Android Canvas API总结和使用方法

//Canvas 操作函数 2015年5月15日 Android 4.4

int MATRIX_SAVE_FLAG = 0x01;
int CLIP_SAVE_FLAG = 0x02;
int HAS_ALPHA_LAYER_SAVE_FLAG = 0x04;
int FULL_COLOR_LAYER_SAVE_FLAG = 0x08;
int CLIP_TO_LAYER_SAVE_FLAG = 0x10;
int ALL_SAVE_FLAG = 0x1F;
int DIRECTION_LTR = 0;

Canvas();
Canvas(Bitmap bitmap);

boolean isHardwareAccelerated();
void setBitmap(Bitmap bitmap);
boolean isOpaque();
int getWidth();
int getHeight();
int getDensity();
void setDensity( int density);
int getMaximumBitmapWidth();
int getMaximumBitmapHeight();

//图层保存与恢复操作
int save();    //保存当前图层
int save( int saveFlags);
//保存指定区域图层
//paint为要保存的画笔，restore()后可以用。一般为null
//saveFlags为要保存的内容
int saveLayer(RectF bounds, Paint paint, int saveFlags);
int saveLayer( float left, float top, float right, float bottom, Paint paint, int saveFlags);
//保存指定区域图层，并修改其透明度
int saveLayerAlpha(RectF bounds, int alpha, int saveFlags);
int saveLayerAlpha( float left, float top, float right, float bottom, int alpha, int saveFlags);
void restore();          //恢复上一层图层
int getSaveCount();      //获得已只在的图层数量
void restoreToCount( int saveCount);   //恢复指定层的图层
//图层变换
void translate( float dx, float dy);
void scale( float sx, float sy);
void scale( float sx, float sy, float px, float py);
void rotate( float degrees);
void rotate( float degrees, float px, float py);
void skew( float sx, float sy);   //扭曲
void concat(Matrix matrix);   //Maxrix矩阵变换

void setMatrix(Matrix matrix);
void getMatrix(Matrix ctm);
Matrix getMatrix();
//裁剪
boolean clipRect(RectF rect, Region.Op op);
boolean clipRect(Rect rect, Region.Op op);
boolean clipRect(RectF rect);
boolean clipRect(Rect rect);
boolean clipRect( float left, float top, float right, float bottom, Region.Op op);
boolean clipRect( float left, float top, float right, float bottom);
boolean clipRect( int left, int top, int right, int bottom);
boolean clipPath(Path path, Region.Op op);
boolean clipPath(Path path);
boolean clipRegion(Region region, Region.Op op);
boolean clipRegion(Region region);

DrawFilter getDrawFilter();
void setDrawFilter(DrawFilter filter);
boolean quickReject(RectF rect, EdgeType type);
boolean quickReject(Path path, EdgeType type);
boolean quickReject( float left, float top, float right, float bottom, EdgeType type);
boolean getClipBounds(Rect bounds);
Rect getClipBounds();

