01 毛笔字效果

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无意中在 GitHub 上找到一个毛笔字效果的项目 canvas_WritingBrush 。其效果如下图所示：

效果图

网页源码精简为：

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<!doctype html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8" />  
    <meta name="viewport" content="initial-scale=1.0, user-scalable=0, minimum-scale=1.0, maximum-scale=1.0"> 
    <title> canvas 递进</title>  
<style type="text/css">  
#canvasId {  
    background-color: #f2e0ba;  
}  
</style>  
</head>  
<body>  
  
<canvas id="canvasId"></canvas><br />  
<input type="button" value="clear" onclick="hw.clear();" />  
<img id="pen22" src="pen22.png"/>
<img id="pen2" src="pen2.png"/>
<!-- <script type="text/javascript" src="jQuery.min.js"></script> -->
<script type="text/javascript">  
    var l = 20;
    var arr = [];
function Handwriting(id) {  
    this.canvas = document.getElementById(id);  
    this.ctx = this.canvas.getContext("2d");  
    this.canvas.setAttribute('width',window.screen.width * 0.9);
    this.canvas.setAttribute('height',window.screen.height *0.8);
    this.ctx.fillStyle = "rgba(0,0,0,0.8)";  
    var _this = this;
    this.canvas.addEventListener("touchstart", this.downEvent.bind(this), false);  
    this.canvas.addEventListener("touchmove", this.moveEvent.bind(this), false);  
    this.canvas.addEventListener("touchend", this.upEvent.bind(this), false);  
    this.canvas.addEventListener("contextmenu", function(e){ e.preventDefault() }, false);  
    // this.canvas.onmousedown = function (e) { _this.downEvent(e)};  
    // this.canvas.onmousemove = function (e) { _this.moveEvent(e)};  
    // this.canvas.onmouseup = function (e) { _this.upEvent(e)};  
    // this.canvas.onmouseout = function (e) { _this.upEvent(e)};  
    this.canvas.addEventListener("mousedown",function(e){ _this.downEvent(e)},false);
    this.canvas.addEventListener("mousemove",function(e){ _this.moveEvent(e)},false);
    this.canvas.addEventListener("mouseup",function(e){ _this.upEvent(e)},false);
    this.canvas.addEventListener("mouseout",function(e){ _this.upEvent(e)},false);
    this.canvas.addEventListener("click",function(e){ _this.clickEvent(e),false});
    this.moveFlag = false;  
    this.upof = {};   
    this.has = [];   
    this.linePressure = 1;  
    this.smoothness = 80;  
    this.img = document.getElementById('pen2');
    this.img1 = document.getElementById('pen22');
}  
  
Handwriting.prototype.clear = function () {  
    this.ctx.clearRect(0,0,this.canvas.width,this.canvas.height);    
}  
Handwriting.prototype.clickEvent = function(e){
    this.cli = this.getXY(e);
    // this.ctx.drawImage(this.img,this.cli.x - l/2,this.cli.y - l/2,l,l);
}
  
Handwriting.prototype.downEvent = function (e) {  
    this.moveFlag = true;  
    this.has = [];  
    this.upof = this.getXY(e);  
    // this.ctx.drawImage(this.img,(this.upof.x - this.big/2),(this.upof.y - this.big/2),this.big,this.big);
    var x1 = this.upof.x;
    var y1 = this.upof.y;
    arr.unshift({x1,y1});
}  
  
