一、内容

设计两种形式的对话框程序，一种是发出提示信息的普通对话框，另一种是用户登录对话框。

二、实现

1.主界面 activity_main.xml

xmlns:app="http://schemas.android.com/apk/res-auto"

xmlns:tools="http://schemas.android.com/tools"

android:layout_width="match_parent"

android:layout_height="match_parent"

tools:context=".MainActivity"

android:orientation="vertical">

android:id="@+id/handwriteview"

android:layout_height="380dp"

android:layout_width="380dp"

tools:ignore="MissingConstraints" />

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="horizontal"

android:gravity="center_horizontal">

android:layout_width="200dp"

android:layout_height="wrap_content"

android:id="@+id/clear"

android:text="清屏"/>

2.主控制程序 MainActivity.java

import android.content.DialogInterface;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.view.View;

import android.widget.Button;

public class MainActivity extends AppCompatActivity {

HandWrite handWrite = null;

Button clear = null;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

handWrite=(HandWrite)findViewById(R.id.handwriteview);

clear=(Button)findViewById(R.id.clear);

clear.setOnClickListener(new mClick());

}

class mClick implements View.OnClickListener{

@Override

public void onClick(View v) {

handWrite.clear();

}

}

}

3.HandWrite.java 的代码

import android.content.Context;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.support.annotation.Nullable;

import android.util.AttributeSet;

import android.view.MotionEvent;

import android.view.View;

public class HandWrite extends View {

Paint paint = null;

Bitmap originalBitmap = null;

Bitmap new1_Bitmap = null;

Bitmap new2_Bitmap = null;

float startX = 0,startY = 0;

float clickX = 0,clickY = 0;

boolean ismove = true;

boolean isClear = false;

int color = Color.YELLOW;

float strokeWidth = 2.0f;

public HandWrite(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

originalBitmap = BitmapFactory.decodeResource(getResources(),R.drawable.cy).copy(Bitmap.Config.ARGB_8888,true);

new1_Bitmap = Bitmap.createBitmap(originalBitmap);

}

public void clear(){

isClear = true;

new2_Bitmap = Bitmap.createBitmap(originalBitmap);

invalidate();

}

public void setstyle(float strokeWidth){

this.strokeWidth = strokeWidth;

}

@Override

protected void onDraw(Canvas canvas){

super.onDraw(canvas);

canvas.drawBitmap(HandWriting(new1_Bitmap),0,0,null);

}

public Bitmap HandWriting(Bitmap o_bitmap){

Canvas canvas = null;

if(isClear){

canvas = new Canvas(new2_Bitmap);

}

else{

canvas = new Canvas(o_bitmap);

}

paint =new Paint();

paint.setStyle(Paint.Style.STROKE);

paint.setAntiAlias(true);

paint.setColor(color);

paint.setStrokeWidth(strokeWidth);

if(ismove){

canvas.drawLine(startX,startY,clickX,clickY,paint);

}

startX = clickX;

startY = clickY;

if(isClear){

return new2_Bitmap;

}

return o_bitmap;

}

@Override

public boolean onTouchEvent(MotionEvent event){

clickX =event.getX();

clickY = event.getY();

if(event.getAction() == MotionEvent.ACTION_DOWN){

ismove = false;

invalidate();

return true;

}

else if(event.getAction() == MotionEvent.ACTION_MOVE){

ismove = true;

invalidate();

return true;

}

return super.onTouchEvent(event);

}

}