//填充RGB
void drawRGB( int r, int g, int b);
void drawARGB( int a, int r, int g, int b);
//填充Color
void drawColor( int color);
void drawColor( int color, PorterDuff.Mode mode);
//指定画笔
void drawPaint(Paint paint);
//画点
void drawPoints( float[] pts, int offset, int count, Paint paint);
void drawPoints( float[] pts, Paint paint);
void drawPoint( float x, float y, Paint paint);
//画直线
void drawLine( float startX, float startY, float stopX, float stopY, Paint paint);
void drawLines( float[] pts, int offset, int count, Paint paint);   //pts数组里的每两个元素为一个点，每两个点画一条直线
void drawLines( float[] pts, Paint paint);
//画矩形
void drawRect(RectF rect, Paint paint);
void drawRect(Rect r, Paint paint);
void drawRect( float left, float top, float right, float bottom, Paint paint);
//画椭圆
void drawOval(RectF oval, Paint paint);
//画圆
void drawCircle( float cx, float cy, float radius, Paint paint);
//画弧,扇形
void drawArc(RectF oval, float startAngle, float sweepAngle, boolean useCenter, Paint paint);
//画圆角矩形
void drawRoundRect(RectF rect, float rx, float ry, Paint paint);
//画路径
void drawPath(Path path, Paint paint);
//画位图
void drawBitmap(Bitmap bitmap, float left, float top, Paint paint);
void drawBitmap(Bitmap bitmap, Rect src, RectF dst, Paint paint);
void drawBitmap(Bitmap bitmap, Rect src, Rect dst, Paint paint);
void drawBitmap( int[] colors, int offset, int stride, float x, float y, int width, int height, boolean hasAlpha,
void drawBitmap( int[] colors, int offset, int stride, int x, int y, int width, int height, boolean hasAlpha, Paint paint);
void drawBitmap(Bitmap bitmap, Matrix matrix, Paint paint);
void drawBitmapMesh(Bitmap bitmap, int meshWidth, int meshHeight, float[] verts, int vertOffset, int[] colors, int colorOffset, Paint paint);
//画顶点
void drawVertices(VertexMode mode, int vertexCount, float[] verts, int vertOffset, float[] texs, int texOffset, int[] colors, int colorOffset, short[] indices, int indexOffset,
//画字
void drawText( char[] text, int index, int count, float x, float y, Paint paint);
void drawText( String text, float x, float y, Paint paint);
void drawText( String text, int start, int end, float x, float y, Paint paint);
void drawText(CharSequence text, int start, int end, float x, float y, Paint paint);
//绝对值画字
void drawPosText( char[] text, int index, int count, float[] pos, Paint paint);
void drawPosText( String text, float[] pos, Paint paint);
//根据路径画字
void drawTextOnPath( char[] text, int index, int count, Path path, float hOffset, float vOffset, Paint paint);
void drawTextOnPath( String text, Path path, float hOffset, float vOffset, Paint paint);
//画图片
void drawPicture(Picture picture);
void drawPicture(Picture picture, RectF dst);
void drawPicture(Picture picture, Rect dst);

Canvas draw系列函数用法示例：

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public class MyCanvasDrawView extends View {

private static final String TAG = null;

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

    }

    @Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//设置背景颜色
        canvas.drawColor(Color.WHITE);
//画弧
        drawMultArc(canvas);
//画路径和文字
        drawPathWithText(canvas);
//画直线
        drawLine(canvas);
//sample
        drawCompass(canvas, 10, 400);
    }

public void drawLine(Canvas canvas) {
        Paint paint = new Paint();
        paint.setColor(Color.YELLOW);
        paint.setStrokeWidth( 5);
float offset = 150 / 6;
float leveOff = 150 / 4;
float[] pts = {600f + offset * 2, 400f - leveOff * 2, 750f - offset * 2, 400f - leveOff * 2,
                       600f + offset, 400f - leveOff , 750f - offset, 400f - leveOff,
                       600f, 400f , 750f, 400f
                      };
        canvas.drawLines(pts , paint);
    }

public void drawMultArc(Canvas canvas) {
        Paint[] mPaints;
boolean[] mUseCenters;
        RectF[] mRectF;

//边框的画笔
        Paint rectPaint = new Paint();
        rectPaint.setAntiAlias(true);
        rectPaint.setColor(Color.GRAY);
        rectPaint.setStyle(Paint.Style.STROKE);
        rectPaint.setStrokeWidth( 5);

        mUseCenters = new boolean[ 4];
        mPaints = new Paint[ 4];
        mRectF = new RectF[ 4];

        initDrawMultArc(mPaints, mUseCenters);

        _drawMultArc(canvas, mPaints, mUseCenters, mRectF, rectPaint);
    }

public void initDrawMultArc(Paint[] mPaints, boolean[] mUseCenters) {
//      1. 填充圆弧但不含圆心：
        mPaints[ 0] = new Paint();
        mPaints[ 0].setAntiAlias(true);
        mPaints[ 0].setStyle(Paint.Style.FILL);
        mPaints[ 0].setColor(0x88FF0000);
        mUseCenters[ 0] = false;

