控件缩放 双指缩放

因为特殊需求，需要让webview控件缩放，但是禁止webview自带的缩放功能，所以在网上找了很多demo，找了很多天才找到的，防止遗失，也方便大家寻找到适合的代码，所以我就发布到这里来了。

注：此类是继承FrameLayout的实现类，在写ViewGroup的时候，只需要将需要缩放的控件包裹起来就可以了。

欢迎互相帮助 Y(^o^)Y

import android.content.Context;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Matrix;import android.graphics.Paint;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.View;import android.widget.FrameLayout;public class ZoomView extends FrameLayout {PRivate static final String TAG = "ZoomView";public ZoomView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);}public ZoomView(Context context, AttributeSet attrs) {super(context, attrs);}public ZoomView(final Context context) {super(context);}/*** Zooming view listener interface.*/public interface ZoomViewListener {void onZoomStarted(float zoom, float zoomx, float zoomy);void onZooming(float zoom, float zoomx, float zoomy);void onZoomEnded(float zoom, float zoomx, float zoomy);}// zoomingfloat zoom = 1.0f;float maxZoom = 2.0f;float smoothZoom = 1.0f;float zoomX, zoomY;float smoothZoomX, smoothZoomY;private boolean scrolling; // NOPMD by karooolek on 29.06.11 11:45// minimap variablesprivate boolean showMinimap = false;private int miniMapColor = Color.WHITE;private int miniMapHeight = -1;private String miniMapCaption;private float miniMapCaptionSize = 10.0f;private int miniMapCaptionColor = Color.WHITE;// touching variablesprivate long lastTapTime;private float touchStartX, touchStartY;private float touchLastX, touchLastY;private float startd;private boolean pinching;private float lastd;private float lastdx1, lastdy1;private float lastdx2, lastdy2;// drawingprivate final Matrix m = new Matrix();private final Paint p = new Paint();// listenerZoomViewListener listener;private Bitmap ch;public float getZoom() {return zoom;}public float getMaxZoom() {return maxZoom;}public void setMaxZoom(final float maxZoom) {if (maxZoom < 1.0f) {return;}this.maxZoom = maxZoom;}public void setMiniMapEnabled(final boolean showMiniMap) {this.showMinimap = showMiniMap;}public boolean isMiniMapEnabled() {return showMinimap;}public void setMiniMapHeight(final int miniMapHeight) {if (miniMapHeight < 0) {return;}this.miniMapHeight = miniMapHeight;}public int getMiniMapHeight() {return miniMapHeight;}public void setMiniMapColor(final int color) {miniMapColor = color;}public int getMiniMapColor() {return miniMapColor;}public String getMiniMapCaption() {return miniMapCaption;}public void setMiniMapCaption(final String miniMapCaption) {this.miniMapCaption = miniMapCaption;}public float getMiniMapCaptionSize() {return miniMapCaptionSize;}public void setMiniMapCaptionSize(final float size) {miniMapCaptionSize = size;}public int getMiniMapCaptionColor() {return miniMapCaptionColor;}public void setMiniMapCaptionColor(final int color) {miniMapCaptionColor = color;}public void zoomTo(final float zoom, final float x, final float y) {this.zoom = Math.min(zoom, maxZoom);zoomX = x;zoomY = y;smoothZoomTo(this.zoom, x, y);}public void smoothZoomTo(final float zoom, final float x, final float y) {smoothZoom = clamp(1.0f, zoom, maxZoom);smoothZoomX = x;smoothZoomY = y;if (listener != null) {listener.onZoomStarted(smoothZoom, x, y);}}public