首页 / 移动开发 / Android / Android手势滑动实现两点触摸缩放图片

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical" > <！-- 引用自定义控件 --> <com.ymw.zoomimage.ZoomImageViewandroid:id="@+id/image"android:layout_width="wrap_content"android:layout_height="wrap_content" > </com.ymw.zoomimage.ZoomImageView></LinearLayout>

package com.ymw.zoomimage;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.util.Log;import android.view.MotionEvent;import android.view.View;public class ZoomImageView extends View implements Observer { /** Paint object used when drawing bitmap. */ private final Paint mPaint = new Paint（Paint.FILTER_BITMAP_FLAG）; /** Rectangle used （and re-used） for cropping source image. */ private final Rect mRectSrc = new Rect（）; /** Rectangle used （and re-used） for specifying drawing area on canvas. */ private final Rect mRectDst = new Rect（）; /** Object holding aspect quotient */ private final AspectQuotient mAspectQuotient = new AspectQuotient（）; /** The bitmap that we"re zooming in, and drawing on the screen. */ private Bitmap mBitmap; /** State of the zoom. */ private ZoomState mState; private BasicZoomControl mZoomControl; private BasicZoomListener mZoomListener; public ZoomImageView（Context context, AttributeSet attrs） {super（context, attrs）;mZoomControl = new BasicZoomControl（）;mZoomListener = new BasicZoomListener（）;mZoomListener.setZoomControl（mZoomControl）;setZoomState（mZoomControl.getZoomState（））;setOnTouchListener（mZoomListener）;mZoomControl.setAspectQuotient（getAspectQuotient（））; } public void zoomImage（float f, float x, float y） {mZoomControl.zoom（f, x, y）; } public void setImage（Bitmap bitmap） {mBitmap = bitmap;mAspectQuotient.updateAspectQuotient（getWidth（）, getHeight（）,mBitmap.getWidth（）, mBitmap.getHeight（））;mAspectQuotient.notifyObservers（）;invalidate（）; } private void setZoomState（ZoomState state） {if （mState ！= null） { mState.deleteObserver（this）;}mState = state;mState.addObserver（this）;invalidate（）; } private AspectQuotient getAspectQuotient（） {return mAspectQuotient; } @Override protected void onDraw（Canvas canvas） {if （mBitmap ！= null && mState ！= null） { Log.d（"ZoomImageView", "OnDraw"）; final float aspectQuotient = mAspectQuotient.get（）; final int viewWidth = getWidth（）; final int viewHeight = getHeight（）; final int bitmapWidth = mBitmap.getWidth（）; final int bitmapHeight = mBitmap.getHeight（）; Log.d（"ZoomImageView", "viewWidth = " + viewWidth）; Log.d（"ZoomImageView", "viewHeight = " + viewHeight）; Log.d（"ZoomImageView", "bitmapWidth = " + bitmapWidth）; Log.d（"ZoomImageView", "bitmapHeight = " + bitmapHeight）; final float panX = mState.getPanX（）; final float panY = mState.getPanY（）; final float zoomX = mState.getZoomX（aspectQuotient） * viewWidth / bitmapWidth; final float zoomY = mState.getZoomY（aspectQuotient） * 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.left = 0; mRectDst.top = 0; // mRectDst.right = getRight（）; mRectDst.right = getWidth（）; mRectDst.bottom = getHeight（）; // 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; } mRectDst.left = 0; mRectDst.top = 0; mRectDst.right = viewWidth; mRectDst.bottom = viewHeight; Log.d（"ZoomImageView", "mRectSrc.top" + mRectSrc.top）; Log.d（"ZoomImageView", "mRectSrc.bottom" + mRectSrc.bottom）; Log.d（"ZoomImageView", "mRectSrc.left" + mRectSrc.left）; Log.d（"ZoomImageView", "mRectSrc.right" + mRectSrc.right）; Log.d（"ZoomImageView", "mRectDst.top" + mRectDst.top）; Log.d（"ZoomImageView", "mRectDst.bottom" + mRectDst.bottom）; Log.d（"ZoomImageView", "mRectDst.left" + mRectDst.left）; Log.d（"ZoomImageView", "mRectDst.right" + mRectDst.right）; canvas.drawBitmap（mBitmap, mRectSrc, mRectDst, mPaint）;} } @Override protected void onLayout（boolean changed, int left, int top, int right, int bottom） {super.onLayout（changed, left, top, right, bottom）;mAspectQuotient.updateAspectQuotient（right - left, bottom - top,mBitmap.getWidth（）, mBitmap.getHeight（））;mAspectQuotient.notifyObservers（）; } @Override public void update（Observable observable, Object