//      2. 填充圆弧带圆心（扇形）
        mPaints[ 1] = new Paint(mPaints[ 0]);
        mPaints[ 1].setColor(0x8800FF00);
        mUseCenters[ 1] = true;

//      3. 只绘圆周，不含圆心
        mPaints[ 2] = new Paint(mPaints[ 0]);
        mPaints[ 2].setStyle(Paint.Style.STROKE);
        mPaints[ 2].setStrokeWidth( 4);
        mPaints[ 2].setColor(0x880000FF);
        mUseCenters[ 2] = false;

//      4. 只绘圆周，带圆心（扇形）
        mPaints[ 3] = new Paint(mPaints[ 2]);
        mPaints[ 3].setColor(0x88888888);
        mUseCenters[ 3] = true;
    }

public void _drawMultArc(Canvas canvas, Paint[] mPaints,
boolean[] mUseCenters, RectF[] mRectF, Paint rectPaint) {
int rectLeft = 10;
int rectTop = 50;
int width = 150;
int rectRight = rectLeft + width;
int rectBottom = rectTop + width;
int offest = rectLeft + width + 30 ;

//初始化弧形的区域，决定弧形的开关和位置
         for( int i = 0; i < 4; i++) {
            mRectF[i] = new RectF(rectLeft + i * offest, rectTop, rectRight + i * offest, rectBottom);
        }

        Log.i(TAG, "mRectF[3] " + mRectF[ 3].left + " " + mRectF[ 3].bottom);

/**
         * 参数1：弧形的区域
         * 参数2：起始的角度
         * 参数3：弧形的角度
         * 参数4：是否有中心角度
         */
for ( int i = 0; i < 4; i++ ) {
            canvas.drawArc(mRectF[i], 30, 260, mUseCenters[i], mPaints[i]);
            canvas.drawRect(mRectF[i], rectPaint);
        }
    }

public void drawPathWithText(Canvas canvas) {
        Paint pathPaint = new Paint();
        pathPaint.setARGB( 70, 238, 18, 137);
        pathPaint.setStyle(Paint.Style.FILL);
        pathPaint.setAntiAlias(true);
        pathPaint.setStrokeWidth( 5);

        Path path = new Path();

int pathStartX = 10;
int pathStartY = 250;
int length = 150;
//第一个三角形
        initPath(canvas, pathPaint, path, pathStartX, pathStartY, length);
        canvas.drawPath(path , pathPaint);

//清除path属性
        path.reset();
        pathPaint.setColor(Color.CYAN);
        pathPaint.setStyle(Paint.Style.STROKE);
        pathStartX = length + 50;
//第二个三角形
        initPath(canvas, pathPaint, path, pathStartX, pathStartY, length);
        canvas.drawPath(path , pathPaint);

//第三个图形
        path.reset();
        pathPaint.setColor(Color.DKGRAY);
        pathStartX = (length + 50) * 2;
//逆时针添加一个圆
         //最后一个参数指定构建方法，逆时针和顺时针，并不影响图形效果，但是会影响文字的构建顺序
        path.addCircle(pathStartX +  length / 2 , pathStartY +  length / 2, length / 2, Path.Direction.CCW);
        canvas.drawPath(path , pathPaint);

//设置字体属性
        pathPaint.setStrokeWidth( 1);
        pathPaint.setTextSize( 30);
        pathPaint.setTypeface(Typeface.SERIF);
        canvas.drawTextOnPath( "Android Canvas&Paint", path, 10, 28, pathPaint);
        pathPaint.setTextSize( 25);
        pathPaint.setStyle(Paint.Style.FILL);
        canvas.drawTextOnPath( "Android", path, 10, - 10, pathPaint);
    }

public void drawCompass(Canvas canvas, int startX, int startY) {

        canvas.save();
        Paint paint;
        paint = new Paint(); //设置一个笔刷大小是3的黄色的画笔
        paint.setColor(Color.BLACK);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeCap(Paint.Cap.ROUND);
        paint.setStrokeWidth( 3);

        paint.setAntiAlias(true);
        paint.setStyle(Paint.Style.STROKE);
        canvas.translate(canvas.getWidth() / 2, 200); //移动画纸的坐标点:canvas.getWidth()/2, 200
        canvas.drawCircle(startX, startY, 100, paint); //画圆圈