ZoomViewListener getListener() {return listener;}public void setListner(final ZoomViewListener listener) {this.listener = listener;}public float getZoomFocusX() {return zoomX * zoom;}public float getZoomFocusY() {return zoomY * zoom;}@Overridepublic boolean dispatchTouchEvent(final MotionEvent ev) {// single touchif (ev.getPointerCount() == 1) {processSingleTouchEvent(ev);}// // double touchif (ev.getPointerCount() == 2) {processDoubleTouchEvent(ev);}// redrawgetRootView().invalidate();invalidate();return true;}private void processSingleTouchEvent(final MotionEvent ev) {final float x = ev.getX();final float y = ev.getY();final float w = miniMapHeight * (float) getWidth() / getHeight();final float h = miniMapHeight;final boolean touchingMiniMap = x >= 10.0f && x <= 10.0f + w&& y >= 10.0f && y <= 10.0f + h;if (showMinimap && smoothZoom > 1.0f && touchingMiniMap) {processSingleTouchOnMinimap(ev);} else {processSingleTouchOutsideMinimap(ev);}}private void processSingleTouchOnMinimap(final MotionEvent ev) {final float x = ev.getX();final float y = ev.getY();final float w = miniMapHeight * (float) getWidth() / getHeight();final float h = miniMapHeight;final float zx = (x - 10.0f) / w * getWidth();final float zy = (y - 10.0f) / h * getHeight();smoothZoomTo(smoothZoom, zx, zy);}private void processSingleTouchOutsideMinimap(final MotionEvent ev) {final float x = ev.getX();final float y = ev.getY();float lx = x - touchStartX;float ly = y - touchStartY;final float l = (float) Math.hypot(lx, ly);float dx = x - touchLastX;float dy = y - touchLastY;touchLastX = x;touchLastY = y;switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:touchStartX = x;touchStartY = y;touchLastX = x;touchLastY = y;dx = 0;dy = 0;lx = 0;ly = 0;scrolling = false;break;case MotionEvent.ACTION_MOVE:if (scrolling || (smoothZoom > 1.0f && l > 30.0f)) {if (!scrolling) {scrolling = true;ev.setAction(MotionEvent.ACTION_CANCEL);super.dispatchTouchEvent(ev);}smoothZoomX -= dx / zoom;smoothZoomY -= dy / zoom;return;}break;case MotionEvent.ACTION_OUTSIDE:case MotionEvent.ACTION_UP:// tapif (l < 30.0f) {// check double tapif (System.currentTimeMillis() - lastTapTime < 500) {if (smoothZoom == 1.0f) {smoothZoomTo(maxZoom, x, y);} else {smoothZoomTo(1.0f, getWidth() / 2.0f,getHeight() / 2.0f);}lastTapTime = 0;ev.setAction(MotionEvent.ACTION_CANCEL);super.dispatchTouchEvent(ev);return;}lastTapTime = System.currentTimeMillis();performClick();}break;default:break;}ev.setLocation(zoomX + (x - 0.5f * getWidth()) / zoom, zoomY+ (y - 0.5f * getHeight()) / zoom);ev.getX();ev.getY();super.dispatchTouchEvent(ev);}private void processDoubleTouchEvent(final MotionEvent ev) {final float x1 = ev.getX(0);final float dx1 = x1 - lastdx1;lastdx1 = x1;final float y1 = ev.getY(0);final float dy1 = y1 - lastdy1;lastdy1 = y1;final float x2 = ev.getX(1);final float dx2 = x2 - lastdx2;lastdx2 = x2;final float y2 = ev.getY(1);final float dy2 = y2 - lastdy2;lastdy2 = y2;// pointers distancefinal float d = (float) Math.hypot(x2 - x1, y2 - y1);final float dd = d - lastd;lastd = d;final float ld = Math.abs(d - startd);Math.atan2(y2 - y1, x2 - x1);switch (ev.getAction()) {case