自定义可伸缩的imageView

直接上代码

/**
 * 自定义可伸缩的ImageView
 */
public class ZoomImageView extends ImageView {
	/** 画笔类 **/
	private Paint mPaint;

	private Runnable mRefresh = null;
	/** 缩放手势监听类 **/
	private ScaleGestureDetector mScaleDetector;
	/** 手势识别类 **/
	private GestureDetector mGestureDetector;
	/** 当前被渲染的Bitmap **/
	private Bitmap mBitmap;

	private int mThisWidth = -1, mThisHeight = -1;

	private Runnable mOnLayoutRunnable = null;

	private Matrix mBaseMatrix = new Matrix();
	private Matrix mDisplayMatrix = new Matrix();
	private Matrix mSuppMatrix = new Matrix();
	private Matrix mMatrix = new Matrix();

	/** 最大的拉伸比例 **/
	private float mMaxZoom;

	private float[] mMatrixValues = new float[9];
	private Runnable mFling = null;

	private double mLastDraw = 0;
	static final int sPaintDelay = 250;

	public ZoomImageView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init();
	}

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

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

	@SuppressLint("NewApi")
	private void init() {
		mPaint = new Paint();
		// 图像抖动处理
		mPaint.setDither(true);
		// 过滤优化操作 加快显示
		mPaint.setFilterBitmap(true);
		// 去掉锯齿
		mPaint.setAntiAlias(true);

		/** 刷新线程 **/
		mRefresh = new Runnable() {
			@Override
			public void run() {
				postInvalidate();
			}
		};

		mScaleDetector = new ScaleGestureDetector(getContext(),
				new ScaleListener());
		mGestureDetector = new GestureDetector(getContext(),
				new MyGestureListener());

		// 判断是否是新的API 开启硬件加速
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
			setLayerType(View.LAYER_TYPE_HARDWARE, null);
		}
	}

	public Bitmap getImageBitmap() {
		return mBitmap;
	}

	/** 回收Bitmap **/
	public void clear() {
		if (mBitmap != null && !mBitmap.isRecycled()) {
			mBitmap.recycle();
			mBitmap = null;
		}
	}

	@Override
	protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
		super.onLayout(changed, left, top, right, bottom);

		mThisWidth = right - left;
		mThisHeight = bottom - top;

		Runnable r = mOnLayoutRunnable;
		if (r != null) {
			mOnLayoutRunnable = null;
			r.run();
		}

		if (mBitmap != null) {
			setBaseMatrix(mBitmap, mBaseMatrix);
			setImageMatrix(getImageViewMatrix());
		}
	}

	private void setBaseMatrix(Bitmap bitmap, Matrix matrix) {
		float viewWidth = getWidth();
		float viewHeight = getHeight();

		matrix.reset();
		float widthScale = Math
				.min(viewWidth / (float) bitmap.getWidth(), 1.0f);
		float heightScale = Math.min(viewHeight / (float) bitmap.getHeight(),
				1.0f);
		float scale;
		if (widthScale > heightScale) {
			scale = heightScale;
		} else {
			scale = widthScale;
		}

		/** 算取比例 进行平移 **/
		matrix.setScale(scale, scale);
		matrix.postTranslate(
				(viewWidth - ((float) bitmap.getWidth() * scale)) / 2F,
				(viewHeight - ((float) bitmap.getHeight() * scale)) / 2F);
	}

	public Matrix getImageViewMatrix() {
		mDisplayMatrix.set(mBaseMatrix);
		mDisplayMatrix.postConcat(mSuppMatrix);
		return mDisplayMatrix;
	}

	public void setImageMatrix(Matrix m) {
		/** Matrix是否为空并是否定义 **/
		if (m != null && m.isIdentity()) {
			m = null;
		}

		if (m == null && !this.mMatrix.isIdentity() || m != null
				&& !this.mMatrix.equals(m)) {
			this.mMatrix.set(m);
			invalidate();
		}
	}

	static private void translatePoint(Matrix matrix, float[] xy) {
		matrix.mapPoints(xy);
	}

	/**
	 * 设置Bitmap
	 *
	 * @param bitmap
	 */
	@SuppressLint("NewApi")
	public void setImageBitmap(final Bitmap bitmap) {
		final int viewWidth = getWidth();

