Android应用源码之(多触点缩放位图)-IT计算机-毕业设计.zip

package com.mcp; import android.content.Context; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.SurfaceHolder.Callback; /** * * @author Himi * */ public class MySurfaceView extends SurfaceView implements Callback, Runnable { private SurfaceHolder sfh; private Paint paint; private Thread th; private boolean flag; private Canvas canvas; private int screenW, screenH; //声明一张icon位图 private Bitmap bmpIcon; //记录两个触屏点的坐标 private int x1, x2, y1, y2; //倍率 private float rate = 1; //记录上次的倍率 private float oldRate = 1; //记录第一次触屏时线段的长度 private float oldLineDistance; //判定是否头次多指触点屏幕 private boolean isFirst = true; /** * SurfaceView初始化函数 */ public MySurfaceView(Context context) { super(context); sfh = this.getHolder(); sfh.addCallback(this); paint = new Paint(); paint.setAntiAlias(true); setFocusable(true); bmpIcon = BitmapFactory.decodeResource(this.getResources(), R.drawable.icon); } /** * SurfaceView视图创建，响应此函数 */ @Override public void surfaceCreated(SurfaceHolder holder) { screenW = this.getWidth(); screenH = this.getHeight(); flag = true; //实例线程 th = new Thread(this); //启动线程 th.start(); } /** * 游戏绘图 */ public void myDraw() { try { canvas = sfh.lockCanvas(); if (canvas != null) { canvas.drawColor(Color.WHITE); canvas.save(); //缩放画布(以图片中心点进行缩放，XY轴缩放比例相同) canvas.scale(rate, rate, screenW / 2, screenH / 2); //绘制位图icon canvas.drawBitmap(bmpIcon, screenW / 2 - bmpIcon.getWidth() / 2, screenH / 2 - bmpIcon.getHeight() / 2, paint); canvas.restore(); //便于观察，这里绘制两个触点时形成的线段 canvas.drawLine(x1, y1, x2, y2, paint); } } catch (Exception e) { // TODO: handle exception } finally { if (canvas != null) sfh.unlockCanvasAndPost(canvas); } } /** * 触屏事件监听 */ @Override public boolean onTouchEvent(MotionEvent event) { //用户手指抬起默认还原为第一次触屏标识位，并且保存本次的缩放比例 if (event.getAction() == MotionEvent.ACTION_UP) { isFirst = true; oldRate = rate; } else { x1 = (int) event.getX(0); y1 = (int) event.getY(0); x2 = (int) event.getX(1); y2 = (int) event.getY(1); if (event.getPointerCount() == 2) { if (isFirst) { //得到第一次触屏时线段的长度 oldLineDistance = (float) Math.sqrt(Math.pow(event.getX(1) - event.getX(0), 2) + Math.pow(event.getY(1) - event.getY(0), 2)); isFirst = false; } else { //得到非第一次触屏时线段的长度 float newLineDistance = (float) Math.sqrt(Math.pow(event.getX(1) - event.getX(0), 2) + Math.pow(event.getY(1) - event.getY(0), 2)); //获取本次的缩放比例 rate = oldRate * newLineDistance / oldLineDistance; } } } return true; } /** * 按键事件监听 */ @Override public boolean onKeyDown(int keyCode, KeyEvent event) { return super.onKeyDown(keyCode, event); } /** * 游戏逻辑 */ private void logic() { } @Override public void run() { while (flag) { long start = System.currentTimeMillis(); myDraw(); logic(); long end = System.currentTimeMillis(); try { if (end - start < 50) { Thread.sleep(50 - (end - start)); } } catch (InterruptedException e) { e.printStackTrace(); } } } /** * SurfaceView视图状态发生改变，响应此函数 */ @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { } /** * SurfaceView视图消亡时，响应此函数 */ @Override public void surfaceDestroyed(SurfaceHolder holder) { flag = false; } }