安卓app开发项目-控件以及双指放大缩小图片、单指拖动图片(源码).zip

package whu.iss.activity; import java.util.Observable; import java.util.Observer; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Canvas; import android.graphics.Paint; import android.graphics.Rect; import android.util.AttributeSet; import android.view.View; public class ImageZoomView extends View implements Observer { private final Paint mPaint = new Paint(Paint.FILTER_BITMAP_FLAG); private final Rect mRectSrc = new Rect(); private final Rect mRectDst = new Rect(); private float mAspectQuotient; private Bitmap mBitmap; private ZoomState mState; public ImageZoomView(Context context, AttributeSet attrs) { super(context, attrs); } public void setZoomState(ZoomState state) { if (mState != null) { mState.deleteObserver(this); } mState = state; mState.addObserver(this); invalidate(); } protected void onDraw(Canvas canvas) { if (mBitmap != null && mState != null) { final int viewWidth = getWidth(); final int viewHeight = getHeight(); final int bitmapWidth = mBitmap.getWidth(); final int bitmapHeight = mBitmap.getHeight(); final float panX = mState.getPanX(); final float panY = mState.getPanY(); final float zoomX = mState.getZoomX(mAspectQuotient) * viewWidth / bitmapWidth; final float zoomY = mState.getZoomY(mAspectQuotient) * viewHeight / bitmapHeight; // Setup source and destination rectangles mRectSrc.left = (int)(panX * bitmapWidth - viewWidth / (zoomX * 2)); mRectSrc.top = (int)(panY * bitmapHeight - viewHeight / (zoomY * 2)); mRectSrc.right = (int)(mRectSrc.left + viewWidth / zoomX); mRectSrc.bottom = (int)(mRectSrc.top + viewHeight / zoomY); mRectDst.left = getLeft(); mRectDst.top = getTop(); mRectDst.right = getRight(); mRectDst.bottom = getBottom(); // Adjust source rectangle so that it fits within the source image. if (mRectSrc.left < 0) { mRectDst.left += -mRectSrc.left * zoomX; mRectSrc.left = 0; } if (mRectSrc.right > bitmapWidth) { mRectDst.right -= (mRectSrc.right - bitmapWidth) * zoomX; mRectSrc.right = bitmapWidth; } if (mRectSrc.top < 0) { mRectDst.top += -mRectSrc.top * zoomY; mRectSrc.top = 0; } if (mRectSrc.bottom > bitmapHeight) { mRectDst.bottom -= (mRectSrc.bottom - bitmapHeight) * zoomY; mRectSrc.bottom = bitmapHeight; } canvas.drawBitmap(mBitmap, mRectSrc, mRectDst, mPaint); } } public void update(Observable observable, Object data) { invalidate(); } private void calculateAspectQuotient() { if (mBitmap != null) { mAspectQuotient = (((float)mBitmap.getWidth()) / mBitmap.getHeight()) / (((float)getWidth()) / getHeight()); } } public void setImage(Bitmap bitmap) { mBitmap = bitmap; calculateAspectQuotient(); invalidate(); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { super.onLayout(changed, left, top, right, bottom); calculateAspectQuotient(); } }