Handwriting.prototype.moveEvent = function (e) {  
    if (!this.moveFlag)  
        return;
    e.preventDefault();  
    var of = this.getXY(e); //move
    var up = this.upof;  //down
    this.has.unshift({time:new Date().getTime() ,dis:this.distance(up,of)});  
    var dis = 0;  
    var time = 0;  
    for (var n = 0; n < this.has.length-1; n++) {  
        dis += this.has[n].dis;  
        time += this.has[n].time-this.has[n+1].time;  
        if (dis>this.smoothness)  
            break;  
    }  
  
    this.upof = of;  
    var len = Math.round(this.has[0].dis/2)+1;  
    for (var i = 0; i < len; i++) {  
        var x = up.x + (of.x-up.x)/len*i;  
        var y = up.y + (of.y-up.y)/len*i;  
        // var r = ur + (or-ur)/len*i;  
        this.ctx.beginPath();  
        // this.ctx.arc(x,y,r,0.2*Math.PI,1.5*Math.PI,true);  
        // this.ctx.fill();  
        // var r_r = r*2;
        x = x-l/2;
        y = y - l/2;
        arr.unshift({x,y});
        this.ctx.drawImage(this.img,x,y,l,l);
        l = l - 0.2;
        if( l < 10) l = 10;
        // console.log(l);
    }  
}  
  
Handwriting.prototype.upEvent = function (e) {  
    this.moveFlag = false;  
    // console.log(p);
    l = 20;
    // console.log(arr);
    if(arr.length >100){
         for(var j = 0; j <60 ;j++){
            // arr[j].x = arr[j].x - 2;
            // arr[j].y = arr[j].y - 1;
            arr[j].x = arr[j].x-l/4;
            arr[j].y = arr[j].y - l/4;          
            this.ctx.drawImage(this.img,arr[j].x,arr[j].y,l,l);
            l = l - 0.3;
            if( l < 5) l = 5;
        }
        l = 20;
        arr = [];       
    }
    if (arr.length==1) {
        // arr[0].x = 
        this.ctx.drawImage(this.img,arr[0].x1 - l/2,arr[0].y1 - l/2,l,l);
        console.log(arr[0].x);
        arr = [];
    }
    console.log(arr);
}  
  
Handwriting.prototype.getXY = function (e)  
{   
    var x = e.clientX || e.touches[0].clientX;
    var y = e.clientY || e.touches[0].clientY;
    // // return {  
    //     x : e.clientX - this.canvas.offsetLeft + (document.body.scrollLeft || document.documentElement.scrollLeft),  
    //     y : e.clientY - this.canvas.offsetTop  + (document.body.scrollTop || document.documentElement.scrollTop)  
    // }  
    return {  
        x : x - this.canvas.offsetLeft + (document.body.scrollLeft || document.documentElement.scrollLeft),  
        y : y - this.canvas.offsetTop  + (document.body.scrollTop || document.documentElement.scrollTop)  
    }  
}  
  
Handwriting.prototype.distance = function (a,b)  
{  
    var x = b.x-a.x , y = b.y-a.y;  
    return Math.sqrt(x*x+y*y);  
}  
 
// $('input').eq(1).val(5);
// $('input').eq(2).val(20); 
var hw = new Handwriting("canvasId");   
hw.linePressure = 2.5;  
hw.smoothness = 100;  
  
