ZenBrush(禅宗画笔)反编译后二次开发（电子签名_毛笔带笔锋的效果）

最近POS机项目有个需求，电子签名，就是一个画板上签名。看了一些文章，把贝塞尔曲线算法用上了效果也
不怎么样，然后在Github上也找了些demo，有个brushes还不错，但没有毛笔笔锋那种效果，找啊找，终于找到
ZenBrush（中文名：禅宗画笔，好像是日本人开发的），的确做的非常好，但没有sdk，也没有开源。
想着能否通过反编译的方式，复用里面的核心代码！通过几天尝试可行，但是，如果二次开发的apk挂在了复用里
面的代码时，就没办法通过java代码修复了，只能通过smail修复了，这个需要反编译相关知识了。
来张毛笔带笔锋的效果图，没有书法功底别见笑。



现在分析下二次开发思路：
1. 写一个打log的文件ApktoolLog.java，方便在反编译的smail文件中注入代码（通常一行，根据需要在
ApktoolLog加函数，争取注入时只要一行代码），下面贴下ApktoolLog.java的简易代码（但很实用哦）

package com.example.helloworld;

import android.util.Log;

public class ApktoolLog {

private static final String TAG = "ApktoolLog";

public static void printStackTrace() {
for (StackTraceElement i : Thread.currentThread().getStackTrace()) {
Log.e(TAG, "" + i);
}
}

public static void e(String info) {
Log.e(TAG, "String:" + info);
}

public static void e(int info) {
Log.e(TAG, "int:" + info);
}

public static void e(long info) {
Log.e(TAG, "long:" + info);
}

public static void e(float info) {
Log.e(TAG, "float:" + info);
}

public static void e(double info) {
Log.e(TAG, "double:" + info);
}

public static void e(float paramFloat1, float paramFloat2,
float paramFloat3, float paramFloat4, float paramFloat5,
float paramFloat6, float paramFloat7, float paramFloat8) {
Log.e(TAG, "paramFloat1:" + paramFloat1 + ", paramFloat2:"
+ paramFloat2 + ", paramFloat3:" + paramFloat3
+ ", paramFloat4:" + paramFloat4 + ", paramFloat5:"
+ paramFloat5 + ", paramFloat6:" + paramFloat6
+ ", paramFloat7:" + paramFloat7 + ", paramFloat8:"
+ paramFloat8);
}

}

将它反编译成smail文件ApktoolLog.smali拷贝到对应目录。

2.反编译原始的ZenBrush.apk在smail中注入log代码，得到关键参数值，下面详解设置画笔样式的关键参数

$ grep -rn "setBrushType" ZenBrush
匹配到二进制文件 ZenBrush/build/apk/lib/armeabi-v7a/libZenBrushRenderer.so
匹配到二进制文件 ZenBrush/build/apk/lib/armeabi/libZenBrushRenderer.so
ZenBrush/smali/jp/co/psoft/zenbrushfree/library/a.smali:209:    invoke-virtual {v0, v1}, Ljp/co/psoft/ZenBrushLib/ZenBrushRenderer;->setBrushType(I)V
ZenBrush/smali/jp/co/psoft/ZenBrushLib/ZenBrushRenderer.smali:528:.method public native setBrushType(I)V

找到设置画笔样式代码在ZenBrush/smali/jp/co/psoft/zenbrushfree/library/a.smali:209

smail和Java Decompiler对比，然后在smail的209行上面注入log代码把v1的值打印出来，就知道ZenBrush.apk
当前设置样式的参数了
.method private c(Ljp/co/psoft/zenbrushfree/library/b;)V

    .locals 2

    iget-object v0, p0, Ljp/co/psoft/zenbrushfree/library/a;->g:Ljp/co/psoft/ZenBrushLib/ZenBrushRenderer;

    invoke-virtual {p1}, Ljp/co/psoft/zenbrushfree/library/b;->a()I

    move-result v1

    invoke-static {v1}, Lcom/example/helloworld/ApktoolLog;->e(I)V

    invoke-virtual {v0, v1}, Ljp/co/psoft/ZenBrushLib/ZenBrushRenderer;->setBrushType(I)V

    iget-object v0, p0, Ljp/co/psoft/zenbrushfree/library/a;->g:Ljp/co/psoft/ZenBrushLib/ZenBrushRenderer;

    iget v1, p1, Ljp/co/psoft/zenbrushfree/library/b;->g:F

    invoke-virtual {v0, v1}, Ljp/co/psoft/ZenBrushLib/ZenBrushRenderer;->setBrushAlpha(F)V