data） {invalidate（）; } private class BasicZoomListener implements View.OnTouchListener {/** Zoom control to manipulate */private BasicZoomControl mZoomControl;private float mFirstX = -1;private float mFirstY = -1;private float mSecondX = -1;private float mSecondY = -1;private int mOldCounts = 0;/** * Sets the zoom control to manipulate ** @param control * Zoom control */public void setZoomControl（BasicZoomControl control） { mZoomControl = control;}public boolean onTouch（View v, MotionEvent event） { switch （event.getAction（）） { case MotionEvent.ACTION_DOWN:mOldCounts = 1;mFirstX = event.getX（）;mFirstY = event.getY（）;break; case MotionEvent.ACTION_MOVE: {float fFirstX = event.getX（）;float fFirstY = event.getY（）;int nCounts = event.getPointerCount（）;if （1 == nCounts） { mOldCounts = 1; float dx = （fFirstX - mFirstX） / v.getWidth（）; float dy = （fFirstY - mFirstY） / v.getHeight（）; mZoomControl.pan（-dx, -dy）;} else if （1 == mOldCounts） { mSecondX = event.getX（event.getPointerId（nCounts - 1））; mSecondY = event.getY（event.getPointerId（nCounts - 1））; mOldCounts = nCounts;} else { float fSecondX = event .getX（event.getPointerId（nCounts - 1））; float fSecondY = event .getY（event.getPointerId（nCounts - 1））; double nLengthOld = getLength（mFirstX, mFirstY, mSecondX, mSecondY）; double nLengthNow = getLength（fFirstX, fFirstY, fSecondX, fSecondY）; float d = （float） （（nLengthNow - nLengthOld） / v.getWidth（））; mZoomControl.zoom（（float） Math.pow（20, d）, （（fFirstX + fSecondX） / 2 / v.getWidth（））, （（fFirstY + fSecondY） / 2 / v.getHeight（）））; mSecondX = fSecondX; mSecondY = fSecondY;}mFirstX = fFirstX;mFirstY = fFirstY;break; } } return true;}private double getLength（float x1, float y1, float x2, float y2） { return Math.sqrt（Math.pow（x1 - x2, 2） + Math.pow（y1 - y2, 2））;} } private class BasicZoomControl implements Observer {/** Minimum zoom level limit */private static final float MIN_ZOOM = 1;/** Maximum zoom level limit */private static final float MAX_ZOOM = 16;/** Zoom state under control */private final ZoomState mState = new ZoomState（）;/** Object holding aspect quotient of view and content */private AspectQuotient mAspectQuotient;/** * Set reference object holding aspect quotient ** @param aspectQuotient * Object holding aspect quotient */public void setAspectQuotient（AspectQuotient aspectQuotient） { if （mAspectQuotient ！= null） {mAspectQuotient.deleteObserver（this）; } mAspectQuotient = aspectQuotient; mAspectQuotient.addObserver（this）;}/** * Get zoom state being controlled ** @return The zoom state */public ZoomState getZoomState（） { return mState;}/** * Zoom ** @param f * Factor of zoom to apply * @param x * X-coordinate of invariant position * @param y * Y-coordinate of invariant position */public void zoom（float f, float x, float y） { // Log.d（"Zoom", "zoom f = " + f）; final float aspectQuotient = mAspectQuotient.get（）; final float prevZoomX = mState.getZoomX（aspectQuotient）; final float prevZoomY = mState.getZoomY（aspectQuotient）; mState.setZoom（mState.getZoom（） * f）; limitZoom（）; final float newZoomX = mState.getZoomX（aspectQuotient）; final float newZoomY = mState.getZoomY（aspectQuotient）; // Pan to keep x and y coordinate invariant mState.setPanX（mState.getPanX（） + （x - .5f） * （1f / prevZoomX - 1f / newZoomX））; mState.setPanY（mState.getPanY（） + （y - .5f） * （1f / prevZoomY - 1f / newZoomY））; limitPan（）; mState.notifyObservers（）;}/** * Pan ** @param dx * Amount to pan in x-dimension * @param dy * Amount to pan in y-dimension */public void pan（float dx, float dy） { final float aspectQuotient = mAspectQuotient.get（）; mState.setPanX（mState.getPanX（） + dx / mState.getZoomX（aspectQuotient））; mState.setPanY（mState.getPanY（） + dy / mState.getZoomY（aspectQuotient））; limitPan（）; mState.notifyObservers（）;}/** * Help function to figure out max delta of pan from center position. ** @param zoom * Zoom value * @return Max delta of pan */private float getMaxPanDelta（float zoom） { return Math.max（0f, .5f * （（zoom - 1） / zoom））;}/** * Force zoom to stay within limits */private void limitZoom（） { if （mState.getZoom（） < MIN_ZOOM） {mState.setZoom（MIN_ZOOM）; } else if （mState.getZoom（） > MAX_ZOOM） {mState.setZoom（MAX_ZOOM）; }}/** * Force pan to stay within limits */private void limitPan（） { final float aspectQuotient = mAspectQuotient.get（）; final float zoomX = mState.getZoomX（aspectQuotient）; final float zoomY = mState.getZoomY（aspectQuotient）; final float panMinX = .5f - getMaxPanDelta（zoomX）; final float panMaxX = .5f + getMaxPanDelta（zoomX）; final float panMinY = .5f - getMaxPanDelta（zoomY）; final float panMaxY = .5f + getMaxPanDelta（zoomY）; if （mState.getPanX（） < panMinX） {mState.setPanX（panMinX）; } if （mState.getPanX（） > panMaxX） {mState.setPanX（panMaxX）; } if （mState.getPanY（） < panMinY） {mState.setPanY（panMinY）; } if （mState.getPanY（） > panMaxY） {mState.setPanY（panMaxY）; }}// Observable interface implementationpublic void update（Observable observable, Object data） { limitZoom（）; limitPan（）;} } private class AspectQuotient extends Observable {/** * Aspect quotient */private float mAspectQuotient;// Public methods/** * Gets aspect quotient ** @return The aspect quotient */public float get（） { return mAspectQuotient;}/** * Updates and recalculates aspect quotient based on supplied view and * content dimensions. ** @param viewWidth * Width of view * @param viewHeight * Height of view * @param contentWidth * Width of content * @param contentHeight * Height of content */public void updateAspectQuotient（float viewWidth, float viewHeight,float contentWidth, float contentHeight） { final float aspectQuotient = （contentWidth / contentHeight） / （viewWidth / viewHeight）; if （aspectQuotient ！= mAspectQuotient） {mAspectQuotient = aspectQuotient;setChanged（）; }} } private class ZoomState extends Observable {/** * Zoom level A value of 1.0 means the content fits the view. */private float mZoom;/** * Pan position x-coordinate X-coordinate of zoom window center * position, relative to the width of the content. */private float mPanX;/** * Pan position y-coordinate Y-coordinate of zoom window center * position, relative to the height of the content. */private float mPanY;// Public methods/** * Get current x-pan ** @return current x-pan */public float getPanX（） { return mPanX;}/** * Get current y-pan ** @return Current y-pan */public float getPanY（） { return mPanY;}/** * Get current zoom value ** @return Current zoom value */public float getZoom（） { return mZoom;}/** * Help function for calculating current zoom value in x-dimension ** @param aspectQuotient * （Aspect ratio content） / （Aspect ratio view） * @return Current zoom value in x-dimension */public float getZoomX（float aspectQuotient） { return Math.min（mZoom, mZoom * aspectQuotient）;}/** * Help function for calculating current zoom value in y-dimension ** @param aspectQuotient * （Aspect ratio content） / （Aspect ratio view） * @return Current zoom value in y-dimension */public float getZoomY（float aspectQuotient） { return Math.min（mZoom, mZoom / aspectQuotient）;}/** * Set pan-x ** @param panX * Pan-x value to set */public void setPanX（float panX） { if （panX ！= mPanX） {mPanX = panX;setChanged（）; }}/** * Set pan-y ** @param panY * Pan-y value to set */public void setPanY（float panY） { if （panY ！= mPanY） {mPanY = panY;setChanged（）; }}/** * Set zoom ** @param zoom * Zoom value to set */public void setZoom（float zoom） { if （zoom ！= mZoom） {mZoom = zoom;setChanged（）; }} }}

package com.ymw.zoomimage;import android.app.Activity;import android.graphics.Bitmap;import android.graphics.BitmapFactory;import android.os.Bundle;public class MainActivity extends Activity { private ZoomImageView zoomImg; @Override public void onCreate（Bundle savedInstanceState） {super.onCreate（savedInstanceState）;setContentView（R.layout.main）;zoomImg = （ZoomImageView） findViewById（R.id.image）;Bitmap bitmap = BitmapFactory.decodeResource（this.getResources（）,R.drawable.a）;zoomImg.setImage（bitmap）; }}