</script>  
</body>  
</html>

本人参考它的源码并在 Android 上实现类似的自定义控件，其效果如下：

Android 效果图

源码如下：

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package com.xxt.xian.view.autograph;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import androidx.annotation.Nullable;
import com.xxt.xian.R;
import java.util.LinkedList;
public class XAutographView extends View {
    private Paint mPaint;
    private boolean isTouching;
    private Bitmap mPenBmp;
    private RectF mRect;
    private float smoothness = 80;
    private float maxL = 50;
    private float l;
    private Bitmap mBitmap;
    private Canvas mCanvas;
    LinkedList<FPoint> mPoints;
    LinkedList<Float> mDisList;
    FPoint prePoint, tempPoint, curPoint;
    public XAutographView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mPaint = new Paint();
        mRect = new RectF();
        mPenBmp = BitmapFactory.decodeResource(getResources(), R.drawable.pen);
        isTouching = false;
        mPoints = new LinkedList<>();
        mDisList = new LinkedList<>();
        prePoint = new FPoint();
        tempPoint = new FPoint();
        curPoint = new FPoint();
        mCanvas = new Canvas();
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldW, int oldH) {
        super.onSizeChanged(w, h, oldW, oldH);
        if (mBitmap != null) mBitmap.recycle();
        mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        mCanvas.setBitmap(mBitmap);
        maxL = w / 30f;
        l = maxL;
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                isTouching = true;
                mPoints.clear();
                prePoint.set(x, y);
                mPoints.addFirst(new FPoint(x, y));
                return true;
            case MotionEvent.ACTION_MOVE:
                drawMoveCanvas(x, y);
                break;
            case MotionEvent.ACTION_UP:
                drawUpCanvas();
                break;
            default:break;
        }
        return super.onTouchEvent(event);
    }
    private void drawUpCanvas() {
        isTouching = false;
        l = maxL;
        if (mPoints.size() > 200) {
            for (int j = 0; j < 100; j++) {
                FPoint p = mPoints.get(j);
                p.x = p.x - l / 4;
                p.y = p.y - l / 4;
                mRect.set(p.x, p.y, p.x+l, p.y+l);
                mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
                l = l - 0.3f;
//                if( l < maxL / 10) l = maxL / 10;
            }
            mPoints.clear();
        }
        if (mPoints.size() == 1) {
            FPoint p = mPoints.get(0);
            float x = p.x - l / 2;
            float y = p.y - l / 2;
            mRect.set(x, y, x+l, y+l);
            mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
            mPoints.clear();
        }
    }
    private void drawMoveCanvas(final float x, final float y) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (isTouching) {
                    curPoint.set(x, y);
                    tempPoint.set(prePoint.x, prePoint.y);
                    mDisList.addFirst(getDistance(tempPoint, curPoint));
                    float dis = 0;
                    for (int n = 0; n < mDisList.size(); n++) {
                        dis += mDisList.get(n);
                        if (dis > smoothness) break;
                    }
                    prePoint.set(curPoint.x, curPoint.y);
                    int len = Math.round(mDisList.get(0) / 2) + 1;
                    for (int i = 0; i < len; i++) {
                        float x1 = tempPoint.x + (curPoint.x - tempPoint.x) / len * i;
                        float y1 = tempPoint.y + (curPoint.y - tempPoint.y) / len * i;
                        x1 = x1 - l/2;
                        y1 = y1 - l/2;
                        mPoints.addFirst(new FPoint(x1, y1));
                        mRect.set(x1, y1, x1+l, y1+l);
                        mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
                        l = l - 0.2f;
                        if( l < maxL / 2) l = maxL / 2;
                    }
                    postInvalidate();
                }
            }
        }).start();
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(mBitmap, 0, 0, mPaint);
    }
    private float getDistance(FPoint p1, FPoint p2) {
        float x = p2.x - p1.x;
        float y = p2.y - p1.y;
        return (float) Math.sqrt(x * x + y * y);
    }
    class FPoint {
        float x;
        float y;
        FPoint() {}
        FPoint(float x, float y) {
            this.x = x;
            this.y = y;
        }
        void set(float x, float y) {
            this.x = x;
            this.y = y;
        }
        @Override
        public boolean equals(Object o) {
            if (this == o) return true;
            if (o == null || getClass() != o.getClass()) return false;
            FPoint point = (FPoint) o;
            if (x != point.x) return false;
