Android 自定义区域截图实现

最近做项目中截图的实现，实现了截图的功能，废话不多，上图才是王道



截图之前



截图之后

实现原理：

1、得到点击截图按钮时候全屏的截图

View view = activity.getWindow().getDecorView();

view.setDrawingCacheEnabled(true);

view.buildDrawingCache();

Bitmap b1 = view.getDrawingCache();

2、把上面得到的全屏截图，作为surfaceview的背景图。（或设置透明背景的surfaceview）

在当前截图区域判断用户的点击滑动（画矩形、平移、拉伸）得到用户最终画出来的矩形。

具体处理比较复杂，详情见shotView中的事件处理。

3、从第一步中的得到的图片中截取出要截取的图片。

saveBitmap = Bitmap.createBitmap( ShotView.this.bitmap, rect.left, rect.top, rect.width( ), rect.height( ) );

主要截图实现类如下

package com.eebbk.view;

import com.eebbk.activity.R;

import android.app.AlertDialog;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PaintFlagsDrawFilter;
import android.graphics.Path;
import android.graphics.PixelFormat;
import android.graphics.Point;
import android.graphics.Rect;
import android.graphics.Paint.Style;
import android.util.AttributeSet;
import android.util.Log;
import android.view.Gravity;
import android.view.KeyEvent;
import android.view.LayoutInflater;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
import android.widget.ImageView;
import android.widget.PopupWindow;
import android.widget.Toast;

import static com.eebbk.util.Calc.getPointDis;

public class ShotView extends SurfaceView implements SurfaceHolder.Callback, Runnable
{
private static final int RAD = 5;
private Paint paint;
private SurfaceHolder sh;
private boolean isRunning = true;
private Canvas canvas;
private Bitmap bitmap = null;
private Rect rect;
private Point[] points = new Point[8];

private Point startPoint;
private Point endPoint;
private Path path;
private PopupWindow popupWindow;
private Bitmap saveBitmap;

// 截图画矩形的状态标志位 0未开始 1完成 2修改 3平移
private int drawState = 0;
// 修改点中的点
private int index = -1;

public void setIsRunning( boolean b )
{
// TODO Auto-generated method stub
this.isRunning = b;
}

public void setBitmap( Bitmap bitmap )
{
this.bitmap = bitmap;
}

public Bitmap getBitmap( )
{
return bitmap;
}

public ShotView( Context context )
{
super( context );
// TODO Auto-generated constructor stub
init( );
}

public ShotView( Context context, AttributeSet attrs )
{
super( context, attrs );
// TODO Auto-generated constructor stub
init( );
}

private void init( )
{
//注释的为实现透明画布效果
//setZOrderOnTop(true);
paint = new Paint( );
sh = this.getHolder( );
sh.addCallback( this );
//sh.setFormat(PixelFormat.TRANSLUCENT);
rect = new Rect( );
startPoint = new Point( );
endPoint = new Point( );
path = new Path( );
this.setFocusable( true );
}

@Override
public void surfaceCreated( SurfaceHolder holder )
{
// TODO Auto-generated method stub
new Thread( this ).start( );

}

@Override
public void surfaceChanged( SurfaceHolder holder, int format, int width, int height )
{
// TODO Auto-generated method stub

}

@Override
public void surfaceDestroyed( SurfaceHolder holder )
{
// TODO Auto-generated method stub
isRunning = false;
try {
Thread.sleep(300);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

@Override
public boolean onTouchEvent( MotionEvent event )
{
switch ( event.getAction( ) )
{

case MotionEvent.ACTION_DOWN:
System.out.println( " down " );
Point downPoint = new Point( ( int ) event.getX( ), ( int ) event.getY( ) );
index = checkDownpoint( downPoint );
if ( drawState == 1 && index != -1 )
{
// 如果点击的是4个顶点
if ( index == 0 || index == 2 || index == 5 || index == 7 )
{
// 点中哪个点，选择对角点为画图起始点(类似于开始作图故不改drawState)
startPoint = points[7 - index];
}
else if(index == 1 || index == 3 || index == 4 || index == 6)
{
drawState = 2;
}
else if ( index == 8 )
{
//平移
drawState = 3;
startPoint = downPoint;
}
}
else
{
startPoint = downPoint;
}

path.moveTo( event.getX( ), event.getY( ) );
break;

case MotionEvent.ACTION_MOVE:

path.lineTo( event.getX( ), event.getY( ) );
endPoint.x = ( int ) event.getX( );
endPoint.y = ( int ) event.getY( );
int left = 0;
int top = 0;
int right = 0;
int bottom = 0;

