Java 如何在android画布中将整个画布保存为jpeg图像？
我在画布上画了一些东西，我想在我的存储器中将这幅画保存为jpeg图像。我使用了下面的方法，它将image sign.jpg保存在我的目录中，但它保存的是空白的黑色图像，它的大小为14.49kb 这里有一个方法Java 如何在android画布中将整个画布保存为jpeg图像？,java,android,image,canvas,bitmap,Java,Android,Image,Canvas,Bitmap,我在画布上画了一些东西，我想在我的存储器中将这幅画保存为jpeg图像。我使用了下面的方法，它将image sign.jpg保存在我的目录中，但它保存的是空白的黑色图像，它的大小为14.49kb 这里有一个方法 public Bitmap savebit(){ Bitmap saveBitmap = Bitmap.createBitmap(this.getWidth(), this.getHeight(), Bitmap.Config.ARGB_8888); C
public Bitmap savebit(){
Bitmap saveBitmap = Bitmap.createBitmap(this.getWidth(), this.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(saveBitmap);
canvas.setBitmap(saveBitmap);
this.draw(canvas);
File file = new File(Environment.getExternalStorageDirectory() + "/sign.jpg");
try {
saveBitmap.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(file));
} catch (Exception e) {
e.printStackTrace();
}
return saveBitmap;
}
import android.annotation.SuppressLint;
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.Rect;
import android.util.AttributeSet;
import android.util.LruCache;
import android.view.MotionEvent;
import android.view.View;
public class MyDrawView extends View {
public Bitmap mBitmap;
public Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private Paint mPaint;
public MyDrawView(Context c, AttributeSet attrs) {
super(c, attrs);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFF000000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(9);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
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;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}
@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;
}
public Bitmap getBitmap()
{
//this.measure(100, 100);
//this.layout(0, 0, 100, 100);
this.setDrawingCacheEnabled(true);
this.buildDrawingCache();
Bitmap bmp = Bitmap.createBitmap(this.getDrawingCache());
this.setDrawingCacheEnabled(false);
return bmp;
}
public void clear(){
mBitmap.eraseColor(Color.GREEN);
invalidate();
System.gc();
}
}
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.view.View.MeasureSpec;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity
{
MyDrawView myDrawView;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// myDrawView = new MyDrawView(this, null);
setContentView(R.layout.activity_main);
myDrawView = (MyDrawView)findViewById(R.id.draw);
Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
File folder = new File(Environment.getExternalStorageDirectory().toString());
boolean success = false;
if (!folder.exists())
{
success = folder.mkdirs();
}
System.out.println(success+"folder");
File file = new File(Environment.getExternalStorageDirectory().toString() + "/sample.png");
if ( !file.exists() )
{
try {
success = file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
System.out.println(success+"file");
FileOutputStream ostream = null;
try
{
ostream = new FileOutputStream(file);
System.out.println(ostream);
View targetView = myDrawView;
// myDrawView.setDrawingCacheEnabled(true);
// Bitmap save = Bitmap.createBitmap(myDrawView.getDrawingCache());
// myDrawView.setDrawingCacheEnabled(false);
// copy this bitmap otherwise distroying the cache will destroy
// the bitmap for the referencing drawable and you'll not
// get the captured view
// Bitmap save = b1.copy(Bitmap.Config.ARGB_8888, false);
//BitmapDrawable d = new BitmapDrawable(b);
//canvasView.setBackgroundDrawable(d);
// myDrawView.destroyDrawingCache();
// Bitmap save = myDrawView.getBitmapFromMemCache("0");
// myDrawView.setDrawingCacheEnabled(true);
//Bitmap save = myDrawView.getDrawingCache(false);
Bitmap well = myDrawView.getBitmap();
Bitmap save = Bitmap.createBitmap(320, 480, Config.ARGB_8888);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
Canvas now = new Canvas(save);
now.drawRect(new Rect(0,0,320,480), paint);
now.drawBitmap(well, new Rect(0,0,well.getWidth(),well.getHeight()), new Rect(0,0,320,480), null);
// Canvas now = new Canvas(save);
//myDrawView.layout(0, 0, 100, 100);
//myDrawView.draw(now);
if(save == null) {
System.out.println("NULL bitmap save\n");
}
save.compress(Bitmap.CompressFormat.PNG, 100, ostream);
//bitmap.compress(Bitmap.CompressFormat.PNG, 100, ostream);
//ostream.flush();
//ostream.close();
}catch (NullPointerException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Null error", Toast.LENGTH_SHORT).show();
}
catch (FileNotFoundException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "File error", Toast.LENGTH_SHORT).show();
}
catch (IOException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "IO error", Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<com.example.draw2.MyDrawView
android:id ="@+id/draw"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></com.example.draw2.MyDrawView>"
<Button
android:id ="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="save"
android:layout_alignParentBottom="true"
></Button>"
</RelativeLayout>
"
"
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.draw2"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.draw2.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
import android.annotation.SuppressLint;
