本文实例为大家分享了android实现手写板功能的具体代码，供大家参考，具体内容如下
自定义个一个手写板的重点:
笔画为一次down-move-up的集合
撤销笔画并非一次path的动作撤销 应该也是一次down-move -up的撤销
为了更好的笔画需要使用贝塞尔曲线来完成
效果如下:
截图中清楚 的意思是清除 !
具体代码如下:
package com.kyli.base.view;
import android.content.context;
import android.graphics.bitmap;
import android.graphics.canvas;
import android.graphics.color;
import android.graphics.paint;
import android.graphics.path;
import android.util.attributeset;
import android.view.motionevent;
import android.view.view;
import androidx.annotation.nullable;
import java.util.arraylist;
import java.util.list;
/**
* 绘制画板
*/
public class signboradview extends view {
/*4个像素点*/
private int beierthreshold = 4;
private float x = 0;
private float y = 0;
/*画笔*/
private paint mpaint;
/*宽度*/
private int strokewidth = 10;
/*yanbse*/
private int color = color.black;
/*当前笔画*/
private path path;
private int state = state.clear;
private interface state {
/*画板可以使用了*/
int start = 0;
/*停止使用画板*/
int stop = 1;
/*清空画板*/
int clear = 2;
}
private list<everypenpath> everypenpaths = new arraylist<>();
/*每一个笔画*/
private static class everypenpath {
public path path;
}
public signboradview(context context) {
super(context);
}
public signboradview(context context, @nullable attributeset attrs) {
super(context, attrs);
}
public signboradview(context context, @nullable attributeset attrs, int defstyleattr) {
super(context, attrs, defstyleattr);
}
private void initpaint() {
if (mpaint == null) {
mpaint = new paint();
mpaint.setstrokewidth(strokewidth);
mpaint.setcolor(color);
mpaint.setstyle(paint.style.stroke);
mpaint.setantialias(true);
mpaint.setflags(paint.anti_alias_flag);
}
}
public void start() {
state = state.start;
initpaint();
}
/*停止使用*/
public void stop() {
state = state.stop;
}
/*清空画板*/
public void clear() {
state = state.clear;
for (int i = everypenpaths.size() - 1; i >= 0; i--) {
everypenpath everypenpath = everypenpaths.get(i);
everypenpath.path.reset();
everypenpath.path.close();
everypenpath.path = null;
}
everypenpaths.clear();
invalidate();
}
public void back() {
int count = everypenpaths.size();
if (count < 1)
return;
everypenpath everypenpath = everypenpaths.get(count - 1);
everypenpath.path.reset();
everypenpath.path.close();
everypenpath.path = null;
everypenpaths.remove(count - 1);
invalidate();
}
@override
protected void ondraw(canvas canvas) {
super.ondraw(canvas);
if (state == state.start) {
/*先绘制完整笔画*/
for (everypenpath e : everypenpaths) {
canvas.drawpath(e.path, mpaint);
}
//当前进行中的 path!=null
if (path != null) {
canvas.drawpath(path, mpaint);
}
}
}
@override
public boolean ontouchevent(motionevent event) {
if (state == state.start) {
if (event.getaction() == motionevent.action_up) {
actionup(event);
invalidate();
return true;
}
if (event.getaction() == motionevent.action_move) {
actionmove(event);
invalidate();
return true;
}
if (event.getaction() == motionevent.action_down) {
actiondown(event);
invalidate();
return true;
}
}
return super.ontouchevent(event);
}
private void actionup(motionevent event) {
actionmove(event);
/*构成一个笔画*/
everypenpath everypenpath = new everypenpath();
everypenpath.path = path;
everypenpaths.add(everypenpath);
//将当前画笔置位null;
path = null;
}
/**/
private void actionmove(motionevent event) {
/*每次移动去绘制贝塞尔曲线*/
float cx = event.getx();
float cy = event.gety();
float dx = math.abs(cx - x);//变化量
float dy = math.abs(cy - y);
if (dx >= beierthreshold || dy >= beierthreshold) {
float rx = x + (cx - x) / 2;
float ry = y + (cy - y) / 2;
path.quadto(rx, ry, cx, cy);
//下次的x 域y 将重新计算
x = cx;
y = cy;
}
}
/*开始时*/
private void actiondown(motionevent event) {
path = new path();
x = event.getx();
y = event.gety();
path.moveto(x, y);
}
public void setbeierthreshold(int beierthreshold) {
this.beierthreshold = beierthreshold;
}
public void setstrokewidth(int strokewidth) {
this.strokewidth = strokewidth;
}
public void setcolor(int color) {
this.color = color;
}
public bitmap getresult(int bgcolor) {
if (everypenpaths.size() == 0)
return null;
bitmap bitmap = bitmap.createbitmap(getwidth(), getheight(), bitmap.config.argb_8888);
canvas canvas = new canvas(bitmap);
canvas.drawcolor(bgcolor);
for (int i = 0; i < everypenpaths.size(); i++) {
if (mpaint == null) {
initpaint();
}
canvas.drawpath(everypenpaths.get(i).path, mpaint);
}
return bitmap;
}
public bitmap getresult() {
return getresult(color.white);
}
}
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。