		// 开启硬件加速
		if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB && bitmap != null && bitmap.getHeight() > 1800) {
			setLayerType(View.LAYER_TYPE_SOFTWARE, null);
		}

		if (viewWidth <= 0) {
			mOnLayoutRunnable = new Runnable() {
				public void run() {
					setImageBitmap(bitmap);
				}
			};
			return;
		}

		if (bitmap != null) {
			setBaseMatrix(bitmap, mBaseMatrix);
			this.mBitmap = bitmap;
		} else {
			mBaseMatrix.reset();
			this.mBitmap = bitmap;
		}

		mSuppMatrix.reset();
		setImageMatrix(getImageViewMatrix());
		mMaxZoom = maxZoom();
		zoomTo(zoomDefault());
	}

	public void zoomTo(float scale) {
		float width = getWidth();
		float height = getHeight();

		zoomTo(scale, width / 2F, height / 2F);
	}

	protected void zoomTo(float scale, float centerX, float centerY) {
		if (scale > mMaxZoom) {
			scale = mMaxZoom;
		}

		float oldScale = getScale();
		float deltaScale = scale / oldScale;

		/** 根据某个中心点按照比例缩放 **/
		mSuppMatrix.postScale(deltaScale, deltaScale, centerX, centerY);
		setImageMatrix(getImageViewMatrix());
		center(true, true, false);
	}

	/**
	 * 计算中心位置
	 *
	 * @param vertical
	 * @param horizontal
	 * @param animate
	 */
	protected void center(boolean vertical, boolean horizontal, boolean animate) {
		if (mBitmap == null)
			return;

		Matrix m = getImageViewMatrix();

		float[] topLeft = new float[] { 0, 0 };
		float[] botRight = new float[] { mBitmap.getWidth(),
				mBitmap.getHeight() };

		translatePoint(m, topLeft);
		translatePoint(m, botRight);

		float height = botRight[1] - topLeft[1];
		float width = botRight[0] - topLeft[0];

		float deltaX = 0, deltaY = 0;

		if (vertical) {
			int viewHeight = getHeight();
			if (height < viewHeight) {
				deltaY = (viewHeight - height) / 2 - topLeft[1];
			} else if (topLeft[1] > 0) {
				deltaY = -topLeft[1];
			} else if (botRight[1] < viewHeight) {
				deltaY = getHeight() - botRight[1];
			}
		}

		if (horizontal) {
			int viewWidth = getWidth();
			if (width < viewWidth) {
				deltaX = (viewWidth - width) / 2 - topLeft[0];
			} else if (topLeft[0] > 0) {
				deltaX = -topLeft[0];
			} else if (botRight[0] < viewWidth) {
				deltaX = viewWidth - botRight[0];
			}
		}

		postTranslate(deltaX, deltaY);
		if (animate) {
			Animation a = new TranslateAnimation(-deltaX, 0, -deltaY, 0);
			a.setStartTime(SystemClock.elapsedRealtime());
			a.setDuration(250);
			setAnimation(a);
		}
		setImageMatrix(getImageViewMatrix());
	}

	protected void postTranslate(float dx, float dy) {
		mSuppMatrix.postTranslate(dx, dy);
	}

	public float getScale() {
		return getScale(mSuppMatrix);
	}

	protected float getScale(Matrix matrix) {
		if (mBitmap != null)
			return getValue(matrix, Matrix.MSCALE_X);
		else
			return 1f;
	}

	protected float getValue(Matrix matrix, int whichValue) {
		matrix.getValues(mMatrixValues);
		return mMatrixValues[whichValue];
	}

	/**
	 * 计算最大的拉伸比例
	 *
	 * @return
	 */
	protected float maxZoom() {
		if (mBitmap == null)
			return 1F;

		float fw = (float) mBitmap.getWidth() / (float) mThisWidth;
		float fh = (float) mBitmap.getHeight() / (float) mThisHeight;
		float max = Math.max(fw, fh) * 16;
		return max;
	}

	/**
	 * 原始显示比例
	 *
	 * @return
	 */
	public float zoomDefault() {
		if (mBitmap == null)
			return 1F;

		float fw = (float) mThisWidth / (float) mBitmap.getWidth();
		float fh = (float) mThisHeight / (float) mBitmap.getHeight();
		return Math.max(Math.min(fw, fh), 1);
	}

	protected void zoomTo(final float scale, final float centerX,
			final float centerY, final float durationMs) {
		final float incrementPerMs = (scale - getScale()) / durationMs;
		final float oldScale = getScale();
		final long startTime = System.currentTimeMillis();

		post(new Runnable() {
			public void run() {
				long now = System.currentTimeMillis();
				float currentMs = Math.min(durationMs,
						(float) (now - startTime));
				float target = oldScale + (incrementPerMs * currentMs);
				zoomTo(target, centerX, centerY);

				if (currentMs < durationMs) {
					post(this);
				}
			}
		});
	}

	protected void scrollBy(float distanceX, float distanceY,
			final float durationMs) {
		final float dx = distanceX;
		final float dy = distanceY;
		final long startTime = System.currentTimeMillis();

		mFling = new Runnable() {
			float old_x = 0;
			float old_y = 0;

			public void run() {
				long now = System.currentTimeMillis();
				float currentMs = Math.min(durationMs, now - startTime);
				float x = easeOut(currentMs, 0, dx, durationMs);
				float y = easeOut(currentMs, 0, dy, durationMs);
				postTranslate((x - old_x), (y - old_y));
				center(true, true, false);

				old_x = x;
				old_y = y;
				if (currentMs < durationMs) {
					post(this);
				}
			}
		};
		post(mFling);
	}

	private float easeOut(float time, float start, float end, float duration) {
		return end * ((time = time / duration - 1) * time * time + 1) + start;
	}