    iput-object p1, p0, Ljp/co/psoft/zenbrushfree/library/a;->d:Ljp/co/psoft/zenbrushfree/library/b;

    iget-object v0, p0, Ljp/co/psoft/zenbrushfree/library/a;->h:[I

    invoke-virtual {p1}, Ljp/co/psoft/zenbrushfree/library/b;->ordinal()I

    move-result v1

    aget v0, v0, v1

    invoke-direct {p0, v0}, Ljp/co/psoft/zenbrushfree/library/a;->b(I)V

    return-void

.end method

然后回编，签名，安装运行抓log，过滤关键字，就能一一找到关键值的参数。
3.
在自己的工程里建同名的包名，类名，函数，可以在Java Decompiler里直接拷贝，将函数体去掉，如果有
返回值的，随便return一个对应值即可。如核心文件ZenBrushRenderer代码

package jp.co.psoft.ZenBrushLib;

import android.opengl.GLSurfaceView;
import android.view.MotionEvent;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.opengles.GL10;

public class ZenBrushRenderer implements GLSurfaceView.Renderer {

static {
System.loadLibrary("ZenBrushRenderer");
}

public ZenBrushRenderer() {
}

private native void onNdkDrawFrame();

private native void onNdkSurfaceChanged(int paramInt1, int paramInt2);

public final int a() {
return 0;
}

public final boolean a(MotionEvent paramMotionEvent) {
return true;
}

public final int b() {
return 0;
}

public native boolean canClearInk();

public native boolean canRedo();

public native boolean canUndo();

public native boolean canvasInitialize(int paramInt1, int paramInt2);

public native boolean canvasUpdate(int paramInt, float paramFloat1,
float paramFloat2, float paramFloat3, double paramDouble);

public native void clearInk();

public native boolean getImageARGB8888(int[] paramArrayOfInt);

public native boolean getInkImageARGB8888(int[] paramArrayOfInt);

public void onDrawFrame(GL10 paramGL10) {
}

public void onSurfaceChanged(GL10 paramGL10, int paramInt1, int paramInt2) {
}

public void onSurfaceCreated(GL10 paramGL10, EGLConfig paramEGLConfig) {
}

public native void redo();

public native void setBackgroundColor(float paramFloat1, float paramFloat2,
float paramFloat3);

public native boolean setBackgroundImageARGB8888(int[] paramArrayOfInt,
int paramInt1, int paramInt2);

public native void setBrushAlpha(float paramFloat);

public native void setBrushSize(float paramFloat);

public native void setBrushTintColor(float paramFloat1, float paramFloat2,
float paramFloat3, float paramFloat4, float paramFloat5,
float paramFloat6, float paramFloat7, float paramFloat8);

public native void setBrushType(int paramInt);

public native boolean setInkImageARGB8888(int[] paramArrayOfInt);

public native void undo();
}

jni的相关函数声明及部分成员函数

4.
编写自己的文件，并调用复用的文件及函数，这一步很复杂，需要对比smail及Java Decompiler的java代码，
并找到调用关系，这个需要反编译相关知识，不懂得略过吧，下面贴出我自己的MainActivity

package com.example.helloworld;

import java.util.concurrent.FutureTask;

import com.example.helloworld.utils.BitmapUtils;

import jp.co.psoft.ZenBrushLib.ZenBrushGLSurfaceView;
import jp.co.psoft.ZenBrushLib.ZenBrushRenderer;
import jp.co.psoft.zenbrushfree.library.e;
import jp.co.psoft.zenbrushfree.library.i;
import jp.co.psoft.zenbrushfree.library.n;
import android.app.Activity;
import android.graphics.Bitmap;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.TextUtils;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.Button;
import android.widget.Toast;

public class MainActivity extends Activity implements OnClickListener, i {

private ZenBrushGLSurfaceView mBrushGLSurfaceView;
private Button mBtnClear;
private Button mBtnUndo;
private Button mBtnRedo;

private float mBrushSize = 10.0f;

private TYPE_CALLBACK mTypeCallback = TYPE_CALLBACK.NONE;

private enum TYPE_CALLBACK {
NONE, SAVE, PRINT
}

private static final int EVENT_SHOW_TOAST = 1;
private Handler mHandler = new Handler() {
public void handleMessage(Message msg) {
switch (msg.what) {
case EVENT_SHOW_TOAST:
Toast.makeText(MainActivity.this, (String) msg.obj,
Toast.LENGTH_LONG).show();
break;
}
}
};

