这个博客介绍了如何在Android平台上实现一个自定义的手写签名视图。代码中详细展示了如何使用Paint和Path来绘制签名，同时提供了清除、保存签名图片以及调整画笔颜色和宽度的功能。用户可以进行手写操作，轨迹实时显示，并在完成后保存为图片。
手写签名自定义实现，看注释就行了
package com.zhuzi.taobamboo.user_defined;
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.graphics.PorterDuff;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import androidx.annotation.ColorInt;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
/**
-
@ Authoor 刘晨
-
@ Time 2022/7/14 0014/11:31
-
@ explain 手写签名
*/
public class PintView extends View {
private Context mContext;
//起点X
private float mX;
//起点Y
private float mY;
//手写画笔
private final Paint mGesturePaint = new Paint();
//路径
private final Path mPath = new Path();
//画布
private Canvas cacheCanvas;
//生成的图片
private Bitmap cachebBitmap;
//画笔宽度 px；
private int mPaintWidth = 10;
//画笔颜色
private int mPenColor = Color.BLACK;
//背景色（指最终签名结果文件的背景颜色，默认为透明色）
private int mBackColor=Color.TRANSPARENT;private int pintInt = 0;
public PintView(Context context) {
super(context);
init(context);
}public PintView(Context context, AttributeSet attrs) {
super(context, attrs);
init(context);
}public PintView(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init(context);
}private void init(Context context) {
this.mContext = context;
//设置抗锯齿
mGesturePaint.setAntiAlias(true);
//设置签名笔画样式
mGesturePaint.setStyle(Paint.Style.STROKE);
//设置笔画宽度
mGesturePaint.setStrokeWidth(mPaintWidth);
//设置签名颜色
mGesturePaint.setColor(mPenColor);
}@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
//创建跟view一样大的bitmap，用来保存签名(在控件大小发生改变时调用。)
cachebBitmap = Bitmap.createBitmap(getWidth(), getHeight(), Bitmap.Config.ARGB_8888);
cacheCanvas = new Canvas(cachebBitmap);
cacheCanvas.drawColor(mBackColor);
}@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
//画此次笔画之前的签名
canvas.drawBitmap(cachebBitmap, 0, 0, mGesturePaint);
// 通过画布绘制多点形成的图形
canvas.drawPath(mPath, mGesturePaint);
}@Override
public boolean onTouchEvent(MotionEvent event) {
switch (event.getAction()){
case MotionEvent.ACTION_DOWN:
touchDown(event);
break;
case MotionEvent.ACTION_MOVE:
pintInt++;
touchMove(event);
break;
case MotionEvent.ACTION_UP://将路径画到bitmap中，即一次笔画完成才去更新bitmap，而手势轨迹是实时显示在画板上的。 cacheCanvas.drawPath(mPath, mGesturePaint); mPath.reset(); break; } // 更新绘制 invalidate(); return true;}
// 手指点下屏幕时调用
private void touchDown(MotionEvent event) {
// 重置绘制路线
mPath.reset();
float x = event.getX();
float y = event.getY();
mX = x;
mY = y;
// mPath绘制的绘制起点
mPath.moveTo(x,y);
}
// 手指在屏幕上滑动时调用
private void touchMove(MotionEvent event) {
final float x = event.getX();
final float y = event.getY();
final float previousX = mX;
final float previousY = mY;
final float dx = Math.abs(x - previousX);
final float dy = Math.abs(y - previousY);
// 两点之间的距离大于等于3时，生成贝塞尔绘制曲线
if (dx >= 3 || dy >= 3) {
// 设置贝塞尔曲线的操作点为起点和终点的一半
float cX = (x + previousX) / 2;
float cY = (y + previousY) / 2;
// 二次贝塞尔，实现平滑曲线；previousX, previousY为操作点，cX, cY为终点
mPath.quadTo(previousX, previousY, cX, cY);
// 第二次执行时，第一次结束调用的坐标值将作为第二次调用的初始坐标值
mX = x;
mY = y;
}
}/**
- 清除画板
*/
public void clear() {
if (cacheCanvas != null) {
pintInt = 0;
//更新画板信息
mGesturePaint.setColor(mPenColor);
cacheCanvas.drawColor(mBackColor, PorterDuff.Mode.CLEAR);
mGesturePaint.setColor(mPenColor);
invalidate();
}
}
/**
- 用来记录会话次数，用来判断用户是否签字
- @return
*/
public int getPinInt(){
return pintInt;
}
/**
- 保存画板
- @param path 保存到路径
*/
public void save(String path) throws IOException {
save(path, false, 0);
}
/**
-
保存画板
-
@param path 保存到路径
-
@param clearBlank 是否清除边缘空白区域
