I have created a simple demo application in android for drawing ,now can any one say me how can i remove view and clear screen in just one click .I have tried as below:please help me to do it....thanx in advance..!
main.java
package com.example.singletouch;
import com.example.singletouch.R.attr;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;
import android.widget.LinearLayout;
public class MainActivity extends Activity {
ImageView pen;
SingleTouchView mDrawView;
ImageView remove;
LinearLayout pens;
LinearLayout pen1, pen2, pen3, pen4;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mDrawView = (SingleTouchView) findViewById(R.id.myview);
pen = (ImageView) findViewById(R.id.pen);
pens = (LinearLayout) findViewById(R.id.linear);
pens.setVisibility(View.GONE);
pen1 = (LinearLayout) findViewById(R.id.pen1);
pen2 = (LinearLayout) findViewById(R.id.pen2);
pen3 = (LinearLayout) findViewById(R.id.pen3);
pen4 = (LinearLayout) findViewById(R.id.pen4);
remove=(ImageView)findViewById(R.id.remove);
/*
* pen1.setOnClickListener(this); pen2.setOnClickListener(this);
* pen3.setOnClickListener(this); pen4.setOnClickListener(this);
*/
pen.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
pens.setVisibility(View.VISIBLE);
}
});pens.setVisibility(View.GONE);
pen1.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_1);
pens.setVisibility(View.GONE);
}
});
pen2.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_2);
pens.setVisibility(View.GONE);
}
});
pen3.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
pens.setVisibility(View.GONE);
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_3);
}
});
pen4.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
pens.setVisibility(View.GONE);
mDrawView.setPen(SingleTouchView.DrawingPens.PEN_4);
}
});
remove.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
}
});
}
}
SingleTouchView.java
package com.example.singletouch;
import java.util.AbstractMap;
import java.util.Map;
import java.util.concurrent.ConcurrentLinkedQueue;
import android.R.color;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff.Mode;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.ImageView;
import android.widget.Switch;
public class SingleTouchView extends View{
public int width;
public int height;
public Bitmap mBitmap;
public Canvas mCanvas;
public Path mPath;
public Paint mBitmapPaint;
Context context;
public Paint circlePaint;
public Path circlePath;
public enum DrawingPens {
PEN_1(6),
PEN_2(4),
PEN_3(2),
PEN_4(1);
final public Paint mPaint;
/**
* Constructor
*
* @param width width of stroke
* @param color color of stroke
*/
private DrawingPens(final int width) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setStrokeWidth(width);
//mPaint.setColor(color);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
}
/**
* @return corresponding paint
*/
Paint getPaint() {
return mPaint;
}
}
public SingleTouchView(final Context context) {
super(context);
init(context);
}
public SingleTouchView(final Context context, final AttributeSet attrs) {
super(context, attrs);
init(context);
}
public SingleTouchView(final Context context, final AttributeSet attrs, final int defStyle) {
super(context, attrs, defStyle);
init(context);
}
/** To store Paint - Path relation */
// TODO: depending on exact limits, more optimal ways can be found
private ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>> mPaths = new ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>>();
/** Cached current path, <b>NOTE:</b> this field is tail at mPaths and is used it only for caching, not drawing */
private Path mCurrentPath;
/**
* Inits internal views data, should be called from every constructor
*
* @param context {@link Context}
*/
private void init(final Context context) {
/* TODO: if some values of paints cannot be determined in static context (in enum),
then Paints should be created here and used via EnumMap */
// Initial pen
setPen(DrawingPens.PEN_1);
}
@Override
public void onDraw(Canvas canvas){
// just to draw background
super.onDraw(canvas);
// Draw all paths
for (Map.Entry<Path, DrawingPens> entry : mPaths) {
canvas.drawPath(entry.getKey(), entry.getValue().getPaint());
}
}
@Override
public boolean onTouchEvent(MotionEvent me){
float eventX = me.getX();
float eventY = me.getY();
switch (me.getAction()) {
case MotionEvent.ACTION_DOWN:
mCurrentPath.moveTo(eventX, eventY);
return true;
case MotionEvent.ACTION_MOVE:
mCurrentPath.lineTo(eventX, eventY);
break;
case MotionEvent.ACTION_UP:
break;
}
invalidate();
return true;
}
/**
* Setter for new pen
*
* @param pen {@link DrawingPens} to be used for next drawing
*/
public void setPen(final DrawingPens pen) {
// put latest item to the queue
mCurrentPath = new Path();
mPaths.add(new AbstractMap.SimpleImmutableEntry<Path, DrawingPens>(mCurrentPath, pen));
}
public void clear(View v){
}
}
main.xml
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
tools:context=".MainActivity" >
<com.example.singletouch.SingleTouchView
android:id="@+id/myview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_above="@+id/pen" />
<LinearLayout
android:id="@+id/linearLayout1"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="@drawable/menubar"
android:padding="2dp"
android:weightSum="4" >
<ImageView
android:id="@+id/pen"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:gravity="center"
android:src="@drawable/pen" />
<ImageView
android:id="@+id/eraser"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="@drawable/eraser" />
<ImageView
android:id="@+id/color"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="@drawable/color" />
<ImageView
android:id="@+id/remove"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_alignParentBottom="true"
android:layout_weight="1"
android:src="@drawable/remove" />
</LinearLayout>
<LinearLayout
android:id="@+id/linear"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:layout_above="@+id/linearLayout1"
android:layout_alignParentLeft="true"
android:background="#eeeeee"
android:orientation="horizontal"
android:visibility="gone"
android:weightSum="4" >
<LinearLayout
android:id="@+id/pen1"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:src="@drawable/pen1" />
</LinearLayout>
<LinearLayout
android:id="@+id/pen2"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:src="@drawable/pen2" />
</LinearLayout>
<LinearLayout
android:id="@+id/pen3"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="@drawable/pen3" />
</LinearLayout>
<LinearLayout
android:id="@+id/pen4"
android:layout_width="wrap_content"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center" >
<ImageView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_weight="1"
android:src="@drawable/pen4" />
</LinearLayout>
</LinearLayout>
</RelativeLayout>
Jus use ...
mCanvas.drawColor(Color.BLACK);
... for clearing the canvas or any other color you want to have in background. E.g.
remove.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
// clear canvas contents
mCanvas.drawColor(Color.BLACK);
// create new path list; old one will be garbage collected
ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>> mPaths =
new ConcurrentLinkedQueue<Map.Entry<Path, DrawingPens>>();
pens.setVisibility(View.VISIBLE);
}
p.s.: for removing a view dynamically from its container use removeView(....), e.g.
((ViewGroup)viewToRemove.getParent()).removeView(viewToRemove);
Hope this helps ... Cheers!
remove.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
layout.removeView(mDrawView);
mDrawView = new SingleTouchView(MainActivity.this);
layout.addView(mDrawView);
}
});
user2041902
Put the portion of the screen you want cleared in a single layout in xml eg
<RelativeLayout
android:id="@+id/layout"
android:layout_width="wrap_content"
android:layout_height= "wrap_content">
The Views that have to be gone on click
</RelativeLayout>
Then in your code in onClick() of the button give
((RelativeLayout) findViewById(R.id.layout)).setVisiblity(View.GONE));
EDIT :
If you want the ImageView cleared use :
((ImageView) findViewById(R.id.imageView)).setImageDrawable(null);
来源：https://stackoverflow.com/questions/17849677/how-to-clear-view-in-android