Android移动开发-Android屏幕手写签名的实现

Android屏幕手写签名的原理就是把手机屏幕当作画板，把用户手指当作画笔，手指在屏幕上在屏幕上划来划去，屏幕就会显示手指的移动轨迹，就像画笔在画板上写字一样。实现手写签名需要结合绘图的路径工具Path，在有按下动作时调用Path对象的moveTo方法，将路径起始点移动到触摸点；在有移动操作时调用Path对象的quadTo方法，将记录本次触摸点与上次触摸点之间的路径；在有移动操作与提起动作时调用Canvas对象的drawPath方法，将本次触摸绘制在画布上。

• layout/activity_signature.xml界面布局代码如下：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:app="http://schemas.android.com/apk/res-auto"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical"    android:padding="5dp">    <ScrollView        android:layout_width="match_parent"        android:layout_height="wrap_content">        <LinearLayout            android:layout_width="match_parent"            android:layout_height="wrap_content"            android:orientation="vertical">            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal">                <Button                    android:id="@+id/btn_add_signature"                    android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:text="开始签名"                    android:textColor="@color/black"                    android:textSize="17sp" />                <Button                    android:id="@+id/btn_reset_signature"                    android:layout_width="0dp"                    android:layout_height="match_parent"                    android:layout_weight="1"                    android:text="重置"                    android:textColor="@color/black"                    android:textSize="17sp" />                <Button                    android:id="@+id/btn_revoke_signature"                    android:layout_width="0dp"                    android:layout_height="match_parent"                    android:layout_weight="1"                    android:text="回退"                    android:textColor="@color/black"                    android:textSize="17sp" />                <Button                    android:id="@+id/btn_end_signature"                    android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:text="结束签名"                    android:textColor="@color/black"                    android:textSize="17sp" />            </LinearLayout>            <com.fukaimei.touchevent.widget.SignatureView                android:id="@+id/view_signature"                android:layout_width="match_parent"                android:layout_height="200dp"                android:background="@color/white"                app:paint_color="#0000aa"                app:stroke_width="3" />            <LinearLayout                android:layout_width="match_parent"                android:layout_height="wrap_content"                android:orientation="horizontal">                <Button                    android:id="@+id/btn_save_signature"                    android:layout_width="0dp"                    android:layout_height="wrap_content"                    android:layout_weight="1"                    android:text="保存图片文件"                    android:textColor="@color/black"                    android:textSize="17sp" />            </LinearLayout>            <ImageView                android:id="@+id/iv_signature_new"                android:layout_width="match_parent"                android:layout_height="200dp"                android:background="@color/white"                android:scaleType="fitCenter" />        </LinearLayout>    </ScrollView></LinearLayout>

• SignatureActivity.java逻辑代码如下：

package com.fukaimei.touchevent;import android.graphics.Bitmap;import android.os.Bundle;import android.os.Handler;import android.support.v7.app.AppCompatActivity;import android.view.View;import android.view.View.OnClickListener;import android.widget.ImageView;import android.widget.Toast;import com.fukaimei.touchevent.filedialog.dialog.FileSaveFragment;import com.fukaimei.touchevent.util.BitmapUtil;import com.fukaimei.touchevent.widget.SignatureView;public class SignatureActivity extends AppCompatActivity implements        OnClickListener, FileSaveFragment.FileSaveCallbacks {    private SignatureView view_signature;    private ImageView iv_signature_new;    private Bitmap mBitmap;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_signature);        view_signature = (SignatureView) findViewById(R.id.view_signature);        iv_signature_new = (ImageView) findViewById(R.id.iv_signature_new);        findViewById(R.id.btn_add_signature).setOnClickListener(this);        findViewById(R.id.btn_end_signature).setOnClickListener(this);        findViewById(R.id.btn_reset_signature).setOnClickListener(this);        findViewById(R.id.btn_revoke_signature).setOnClickListener(this);        findViewById(R.id.btn_save_signature).setOnClickListener(this);    }    @Override    public void onClick(View v) {        if (v.getId() == R.id.btn_save_signature) {            if (mBitmap == null) {                Toast.makeText(this, "请先开始然后结束签名", Toast.LENGTH_LONG).show();                return;            }            FileSaveFragment.show(this, "jpg");        } else if (v.getId() == R.id.btn_add_signature) {            view_signature.setDrawingCacheEnabled(true);        } else if (v.getId() == R.id.btn_reset_signature) {            view_signature.clear();        } else if (v.getId() == R.id.btn_revoke_signature) {            view_signature.revoke();        } else if (v.getId() == R.id.btn_end_signature) {            if (view_signature.isDrawingCacheEnabled() != true) {                Toast.makeText(this, "请先开始签名", Toast.LENGTH_LONG).show();            } else {                mBitmap = view_signature.getDrawingCache();                iv_signature_new.setImageBitmap(mBitmap);                mHandler.postDelayed(mResetCache, 100);            }        }    }    private Handler mHandler = new Handler();    private Runnable mResetCache = new Runnable() {        @Override        public void run() {            view_signature.setDrawingCacheEnabled(false);            view_signature.setDrawingCacheEnabled(true);        }    };    @Override    public boolean onCanSave(String absolutePath, String fileName) {        return true;    }    @Override    public void onConfirmSave(String absolutePath, String fileName) {        String path = String.format("%s/%s", absolutePath, fileName);        BitmapUtil.saveBitmap(path, mBitmap, "jpg", 80);        Toast.makeText(this, "成功保存图片文件：" + path, Toast.LENGTH_LONG).show();    }}

• Demo程序运行效果界面截图如下：

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