Android自定义view四手势缩放移动的ImageView

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/qq_34942689/article/details/88743325

自定义view四：手势缩放和可移动的ImageView

public class ZoomImageView extends AppCompatImageView implements OnScaleGestureListener,
    OnTouchListener, ViewTreeObserver.OnGlobalLayoutListener {
private static final String TAG       = ZoomImageView.class.getSimpleName();
public static final  float  SCALE_MAX = 15.0f;
private static final float  SCALE_MID = 5.0f;

/**
 * 初始化时的缩放比例，如果图片宽或高大于屏幕，此值将小于0
 */
private float   initScale = 4.0f;
private boolean once      = true;

/**
 * 用于存放矩阵的9个值
 */
private final float[] matrixValues = new float[9];

/**
 * 缩放的手势检测
 */
private       ScaleGestureDetector mScaleGestureDetector = null;
private final Matrix               mScaleMatrix          = new Matrix();

/**
 * 用于双击检测
 */
private GestureDetector mGestureDetector;
private boolean         isAutoScale;

private int mTouchSlop;

private float mLastX;
private float mLastY;

private boolean isCanDrag;
private int     lastPointerCount;

private boolean isCheckTopAndBottom = true;
private boolean isCheckLeftAndRight = true;
private float             scale;
private SingleTapListener singleTapListener;

public ZoomImageView(Context context) {
    this(context, null);
}

public ZoomImageView(Context context, AttributeSet attrs) {
    super(context, attrs);
    super.setScaleType(ScaleType.MATRIX);
    mGestureDetector = new GestureDetector(context,
            new SimpleOnGestureListener() {
                @Override
                public boolean onDoubleTap(MotionEvent e) {
                    if (isAutoScale)
                        return true;

                    float x = e.getX();
                    float y = e.getY();
                    Log.e("DoubleTap", getScale() + " , " + initScale);
                    if (getScale() < SCALE_MID) {
                        ZoomImageView.this.postDelayed(
                                new AutoScaleRunnable(SCALE_MID, x, y), 16);
                        isAutoScale = true;
                    } else if (getScale() >= SCALE_MID
                            && getScale() < SCALE_MAX) {
                        ZoomImageView.this.postDelayed(
                                new AutoScaleRunnable(SCALE_MAX, x, y), 16);
                        isAutoScale = true;
                    } else {
                        ZoomImageView.this.postDelayed(
                                new AutoScaleRunnable(initScale, x, y), 16);
                        isAutoScale = true;
                    }

                    return true;
                }

                @Override
                public boolean onSingleTapConfirmed(MotionEvent e) {
                    if (singleTapListener != null) {
                        singleTapListener.doSingle();
                    }
                    return super.onSingleTapConfirmed(e);
                }
            });
    mScaleGestureDetector = new ScaleGestureDetector(context, this);
    this.setOnTouchListener(this);
}

/**
 * 自动缩放的任务
 *
 * @author zhy
 */
private class AutoScaleRunnable implements Runnable {
    static final float BIGGER  = 1.07f;
    static final float SMALLER = 0.93f;
    private float mTargetScale;
    private float tmpScale;

    /**
     * 缩放的中心
     */
    private float x;
    private float y;

    /**
     * 传入目标缩放值，根据目标值与当前值，判断应该放大还是缩小
     *
     * @param targetScale
     */
    public AutoScaleRunnable(float targetScale, float x, float y) {
        this.mTargetScale = targetScale;
        this.x = x;
        this.y = y;
        if (getScale() < mTargetScale) {
            tmpScale = BIGGER;
        } else {
            tmpScale = SMALLER;
        }

    }

    @Override
    public void run() {
        // 进行缩放
        mScaleMatrix.postScale(tmpScale, tmpScale, x, y);
        checkBorderAndCenterWhenScale();
        setImageMatrix(mScaleMatrix);

        final float currentScale = getScale();
        // 如果值在合法范围内，继续缩放
        if (((tmpScale > 1f) && (currentScale < mTargetScale))
                || ((tmpScale < 1f) && (mTargetScale < currentScale))) {
            ZoomImageView.this.postDelayed(this, 16);
        } else
        // 设置为目标的缩放比例
        {
            final float deltaScale = mTargetScale / currentScale;
            mScaleMatrix.postScale(deltaScale, deltaScale, x, y);
            checkBorderAndCenterWhenScale();
            setImageMatrix(mScaleMatrix);
            isAutoScale = false;
        }

