无锡网站制作选哪家,网站开发就业外部威胁,电商网站会员体制怎么做,网站开发报价 福州实现了一个有趣的小东西#xff1a;使用自定义view绘图#xff0c;一边画线#xff0c;画出的线条渐渐变淡#xff0c;直到消失。效果如下图所示#xff1a;用属性动画或者渐变填充(shader)可以做到一笔一笔的变化#xff0c;但要想一笔渐变(手指不抬起边画边渐隐)#…实现了一个有趣的小东西使用自定义view绘图一边画线画出的线条渐渐变淡直到消失。效果如下图所示用属性动画或者渐变填充(shader)可以做到一笔一笔的变化但要想一笔渐变(手指不抬起边画边渐隐)没在android中找到现成的api可用。所以自己做了一个。基本的想法是这样的•在view的ontouchevent中记录触摸点生成一条一条的线lineelement放在一个list中。给每个lineelement配置一个paint实例。•在ondraw中绘制线段。•变换lineelement的paint实例的alpha值。•根据alpha值重组线段列表别的不说了上代码package com.example.disappearinglines;import android.content.context;import android.graphics.canvas;import android.graphics.paint;import android.graphics.path;import android.graphics.rectf;import android.os.handler;import android.os.message;import android.os.systemclock;import android.support.annotation.nonnull;import android.util.attributeset;import android.util.log;import android.view.motionevent;import android.view.view;import java.util.arraylist;import java.util.collection;import java.util.iterator;import java.util.list;import java.util.listiterator;public class disappearingdoodleview extends view {final static string tag doodleview;class lineelement {static final public int alpha_step 5;static final public int subpath_dimension 8;public lineelement(){mpaint new paint();mpaint.setargb(255, 255, 0, 0);mpaint.setantialias(true);mpaint.setstrokewidth(16);mpaint.setstrokecap(paint.cap.butt);mpaint.setstyle(paint.style.stroke);}public lineelement(paint paint){mpaint paint;}public void setpaint(paint paint){mpaint paint;}public void setalpha(int alpha){mpaint.setalpha(alpha);}public float mstartx -1;public float mstarty -1;public float mendx -1;public float mendy -1;public paint mpaint;}private lineelement mcurrentline null;private list mlines null;private long melapsed 0;private handler mhandler new handler(){overridepublic void handlemessage(message msg){disappearingdoodleview.this.invalidate();}};public disappearingdoodleview(context context){super(context);}public disappearingdoodleview(context context, attributeset attrs){super(context, attrs);}overrideprotected void ondraw(canvas canvas){melapsed systemclock.elapsedrealtime();if(mlines ! null) {for (lineelement e : mlines) {if(e.mstartx 0 || e.mendy 0) continue;canvas.drawline(e.mstartx, e.mstarty, e.mendx, e.mendy, e.mpaint);}compactpaths();}}overridepublic boolean ontouchevent(motionevent event){float x event.getx();float y event.gety();int action event.getaction();if(action motionevent.action_up){// end one line after finger releasemcurrentline.mendx x;mcurrentline.mendy y;mcurrentline null;invalidate();return true;}if(action motionevent.action_down){mcurrentline new lineelement();addtopaths(mcurrentline);mcurrentline.mstartx x;mcurrentline.mstarty y;return true;}if(action motionevent.action_move) {mcurrentline.mendx x;mcurrentline.mendy y;mcurrentline new lineelement();addtopaths(mcurrentline);mcurrentline.mstartx x;mcurrentline.mstarty y;}if(mhandler.hasmessages(1)){mhandler.removemessages(1);}message msg new message();msg.what 1;mhandler.sendmessagedelayed(msg, 0);return true;}private void addtopaths(lineelement element){if(mlines null) {mlines new arraylist() ;}mlines.add(element);}public void compactpaths(){int size mlines.size();int index size - 1;if(size 0) return;int basealpha 255 - lineelement.alpha_step;int itselfalpha;lineelement line;for(; index 0 ; index--, basealpha - lineelement.alpha_step){line mlines.get(index);itselfalpha line.mpaint.getalpha();if(itselfalpha 255){if(basealpha 0){index;break;}line.setalpha(basealpha);}else{itselfalpha - lineelement.alpha_step;if(itselfalpha 0){index;break;}line.setalpha(itselfalpha);}}if(index size){// all sub-path should disappearmlines null;}else if(index 0){//log.i(tag, compactpaths from index to (size - 1));mlines mlines.sublist(index, size);}else{// no sub-path should disappear}long interval 40 - systemclock.elapsedrealtime() melapsed;if(interval 0) interval 0;message msg new message();msg.what 1;mhandler.sendmessagedelayed(msg, interval);}}这个示例还可以添加一些效果比如让线条一边变淡一边变细。目前还有一些问题线条粗的话可以明显看到线段与线段之间有缝隙或裂口哪位想到怎么优化以上就是本文的全部内容希望对大家的学习有所帮助也希望大家多多支持萬仟网。
