网上的画板代码收集和整理
修改后的代码[1]为，少了一个}
package com.example.administrator.myapplication;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.widget.Button;
public class MyWallActivity extends Activity
{
private SurfaceView mSurfaceView = null;
private SurfaceHolder mSurfaceHolder = null;
private Button cleanButton = null;
private Button colorButton = null;
private float oldX = 0f;
private float oldY = 0f;
private boolean canDraw = false;
private Paint mPaint = null;
//用来记录当前是哪一种颜色
private int whichColor = 0;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mSurfaceView = (SurfaceView) this.findViewById(R.id.surfaceview);
mSurfaceHolder = mSurfaceView.getHolder();
mPaint = new Paint();
//画笔的颜色
mPaint.setColor(Color.RED);
//画笔的粗细
mPaint.setStrokeWidth(2.0f);
cleanButton = (Button) this.findViewById(R.id.flushbutton);
//按钮监听
cleanButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
//锁定整个SurfaceView
Canvas mCanvas = mSurfaceHolder.lockCanvas();
mCanvas.drawColor(Color.BLACK);
//绘制完成，提交修改
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
//重新锁一次
mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
}
});
colorButton = (Button) this.findViewById(R.id.colorbutton);
//按钮监听
colorButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
Dialog mDialog = new AlertDialog.Builder(MyWallActivity.this)
.setTitle("corlor setting")
.setSingleChoiceItems(new String[]{"red", "green", "blue"}, whichColor, new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
switch (which) {
case 0: {
//画笔的颜色
mPaint.setColor(Color.RED);
whichColor = 0;
break;
}
case 1: {
//画笔的颜色
mPaint.setColor(Color.GREEN);
whichColor = 1;
break;
}
case 2: {
//画笔的颜色106
mPaint.setColor(Color.BLUE);
whichColor = 2;
break;
}
}
}
})
.setPositiveButton("confirm", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface dialog, int which) {
// TODO Auto-generated method stub
dialog.dismiss();
}
})
.create();
mDialog.show();
}
});
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
//获取x坐标
float x = event.getX();
//获取y坐标（不知道为什么要减去一个偏移值才对得准屏幕）
float y = event.getY();
//第一次进来先不管
if(canDraw)
{
//获取触屏事件
switch(event.getAction())
{
//如果是拖动事件
case MotionEvent.ACTION_MOVE:
{
//锁定整个SurfaceView
Canvas mCanvas = mSurfaceHolder.lockCanvas();
mCanvas.drawLine(x, y, oldX, oldY, mPaint);
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
//重新锁一次
mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));
mSurfaceHolder.unlockCanvasAndPost(mCanvas);
break;
}
}
}
//保存目前的x坐标值
oldX = x;
//保存目前的y坐标值
oldY = y;
canDraw = true;
return true;
}
}
[2]里面有个demo可以直接使用，应该是eclipse上的，我转换为了as的，不过有锯齿
[3]使用贝塞尔曲线的方法去除了锯齿
在[4]中可以使用橡皮擦，貌似需要更改一些东西，否则会闪退，可能和用的是as相关
package com.example.administrator.myapplication;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
private int SCREEN_W;
private int SCREEN_H;
private int Pen = 1;
private int Eraser = 2;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
LinearLayout layout = new LinearLayout(this);
layout.setOrientation(LinearLayout.VERTICAL);
LayoutParams params = new LayoutParams(LayoutParams.WRAP_CONTENT,
LayoutParams.WRAP_CONTENT);
Button paint = new Button(this);
paint.setText("画笔");
layout.addView(paint, params);
Button eraser = new Button(this);
eraser.setText("橡皮");
layout.addView(eraser, params);
final MyView myView = new MyView(this);
layout.addView(myView);
setContentView(layout);
paint.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
myView.setMode(Pen);
}
});
eraser.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
myView.setMode(Eraser);
}
});
}
//MyView就是自定义的画板
class MyView extends View {
private int mMode = 1;
private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mEraserPaint;
private Paint mPaint;
private Path mPath;
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
public MyView(Context context) {
super(context);
setFocusable(true);
setScreenWH();
initPaint();
}
private void setScreenWH() {
DisplayMetrics dm = new DisplayMetrics();
dm = this.getResources().getDisplayMetrics();
int screenWidth = dm.widthPixels;
int screenHeight = dm.heightPixels;
SCREEN_W = screenWidth;
SCREEN_H = screenHeight;
}
//设置绘制模式是“画笔”还是“橡皮擦”
public void setMode(int mode){
this.mMode = mode;
}
private void initPaint() {
//画笔
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setColor(Color.BLACK);
mPaint.setStrokeWidth(10);
//橡皮擦
mEraserPaint = new Paint();
mEraserPaint.setAlpha(0);
//这个属性是设置paint为橡皮擦重中之重
//这是重点
//下面这句代码是橡皮擦设置的重点
mEraserPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
//上面这句代码是橡皮擦设置的重点（重要的事是不是一定要说三遍）
mEraserPaint.setAntiAlias(true);
mEraserPaint.setDither(true);
mEraserPaint.setStyle(Paint.Style.STROKE);
mEraserPaint.setStrokeJoin(Paint.Join.ROUND);
mEraserPaint.setStrokeWidth(30);
mPath = new Path();
mBitmap = Bitmap.createBitmap(SCREEN_W, SCREEN_H, Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
if (mBitmap != null) {
canvas.drawBitmap(mBitmap, 0, 0, mPaint);
}
super.onDraw(canvas);
}
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
//如果是“画笔”模式就用mPaint画笔进行绘制
if (mMode == Pen) {
mCanvas.drawPath(mPath, mPaint);
}
//如果是“橡皮擦”模式就用mEraserPaint画笔进行绘制
if (mMode == Eraser) {
mCanvas.drawPath(mPath, mEraserPaint);
}
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
if (mMode == Pen) {
mCanvas.drawPath(mPath, mPaint);
}
if (mMode == Eraser) {
mCanvas.drawPath(mPath, mEraserPaint);
}
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
if (mMode == Pen) {
mCanvas.drawPath(mPath, mPaint);
}
if (mMode == Eraser) {
mCanvas.drawPath(mPath, mEraserPaint);
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
}[1] 一个简单涂鸦http://www.jizhuomi.com/android/example/19.html
[2] 安卓实现代码的多种方式
[3] 安卓path类的lineTo和quadTo方法的区别
[4] 带画板http://www.mamicode.com/info-detail-1480421.html