    }
}

@SuppressLint("NewApi")
@Override
public boolean onScale(ScaleGestureDetector detector) {
    float scale       = getScale();
    float scaleFactor = detector.getScaleFactor();

    if (getDrawable() == null)
        return true;

    /**
     * 缩放的范围控制
     */
    if ((scale < SCALE_MAX && scaleFactor > 1.0f)
            || (scale > initScale && scaleFactor < 1.0f)) {
        /**
         * 最大值最小值判断
         */
        if (scaleFactor * scale < initScale) {
            scaleFactor = initScale / scale;
        }
        if (scaleFactor * scale > SCALE_MAX) {
            scaleFactor = SCALE_MAX / scale;
        }
        /**
         * 设置缩放比例
         */
        mScaleMatrix.postScale(scaleFactor, scaleFactor,
                detector.getFocusX(), detector.getFocusY());
        checkBorderAndCenterWhenScale();
        setImageMatrix(mScaleMatrix);
    }
    return true;

}

/**
 * 在缩放时，进行图片显示范围的控制
 */
private void checkBorderAndCenterWhenScale() {

    RectF rect   = getMatrixRectF();
    float deltaX = 0;
    float deltaY = 0;

    int width  = getWidth();
    int height = getHeight();

    // 如果宽或高大于屏幕，则控制范围
    if (rect.width() >= width) {
        if (rect.left > 0) {
            deltaX = -rect.left;
        }
        if (rect.right < width) {
            deltaX = width - rect.right;
        }
    }
    if (rect.height() >= height) {
        if (rect.top > 0) {
            deltaY = -rect.top;
        }
        if (rect.bottom < height) {
            deltaY = height - rect.bottom;
        }
    }
    // 如果宽或高小于屏幕，则让其居中
    if (rect.width() < width) {
        deltaX = width * 0.5f - rect.right + 0.5f * rect.width();
    }
    if (rect.height() < height) {
        deltaY = height * 0.5f - rect.bottom + 0.5f * rect.height();
    }
    Log.e(TAG, "deltaX = " + deltaX + " , deltaY = " + deltaY);

    mScaleMatrix.postTranslate(deltaX, deltaY);

}

/**
 * 根据当前图片的Matrix获得图片的范围
 *
 * @return
 */
private RectF getMatrixRectF() {
    Matrix   matrix = mScaleMatrix;
    RectF    rect   = new RectF();
    Drawable d      = getDrawable();
    if (null != d) {
        rect.set(0, 0, d.getIntrinsicWidth(), d.getIntrinsicHeight());
        matrix.mapRect(rect);
    }
    return rect;
}

@Override
public boolean onScaleBegin(ScaleGestureDetector detector) {
    return true;
}

@Override
public void onScaleEnd(ScaleGestureDetector detector) {
}

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

    if (mGestureDetector.onTouchEvent(event))
        return true;
    mScaleGestureDetector.onTouchEvent(event);

    float x = 0, y = 0;
    // 拿到触摸点的个数
    final int pointerCount = event.getPointerCount();
    // 得到多个触摸点的x与y均值
    for (int i = 0; i < pointerCount; i++) {
        x += event.getX(i);
        y += event.getY(i);
    }
    x = x / pointerCount;
    y = y / pointerCount;

    /**
     * 每当触摸点发生变化时，重置mLasX , mLastY
     */
    if (pointerCount != lastPointerCount) {
        isCanDrag = false;
        mLastX = x;
        mLastY = y;
    }

    lastPointerCount = pointerCount;
    RectF rectF = getMatrixRectF();
    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            if (rectF.width() > getWidth() || rectF.height() > getHeight()) {
                getParent().requestDisallowInterceptTouchEvent(true);
            }
            break;
        case MotionEvent.ACTION_MOVE:
            if (rectF.width() > getWidth() || rectF.height() > getHeight()) {
                getParent().requestDisallowInterceptTouchEvent(true);
            }
            Log.e(TAG, "ACTION_MOVE");
            float dx = x - mLastX;
            float dy = y - mLastY;

            if (!isCanDrag) {
                isCanDrag = isCanDrag(dx, dy);
            }
            if (isCanDrag) {