//使用path绘制路径文字
        canvas.save();      //保存上面图层的信息
        canvas.translate(startX - 75, startY - 75);
        Path path = new Path();
        path.addArc( new RectF( 0, 0, 150, 150), - 145, 180);
        Paint citePaint = new Paint(paint);
        citePaint.setTextSize( 14);
        citePaint.setStrokeWidth( 1);
        citePaint.setColor(Color.GRAY);
        paint.setStyle(Paint.Style.FILL);
        canvas.drawTextOnPath( "my compass", path, 28, 0, citePaint);
        canvas.restore();      //恢复保存的图层

        Paint tmpPaint = new Paint(paint); //小刻度画笔对象
        tmpPaint.setStrokeWidth( 1);

float  y = startY - 100;
int count = 60; //总刻度数

for( int i = 0 ; i < count ; i++) {

if(i % 5 == 0) {
                canvas.drawLine(0f, y, 0f, y - 12f, paint);
                canvas.drawText( String.valueOf( i / 5 ), -4f, y - 20f, tmpPaint);

            } else {
                canvas.drawLine(0f, y, 0f, y - 5f, tmpPaint);
            }
            canvas.rotate( 360 / count, startX, startY); //旋转画纸
        }

//绘制中心点
        tmpPaint.setStyle(Paint.Style.FILL);
        tmpPaint.setColor(Color.GRAY);
        tmpPaint.setStrokeWidth( 4);
        canvas.drawCircle(startX, startY, 7, tmpPaint);
        tmpPaint.setStyle(Paint.Style.FILL);
//绘制指针
        canvas.drawLine(startX, startY,  startX, startY - 65, paint);
        canvas.restore();
    }

public void initPath(Canvas canvas, Paint pathPaint, Path path,
int pathStartX, int pathStartY, int length) {
int pathX = pathStartX;
int pathY = pathStartY;
int pathLength = ( int) Math.sqrt(Math.pow(length, 2) + Math.pow(length, 2));

//设置开始位置
        path.moveTo(pathX, pathY);
        pathX += ( int) (pathLength * Math.cos(Math.toRadians( 45)));
        pathY += ( int) (pathLength * Math.sin(Math.toRadians( 45)));
        path.lineTo(pathX, pathY);
//第二条线
        path.lineTo(pathStartX, pathY);
    }
}

Canvas 平移和形变

Canvas的平移和形变是画面的平移和形变，平衡和形变后会形成新的画布与之前的画面进行合并，并不影响原来的图像

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    @Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
        Paint paint = new Paint();
        paint.setColor(Color.GREEN);
        paint.setStyle(Style.STROKE);
        paint.setStrokeWidth( 3);

//平移
        canvas.save();
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.translate( 25, 10);
        paint.setColor(Color.RED);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.restore();

//旋转
        canvas.save();   //如果不保存最原始的数据，新的平移会以上次的平移为基础
        canvas.translate( 230, 0);
        paint.setColor(Color.GREEN);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.rotate( 30);
        paint.setColor(Color.RED);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.rotate( 30);
        paint.setColor(Color.GRAY);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.restore();

//扭曲
        canvas.save();
        canvas.translate( 360, 0);
        paint.setColor(Color.GREEN);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        paint.setColor(Color.RED);
        canvas.skew( 1.2f, 0);   //X轴倾斜，Y轴不变
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.restore();

