ImageView在调整大小时超出范围

Question

我的Activity中有一个ImageView和一个surfaceView。我想使用多点触控移动（拖动）并调整imageView的大小。所以，这是touchListener类：

private final class MyTouchListener implements View.OnTouchListener {


    private static final int NONE = 0;
    private static final int DRAG = 1;
    private static final int ZOOM = 2;

    private static final float MIN_ZOOM = 0.5f;
    private static final float MAX_ZOOM = 5f;

    private Matrix matrix;
    private Matrix savedMatrix = new Matrix();

    private PointF start = new PointF();
    private PointF mid = new PointF();

    private int mode = NONE;
    private float oldDistance = 1f;

    private float dx; // postTranslate X distance
    private float dy; // postTranslate Y distance
    private float[] matrixValues = new float[9];
    float matrixX = 0; // X coordinate of matrix inside the ImageView
    float matrixY = 0; // Y coordinate of matrix inside the ImageView
    float width = 0; // width of drawable
    float height = 0; // height of drawable
    private MyTouchListener (Matrix m){
        this.matrix = m;
    }
    public boolean onTouch(View view, MotionEvent event) {
        ImageView imageView = (ImageView)view;

        switch(event.getAction() & MotionEvent.ACTION_MASK) {

            case MotionEvent.ACTION_DOWN:
                savedMatrix.set(matrix);
                start.set(event.getX(), event.getY());
                mode = DRAG;
                break;

            case MotionEvent.ACTION_POINTER_DOWN:
                oldDistance = spacing(event);
                if(oldDistance > 10f) {
                    savedMatrix.set(matrix);
                    midPoint(mid, 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.getValues(matrixValues);
                    matrixX = matrixValues[2];
                    matrixY = matrixValues[5];
                    width = matrixValues[0] * (((ImageView) view).getDrawable()
                            .getIntrinsicWidth());
                    height = matrixValues[4] * (((ImageView) view).getDrawable()
                            .getIntrinsicHeight());

                    dx = event.getX() - start.x;
                    dy = event.getY() - start.y;

                    //if image will go outside left bound
                    if (matrixX + dx < 0){
                        dx = -matrixX;
                    }
                    //if image will go outside right bound
                    if(matrixX + dx + width > view.getWidth()){
                        dx = view.getWidth() - matrixX - width;
                    }
                    //if image will go oustside top bound
                    if (matrixY + dy < 0){
                        dy = -matrixY;
                    }
                    //if image will go outside bottom bound
                    if(matrixY + dy + height > view.getHeight()){
                        dy = view.getHeight() - matrixY - height;
                    }
                    matrix.postTranslate(dx, dy);
                }
                else if(mode == ZOOM) {
                    float newDistance = spacing(event);
                    if(newDistance > 10f) {
                        matrix.set(savedMatrix);
                        float scale = newDistance / oldDistance;
                        float[] values = new float[9];
                        matrix.getValues(values);
                        float currentScaleX = values[Matrix.MSCALE_X];
                        float currentScaleY = values[Matrix.MSCALE_X];
                        if(scale * currentScaleX > MAX_ZOOM)

                            scale = MAX_ZOOM / currentScaleX;
                        else if (scale * currentScaleX < MIN_ZOOM)
                            scale = MIN_ZOOM / currentScaleX;

                        matrix.postScale(scale, scale, mid.x, mid.y);

                    }
                }
                break;
        }

            imageView.setImageMatrix(matrix);

        return true;
    }

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

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

问题是当我调整图像大小时，没有模仿，而且屏幕尺寸会变大。

Answer 1

首先，您需要显示图像的视图的宽度和高度。您可能需要将其传递给MyTouchListener。

之后，当您调整缩放时，只需添加更多级别的检查，如下所示：

Drawable imageDrawable = imageView.getDrawable();

// Checks if current scale would cause the image to get bigger than its container
if (imageDrawable.getIntrinsicWidth() * scale > containerViewWidth 
    || imageDrawable.getIntrinsicHeight() * scale > containerViewHeight) {

    // Gets the minimal scale that prevents the overflow in zoom
    scale = Math.min(targetViewWidth/imageDrawable.getIntrinsicWidth(),
                     targetViewHeight/imageDrawable.getIntrinsicHeight());
}

if (scale * currentScaleX > MAX_ZOOM) {
    scale = MAX_ZOOM / currentScaleX;
} else if (scale * currentScaleX < MIN_ZOOM) {
    scale = MIN_ZOOM / currentScaleX;
}

Answer 2

使用此代码为自定义图像视图创建一个类：

import android.content.Context;
import android.graphics.Matrix;
import android.graphics.PointF;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.ScaleGestureDetector;
import android.view.View;
import android.widget.ImageView;

public class TouchImageView extends ImageView {

Matrix 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;

int viewWidth, viewHeight;
static final int CLICK = 3;
float saveScale = 1f;
protected float origWidth, origHeight;
int oldMeasuredWidth, oldMeasuredHeight;

ScaleGestureDetector mScaleDetector;

Context context;

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

public TouchImageView(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);

    //
    // Rescales image on rotation
    //
    if (oldMeasuredHeight == viewWidth && oldMeasuredHeight == viewHeight
            || viewWidth == 0 || viewHeight == 0)
        return;
    oldMeasuredHeight = viewHeight;
    oldMeasuredWidth = viewWidth;

    if (saveScale == 1) {
        // Fit to screen.
        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);`enter code here`
        redundantYSpace /= (float) 2;
        redundantXSpace /= (float) 2;

        matrix.postTranslate(redundantXSpace, redundantYSpace);

        origWidth = viewWidth - 2 * redundantXSpace;
        origHeight = viewHeight - 2 * redundantYSpace;
        setImageMatrix(matrix);
    }
    fixTrans();
    }
}

现在使用xml：

<(your package name).TouchImageView
        android:id="@+id/imgDisplay"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:scaleType="fitCenter" />

现在你可以像这样使用它：

imgDisplay = (TouchImageView) viewLayout.findViewById(R.id.imgDisplay);
    Bitmap bitmap = BitmapFactory.decodeFile(_imagePaths.get(position), options);
    imgDisplay.setImageBitmap(bitmap);