-
@param blank 要保留的边缘空白距离
*/
public void save(String path, boolean clearBlank, int blank) throws IOException {Bitmap bitmap=cachebBitmap;
//BitmapUtil.createScaledBitmapByHeight(srcBitmap, 300);// 压缩图片
if (clearBlank) {
bitmap = clearBlank(bitmap, blank);
}
ByteArrayOutputStream bos = new ByteArrayOutputStream();
bitmap.compress(Bitmap.CompressFormat.PNG, 100, bos);
byte[] buffer = bos.toByteArray();
if (buffer != null) {
File file = new File(path);
if (file.exists()) {
file.delete();
}
OutputStream outputStream = new FileOutputStream(file);
outputStream.write(buffer);
outputStream.close();
}
}
/**
-
保存画板
-
@param clearBlank 是否清除边缘空白区域
-
@param blank 要保留的边缘空白距离
*/
public Bitmap saveToBitmap(boolean clearBlank, int blank){Bitmap bitmap=cachebBitmap;
//BitmapUtil.createScaledBitmapByHeight(srcBitmap, 300);// 压缩图片
if (clearBlank) {
bitmap = clearBlank(bitmap, blank);
}
// int width = bitmap.getWidth();
// int height = bitmap.getHeight();
// int w;
// int h;
// if(width>2height){
// w = width -(width - 2height);
// h = height;
// } else {
// w = width;
// h = height - (height - width/2);
// }
// return ThumbnailUtils.extractThumbnail(bitmap,w,h);
return bitmap;
}
/**
-
获取画板的bitmap
-
@return
*/
public Bitmap getBitMap()
{
destroyDrawingCache();
setDrawingCacheEnabled(true);return getDrawingCache();
}
/**
- 逐行扫描 清楚边界空白。
- @param bp
- @param blank 边距留多少个像素
- @return
*/
private Bitmap clearBlank(Bitmap bp, int blank) {
int HEIGHT = bp.getHeight();
int WIDTH = bp.getWidth();
int top = 0, left = 0, right = 0, bottom = 0;
int[] pixs = new int[WIDTH];
boolean isStop;
//扫描上边距不等于背景颜色的第一个点
for (int y = 0; y < HEIGHT; y++) {
bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);
isStop = false;
for (int pix : pixs) {
if (pix != mBackColor) {
top = y;
isStop = true;
break;
}
}
if (isStop) {
break;
}
}
//扫描下边距不等于背景颜色的第一个点
for (int y = HEIGHT - 1; y >= 0; y–) {
bp.getPixels(pixs, 0, WIDTH, 0, y, WIDTH, 1);
isStop = false;
for (int pix : pixs) {
if (pix != mBackColor) {
bottom = y;
isStop = true;
break;
}
}
if (isStop) {
break;
}
}
pixs = new int[HEIGHT];
//扫描左边距不等于背景颜色的第一个点
for (int x = 0; x < WIDTH; x++) {
bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);
isStop = false;
for (int pix : pixs) {
if (pix != mBackColor) {
left = x;
isStop = true;
break;
}
}
if (isStop) {
break;
}
}
//扫描右边距不等于背景颜色的第一个点
for (int x = WIDTH - 1; x > 0; x–) {
bp.getPixels(pixs, 0, 1, x, 0, 1, HEIGHT);
isStop = false;
for (int pix : pixs) {
if (pix != mBackColor) {
right = x;
isStop = true;
break;
}
}
if (isStop) {
break;
}
}
if (blank < 0) {
blank = 0;
}
//计算加上保留空白距离之后的图像大小
left = left - blank > 0 ? left - blank : 0;
top = top - blank > 0 ? top - blank : 0;
right = right + blank > WIDTH - 1 ? WIDTH - 1 : right + blank;
bottom = bottom + blank > HEIGHT - 1 ? HEIGHT - 1 : bottom + blank;
//防止创建null的bitmap 引发的崩溃
if (left0&&top0&&right0&&bottom0){
left=1;
top=1;
right=351;
bottom=251;
}
return Bitmap.createBitmap(bp, left, top, right - left, bottom - top);
}
/**
- 设置画笔宽度 默认宽度为10px
- @param mPaintWidth
*/
public void setPaintWidth(int mPaintWidth) {
mPaintWidth = mPaintWidth > 0 ? mPaintWidth : 10;
this.mPaintWidth = mPaintWidth;
mGesturePaint.setStrokeWidth(mPaintWidth);
}
public void setBackColor(@ColorInt int backColor)
{
mBackColor=backColor;
}/**
- 设置画笔颜色
- @param mPenColor
*/
public void setPenColor(int mPenColor) {
this.mPenColor = mPenColor;
mGesturePaint.setColor(mPenColor);
}
}
- 清除画板
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