我正在尝试将自定义 View 另存为图像，但这并没有发生，当我在 Android 设备库中打开它时，它只会显示黑色图像。自定义 View 是这样的
public class page extends View
{
private static final String TAG = "DrawView";
private boolean clearflag = false;
private static final float MINP = 0.25f;
private static final float MAXP = 0.75f;
private Context context;
private Paint mPaint = new Paint();
private int[] pencolor = { Color.BLUE, Color.GREEN, Color.MAGENTA,
Color.BLACK, Color.CYAN, Color.GRAY, Color.RED, Color.DKGRAY,
Color.LTGRAY, Color.YELLOW };
private Canvas mCanvas;
private Path mPath;
private ArrayList<Path> paths = new ArrayList<Path>();
public void ClearScreen()
{
clearflag = true;
invalidate();
}
public void resetPenColor()
{
Random random = new Random();
random.setSeed(System.currentTimeMillis());
int color_index = random.nextInt(pencolor.length);
// Toast.makeText(context, "Pen Color "+color_index, Toast.LENGTH_SHORT).show();
mPaint.setColor(pencolor[color_index]);
}
public void init(Context context) {
//super(context);
this.context = context;
setFocusable(true);
setFocusableInTouchMode(true);
//this.setOnTouchListener(this);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(6);
mCanvas = new Canvas();
mPath = new Path();
paths.add(mPath);
}
public page(Context context, AttributeSet attrs)
{
super(context, attrs);
init(context);
this.context = context;
}
public page(Context context, AttributeSet attrs, int defStyle)
{
super(context, attrs, defStyle);
init(context);
this.context = context;
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh)
{
super.onSizeChanged(w, h, oldw, oldh);
}
@Override
protected void onDraw(Canvas canvas)
{
if(clearflag)
{
canvas.drawColor(Color.WHITE);
clearflag = false;
paths.clear();
paths.add(mPath);
Log.v("Clear Screen", "---");
}
else
{
for (Path p : paths)
{
canvas.drawPath(p, mPaint);
Log.v("draw", "---line");
}
}
}
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;
Log.v("Touch", "Start");
}
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;
}
Log.v("Touch", "Move");
}
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 = new Path();
paths.add(mPath);
Log.v("Touch", "Move");
}
@Override
public boolean onTouchEvent(MotionEvent event)
{
super.onTouchEvent(event);
float x = event.getX();
float y = event.getY();
switch (event.getActionMasked())
{
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;
case MotionEvent.ACTION_POINTER_DOWN:
resetPenColor();
// Toast.makeText(context, "Multitouch", Toast.LENGTH_SHORT).show();
invalidate();
break;
}
return true;
}
我保存位图的主要 Activity 是这样的
public class Book extends Activity
{
private ImageButton refresh;
private ImageButton save;
private page pg;
public void init()
{
refresh = (ImageButton) findViewById(R.id.refresh);
save = (ImageButton) findViewById(R.id.save);
pg = (page) findViewById(R.id.page);
}
public void onCreate(Bundle onsavestate)
{
super.onCreate(onsavestate);
setContentView(R.layout.book);
init();
addListeners();
}
public void addListeners()
{
refresh.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View arg0)
{
// TODO Auto-generated method stub
pg.ClearScreen();
}
});
save.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
// TODO Auto-generated method stub
saveautograph();
}
});
}
public void saveautograph()
{
Bitmap returnedbitmap = Bitmap.createBitmap(pg.getWidth(), pg.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(returnedbitmap);
pg.draw(canvas);
/*Drawable bgDrawable = pg.getBackground();
if(bgDrawable != null)
{
bgDrawable.draw(canvas);
}*/
OutputStream stream = null;
try
{
stream = new FileOutputStream(Environment.getExternalStorageDirectory()+"/autograph.jpeg");
}
catch (FileNotFoundException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
try
{
stream.flush();
stream.close();
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
if(stream == null)
{
Log.v("Stream", "null");
}
if(returnedbitmap == null)
{
Log.v("bitmap", "null");
}
returnedbitmap.compress(CompressFormat.PNG, 90, stream);
}
}
这是xml文件
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/rl"
android:layout_width="wrap_content"
android:layout_height="wrap_content" >
<LinearLayout
android:id="@+id/buttonlayout"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="@drawable/buttoncontainer"
android:gravity="bottom|center"
android:orientation="horizontal" >
<ImageButton
android:id="@+id/refresh"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:background="@color/white"
android:src="@drawable/refresh"
android:layout_marginLeft="4dp" />
<ImageButton
android:id="@+id/save"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
android:background="@color/white"
android:src="@drawable/save"
android:layout_marginLeft="4dp"
android:layout_marginRight="4dp" />
</LinearLayout>
<com.gsmappstabs.autographplease.page
android:id="@+id/page"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_above="@+id/buttonlayout" />
</RelativeLayout>
请帮忙
最佳答案
如下更新您的saveautograph 方法:
public void saveautograph()
{
pg.setDrawingCacheEnabled(true);
pg.buildDrawingCache();
Bitmap returnedBitmap = pg.getDrawingCache();
try {
FileOutputStream out = new FileOutputStream(Environment.getExternalStorageDirectory()+"/autograph.jpeg");
returnedBitmap.compress(Bitmap.CompressFormat.PNG, 90, out);
out.close();
} catch (Exception e) {
e.printStackTrace();
}
pg.setDrawingCacheEnabled(false);
}
基本上，您可以使用 getDrawingCache 方法将 View 作为位图获取。然后直接将位图保存到文件..
关于java - 位图没有正确保存只有黑色图像，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19721851/