Canvas clipping and region, Regioniterator

Mainly to look this article study: http://blog.csdn.net/lonelyroamer/article/details/8349601

Region.op parameters

1. difference (0),  //final area region1  and   Region2 different area  
2. intersect (1),  //  the final area is region1  with  region2;
3. union (2),       // The final area is the area    of the region1  and  region2 combination;
4. XOR (3),         //the final area is an area outside the region1 - region2 intersection   
5. reverse_difference (4),  //the final area is region2  and  region1 different areas   
6. REPLACE (5)  //the final area region2 for  

Canvas Cropping related methods:

1, the most basic cliprect, cutting a rectangle

2, Clippath, clipping path includes the scope, path includes the scope is not empty to be effective.

3, Clipregion.

 Public classCustomViewextendsView {Privatecontext Context; //brush variables, must be created    PrivatePaint paint; Privatepath Path;  PublicCustomView (Context context) {Super(context);  This. Context =context;    Initview (); }     PublicCustomView (context context, AttributeSet attrs,intdefstyleattr) {        Super(context, attrs, defstyleattr);  This. Context =context;    Initview (); }     PublicCustomView (Context context, AttributeSet attrs) {Super(context, attrs);  This. Context =context;    Initview (); }    Private voidInitview () {Paint=NewPaint (); //anti-aliasingPaint.setantialias (true); Paint.settextsize (6); //where to draw text//Paint.Align.CENTER//Paint.Align.LEFT//Paint.Align.LEFTpaint.settextalign (Paint.Align.RIGHT); Path=NewPath (); } @Overrideprotected voidOnDraw (canvas canvas) {Super. OnDraw (canvas); //Setting the canvas colorCanvas.drawcolor (Color.yellow); //Specific Explanation:http://www.jcodecraeer.com/a/anzhuokaifa/androidkaifa/2013/0304/960.html        //Save : Used to save the state of the canvas.        After save, you can invoke canvas panning, indenting, rotating, trimming, cropping, and so on. //Restore : The state used to restore the canvas before it is saved. Preventing the actions that are performed on the canvas after save has an impact on subsequent drawing. Canvas.save (); //Canvas for horizontal movementCanvas.translate (10, 10);        Drawscene (canvas);        Canvas.restore (); //Start crop Operation//Save the canvas state firstCanvas.save (); Canvas.translate (160, 10); Canvas.cliprect (20, 20, 100, 100); //region, Chinese meaning is the meaning of an area, which represents a block of closed area on a canvas layer. //refer to http://blog.csdn.net/lonelyroamer/article/details/8349601//Region.Op.INTERSECT//Region.Op.REPLACE//Region.Op.REVERSE_DIFFERENCE//Region.Op.UNION//Region.Op.XOR//Region.Op.DIFFERENCECanvas.cliprect (40, 40, 80, 80, Region.Op.DIFFERENCE);    Drawscene (canvas); }    Private voiddrawscene (canvas canvas) {//Draw Rectangle 0,0 upper left corner, 100,100 lower right cornerCanvas.cliprect (0, 0, 100, 100); //Canvas color is whiteCanvas.drawcolor (Color.White); //Brush is redPaint.setcolor (color.red); //draw a line from the upper-left corner of the rectangle to the lower-right corner of the rectangleCanvas.drawline (0, 0, 100, 100, paint); //brush color is greenPaint.setcolor (Color.green); //Draw Circle, center Point, 30, 70, RadiusCanvas.drawcircle (30, 70, 30, paint); //Brush is bluePaint.setcolor (Color.Blue); //draw text, text coordinates 100,30Canvas.drawtext ("Clipping", 100, 30, paint); }}

Effect:

Not detailed, the back

Canvas clipping and region, Regioniterator