MotionEvent.ACTION_DOWN:startd = d;pinching = false;break;case MotionEvent.ACTION_MOVE:if (pinching || ld > 30.0f) {pinching = true;final float dxk = 0.5f * (dx1 + dx2);final float dyk = 0.5f * (dy1 + dy2);smoothZoomTo(Math.max(1.0f, zoom * d / (d - dd)), zoomX - dxk/ zoom, zoomY - dyk / zoom);}break;case MotionEvent.ACTION_UP:default:pinching = false;break;}ev.setAction(MotionEvent.ACTION_CANCEL);super.dispatchTouchEvent(ev);}private float clamp(final float min, final float value, final float max) {return Math.max(min, Math.min(value, max));}private float lerp(final float a, final float b, final float k) {return a + (b - a) * k;}private float bias(final float a, final float b, final float k) {return Math.abs(b - a) >= k ? a + k * Math.signum(b - a) : b;}@Overrideprotected void dispatchDraw(final Canvas canvas) {// do zoomzoom = lerp(bias(zoom, smoothZoom, 0.05f), smoothZoom, 0.2f);smoothZoomX = clamp(0.5f * getWidth() / smoothZoom, smoothZoomX,getWidth() - 0.5f * getWidth() / smoothZoom);smoothZoomY = clamp(0.5f * getHeight() / smoothZoom, smoothZoomY,getHeight() - 0.5f * getHeight() / smoothZoom);zoomX = lerp(bias(zoomX, smoothZoomX, 0.1f), smoothZoomX, 0.35f);zoomY = lerp(bias(zoomY, smoothZoomY, 0.1f), smoothZoomY, 0.35f);if (zoom != smoothZoom && listener != null) {listener.onZooming(zoom, zoomX, zoomY);}final boolean animating = Math.abs(zoom - smoothZoom) > 0.0000001f|| Math.abs(zoomX - smoothZoomX) > 0.0000001f|| Math.abs(zoomY - smoothZoomY) > 0.0000001f;// nothing to drawif (getChildCount() == 0) {return;}// prepare matrixm.setTranslate(0.5f * getWidth(), 0.5f * getHeight());m.preScale(zoom, zoom);m.preTranslate(-clamp(0.5f * getWidth() / zoom, zoomX, getWidth() - 0.5f* getWidth() / zoom),-clamp(0.5f * getHeight() / zoom, zoomY, getHeight() - 0.5f* getHeight() / zoom));// get viewfinal View v = getChildAt(0);m.preTranslate(v.getLeft(), v.getTop());// get drawing cache if availableif (animating && ch == null && isAnimationCacheEnabled()) {v.setDrawingCacheEnabled(true);ch = v.getDrawingCache();}// draw using cache while animatingif (animating && isAnimationCacheEnabled() && ch != null) {p.setColor(0xffffffff);canvas.drawBitmap(ch, m, p);} else { // zoomed or cache unavailablech = null;canvas.save();canvas.concat(m);v.draw(canvas);canvas.restore();}// draw minimapif (showMinimap) {if (miniMapHeight < 0) {miniMapHeight = getHeight() / 4;}canvas.translate(10.0f, 10.0f);p.setColor(0x80000000 | 0x00ffffff & miniMapColor);final float w = miniMapHeight * (float) getWidth() / getHeight();final float h = miniMapHeight;canvas.drawRect(0.0f, 0.0f, w, h, p);if (miniMapCaption != null && miniMapCaption.length() > 0) {p.setTextSize(miniMapCaptionSize);p.setColor(miniMapCaptionColor);p.setAntiAlias(true);canvas.drawText(miniMapCaption, 10.0f,10.0f + miniMapCaptionSize, p);p.setAntiAlias(false);}p.setColor(0x80000000 | 0x00ffffff & miniMapColor);final float dx = w * zoomX / getWidth();final float dy = h * zoomY / getHeight();canvas.drawRect(dx - 0.5f * w / zoom, dy - 0.5f * h / zoom, dx+ 0.5f * w / zoom, dy + 0.5f * h / zoom, p);canvas.translate(-10.0f, -10.0f);}// redrawgetRootView().invalidate();invalidate();}}