点击触控


package com.example.day04_1;

import android.app.Activity;

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Matrix;

import android.graphics.Paint;

import android.os.Bundle;

import android.util.DisplayMetrics;

import android.view.Menu;

import android.view.MenuItem;

import android.view.MotionEvent;

import android.view.SurfaceHolder;

import android.view.SurfaceView;

import android.view.WindowManager;

public class MainActivity extends Activity {

//声明holder

SurfaceHolder holder;

//获取屏幕的宽度和高度

int width;

int height;

//图片的x,y周

int imageX;

int imageY;

//图片的宽度和高度

int imageW;

int imageH;

//bitmap对象

Bitmap bitmap;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

//屏幕宽度和高度

DisplayMetrics metric = new DisplayMetrics();

getWindowManager().getDefaultDisplay().getMetrics(metric);

width = metric.widthPixels; // 屏幕宽度（像素）

height = metric.heightPixels; // 屏幕高度（像素）

bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.android_book);

imageW = bitmap.getWidth();

imageH = bitmap.getHeight();

//图片的位置

imageX = (width - imageW)/2;

imageY = (height - imageH)/2;

setContentView(new MySurface(this));

}

//surface

class MySurface extends SurfaceView implements SurfaceHolder.Callback{

public MySurface(Context context) {

super(context);

// TODO Auto-generated constructor stub

holder = getHolder();

holder.addCallback(this);

setFocusable(true);

}

@Override

public void surfaceCreated(SurfaceHolder holder) {

// TODO Auto-generated method stub

SetImage(1.0f, bitmap.getWidth(), bitmap.getHeight());

}

@Override

public void surfaceChanged(SurfaceHolder holder, int format, int width,

int height) {

// TODO Auto-generated method stub

}

@Override

public void surfaceDestroyed(SurfaceHolder holder) {

// TODO Auto-generated method stub

}

}

//绘制图片

public void SetImage(float scalse,int width,int height){

//得到画布

Canvas canvas = holder.lockCanvas();

//画布重绘

canvas.drawColor(Color.BLACK);

//设置画笔

Paint paint = new Paint();

//画矩形

canvas.drawRect(0, 0, width, height, paint);

//得到marix 类

Matrix matrix = new Matrix();

//设置缩放比例

matrix.postScale(scalse, scalse);

//得到缩放后的bitmap

Bitmap bafter = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix, true);

//得到新的bitmap的宽度和高度并且重新计算位置

imageW = bafter.getWidth();

imageH = bafter.getHeight();

imageX = (width - imageW)/2;

imageY = (height - imageH)/2;

//平移过去

canvas.translate(imageX, imageY);

//重新绘制bitmap

canvas.drawBitmap(bitmap, matrix, paint);

//解锁

holder.unlockCanvasAndPost(canvas);

}

@Override

public boolean onTouchEvent(MotionEvent event) {

// TODO Auto-generated method stub

//获取触控点个数

int pointcount = event.getPointerCount();

//两个点代表双点触控

if(pointcount == 2){

//获取两个点的距离

float pointA = event.getX(0);

float PointB = event.getX(1);

//判断那个比较大

//如果前面小于后面换

if(pointA<PointB){

float t = pointA;

pointA = PointB;

PointB = t;

}

//只要手指不抬起来,就进行缩放

if(!(event.getAction()==MotionEvent.ACTION_UP)){

float scale = getScale(pointA, PointB)/3;

SetImage(scale,bitmap.getWidth(), bitmap.getHeight());

}

}

return super.onTouchEvent(event);

}

//缩放比

public float getScale(float pointA,float PointB){

float scale = pointA/PointB;

return scale;

}

}