Android绘图：自定义View——路径（Path）、贝塞尔曲线（绘制可动的波浪线）、Bitmap

更多贝塞尔曲线细节可参照：http://blog.csdn.net/flash129/article/details/8234599

Path的介绍

Path就像它的原本的意思一样是路径的意思，它可以根据设置点来绘制各种图形。

Path的初始化也是用new完成的。一般在第二个构造器中。
Path的对象用path.moveTo(100,100);设置起始位置， 即我们下笔的位置path.lineTo(0,200);设置下一个位置。当需要一个闭合图形时最后调用
path.close();//收尾连接.
在path中还定义了一些特殊的图形，例如圆。与canvas直接调用方法画圆的方法有些不同，这里还指出了方向Path.Direction.CCW表示逆时针，Path.Direction.CW表示顺时针。

BitMap的用法

BitMap就是将某个图像写到自定义的View中并可以对其进行包括平移，旋转缩放等操作。
BitMap的初始化:
mbitMap= BitmapFactory.decodeResource(getResources(), R.mipmap.aa);//对BitMap初始化。R.mipmap.aa就是我们进行写入的图片。

可以通过调用bitwidth=mbitMap.getWidth();
bitheigt=mbitMap.getHeight();获得图片的宽度和高度。
在 onDraw（）中调用 canvas.drawBitmap(bitmap,0,0,mpaint);就可以将图片画到画布上。（0，0）是图片开始的位置。

Matrix(矩阵)的功能

可以通过Matrix的值的设置对图片进行平移，旋转，缩放等操作。
Matrix的初始化为： private Matrix matrix=new Matrix （）；
matrix.reset();为将matrix中的数据清空，恢复为默认值。

PorterDuffXfermode是用来干啥的呢？

它是设置paint的画图模式的。
当我们不是根据现有的图片在画布上进行BiMap绘制的时候，想自己画一些集合图形的时候，就必须在BitMap上再创建一个Canvas，在这个Canvas上进行绘制，最后再调用原有的Canvas进行绘制。

用法

1、建立PorterDuffXfermode的对象，并设置相应的mode。
PorterDuffXfermode mode = new PorterDuffXfermode(PorterDuff.Mode.XOR);

2、当建立了mode，就要设置到相应的画笔上：

代码如下：

PorterDuffXfermode mode=new PorterDuffXfermode(PorterDuff.Mode.DST_OUT);
mPaintRect.setXfermode(mode);

3、既然是自定义的bitmap就一定要设置其宽度和高度。一般在onMeasure方法中设置，因为我们可能要用到View的宽和高。只有运行到onMeasure才能获得View的宽和高。
mBitmap=Bitmap.createBitmap(mWidth,mHeight,Bitmap.Config.ARGB_8888);

4、新建一个Canvas，并将其设置为BitMap的。在onMeasure中代码如下：
private Canvas canvasBit;

 canvasBit=new Canvas(mBitmap);

5、效果图

相应的mode对应的效果图如下：

画可动的波浪线

public class MyPathView extends View {
    private Paint mPaint;
    private Paint mPaintPoint;
    private int mWidth;
    private int mHeight;
    private Path mPath;
    private static final int NEED_INVALIDATE=0X23;
    private int count=0;
    private int size=0;
    private boolean isAdd=true;
    private Handler handler=new Handler(){
        @Override
        public void handleMessage(Message msg) {
            super.handleMessage(msg);
            switch (msg.what){
                case NEED_INVALIDATE:
                    count+=5;


                    if (count>160){
                        count=0;
                    }
                    if (isAdd){
                        size++;
                        if (size>20){
                            isAdd=false;
                        }
                    }else {
                        size--;
                        if (size<-21){
                            isAdd=true;
                        }
                    }
                    invalidate();
                    handler.sendEmptyMessageDelayed(NEED_INVALIDATE,50);
                    break;
            }
        }
    };
    public MyPathView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint=new Paint();
        mPaint.setColor(Color.GREEN);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);
        mPaint.setTextSize(50);
        mPath=new Path();


        mPaintPoint=new Paint();
        mPaintPoint.setColor(Color.RED);
        mPaintPoint.setStrokeWidth(10);
        mPaintPoint.setStyle(Paint.Style.STROKE);
        handler.sendEmptyMessageDelayed(NEED_INVALIDATE,100);
    }

    public MyPathView(Context context) {
        super(context);


    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        mHeight = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }
     mPath.reset();//重置，避免波浪线加宽
        mPath.moveTo(count, mHeight / 2);

        for (int i=0;i<10;i++){
            mPath.rQuadTo(50,size,80,0);
            mPath.rQuadTo(50,-size,80,0);
        }

        canvas.drawPath(mPath, mPaint);
        canvas.drawCircle(mWidth/2,mHeight/2,150,mPaintPoint);