@Override
protected void onCreate(Bundle bundle) {
super.onCreate(bundle);
setContentView(R.layout.activity_main);
try {
getWindow().addFlags(
WindowManager.LayoutParams.class.getField(
"FLAG_NEEDS_MENU_KEY").getInt(null));
} catch (NoSuchFieldException e) {
} catch (IllegalAccessException e) {
}

mBrushGLSurfaceView = (ZenBrushGLSurfaceView) findViewById(R.id.view);
// 设置画布背景颜色
mBrushGLSurfaceView.a.setBackgroundColor(255F, 255F, 255F);
// 设置画笔颜色
mBrushGLSurfaceView.a.setBrushTintColor(0f, 0f, 0f, 1.0f, 0f, 0f, 0f,
1.0f);
// 设置画笔类型
mBrushGLSurfaceView.a.setBrushType(0);
mBrushGLSurfaceView.a.setBrushAlpha(1.0f);
// 设置画笔大小
mBrushGLSurfaceView.a.setBrushSize(mBrushSize);

mBtnClear = (Button) findViewById(R.id.clear_lnk);
mBtnUndo = (Button) findViewById(R.id.undo);
mBtnRedo = (Button) findViewById(R.id.redo);
mBtnClear.setOnClickListener(this);
mBtnUndo.setOnClickListener(this);
mBtnRedo.setOnClickListener(this);

}

@Override
public void onClick(View view) {
// TODO Auto-generated method stub
if (view == mBtnClear) {
mBrushGLSurfaceView.a.clearInk();
} else if (view == mBtnUndo) {
mBrushGLSurfaceView.a.undo();
} else if (view == mBtnRedo) {
mBrushGLSurfaceView.a.redo();
}
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// TODO Auto-generated method stub
getMenuInflater().inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
// TODO Auto-generated method stub
switch (item.getItemId()) {
case R.id.action_save:
mTypeCallback = TYPE_CALLBACK.SAVE;
new e(mBrushGLSurfaceView).a(this);
break;
case R.id.action_print:
mTypeCallback = TYPE_CALLBACK.PRINT;
new e(mBrushGLSurfaceView).a(this);
break;
case R.id.action_brush_size_increase:
mBrushSize += 1;
mBrushGLSurfaceView.a.setBrushSize(mBrushSize);
Toast.makeText(this, "Set brush size : " + mBrushSize,
Toast.LENGTH_SHORT).show();
break;
case R.id.action_brush_size_decrease:
mBrushSize -= 1;
mBrushGLSurfaceView.a.setBrushSize(mBrushSize);
Toast.makeText(this, "Set brush size : " + mBrushSize,
Toast.LENGTH_SHORT).show();
break;
}
return super.onOptionsItemSelected(item);
}

private Bitmap getGLBitmap() {
int width = mBrushGLSurfaceView.getWidth();
int height = mBrushGLSurfaceView.getHeight();
Bitmap bitmap = Bitmap.createBitmap(width, height,
Bitmap.Config.ARGB_8888);
int[] pixels = new int[width * height];
mBrushGLSurfaceView.a.getImageARGB8888(pixels);
bitmap.setPixels(pixels, 0, width, 0, 0, width, height);
return bitmap;
}

@Override
public void a(n paramn) {
// TODO Auto-generated method stub
Bitmap bitmap = BitmapUtils.createBitmap(paramn);
switch (mTypeCallback) {
case SAVE:
String fileName = BitmapUtils.saveBitmapAsPng(BitmapUtils
.adjustPhotoRotation(bitmap, 90));
if (!TextUtils.isEmpty(fileName)) {
mHandler.sendMessage(mHandler.obtainMessage(EVENT_SHOW_TOAST,
fileName));
}
break;
case PRINT:
break;
}

}

}

拓展，POS机打印电子签名，有响应的SDK打印Bitmap（可能需要旋转，放缩等动作）即可

@Override
public void a(n paramn) {
// TODO Auto-generated method stub
Bitmap bitmap = BitmapUtils.createBitmap(paramn);
switch (mTypeCallback) {
case SAVE:
String fileName = BitmapUtils.saveBitmapAsPng(BitmapUtils
.adjustPhotoRotation(bitmap, 90));
if (!TextUtils.isEmpty(fileName)) {
mHandler.sendMessage(mHandler.obtainMessage(EVENT_SHOW_TOAST,
fileName));
}
break;
case PRINT:
mESCPrinter.sendBitmap(
0,
BitmapUtils.scaleBitmap(bitmap, 1.0f
* ESCPrinter.PAGE_WIDTH / bitmap.getWidth()));
break;
}

}

效果图如下：



打印效果还可以哈


附件下载（包括MyZenBrush（不支持打印），MyZenBrush_ESCPrinter（支持打印），ZenBrush_smail（复用核心代码））