                if (getDrawable() != null) {
                    // if (getMatrixRectF().left == 0 && dx > 0)
                    // {
                    // getParent().requestDisallowInterceptTouchEvent(false);
                    // }
                    //
                    // if (getMatrixRectF().right == getWidth() && dx < 0)
                    // {
                    // getParent().requestDisallowInterceptTouchEvent(false);
                    // }
                    isCheckLeftAndRight = isCheckTopAndBottom = true;
                    // 如果宽度小于屏幕宽度，则禁止左右移动
                    if (rectF.width() < getWidth()) {
                        dx = 0;
                        isCheckLeftAndRight = false;
                    }
                    // 如果高度小雨屏幕高度，则禁止上下移动
                    if (rectF.height() < getHeight()) {
                        dy = 0;
                        isCheckTopAndBottom = false;
                    }


                    mScaleMatrix.postTranslate(dx, dy);
                    checkMatrixBounds();
                    setImageMatrix(mScaleMatrix);
                }
            }
            mLastX = x;
            mLastY = y;
            break;

        case MotionEvent.ACTION_UP:
        case MotionEvent.ACTION_CANCEL:
            Log.e(TAG, "ACTION_UP");
            lastPointerCount = 0;
            break;
    }

    return true;
}

/**
 * 获得当前的缩放比例
 *
 * @return
 */
public final float getScale() {
    mScaleMatrix.getValues(matrixValues);
    return matrixValues[Matrix.MSCALE_X];
}

@Override
protected void onAttachedToWindow() {
    super.onAttachedToWindow();
    getViewTreeObserver().addOnGlobalLayoutListener(this);
}

@SuppressWarnings("deprecation")
@Override
protected void onDetachedFromWindow() {
    super.onDetachedFromWindow();
    getViewTreeObserver().removeGlobalOnLayoutListener(this);
}

public void setScale(float scale) {
    this.scale = scale;
}

@Override
public void onGlobalLayout() {
    Drawable d = getDrawable();
    if (d == null) return;
    if (once) {
        Log.e(TAG, d.getIntrinsicWidth() + " , " + d.getIntrinsicHeight());
        int width  = getWidth();
        int height = getHeight();
        // 拿到图片的宽和高
        int dw = d.getIntrinsicWidth();
        int dh = d.getIntrinsicHeight();
        scale = 1f;
        // 如果宽和高都大于屏幕，则让其按按比例适应屏幕大小
        if (dw > width && dh > height) {
            scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
        } else if (dw > width && dh <= height) {// 如果图片的宽或者高大于屏幕，则缩放至屏幕的宽或者高
            scale = width * 1.0f / dw;
        } else if (dh > height && dw <= width) {
            scale = height * 1.0f / dh;
        } else if (dh < height && dw < width) {//图片长宽都小于屏幕，则放大至屏幕的宽或者高
            scale = Math.min(width * 1.0f / dw, height * 1.0f / dh);
        }
        initScale = scale;

        Log.e(TAG, "initScale = " + initScale);
        mScaleMatrix.postTranslate((width - dw) / 2, (height - dh) / 2);
        mScaleMatrix.postScale(scale, scale, getWidth() / 2,
                getHeight() / 2);
        // 图片移动至屏幕中心
        setImageMatrix(mScaleMatrix);
        once = false;
    }

}

/**
 * 移动时，进行边界判断，主要判断宽或高大于屏幕的
 */
private void checkMatrixBounds() {
    RectF rect = getMatrixRectF();

    float       deltaX     = 0, deltaY = 0;
    final float viewWidth  = getWidth();
    final float viewHeight = getHeight();
    // 判断移动或缩放后，图片显示是否超出屏幕边界
    if (rect.top > 0 && isCheckTopAndBottom) {
        deltaY = -rect.top;
    }
    if (rect.bottom < viewHeight && isCheckTopAndBottom) {
        deltaY = viewHeight - rect.bottom;
    }
    if (rect.left > 0 && isCheckLeftAndRight) {
        deltaX = -rect.left;
    }
    if (rect.right < viewWidth && isCheckLeftAndRight) {
        deltaX = viewWidth - rect.right;
    }
    mScaleMatrix.postTranslate(deltaX, deltaY);
}

/**
 * 是否是推动行为
 *
 * @param dx
 * @param dy
 * @return
 */
private boolean isCanDrag(float dx, float dy) {
    return Math.sqrt((dx * dx) + (dy * dy)) >= mTouchSlop;
}

public interface SingleTapListener {
    void doSingle();
}

public void setOnSingleTapListener(SingleTapListener singleTapListener) {
    this.singleTapListener = singleTapListener;
}

}