    }
}

图片

画弧线

public class MyPathView extends View {
    private Paint mPaint;
    private Paint mPaintPoint;
    private int mWidth;
    private int mHeight;
    private Path mPath;
    public MyPathView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint=new Paint();
        mPaint.setColor(Color.GREEN);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);
        mPaint.setTextSize(50);
        mPath=new Path();


        mPaintPoint=new Paint();
        mPaintPoint.setColor(Color.RED);
        mPaintPoint.setStrokeWidth(10);
        mPaintPoint.setStyle(Paint.Style.STROKE);
        handler.sendEmptyMessageDelayed(NEED_INVALIDATE,100);
    }

    public MyPathView(Context context) {
        super(context);


    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        mHeight = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }
 mPath.moveTo(100,100);//贝塞尔曲线开始点的坐标
        mPath.quadTo(100, 400, 300, 300);//前两个为控制点坐标，后两个是结束点坐标
        canvas.drawPath(mPath, mPaint);
        canvas.drawPoint(100,100,mPaintPoint);
        canvas.drawPoint(100,400,mPaintPoint);
        canvas.drawPoint(300,300,mPaintPoint);

>

画三角形

public class MyPathView extends View {
    private Paint mPaint;
    private Paint mPaintPoint;
    private int mWidth;
    private int mHeight;
    private Path mPath;
    public MyPathView(Context context, AttributeSet attrs) {
        super(context, attrs);
        mPaint=new Paint();
        mPaint.setColor(Color.GREEN);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeWidth(5);
        mPaint.setTextSize(50);
        mPath=new Path();


        mPaintPoint=new Paint();
        mPaintPoint.setColor(Color.RED);
        mPaintPoint.setStrokeWidth(10);
        mPaintPoint.setStyle(Paint.Style.STROKE);
        handler.sendEmptyMessageDelayed(NEED_INVALIDATE,100);
    }

    public MyPathView(Context context) {
        super(context);


    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        mHeight = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        mPath.moveTo(100, 100);
        mPath.lineTo(0, 200);
        mPath.lineTo(200, 200);
        mPath.addCircle(mWidth/2,mHeight/2,300,Path.Direction.CCW);
        mPath.close();//前面设置为空心的时候需要关闭画线。
        canvas.drawPath(mPath,mPaint);
        canvas.drawTextOnPath("请把这个沿着三角形的边写上去",mPath,0,0,mPaint);

图片

布局

<com.example.administrator.definedviewdemo.Wiget.MyPathView
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

Bitmap（图片）——放大、缩小、平移、旋转、错切、对称

public class MyBitMap extends View {
    private int mWidth;
    private int mHeight;
    private Paint mPaint;
    private Bitmap mBitmap;
    private Matrix matrix;
    private int mBitmapWidth;
    private int mBitmapHeight;
    public MyBitMap(Context context) {
        super(context);
    }

    public MyBitMap(Context context, AttributeSet attrs) {
        super(context, attrs);
        mBitmap= BitmapFactory.decodeResource(getResources(), R.mipmap.childen);
        mPaint=new Paint();
        matrix=new Matrix();
        mBitmapWidth=mBitmap.getWidth();
        mBitmapHeight=mBitmap.getHeight();
        Log.d("bitmap1","高："+mBitmap.getHeight()+"宽"+mBitmap.getWidth());
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        mWidth = getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec);
        mHeight = getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec);
        setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec),
                getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec));
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
          canvas.drawBitmap(mBitmap, 0, 0, mPaint);
        matrix.reset();
        canvas.drawBitmap(mBitmap, matrix, mPaint);
        matrix.postScale(2, 2);//放大，缩小
        canvas.drawBitmap(mBitmap, matrix, mPaint);
        matrix.reset();
        canvas.drawBitmap(mBitmap, matrix, mPaint);//可以不用
        matrix.postTranslate(0, mBitmapHeight * 2);//平移
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        matrix.reset();
        matrix.postRotate(180);//旋转 必须和后面这句postTranslate同时用
        matrix.postTranslate(mBitmapWidth, mBitmapHeight);
        canvas.drawBitmap(mBitmap, matrix, mPaint);

        matrix.reset();
        matrix.postSkew(0, 1);//错切
        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
        matrix.setValues(matrix_values);
        matrix.postTranslate(0, mBitmapHeight * 1);
        canvas.drawBitmap(mBitmap, matrix, mPaint);


        matrix.reset();
        float matrix_values2[] = {-1f, 0f, 0f, 0f, 1f, 0f, 0f, 0f, 1f};//沿y轴翻转
        matrix.setValues(matrix_values2);
        matrix.postTranslate(mBitmapWidth*2, 0);
        canvas.drawBitmap(mBitmap, matrix, mPaint);
    }
}

布局

<com.example.administrator.definedviewdemo.Wiget.MyBitMap
        android:layout_width="match_parent"
        android:layout_height="match_parent" />