Android界面] 如何实现滑动图片界面，双击图片放大缩小，多点缩放

/** * MyImageView.java * @version 1.0 * @author Haven * @createTime 2011-12-9 下午03:12:30 * 此类代码是根据android系统自带的ImageViewTouchBase代码修改 */ package com.havenliu.demo; import android.content.Context; import android.graphics.Bitmap; import android.graphics.Matrix; import android.graphics.RectF; import android.os.Handler; import android.util.AttributeSet; import android.view.KeyEvent; import android.widget.ImageView; public class MyImageView extends ImageView { @SuppressWarnings("unused") private static final String TAG = "ImageViewTouchBase"; // This is the base transformation which is used to show the image // initially. The current computation for this shows the image in // it's entirety, letterboxing as needed. One could choose to // show the image as cropped instead. // // This matrix is recomputed when we go from the thumbnail image to // the full size image. protected Matrix mBaseMatrix = new Matrix(); // This is the supplementary transformation which reflects what // the user has done in terms of zooming and panning. // // This matrix remains the same when we go from the thumbnail image // to the full size image. protected Matrix mSuppMatrix = new Matrix(); // This is the final matrix which is computed as the concatentation // of the base matrix and the supplementary matrix. private final Matrix mDisplayMatrix = new Matrix(); // Temporary buffer used for getting the values out of a matrix. private final float[] mMatrixValues = new float[9]; // The current bitmap being displayed. // protected final RotateBitmap mBitmapDisplayed = new RotateBitmap(null); protected Bitmap image = null; int mThisWidth = -1, mThisHeight = -1; float mMaxZoom = 2.0f;// 最大缩放比例 float mMinZoom ;// 最小缩放比例 private int imageWidth;// 图片的原始宽度 private int imageHeight;// 图片的原始高度 private float scaleRate;// 图片适应屏幕的缩放比例 public MyImageView(Context context, int imageWidth, int imageHeight) { super(context); this.imageHeight = imageHeight; this.imageWidth = imageWidth; init(); } public MyImageView(Context context, AttributeSet attrs, int imageWidth, int imageHeight) { super(context, attrs); this.imageHeight = imageHeight; this.imageWidth = imageWidth; init(); } /** * 计算图片要适应屏幕需要缩放的比例 */ private void arithScaleRate() { float scaleWidth = Main.screenWidth / (float) imageWidth; float scaleHeight = Main.screenHeight / (float) imageHeight; scaleRate = Math.min(scaleWidth, scaleHeight); } public float getScaleRate() { return scaleRate; } public int getImageWidth() { return imageWidth; } public void setImageWidth(int imageWidth) { this.imageWidth = imageWidth; } public int getImageHeight() { return imageHeight; } public void setImageHeight(int imageHeight) { this.imageHeight = imageHeight; } @Override public boolean onKeyDown(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_BACK && event.getRepeatCount() == 0) { event.startTracking(); return true; } return super.onKeyDown(keyCode, event); } @Override public boolean onKeyUp(int keyCode, KeyEvent event) { if (keyCode == KeyEvent.KEYCODE_BACK && event.isTracking() && !event.isCanceled()) { if (getScale() > 1.0f) { // If we're zoomed in, pressing Back jumps out to show the // entire image, otherwise Back returns the user to the gallery. zoomTo(1.0f); return true; } } return super.onKeyUp(keyCode, event); } protected Handler mHandler = new Handler(); @Override public void setImageBitmap(Bitmap bitmap) { super.setImageBitmap(bitmap); image = bitmap; // 计算适应屏幕的比例 arithScaleRate(); //缩放到屏幕大小 zoomTo(scaleRate,Main.screenWidth / 2f, Main.screenHeight / 2f); //居中 layoutToCenter(); // imageView.zoomTo(scaleRate, Main.screenWidth / 2, Main.screenHeight / 2 // center(true, true); } // Center as much as possible in one or both axis. Centering is // defined as follows: if the image is scaled down below the // view's dimensions then center it (literally). If the image // is scaled larger than the view and is translated out of view // then translate it back into view (i.e. eliminate black bars). protected void center(boolean horizontal, boolean vertical) { // if (mBitmapDisplayed.getBitmap() == null) { // return; // } if (image == null) { return; } Matrix m = getImageViewMatrix(); RectF rect = new RectF(0, 0, image.getWidth(), image.getHeight()); // RectF rect = new RectF(0, 0, imageWidth*getScale(), imageHeight*getScale()); m.mapRect(rect); float height = rect.height(); float width = rect.width(); float deltaX = 0, deltaY = 0; if (vertical) { int viewHeight = getHeight(); if (height < viewHeight) { deltaY = (viewHeight - height) / 2 - rect.top; } else if (rect.top > 0) { deltaY = -rect.top; } else if (rect.bottom < viewHeight) { deltaY = getHeight() - rect.bottom; } } if (horizontal) { int viewWidth = getWidth(); if (width < viewWidth) { deltaX = (viewWidth - width) / 2 - rect.left; } else if (rect.left > 0) { deltaX = -rect.left; } else if (rect.right < viewWidth) { deltaX = viewWidth - rect.right; } } postTranslate(deltaX, deltaY); setImageMatrix(getImageViewMatrix()); } private void init() { setScaleType(ImageView.ScaleType.MATRIX); } /** * 设置图片居中显示 */ public void layoutToCenter() { //正在显示的图片实际宽高 float width = imageWidth*getScale(); float height = imageHeight*getScale(); //空白区域宽高 float fill_width = Main.screenWidth - width; float fill_height = Main.screenHeight - height; //需要移动的距离 float tran_width = 0f; float tran_height = 0f; if(fill_width>0) tran_width = fill_width/2; if(fill_height>0) tran_height = fill_height/2; postTranslate(tran_width, tran_height); setImageMatrix(getImageViewMatrix()); } protected float getValue(Matrix matrix, int whichValue) { matrix.getValues(mMatrixValues); mMinZoom =( Main.screenWidth/2f)/imageWidth; return mMatrixValues[whichValue]; } // Get the scale factor out of the matrix. protected float getScale(Matrix matrix) { return getValue(matrix, Matrix.MSCALE_X); } protected float getScale() { return getScale(mSuppMatrix); } // Combine the base matrix and the supp matrix to make the final matrix. protected Matrix getImageViewMatrix() { // The final matrix is computed as the concatentation of the base matrix // and the supplementary matrix. mDisplayMatrix.set(mBaseMatrix); mDisplayMatrix.postConcat(mSuppMatrix); return mDisplayMatrix; } static final float SCALE_RATE = 1.25F; // Sets the maximum zoom, which is a scale relative to the base matrix. It // is calculated to show the image at 400% zoom regardless of screen or // image orientation. If in the future we decode the full 3 megapixel image, // rather than the current 1024x768, this should be changed down to 200%. protected float maxZoom() { if (image == null) { return 1F; } float fw = (float) image.getWidth() / (float) mThisWidth; float fh = (float) image.getHeight() / (float) mThisHeight; float max = Math.max(fw, fh) * 4; return max; } protected void zoomTo(float scale, float centerX, float centerY) { if (scale > mMaxZoom) { scale = mMaxZoom; } else if (scale < mMinZoom) { scale = mMinZoom; } float oldScale = getScale(); float deltaScale = scale / oldScale; mSuppMatrix.postScale(deltaScale, deltaScale, centerX, centerY);