	@SuppressLint("NewApi")
	@Override
	protected void onDraw(Canvas canvas) {
		if (mBitmap != null && !mBitmap.isRecycled()) {
			if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB && getLayerType() == View.LAYER_TYPE_HARDWARE) {
				canvas.drawBitmap(mBitmap, mMatrix, null);
			} else {
				if ((System.currentTimeMillis() - mLastDraw) > sPaintDelay) {
					canvas.drawBitmap(mBitmap, mMatrix, mPaint);
					mLastDraw = System.currentTimeMillis();
				} else {
					canvas.drawBitmap(mBitmap, mMatrix, null);
					removeCallbacks(mRefresh);
					postDelayed(mRefresh, sPaintDelay);
				}
			}
		}
	}

	/**
	 * @author Administrator
	 *
	 *         手势缩放监听
	 */
	class ScaleListener extends
			ScaleGestureDetector.SimpleOnScaleGestureListener {

		@Override
		public boolean onScale(ScaleGestureDetector detector) {
			if (detector != null && detector.isInProgress()) {
				try {
					float targetScale = getScale() * detector.getScaleFactor();
					targetScale = Math.min(maxZoom(),
							Math.max(targetScale, 1.0f));

					zoomTo(targetScale, detector.getFocusX(),
							detector.getFocusY());
					invalidate();
					return true;
				} catch (IllegalArgumentException e) {
					e.printStackTrace();
				}
			}
			return false;
		}
	};

	/**
	 * @author Administrator
	 *
	 *         手势识别监听
	 */
	class MyGestureListener extends GestureDetector.SimpleOnGestureListener {

		@Override
		public boolean onScroll(MotionEvent e1, MotionEvent e2,
				float distanceX, float distanceY) {
			if ((e1 != null && e1.getPointerCount() > 1)
					|| (e2 != null && e2.getPointerCount() > 1)
					|| (mScaleDetector != null && mScaleDetector.isInProgress())) {
				return false;
			}

			if (getScale() > zoomDefault()) {
				removeCallbacks(mFling);
				postTranslate(-distanceX, -distanceY);
				center(true, true, false);
			}

			return true;
		}

		@Override
		public boolean onFling(MotionEvent e1, MotionEvent e2, float velocityX,
				float velocityY) {
			if ((e1 != null && e1.getPointerCount() > 1) || (e2 != null && e2.getPointerCount() > 1)) {
				return false;
			}

			if (mScaleDetector.isInProgress()) {
				return false;
			}

			try {
				float diffX = e2.getX() - e1.getX();
				float diffY = e2.getY() - e1.getY();

				if (Math.abs(velocityX) > 800 || Math.abs(velocityY) > 800) {
					scrollBy(diffX / 2, diffY / 2, 300);
					invalidate();
				}
			} catch (NullPointerException e) {
				e.printStackTrace();
			}

			return super.onFling(e1, e2, velocityX, velocityY);
		}

		@Override
		public boolean onDoubleTap(MotionEvent e) {
			if (getScale() > zoomDefault()) {
				zoomTo(zoomDefault());
			} else
				zoomTo(zoomDefault() * 3, e.getX(), e.getY(), 200);
			return true;
		}

		@Override
		public boolean onSingleTapConfirmed(MotionEvent e) {
			// 设置点击事件
			if (mImageTouchedListener != null) {
				mImageTouchedListener.onImageTouched();
				return false;
			}
			return super.onSingleTapConfirmed(e);
		}

	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		if (mBitmap != null) {
			mScaleDetector.onTouchEvent(event);

			if (!mScaleDetector.isInProgress()) {
				mGestureDetector.onTouchEvent(event);
			}
		}

		return true;
	};

	/**
	 *
	 * @author Administrator
	 *
	 *         点击接口
	 */
	private onImageTouchedListener mImageTouchedListener;

	public interface onImageTouchedListener {
		void onImageTouched();
	}

	public void setOnImageTouchedListener(onImageTouchedListener listener) {
		this.mImageTouchedListener = listener;
	}
}