CODEWITHSUNDEEP
androidimagecanvaspngsignature
alevee
alevee

Reputation: 35

Android: Load PNG image with Canvas


I'm implementing a graphical signature capture function for my Android app. Online I've found a perfectly working function and it is already inside my code. The user draws his signature and the image is correctly saved!
Now I want to add this code: when onCreate function is called, I want to check if a signature image already exists and, if yes, load it. With this implementation, users can check their own signature.
Is that possible? Suggestions are really appreciated! Thanks in advance!

Here's my code:

@Override
public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    this.requestWindowFeature(Window.FEATURE_NO_TITLE);
    setContentView(R.layout.firma_allievo);
    tempDir =  Environment.getExternalStorageDirectory().toString() + "/temp/"+corsok+"/";
    ContextWrapper cw = new ContextWrapper(getApplicationContext());

    current = tempDir + allievo + ".png"; // THIS IS THE PATH OF THE SIGNATURE IMAGE FILE

    mypath= new File(current);
    mContent = (LinearLayout) findViewById(R.id.linearLayout);

    mSignature = new signature(this, null);
    mSignature.setBackgroundColor(Color.WHITE);
    mContent.addView(mSignature, LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT);

    mClear = (Button)findViewById(R.id.clear);
    mGetSign = (Button)findViewById(R.id.getsign);
    mGetSign.setEnabled(true);
    mCancel = (Button)findViewById(R.id.cancel);
    mView = mContent;

    mClear.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
            mSignature.clear();
        }
    });

    mGetSign.setOnClickListener(new OnClickListener()
    {
        public void onClick(View v)
        {
            boolean error = captureSignature();
            if(!error){
                mView.setDrawingCacheEnabled(true);
                mSignature.save(mView);
                Bundle b = new Bundle();
                b.putString("status", "done");
                Intent intent = new Intent();
                intent.putExtras(b);
                setResult(RESULT_OK,intent);
                finish();
             }
        }
    });
}

Upvotes: 2

Views: 7953

Answers (3)

alevee
alevee

Reputation: 35

SOLVED by myself! The bitmap loaded is set as background in the Canvas component. Here's the code:

File file = new File(current);
if(file.exists()) {
    Bitmap bMap = BitmapFactory.decodeFile(current);
    Drawable d = new BitmapDrawable(bMap);
    mSignature.setBackground(d);
}

Note: minimum API level 16!

Upvotes: 1

alevee
alevee

Reputation: 35

Here the signature is below: 

public class signature extends View
    {
        private static final float STROKE_WIDTH = 5f;
        private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
        private Paint paint = new Paint();
        private Path path = new Path();

    private float lastTouchX;
    private float lastTouchY;
    private final RectF dirtyRect = new RectF();

    public signature(Context context, AttributeSet attrs)
    {
        super(context, attrs);
        paint.setAntiAlias(true);
        paint.setColor(Color.BLACK);
        paint.setStyle(Paint.Style.STROKE);
        paint.setStrokeJoin(Paint.Join.ROUND);
        paint.setStrokeWidth(STROKE_WIDTH);
    }

    public void save(View v)
    {
        if(mBitmap == null)
        {
            mBitmap =  Bitmap.createBitmap (mContent.getWidth(), mContent.getHeight(), Bitmap.Config.RGB_565);;
        }
        Canvas canvas = new Canvas(mBitmap);
        try
        {
            FileOutputStream mFileOutStream = new FileOutputStream(mypath);

            v.draw(canvas);
            mBitmap.compress(Bitmap.CompressFormat.PNG, 90, mFileOutStream);
            mFileOutStream.flush();
            mFileOutStream.close();
            String url = Images.Media.insertImage(getContentResolver(), mBitmap, "title", null);
                //In case you want to delete the file
                //boolean deleted = mypath.delete();
                //Log.v("log_tag","deleted: " + mypath.toString() + deleted);
                //If you want to convert the image to string use base64 converter

        }
        catch(Exception e)
        {
            Log.v("log_tag", e.toString());
        }
    }

    public void clear()
    {
        path.reset();
        invalidate();
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        canvas.drawPath(path, paint);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event)
    {
        float eventX = event.getX();
        float eventY = event.getY();
        mGetSign.setEnabled(true);
        acquisisciFirma = "SI";

        switch (event.getAction())
        {
            case MotionEvent.ACTION_DOWN:
                path.moveTo(eventX, eventY);
                lastTouchX = eventX;
                lastTouchY = eventY;
                return true;

            case MotionEvent.ACTION_MOVE:

            case MotionEvent.ACTION_UP:

                resetDirtyRect(eventX, eventY);
                int historySize = event.getHistorySize();
                for (int i = 0; i < historySize; i++)
                {
                    float historicalX = event.getHistoricalX(i);
                    float historicalY = event.getHistoricalY(i);
                    expandDirtyRect(historicalX, historicalY);
                    path.lineTo(historicalX, historicalY);
                }
                path.lineTo(eventX, eventY);
                break;

            default:
                debug("Ignored touch event: " + event.toString());
                return false;
        }

        invalidate((int) (dirtyRect.left - HALF_STROKE_WIDTH),
                (int) (dirtyRect.top - HALF_STROKE_WIDTH),
                (int) (dirtyRect.right + HALF_STROKE_WIDTH),
                (int) (dirtyRect.bottom + HALF_STROKE_WIDTH));

        lastTouchX = eventX;
        lastTouchY = eventY;

        return true;
    }

    private void debug(String string){
    }

    private void expandDirtyRect(float historicalX, float historicalY)
    {
        if (historicalX < dirtyRect.left)
        {
            dirtyRect.left = historicalX;
        }
        else if (historicalX > dirtyRect.right)
        {
            dirtyRect.right = historicalX;
        }

        if (historicalY < dirtyRect.top)
        {
            dirtyRect.top = historicalY;
        }
        else if (historicalY > dirtyRect.bottom)
        {
            dirtyRect.bottom = historicalY;
        }
    }

    private void resetDirtyRect(float eventX, float eventY)
    {
        dirtyRect.left = Math.min(lastTouchX, eventX);
        dirtyRect.right = Math.max(lastTouchX, eventX);
        dirtyRect.top = Math.min(lastTouchY, eventY);
        dirtyRect.bottom = Math.max(lastTouchY, eventY);
    }
}

Upvotes: 0

Ali
Ali

Reputation: 12664

It should be as simple as doing this:

ImageView image = (ImageView) findViewById(R.id.test_image);
Bitmap bMap = BitmapFactory.decodeFile("/sdcard/test2.png");
image.setImageBitmap(bMap);

If you want to draw the image on Canvas, then you can use the Bitmap to create a BitmapDrawable and then drawing a Drawable on canvas is trivial.

Bitmap bMap = BitmapFactory.decodeFile("/sdcard/test2.png");
Drawable d = new BitmapDrawable(bMap);
d.setBounds(left, top, right, bottom);  
d.draw(canvas);

Upvotes: 3

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