CODEWITHSUNDEEP
androidcanvas
Ruthwik Warrier
Ruthwik Warrier

Reputation: 94

Android Canvas Drawing Line

I am creating a basic drawing application. The following functions are used to draw the line.

public void touchEventLine(MotionEvent event){

        Log.e("Canvas","Line Specific Event");
        float x = event.getX();
        float y = event.getY();


        switch (event.getAction()){

            case MotionEvent.ACTION_DOWN:

                Log.e("Canvas","Line Specific Event: Action Down");
                startX=x;
                startY=y;
                mPath.moveTo(startX,startY);
                Log.e("Canvas","Line Specific Event: Moved to X:"+startX+"  Y:"+startY);
                mX=x;
                mY=y;
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:

                Log.e("Canvas","Line Specific Event: Action Move");
                endX=x;
                endY=y;
                drawLine(endX,endY);
                Log.e("Canvas","Line Specific Event: Drawing From X:"+startX+"  Y:"+startY+"   to X:"+endX+"  Y:"+endY);
                paths.add(mPath);
                colorsMap.put(mPath,selectedColor);
                mPath = new Path();
                isDrawing++;
                invalidate();
                if(isDrawing>1) {
                    paths.remove(paths.size() - 2);
                    isDrawing--;
                }
                break;
            case MotionEvent.ACTION_UP:



                Log.e("Canvas","Line Specific Event: Action Up");
                endX=x;
                endY=y;

                drawLine(endX,endY);
                paths.add(mPath);
                colorsMap.put(mPath,selectedColor);
                mPath = new Path();
                paths.remove(paths.size() - 2);
                invalidate();
                isDrawing=0;
                break;



        }

    }

and the drawLine() function is

private void drawLine(float x2,float y2){

        mPath.lineTo(x2,y2);
        invalidate();
        Log.e("Canvas","Line Drawn");

    }

and my onDraw() function is

protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawBitmap(mBitmap, 0, 0, canvasPaint);
        canvas.drawPath(mPath,drawPaint);

        for (Path p : paths) {

            int curColor= colorsMap.get(p);
            drawPaint.setColor(curColor);
            canvas.drawPath(p, drawPaint);
        }

        Log.e("Canvas","OnDraw() Called");


    }

My problem is that the line is drawing from top left corner of screen. I believe it is (0,0). I used the same logic for drawing circle and rectangle and both working fine. Is there any mistake in my logic.? How can I fix this..? Thanks in advance

Upvotes: 0

Views: 894

Answers (1)

MehDi
MehDi

Reputation: 514

It's easy. you should call

path.moveTo(firstPoint_X, firstPoint_y);

at the first of the drawing.

(after each line that you call mPath = new Path(); )

if you don't call

path.moveTo

method after you make a new instance of Path class,by default it start drawing from position(0,0) of screen

Upvotes: 2

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