Android - Paint Simple - Tạo View vẽ hình đơn giản trên Android Studio

Tạo một lớp SimplePaintView

public class SimplePaintView extends View {
    public int width;    

public int height;    

private Bitmap mBitmap;    

private Canvas mCanvas;    

private Path mPath;    

private Paint mBitmapPaint;    

Context context;    

private Paint circlePaint;    

private Path circlePath;    

private Paint pencil;
    public SimplePaintView(Context c, int lineColor) {
        super(c);        

getPencil(lineColor);        

context = c;       

mPath = new Path();        

mBitmapPaint = new Paint(Paint.DITHER_FLAG);        

circlePaint = new Paint();        

circlePath = new Path();        

circlePaint.setAntiAlias(true);        

circlePaint.setColor(getResources().getColor(R.color.colorPrimary));        

circlePaint.setStyle(Paint.Style.STROKE);        

circlePaint.setStrokeJoin(Paint.Join.MITER);        

circlePaint.setStrokeWidth(4f);    

}

    private void getPencil(int lineColor) {
        pencil = new Paint();        

pencil.setAntiAlias(true);        

pencil.setDither(true);        

pencil.setColor(lineColor);        

pencil.setStyle(Paint.Style.STROKE);        

pencil.setStrokeJoin(Paint.Join.ROUND);        

pencil.setStrokeCap(Paint.Cap.ROUND);        

pencil.setStrokeWidth(12);   

 }

    @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) {
        super.onDraw(canvas);
        canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);       

 canvas.drawPath(mPath, pencil);        

canvas.drawPath(circlePath, circlePaint);    

}

    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;
            circlePath.reset();            

circlePath.addCircle(mX, mY, 30, Path.Direction.CW);        

}
    }

    private void touch_up() {
        mPath.lineTo(mX, mY);        circlePath.reset();     
        mCanvas.drawPath(mPath, pencil);  
        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;    }

}

Sử dụng trong Activity:

SimplePaintView simplePaint = new SimplePaintView(this, 

getResources().getColor(R.color.line_color));

Tham số truyền vào là context và màu của nét vẽ

Ta có thể tạo một ViewGroup bất kỳ để addView(simplePaint); (nên có kích thước xác định)

.... còn tiếp