Android小知识

Android一些琐碎小知识的积累记录,不定期更~

mDrawable.draw(canvas)使用;

Drawable mDrawable = getResources().getDrawable(R.drawable.music);//获取drawable图像的真实宽高int dHeight = mDrawable.getIntrinsicHeight();int dWidth = mDrawable.getintrinsicWidth();//在调用mDrawable.draw()方法前,必须要对mDrawable进行setBounds()mDrawable.setBounds(0, 0, dWidth, dHeight);//将mDrawable的图像信息画到画布上mDrawable.draw(canvas);

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Camera和Matrix简单使用

init();

Camera mCamera = new Camera();Matrix mMatrix = new Matrix();//设置camera的Z轴投射坐标,避免出现呼脸效果mCamera.setLocation(0, 0, 100);

onDraw();

//使用MatrixmCamera.save();mMatrix.reset();mCamera.rotateX(degree);mCamera.getMatrix(mMatrix);mCamera.restore();​mMatrix.preTranslate(-centerX, -centerY);mMatrix.postTranslate(centerX, centerY);mCanvas.concat(mMatrix);​mCanvas.drawXXX();mCanvas.restore();

//直接使用canvas.translatemCamera.save();mCamera.retateX(degree);mCanvas.translate(centerX, centerY);mCamera.applyToCanvas(canvas);mCanvas.translate(-centerX, -centerY);mCamera.restore();​mCanvas.drawXXX();mCanvas.restore();

HandlerThread简单使用

HandlerThread其实是内部建立了Looper的Thread.(新建线程是没有开启消息循环的)

注意:HandlerThread仍为普通线程,串行执行任务

private HandlerThread mHandlerThread;private Handler mHander;​onCreate(){    ...    //创建HandlerThread,并将线程命名为:handlerThread    mHandlerThread = new HandlerThread("handlerThread");    mHandlerThread.start();    mHandler = new Handler(mHandlerThread.getLooper){        @Overtide        public void handleMessage(Message msg){            super.handleMessage(msg);            //该方法运行在HandlerThread线程中,可执行耗时操作            Log.e("Msg:", msg.what + "线程 : " + Thread.currentThread().getName());        }    }      mHandler.sendEmptyMessage(0);    //使用post同样可以将run()操作运行在HandlerThread中    mHandler.post(new Runnable() {                @Override                public void run() {                    Log.e("Msg:", 1 + "线程 : " + Thread.currentThread().getName());                }            });  }​

Log:Msg:0 线程 : handlerThreadMsg:1 线程 : handlerThread