//缩放
        canvas.save();
        canvas.translate( 600, 0);
        paint.setStyle(Style.FILL);
        paint.setColor(Color.GREEN);
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        paint.setColor(Color.RED);
        canvas.scale( 0.5f, 0.8f);   //所有坐标按比例缩小
        canvas.drawRect( new Rect( 10, 10, 100, 100), paint);
        canvas.restore();
    }

Canvas 图层的保存与恢复

Canvas的图层保存与恢复是以栈的结构进行保存。遵循都先入后出的原则。通过sava()函数来把当前图层压栈。restore()函数来出栈上一次入栈的图层。也可能通多次调用save()来多次保存图层。 restoreToCount()来恢复指定层数的图层。

saveFlags参数说明

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/** 保存Matrix **/
public static final int MATRIX_SAVE_FLAG = 0x01;
/** 保存Clip **/
public static final int CLIP_SAVE_FLAG = 0x02;
/** 保存Alpha */
public static final int HAS_ALPHA_LAYER_SAVE_FLAG = 0x04;
/** 保存Color */
public static final int FULL_COLOR_LAYER_SAVE_FLAG = 0x08;
/** 保存整个Layer的Clip */
public static final int CLIP_TO_LAYER_SAVE_FLAG = 0x10;
/** 保存所有，很少用 */
public static final int ALL_SAVE_FLAG = 0x1F;

saveLayerAlpha的使用

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canvas.drawColor(Color.WHITE);

canvas.translate( 10, 10);

mPaint.setColor(Color.RED);
canvas.drawCircle( 75, 75, 75, mPaint);
//保存指定区域图层，并修改其透明度
canvas.saveLayerAlpha( 0, 0, 200, 200, 0x55, LAYER_FLAGS);
mPaint.setColor(Color.BLUE);
//设置整个图层的透明度。在这里和上面的效果一样，但是要在setColor后面
// mPaint.setAlpha(70);
canvas.drawCircle( 125, 125, 75, mPaint);

canvas.restore();

Canvas Region API总结

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//Region API Android4.4 2015年5月16日
/**构造方法*/
Region();                    //创建一个空的区域
Region(Region region);       //拷贝一个region
Region(Rect r);              //根据Rect创建
Region( int left, int top, int right, int bottom); //创建一个矩形的区域

/*设置函数方法*/
void setEmpty();
boolean set(Region region); //利用新的区域值来替换原来的区域
boolean set(Rect r);         //利用矩形所代表的区域替换原来的区域
boolean set( int left, int top, int right, int bottom); //根据矩形的两个点构造出矩形区域来替换原来的区域值
boolean setPath(Path path, Region clip);     //根据路径的区域与某区域的交集，构造出新区域

//判断
boolean isEmpty();
boolean isRect();
boolean isComplex();

//返回边界
Rect getBounds();
boolean getBounds(Rect r);
Path getBoundaryPath();
boolean getBoundaryPath(Path path);

//判断是否相交
boolean contains( int x, int y);      //是否有包含某点
boolean quickContains(Rect r);       //是否有包含矩区域
boolean quickContains( int left, int top, int right,   //根据两点是有否包含矩区域
boolean quickReject(Rect r);         //是否没包含矩形
boolean quickReject( int left, int top, int right, int bottom); //根据两点是否没包含矩区域
boolean quickReject(Region rgn);     //是否没和该矩阵相交

//平移和变换
void translate( int dx, int dy);
void translate( int dx, int dy, Region dst);
void scale( float scale);             //hide
void scale( float scale, Region dst); //hide

//组合
boolean union(Rect r);
boolean op(Rect r, Op op);
boolean op( int left, int top, int right, int bottom, Op op);
boolean op(Region region, Op op);
boolean op(Rect rect, Region region, Op op);
boolean op(Region region1, Region region2, Op op);
//组合方式：假设用region1  去组合region2
public enum Op {
        DIFFERENCE( 0), //最终区域为region1 与 region2不同的区域
        INTERSECT( 1), // 最终区域为region1 与 region2相交的区域
        UNION( 2),       //最终区域为region1 与 region2组合一起的区域
        XOR( 3),         //最终区域为region1 与 region2相交之外的区域
        REVERSE_DIFFERENCE( 4), //最终区域为region2 与 region1不同的区域
        REPLACE( 5); //最终区域为为region2的区域
}
int describeContents();
void writeToParcel(Parcel p, int flags);