            if (y != point.y) return false;
            return true;
        }
        @Override
        public String toString() {
            return "Point(" + x + ", " + y + ")";
        }
    }
}package xian.xiao.tao.ui;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import androidx.annotation.Nullable;
import java.util.LinkedList;
import xian.xiao.tao.R;
public class XAutographView extends View {
    private Paint mPaint;
    private boolean isTouching;
    private Bitmap mPenBmp;
    private RectF mRect;
    private float smoothness = 80;
    private float maxL = 50;
    private float l;
    private Bitmap mBitmap;
    private Canvas mCanvas;
    LinkedList<XPoint> mPoints;
    LinkedList<Float> mDisList;
    XPoint prePoint, tempPoint, curPoint;
    public XAutographView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
        mPaint = new Paint();
        mRect = new RectF();
        mPenBmp = BitmapFactory.decodeResource(getResources(), R.mipmap.ui_x_autograph_view_nib);
        isTouching = false;
        mPoints = new LinkedList<>();
        mDisList = new LinkedList<>();
        prePoint = new XPoint();
        tempPoint = new XPoint();
        curPoint = new XPoint();
        mCanvas = new Canvas();
    }
    @Override
    protected void onSizeChanged(int w, int h, int oldW, int oldH) {
        super.onSizeChanged(w, h, oldW, oldH);
        if (mBitmap != null) mBitmap.recycle();
        mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
        mCanvas.setBitmap(mBitmap);
        maxL = w / 30f;
        l = maxL;
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        float x = event.getX();
        float y = event.getY();
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                isTouching = true;
                mPoints.clear();
                prePoint.set(x, y);
                mPoints.addFirst(new XPoint(x, y));
                return true;
            case MotionEvent.ACTION_MOVE:
                drawMoveCanvas(x, y);
                break;
            case MotionEvent.ACTION_UP:
                drawUpCanvas();
                break;
            default:break;
        }
        return super.onTouchEvent(event);
    }
    private void drawMoveCanvas(final float x, final float y) {
        new Thread(new Runnable() {
            @Override
            public void run() {
                if (isTouching) {
                    curPoint.set(x, y);
                    tempPoint.set(prePoint.x, prePoint.y);
                    mDisList.addFirst(getDistance(tempPoint, curPoint));
                    float dis = 0;
                    for (int n = 0; n < mDisList.size(); n++) {
                        dis += mDisList.get(n);
                        if (dis > smoothness) break;
                    }
                    prePoint.set(curPoint.x, curPoint.y);
                    int len = Math.round(mDisList.get(0) / 2) + 1;
                    for (int i = 0; i < len; i++) {
                        float x1 = tempPoint.x + (curPoint.x - tempPoint.x) / len * i;
                        float y1 = tempPoint.y + (curPoint.y - tempPoint.y) / len * i;
                        x1 = x1 - l/2;
                        y1 = y1 - l/2;
                        mPoints.addFirst(new XPoint(x1, y1));
                        mRect.set(x1, y1, x1+l, y1+l);
                        mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
                        l = l - 0.2f;
                        if( l < maxL / 2) l = maxL / 2;
                    }
                    postInvalidate();
                }
            }
        }).start();
    }
    private void drawUpCanvas() {
        isTouching = false;
        l = maxL;
        if (mPoints.size() > 200) {
            for (int j = 0; j < 100; j++) {
                XPoint p = mPoints.get(j);
                p.x = p.x - l / 4;
                p.y = p.y - l / 4;
                mRect.set(p.x, p.y, p.x+l, p.y+l);
                mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
                l = l - 0.3f;
            }
            mPoints.clear();
        }
        if (mPoints.size() == 1) {
            XPoint p = mPoints.get(0);
            float x = p.x - l / 2;
            float y = p.y - l / 2;
            mRect.set(x, y, x+l, y+l);
            mCanvas.drawBitmap(mPenBmp, null, mRect, mPaint);
            mPoints.clear();
        }
    }
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawBitmap(mBitmap, 0, 0, mPaint);
    }
    private float getDistance(XPoint p1, XPoint p2) {
        float x = p2.x - p1.x;
        float y = p2.y - p1.y;
        return (float) Math.sqrt(x * x + y * y);
    }
    class XPoint {
        float x;
        float y;
        XPoint() {}
        XPoint(float x, float y) {
            this.x = x;
            this.y = y;
        }
        void set(float x, float y) {
            this.x = x;
            this.y = y;
        }
    }
}

资源图片：

pen2.png

pen22.png