// 第一次画 或者 画完之后第二次改变4个顶点
if ( drawState == 0 || drawState == 1 )
{
left = Math.min( startPoint.x, endPoint.x );
top = Math.min( startPoint.y, endPoint.y );
right = Math.max( startPoint.x, endPoint.x );
bottom = Math.max( startPoint.y, endPoint.y );
rect.set( left, top, right, bottom );
}
// 第二次修改边上的中点
else if ( drawState == 2 )
{
// 如果点击的是截图矩形宽的中点
if ( index == 1 || index == 6 )
{
top = points[index - 1].y;
bottom = points[index + 1].y;
left = Math.min( points[7 - index].x, endPoint.x );
right = Math.max( points[7 - index].x, endPoint.x );
}
// 点击的是截图矩形长的中点
else if ( index == 3 || index == 4 )
{
left = points[index - 2].x;
right = points[index + 2].x;
top = Math.min( points[7 - index].y, endPoint.y );
bottom = Math.max(  points[7 - index].y, endPoint.y );
}
rect.set( left, top, right, bottom );
}
//平移画好的四边形
else if (drawState == 3)
{
int dx = endPoint.x - startPoint.x;
int dy = endPoint.y - startPoint.y;
//在屏幕区域内移动矩形框
if ( rect.left > 0 && rect.right < getWidth( ) && rect.top > 0 && rect.bottom < getHeight( ))
{
//如果这步移动之后截图矩形出去了，就不要移动了
if ( !(rect.left + dx > 0 && rect.right + dx < getWidth( ) && rect.top + dy > 0 && rect.bottom + dy < getHeight( )) )
{
break;
}
rect.offset( dx,  dy);
startPoint.x = endPoint.x;
startPoint.y = endPoint.y;
}
System.out.println(rect);
}

break;

case MotionEvent.ACTION_UP:

Log.i( "MotionEvent.ACTION_UP", event.getX( ) + " " + event.getY( ) );
if ( popupWindow != null )
{
popupWindow.dismiss( );
popupWindow = null;
}

drawState = 1;
View view = LayoutInflater.from( getContext( ) ).inflate( R.layout.popwindow_confirm, null );
popupWindow = new PopupWindow( view, LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT );
popupWindow.setOutsideTouchable( true );
popupWindow.showAtLocation( this, Gravity.LEFT | Gravity.TOP, rect.right, rect.bottom );
setPopListener( view );
break;
}

return true;
}

// 检查down的点是否在画好的rect关键点上， 如果在返回-1，否则返回改点的index
private int checkDownpoint( Point downPoint )
{
// TODO Auto-generated method stub

points[0] = new Point( rect.left, rect.top );
points[1] = new Point( rect.left, ( rect.top + rect.bottom ) / 2 );
points[2] = new Point( rect.left, rect.bottom );
points[3] = new Point( ( rect.left + rect.right ) / 2, rect.top );
points[4] = new Point( ( rect.left + rect.right ) / 2, rect.bottom );
points[5] = new Point( rect.right, rect.top );
points[6] = new Point( rect.right, ( rect.top + rect.bottom ) / 2 );
points[7] = new Point( rect.right, rect.bottom );

for ( int i = 0; i < points.length; i++ )
{
if ( getPointDis( points[i], downPoint ) < 3 * RAD )
{
return i;
}
}

if ( downPoint.x > rect.left && downPoint.x < rect.right && downPoint.y > rect.top && downPoint.y < rect.bottom)
{
return 8;
}

return -1;
}

private void setPopListener( View view )
{
// TODO Auto-generated method stub
popupWindow.getContentView( ).setOnTouchListener( new View.OnTouchListener( )
{