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.Rect;
import android.util.AttributeSet;
import android.util.LruCache;
import android.view.MotionEvent;
import android.view.View;
public class MyDrawView extends View {
public Bitmap mBitmap;
public Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private Paint mPaint;
public MyDrawView(Context c, AttributeSet attrs) {
super(c, attrs);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFF000000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(9);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
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;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}
@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;
}
public Bitmap getBitmap()
{
//this.measure(100, 100);
//this.layout(0, 0, 100, 100);
this.setDrawingCacheEnabled(true);
this.buildDrawingCache();
Bitmap bmp = Bitmap.createBitmap(this.getDrawingCache());
this.setDrawingCacheEnabled(false);
return bmp;
}
public void clear(){
mBitmap.eraseColor(Color.GREEN);
invalidate();
System.gc();
}
}
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.drawable.BitmapDrawable;
import android.os.Bundle;
import android.os.Environment;
import android.view.Menu;
import android.view.View;
import android.view.View.MeasureSpec;
import android.widget.Button;
import android.widget.Toast;
public class MainActivity extends Activity
{
MyDrawView myDrawView;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
// myDrawView = new MyDrawView(this, null);
setContentView(R.layout.activity_main);
myDrawView = (MyDrawView)findViewById(R.id.draw);
Button button1 = (Button)findViewById(R.id.button1);
button1.setOnClickListener(new View.OnClickListener()
{
public void onClick(View v)
{
File folder = new File(Environment.getExternalStorageDirectory().toString());
boolean success = false;
if (!folder.exists())
{
success = folder.mkdirs();
}
System.out.println(success+"folder");
File file = new File(Environment.getExternalStorageDirectory().toString() + "/sample.png");
if ( !file.exists() )
{
try {
success = file.createNewFile();
} catch (IOException e) {
e.printStackTrace();
}
}
System.out.println(success+"file");
FileOutputStream ostream = null;
try
{
ostream = new FileOutputStream(file);
System.out.println(ostream);
View targetView = myDrawView;
// myDrawView.setDrawingCacheEnabled(true);
// Bitmap save = Bitmap.createBitmap(myDrawView.getDrawingCache());
// myDrawView.setDrawingCacheEnabled(false);
// copy this bitmap otherwise distroying the cache will destroy
// the bitmap for the referencing drawable and you'll not
// get the captured view
// Bitmap save = b1.copy(Bitmap.Config.ARGB_8888, false);
//BitmapDrawable d = new BitmapDrawable(b);
//canvasView.setBackgroundDrawable(d);
// myDrawView.destroyDrawingCache();
// Bitmap save = myDrawView.getBitmapFromMemCache("0");
// myDrawView.setDrawingCacheEnabled(true);
//Bitmap save = myDrawView.getDrawingCache(false);
Bitmap well = myDrawView.getBitmap();
Bitmap save = Bitmap.createBitmap(320, 480, Config.ARGB_8888);
Paint paint = new Paint();
paint.setColor(Color.WHITE);
Canvas now = new Canvas(save);
now.drawRect(new Rect(0,0,320,480), paint);
now.drawBitmap(well, new Rect(0,0,well.getWidth(),well.getHeight()), new Rect(0,0,320,480), null);
// Canvas now = new Canvas(save);
//myDrawView.layout(0, 0, 100, 100);
//myDrawView.draw(now);
if(save == null) {
System.out.println("NULL bitmap save\n");
}
save.compress(Bitmap.CompressFormat.PNG, 100, ostream);
//bitmap.compress(Bitmap.CompressFormat.PNG, 100, ostream);
//ostream.flush();
//ostream.close();
}catch (NullPointerException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "Null error", Toast.LENGTH_SHORT).show();
}
catch (FileNotFoundException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "File error", Toast.LENGTH_SHORT).show();
}
catch (IOException e)
{
e.printStackTrace();
Toast.makeText(getApplicationContext(), "IO error", Toast.LENGTH_SHORT).show();
}
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
}
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<com.example.draw2.MyDrawView
android:id ="@+id/draw"
android:layout_width="wrap_content"
android:layout_height="wrap_content"></com.example.draw2.MyDrawView>"
<Button
android:id ="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="save"
android:layout_alignParentBottom="true"
></Button>"
</RelativeLayout>
"
"
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.draw2"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.draw2.MainActivity"
android:label="@string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
您的类
abcAbc abc;
Bitmap bmp = viewToBitmap(abc);
Bitmap bmp = viewToBitmap(frameLayout);
Bitmap bmp = viewToBitmap(LinearLayout);
Bitmap bmp = viewToBitmap(AnyView);
您的类
abcAbc abc;
Bitmap bmp = viewToBitmap(abc);
Bitmap bmp = viewToBitmap(frameLayout);
Bitmap bmp = viewToBitmap(LinearLayout);
Bitmap bmp = viewToBitmap(AnyView);
这是什么类型的类？公共类abc扩展视图你如何确定你在画布上绘制了一些东西？我正在画布上绘制线条和位图。如果你在特定的
视图上明确设置了背景，它将是黑色的。您可能只需要先用Canvas#drawColor（）
在this.draw（）之前设置背景色
调用。这是什么类？公共类abc扩展视图如何确定在画布上绘制内容？我正在画布上绘制线条和位图。如果您在特定的视图上明确设置了背景，它将是黑色的。在调用this.draw（）
之前，您可能只需要先用Canvas#drawColor（）
设置背景色。