Android Graphics Setxfermode processing Two graphs cross the situation

Setxfermode

Set the mode at which two pictures intersect

We know that under normal circumstances, drawing on an existing image will add a new layer of shape on top of it. If the new paint is completely opaque, it will completely obscure the paint below;

And setxfermode can solve this problem.


In general, the usage is like this.

New Canvas (BITMAP1);p Aint.setxfermode (new  Porterduffxfermode (mode.src_in)); Canvas.drawbitmap ( Mask, 0f, 0f, paint);  

It is the problem that is displayed when the image mask is drawn on the image bitmap1.

Canvas's original picture can be understood as the background is DST
The picture on the new picture can be understood as the foreground is SRC


The values of mode are as follows

Demo of a sliding layer

 PackageCom.weidingqiang.testviewb;ImportAndroid.content.Context;ImportAndroid.graphics.Bitmap;Importandroid.graphics.BitmapFactory;ImportAndroid.graphics.Canvas;ImportAndroid.graphics.Color;ImportAndroid.graphics.Paint;ImportAndroid.graphics.Path;ImportAndroid.graphics.PorterDuff;ImportAndroid.graphics.PorterDuffXfermode;ImportAndroid.util.AttributeSet;Importandroid.view.MotionEvent;ImportAndroid.view.View;/*** Created by Weidingqiang on 15/11/20.*/ Public classXfermodeviewextendsView {PrivateBitmap Mbgbitmap,mfgbitmap; PrivatePaint Mpaint; PrivateCanvas Mcanvas; PrivatePath MPath;  PublicXfermodeview (Context context) {Super(context); }     PublicXfermodeview (Context context, AttributeSet attrs) {Super(context, attrs);    Init (); }    Private voidinit () {Mpaint=NewPaint (); Mpaint.setalpha (0); Mpaint.setxfermode (NewPorterduffxfermode (PorterDuff.Mode.DST_IN));        Mpaint.setstyle (Paint.Style.STROKE);        Mpaint.setstrokejoin (Paint.Join.ROUND); Mpaint.setstrokewidth (50);        Mpaint.setstrokecap (Paint.Cap.ROUND); MPath=NewPath (); Mbgbitmap=Bitmapfactory.decoderesource (Getresources (), R.MIPMAP.IMAGE_BG); Mfgbitmap=Bitmap.createbitmap (Mbgbitmap.getwidth (), Mbgbitmap.getheight (), Bitmap.Config.ARGB_8888); Mcanvas=NewCanvas (MFGBITMAP);    Mcanvas.drawcolor (Color.gray); } @Override Public Booleanontouchevent (Motionevent event) {Switch(Event.getaction ()) { CaseMotionEvent.ACTION_DOWN:mPath.reset ();                Mpath.moveto (Event.getx (), event.gety ());  Break;  CaseMotionEvent.ACTION_MOVE:mPath.lineTo (Event.getx (), event.gety ());  Break;        } mcanvas.drawpath (Mpath,mpaint);        Invalidate (); return true; } @Overrideprotected voidOnDraw (canvas canvas) {canvas.drawbitmap (Mbgbitmap,0,0,NULL); Canvas.drawbitmap (Mfgbitmap,0,0,NULL); }}

Android Graphics Setxfermode processing Two graphs cross the situation