@Override
public boolean onTouch( View v, MotionEvent event )
{
if ( event.getAction( ) == MotionEvent.ACTION_OUTSIDE )
{
System.out.println( " 点击了外部，销毁啦！！！" );
popupWindow.dismiss( );
popupWindow = null;
}
return true;
}
} );

view.findViewById( R.id.cancle_ll ).setOnClickListener( new OnClickListener( )
{

@Override
public void onClick( View v )
{
// TODO Auto-generated method stub
Toast.makeText( getContext( ), "重新截图！", Toast.LENGTH_SHORT ).show( );
rect.setEmpty( );
invalidate( );
if ( popupWindow != null )
{
popupWindow.dismiss( );
popupWindow = null;
}
}
} );

view.findViewById( R.id.back_ll ).setOnClickListener( new OnClickListener( )
{

@Override
public void onClick( View v )
{
// TODO Auto-generated method stub
Toast.makeText( getContext( ), "回到原来视图！", Toast.LENGTH_SHORT ).show( );
rect.setEmpty( );
invalidate( );
if ( popupWindow != null )
{
popupWindow.dismiss( );
popupWindow = null;
}
isRunning = false;
setVisibility( View.INVISIBLE );
}
} );

view.findViewById( R.id.ok_ll ).setOnClickListener( new OnClickListener( )
{

@Override
public void onClick( View v )
{
// TODO Auto-generated method stub
Toast.makeText( getContext( ), "截图完成！", Toast.LENGTH_SHORT ).show( );

saveBitmap = Bitmap.createBitmap( ShotView.this.bitmap, rect.left, rect.top , rect.width( ), rect.height( ) );

ImageView imgView = new ImageView( getContext());
imgView.setImageBitmap( saveBitmap );
new AlertDialog.Builder(getContext( ))
.setTitle("截取到的图片")
.setView(imgView)
.setPositiveButton("确定", null)
.show();

}
} );
}

@Override
public void run( )
{
// TODO Auto-generated method stub
while ( isRunning )
{
drawView( );
try
{
Thread.sleep( 100 );
}
catch ( InterruptedException e )
{
// TODO Auto-generated catch block
e.printStackTrace( );
}
}
}

private void drawView( )
{
// TODO Auto-generated method stub
try
{
if ( sh != null )
{
canvas = sh.lockCanvas( );
//抗锯齿
canvas.setDrawFilter( new PaintFlagsDrawFilter( 0, Paint.ANTI_ALIAS_FLAG | Paint.FILTER_BITMAP_FLAG ) );
canvas.drawBitmap( bitmap, 0,0, null );
// 不填充
paint.setStyle( Style.STROKE );
// canvas.drawPath( path, paint );
paint.setColor( Color.BLUE );
paint.setStrokeWidth( 2 );
canvas.drawRect( rect, paint );

paint.setStyle( Paint.Style.FILL );
paint.setColor( Color.GREEN );
//paint.setStrokeWidth( 3 );

canvas.drawCircle( rect.left, rect.top, RAD, paint );// 画点，参数一水平x轴，参数二垂直y轴，第三个参数为Paint对象。
canvas.drawCircle( rect.left, ( rect.top + rect.bottom ) / 2, RAD, paint );
canvas.drawCircle( rect.left, rect.bottom, RAD, paint );
canvas.drawCircle( ( rect.left + rect.right ) / 2, rect.top, RAD, paint );
canvas.drawCircle( ( rect.left + rect.right ) / 2, rect.bottom, RAD, paint );
canvas.drawCircle( rect.right, rect.top, RAD, paint );
canvas.drawCircle( rect.right, ( rect.top + rect.bottom ) / 2, RAD, paint );
canvas.drawCircle( rect.right, rect.bottom, RAD, paint );

}
}
catch ( Exception e )
{
e.printStackTrace( );
}
finally
{
if ( canvas != null )
sh.unlockCanvasAndPost( canvas );
}

}

@Override
public boolean onKeyDown(int keyCode, KeyEvent event)
{
if(keyCode == KeyEvent.KEYCODE_BACK)
{
isRunning = false;
}
return super.onKeyDown(keyCode, event);
}

}

经过测试，没有明显严重bug，最后附上demo源码

http://download.csdn.net/detail/tianmi1988/4859217

难免会有疏漏，欢迎大家指正，共同进步！