Image on canvas to JPEG file

问题

I\'m drawing 2D images on the canvas.

I want to save image shown on canvas to JPEG file, how can I do it?

回答1:

1. create an empty bitmap
2. create a new Canvas object and pass this bitmap to it
3. call view.draw(Canvas) passing it the canvas object you just created. Refer Documentation of method for details.
4. Use Bitmap.compress() to write the contents of the bitmap to an OutputStream, file maybe.

Pseudo code:

Bitmap  bitmap = Bitmap.createBitmap( view.getWidth(), view.getHeight(), Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
view.draw(canvas); 
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos); 

回答2:

1. set Drawing Cache Enabled
2. Draw whatever you want
3. Get Bitmap object from view
4. Compress and save the image file

import java.io.File;
import java.io.FileOutputStream;

import android.app.Activity;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.util.Log;
import android.view.View;

public class CanvasTest extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        Draw2d d = new Draw2d(this);
        setContentView(d);
    }

    public class Draw2d extends View {

        public Draw2d(Context context) {
            super(context);
            setDrawingCacheEnabled(true);
        }

        @Override
        protected void onDraw(Canvas c) {
            Paint paint = new Paint();
            paint.setColor(Color.RED);          
            c.drawCircle(50, 50, 30, paint);

            try {
                getDrawingCache().compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File("/mnt/sdcard/arun.jpg")));
            } catch (Exception e) {
                Log.e("Error--------->", e.toString());
            }
            super.onDraw(c);
        }

    }

}

回答3:

Canvas to JPG:

Canvas canvas = null;
FileOutputStream fos = null;
Bitmap bmpBase = null;

bmpBase = Bitmap.createBitmap(image_width, image_height, Bitmap.Config.ARGB_8888);
canvas = new Canvas(bmpBase);
// draw what ever you want canvas.draw...

// Save Bitmap to File
try
{
    fos = new FileOutputStream(your_path);
    bmpBase.compress(Bitmap.CompressFormat.PNG, 100, fos);

    fos.flush();
    fos.close();
    fos = null;
}
catch (IOException e)
{
    e.printStackTrace();
}
finally
{
    if (fos != null)
    {
        try
        {
            fos.close();
            fos = null;
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
    }
}

来源：https://stackoverflow.com/questions/2174875/image-on-canvas-to-jpeg-file