BitMap位图

1.图片压缩
2.初始化方式

mBitmap= BitmapFactory.decodeResource(getResources(), R.mipmap.bb);
mBitmap=Bitmap.createBitmap(wide,height,Bitmap.Config.ARGB_8888);

3.得到位图的宽和高

bitmapwide=mBitmap.getWidth();
        bitmapheight=mBitmap.getHeight();

4.平移，旋转，缩放，斜切，对称，matrix矩阵

//x和y方向上各放大多少倍
        matrix.reset();
        matrix.postScale(2, 2);//缩小0.5f
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        canvas.drawBitmap(mBitmap, 0, 0, mPaint);//显示原图，其中0表示原图中需要扣出来的矩形，0表示新建的图位置的矩形

        matrix.reset();
        matrix.postTranslate(0, bitmapheight * 2);//x坐标不动，y坐标平移两倍高度长
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        matrix.reset();
        matrix.postRotate(180);//旋转180度，不注明中心的话默认以左上角为中心
        matrix.postTranslate(bitmapwide * 2, bitmapheight * 3);
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        matrix.reset();
        float matrix_values[]={1f,0f,0f,0f,-1f,0f,0f,0f,1f};//关于x轴对称，倒影效果
        matrix.setValues(matrix_values);
        matrix.postTranslate(0, bitmapheight * 2);
        canvas.drawBitmap(mBitmap,matrix,mPaint);

        matrix.reset();
        float matrix_values2[]={-1f,0f,0f,0f,1f,0f,0f,0f,1f};//关于Y轴对称，镜面效果
        matrix.setValues(matrix_values2);
        matrix.postTranslate(bitmapwide * 2, 0);
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        matrix.reset();
        matrix.setSkew(0.5f, 0.5f);// 斜切
        matrix.postScale(0.5f, 0.5f);// 缩小为原来的一半
        canvas.drawBitmap(mBitmap,matrix,mPaint);

5.PorterDuffXfermode

PorterDuffXfermode mode=new PorterDuffXfermode(PorterDuff.Mode.XOR);
        mPaint_square.setXfermode(mode);//必须画在Bitmap上

//onmeasure方法中
mBitmap=Bitmap.createBitmap(wide,height,Bitmap.Config.ARGB_8888);
        canvasBit=new Canvas(mBitmap);//在bitmap上创建一个画布


//draw方法中
canvas.drawColor(Color.RED);

        canvasBit.drawCircle(wide / 2, height / 2, wide / 2, mPaint_circle);
        canvasBit.drawRect(0, 0, wide / 2, height / 2, mPaint_square);

        canvas.drawBitmap(mBitmap,0,0,null);

6.OnTouchEvent 所有View都有此方法
Action_Down按下瞬间 Action_Move 移动 Action_up抬起 发生的事件
7.观察者模式
View中

public interface OnItemSelect{
        public void onItemSelected(int index,char letter);
    }
    private OnItemSelect listener;

    public void setOnItemSelectListener(OnItemSelect listener) {
        this.listener = listener;
    }

代码中使用匿名内部类