An example of a simple scraping card lottery effect in Android app _android

Main ideas:
Design a view into multi-layer: Background layer, including winning information, etc.;
Covering layer, used for scraping prizes, using a bitmap to associate a canvas
On the bitmap, use its Canvas.drawpath API to handle gesture sliding (similar to the scraping award)
Use Paint.setxfermode to remove the gesture slip area

public class Guaview extends View {private Bitmap mbitmap;//obscured layer private Canvas mcanvas;//Draw Overlay Layer Private P 
  Aint mouterpaint; 
  Private Path MPath; 
  private float mlastx; 
 
  private float mlasty; Private Bitmap Mcoverbitmap; 
  Cover Figure private int mwidth, mheight; 
  Private Paint Minnerpaint; 
 
 
  Private String MInfo; 
  Public Guaview {This (context, NULL); 
 
    Public Guaview (context, AttributeSet attrs) {Super (context, attrs); 
  Init (); 
    private void Init () {mpath = new Path (); 
    Mouterpaint = new Paint (); 
    Minnerpaint = new Paint (); 
 
    Mcoverbitmap = Bitmapfactory.decoderesource (Getresources (), R.drawable.fg_guaguaka); 
  MInfo = "￥5 0 0"; @Override protected void onmeasure (int widthmeasurespec, int heightmeasurespec) {super.onmeasure (widthmeas 
    Urespec, Heightmeasurespec); 
    Mwidth = Mcoverbitmap.getwidth (); 
    Mheight = Mcoverbitmap.getheight (); SetmeasureDdimension (Mwidth, mheight); 
    Mbitmap = Bitmap.createbitmap (Mwidth, Mheight, Bitmap.Config.ARGB_8888); 
    Mcanvas = new Canvas (MBITMAP); 
 
    Mcanvas.drawbitmap (mcoverbitmap, 0, 0, NULL); 
    Setouterpaint (); 
 
  Setinnerpaint (); 
    private void Setinnerpaint () {minnerpaint.setcolor (color.red); 
    Minnerpaint.setstyle (Paint.Style.STROKE); 
    Minnerpaint.setstrokecap (Paint.Cap.ROUND); 
    Minnerpaint.setstrokejoin (Paint.Join.ROUND); 
    Minnerpaint.setantialias (TRUE); Minnerpaint.setdither (TRUE); 
    Anti-Stabilization Minnerpaint.setstrokewidth (5); 
    Minnerpaint.settextsize (100); 
  Minnerpaint.settextalign (Paint.Align.CENTER); 
    private void Setouterpaint () {mouterpaint.setcolor (color.green); 
    Mouterpaint.setstyle (Paint.Style.STROKE); 
    Mouterpaint.setstrokecap (Paint.Cap.ROUND); 
    Mouterpaint.setstrokejoin (Paint.Join.ROUND); 
    Mouterpaint.setantialias (TRUE); Mouterpaint.setdither (TRUE); Anti-stabilization Mouterpaint.setstrokewidth (20); 
    @Override//path Public boolean ontouchevent (Motionevent event) {float x = Event.getx (); 
    Float y = event.gety (); 
        Switch (event.getaction ()) {Case MotionEvent.ACTION_DOWN:mLastX = x; 
        Mlasty = y; 
        Mpath.moveto (x, y); 
      Break 
        Case MotionEvent.ACTION_MOVE:float DeltaX = Math.Abs (X-MLASTX); 
        float DeltaY = Math.Abs (y-mlasty); 
        if (DeltaX > 5 | | deltay > 5) {mpath.lineto (x, y); 
        } MLASTX = x; 
        Mlasty = y; 
      Break 
    Case MotionEvent.ACTION_UP:break; 
  Invalidate ();//Call OnDraw return true; 
 
    } @Override protected void OnDraw (Canvas Canvas) {Super.ondraw (Canvas); Canvas.drawcolor (Color.parsecolor ("#bbbbbb")); Background color gray Canvas.drawtext (MInfo, MWIDTH/2, MHEIGHT/4 * 3, Minnerpaint); Draw Text Canvas.drawbitmap (mbitmap, 0, 0, NULL); Draw Mbitmap This is a variable bitmap, drawn by Mcanvas, first drawnThe Mcoverbitmap DrawPath (); The private void DrawPath () {///MODE:DST intersects with SRC, preserves only DST and removes the intersecting partial mouterpaint.setxfermode (new Porterduffxfe 
    Rmode (PorterDuff.Mode.DST_OUT)); 
  Mcanvas.drawpath (MPath, mouterpaint); 

 } 
}

Paint.join Continuous Brush Cohesion:

• Miter the outer edge with an acute angle
• ROUND with an arc
• Bevel with a straight line

PAINT.CAP specifies how the start and end points for lines and paths (lines and paths) are handled:

• Butt ends with the path does not surpass it
• ROUND with the center in the path semicircle
• Square with the center in the path square