 3;
    float saveScale = 1f;
    protected float origWidth, origHeight;
    int oldMeasuredWidth, oldMeasuredHeight;
    ScaleGestureDetector mScaleDetector;
    Context context;
    public Zooming(Context context) {
        super(context);
        sharedConstructing(context);
    }
    public Zooming(Context context, AttributeSet attrs) {
        super(context, attrs);
        sharedConstructing(context);
    }
    private void sharedConstructing(Context context) {
        super.setClickable(true);
        this.context = context;
        mScaleDetector = new ScaleGestureDetector(context, new ScaleListener());
        matrix = new Matrix();
        m = new float[9];
        setImageMatrix(matrix);
        setScaleType(ScaleType.MATRIX);
        setOnTouchListener(new OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                mScaleDetector.onTouchEvent(event);
                PointF curr = new PointF(event.getX(), event.getY());
                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    last.set(curr);
                    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 fixTransX = getFixDragTrans(deltaX, viewWidth,
                                origWidth * saveScale);
                        float fixTransY = getFixDragTrans(deltaY, viewHeight,
                                origHeight * saveScale);
                        matrix.postTranslate(fixTransX, fixTransY);
                        fixTrans();
                        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
            }
        });
    }
    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 = detector.getScaleFactor();
            float origScale = saveScale;
            saveScale *= mScaleFactor;
            if (saveScale > maxScale) {
                saveScale = maxScale;
                mScaleFactor = maxScale / origScale;
            } else if (saveScale < minScale) {
                saveScale = minScale;
                mScaleFactor = minScale / origScale;
            }
            if (origWidth * saveScale <= viewWidth
                    || origHeight * saveScale <= viewHeight)
                matrix.postScale(mScaleFactor, mScaleFactor, viewWidth / 2,
                        viewHeight / 2);
            else
                matrix.postScale(mScaleFactor, mScaleFactor,
                        detector.getFocusX(), detector.getFocusY());
            fixTrans();
            return true;
        }
    }
    void fixTrans() {
        matrix.getValues(m);
        float transX = m[Matrix.MTRANS_X];
        float transY = m[Matrix.MTRANS_Y];
        float fixTransX = getFixTrans(transX, viewWidth, origWidth * saveScale);
        float fixTransY = getFixTrans(transY, viewHeight, origHeight
                * saveScale);
        if (fixTransX != 0 || fixTransY != 0)
            matrix.postTranslate(fixTransX, fixTransY);
    }
    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;
    }
    float getFixDragTrans(float delta, float viewSize, float contentSize) {
        if (contentSize <= viewSize) {
            return 0;
        }
        return delta;
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        viewWidth = MeasureSpec.getSize(widthMeasureSpec);
        viewHeight = MeasureSpec.getSize(heightMeasureSpec);
        if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
                || viewWidth == 0 || viewHeight == 0)
            return;
        oldMeasuredHeight = viewHeight;
        oldMeasuredWidth = viewWidth;
        if (saveScale == 1) {
            float scale;
            Drawable drawable = getDrawable();
            if (drawable == null || drawable.getIntrinsicWidth() == 0
                    || drawable.getIntrinsicHeight() == 0)
                return;
            int bmWidth = drawable.getIntrinsicWidth();
            int bmHeight = drawable.getIntrinsicHeight();
            Log.d("bmSize", "bmWidth: " + bmWidth + " bmHeight : " + bmHeight);
            float scaleX = (float) viewWidth / (float) bmWidth;
            float scaleY = (float) viewHeight / (float) bmHeight;
            scale = Math.min(scaleX, scaleY);
            matrix.setScale(scale, scale);
            // Center the image
            float redundantYSpace = (float) viewHeight
                    - (scale * (float) bmHeight);
            float redundantXSpace = (float) viewWidth
                    - (scale * (float) bmWidth);
            redundantYSpace /= (float) 2;
            redundantXSpace /= (float) 2;
            matrix.postTranslate(redundantXSpace, redundantYSpace);
            origWidth = viewWidth - 2 * redundantXSpace;
            origHeight = viewHeight - 2 * redundantYSpace;
            setImageMatrix(matrix);
        }
        fixTrans();
    }
}

和主动脉类别如下：

public class MainActivity extends Activity {
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        Zooming img = new Zooming(this);
        img.setImageResource(R.drawable.pic_1);
        img.setMaxZoom(4f);
        setContentView(img);
    }

它工作正常。我可以轻松放大图片。我的问题是，我想使用main.xml文件缩小图片。那就是使用imageView或customView（com.zomthepic.zooming）并在其中赋予图像源。我通过在我的main.xml

中使用Zooming CustomView添加imageView以及使用Zooming Customview尝试

main.xml

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
<com.zoomthepic.zooming
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:id="@+id/pic_id"
    android:src="@drawable/pic_1"/>

<LinearLayout/>

以及通过以下方式更改主攻击的代码：

公共班级主进扩展活动{

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    Zooming img = (Zooming)findViewById(R.id.pic_id);
    img.setMaxZoom(4);
}

，但不幸的是，该应用程序停止了。是否可以通过添加android：src ="@drawable/pic_1"，而不是通过使用r.drawable.pic_1在Java类中定义PIC来获得布局文件中给出的图像的缩放效果。Java课？谁能帮助我解决问题？

Answer 1

问题是

<com.zoomthepic.zoom
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/pic_id"
android:src="@drawable/pic_1"/>

而不是com.zoomthepic.zoom，使用com.zoomthepic.zoom它工作正常。

Answer 2

xml中的ID是

android:id="@+id/pic"

在您正在寻找的代码中...

Zooming img = (Zooming)findViewById(R.id.pic_id);

ID是错误的。