Canvas Region用法示例

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@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);

    Paint paint = new Paint();
    paint.setColor(Color.RED);
    paint.setStyle(Style.STROKE);
    paint.setStrokeWidth( 2);
    Path path = new Path();

//总的显示荡然无存
    RectF rectf = new RectF( 50, 50, 200, 500);
    path.addOval(rectf, Direction.CCW);

    Region rgn = new Region();
//会显示的区域
    rgn.setPath(path, new Region( 50, 50, 300, 600));

    drawRegion(canvas, rgn, paint);
}

private void drawRegion(Canvas canvas, Region rgn, Paint paint) {
//把要显示的图像能过一个矩形组合来显示,放大显示出来的图像会发觉由很多小的矩形组成
    RegionIterator iter = new RegionIterator(rgn);
    Rect r = new Rect();

while (iter.next(r)) {
        canvas.drawRect(r, paint);
    }
}

Canvas clip系列函数用法示例

clip意为剪切，其实我觉得在这里意思为选中更为贴切，因为只有选中的区域才会操作有效。

public class MyClipView extends View {
     private Paint mPaint;
     private Path mPath;

     public MyClipView(Context context) {
         super(context);
        setFocusable(true);

        mPaint = new Paint();
        mPaint.setAntiAlias(true);
        mPaint.setStrokeWidth( 6);
        mPaint.setTextSize( 16);
        mPaint.setTextAlign(Paint.Align.RIGHT);

        mPath = new Path();
    }

     private void drawScene(Canvas canvas) {
         //下面的画图只在已被剪切的范围内有效
       canvas.clipRect( 0, 0, 100, 100);

        canvas.drawColor(Color.WHITE);

        mPaint.setColor(Color.RED);
        canvas.drawLine( 0, 0, 100, 100, mPaint);

        mPaint.setColor(Color.GREEN);
        canvas.drawCircle( 30, 70, 30, mPaint);

        mPaint.setColor(Color.BLUE);
        canvas.drawText( "Clipping", 100, 30, mPaint);
    }

    @Override protected void onDraw(Canvas canvas) {
//        canvas.drawColor(Color.GRAY);

         //没有被多次剪切的情况
        canvas.save();
        canvas.translate( 10, 10);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 160, 10);
        canvas.clipRect( 10, 10, 90, 90);
        canvas.clipRect( 30, 30, 70, 70, Region.Op.DIFFERENCE);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 10, 160);
        mPath.reset();
        canvas.clipPath(mPath); // makes the clip empty
        mPath.addCircle( 50, 50, 50, Path.Direction.CCW);
        canvas.clipPath(mPath, Region.Op.REPLACE);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 160, 160);
        canvas.clipRect( 0, 0, 60, 60);
        canvas.clipRect( 40, 40, 100, 100, Region.Op.UNION);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 10, 310);
        canvas.clipRect( 0, 0, 60, 60);
        canvas.clipRect( 40, 40, 100, 100, Region.Op.INTERSECT);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 160, 310);
        canvas.clipRect( 0, 0, 60, 60);
        canvas.clipRect( 40, 40, 100, 100, Region.Op.XOR);
        drawScene(canvas);
        canvas.restore();

        canvas.save();
        canvas.translate( 10, 460);
        canvas.clipRect( 0, 0, 60, 60);
        canvas.clipRect( 40, 40, 100, 100, Region.Op.REVERSE_DIFFERENCE);
        drawScene(canvas);
        canvas.restore();

    }
}

加入顶点

参考文章：

http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2012/1212/703.html

http://blog.csdn.net/lonelyroamer/article/details/8349601

http://blog.csdn.net/harvic880925/article/details/38875149