public class MyView extends View {
// int bh = originalBitmap.getHeight();
// int bw = originalBitmap.getWidth();
public MyView(Context c,int w,int h) {
super(c);
mBitmap = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);
// Bitmap mBitmap =
// Bitmap.createScaledBitmap(originalBitmap,200,true);
mCanvas = new Canvas(mBitmap);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
//mBitmapPaint.setColor(Color.YELLOW);
//mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
}
@Override
protected void onSizeChanged(int w,int h,int oldw,int oldh) {
super.onSizeChanged(w,oldw,oldh);
// mBitmap = Bitmap.createBitmap(bw,bh,Bitmap.Config.ARGB_8888);
// mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
//canvas.drawColor(customColor);
canvas.drawBitmap(mBitmap,mBitmapPaint);
canvas.drawPath(mPath,mPaint);
}
// //////************touching evants for painting**************///////
private float mX,mY;
private static final float TOUCH_TOLERANCE = 5;
private void touch_start(float x,float y) {
//mCanvas.drawCircle(x,y,progress+1,mPaint);
mPath.reset();
mPath.moveTo(x,y);
//mPaint.setStyle(Paint.Style.FILL);
//mPath.addCircle(x,(float) (progress+0.15),Direction.CW);
mCanvas.drawPath(mPath,mPaint);
mX = x;
mY = y;
//mPaint.setStyle(Paint.Style.STROKE);
}
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;
}
}
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.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;
} // end of touch events for image
}
解决方法
is there any way to draw circle or point using path?
而不是尝试这样做使用类Canvas中的方法drawPoint(float x,float y,Paint paint).
要在API演示中使用它,您需要更改3件事：
>有一个私有布尔mDrawPoint;在MyView类中区分点击和幻灯片.
>如果路径已更改(即在if语句中),则在touch_start()中将mDrawPoint设置为true,在touch_move()中将mDrawPoint设置为false.
>在touch_up()中检查mDrawPoint的值.如果它是假的,那么该函数之前做了什么,如果它是真的,那么在画布上绘制点：
mCanvas.drawPoint(mX,mPaint);
新版touch_up()：
private void touch_up() {
if(mDrawPoint == true) {
mCanvas.drawPoint(mX,mPaint);
} else {
mPath.lineTo(mX,mPaint);
// kill this so we don't double draw
mPath.reset();
}
}
when i move up my finger after drawing a line it automatically draws a point next to it,where the line ended. And when i starts a new line/curve the prevIoUsly drawn line would remove /clear from the canvas leaving only dots behind that were drawn.
您不需要比我的答案更多的修改.你可能忘了实现它的一部分.
我在尝试它时遇到了同样的问题并在发布我的答案之前解决了它.这是因为你在两个不同的画布上绘制,在onDraw方法上,当你的手指起来时它会丢失而另一个是mCanvas,这是在touch_up中保存行的地方.这就是为什么touch_up有一个if：
如果我们没有移动手指(只是点击),那么我们将点绘制到mCanvas,以便它仍然存在于下一个onDraw上(onDraw将mCanvas绘制到它作为参数接收的画布上,以便绘制旧的线条和点mCanvas仍然可见).
如果我们移动了手指,那么我们将传递给onDraw的画布所绘制的路径保存到mCanvas,以便在获得手指后它仍然存在.
您遇到的问题来自touch_up函数的else部分永远不会被执行,因此在touch_up上无论是否应该绘制一个点,并且路径永远不会被提交到mCanvas,因此下次onDraw被调用时会消失.
这很可能源于你在touch_start()中将mDrawPoint设置为true,正如我在第2点中所说的那样.但忘记在touch_move中将mDrawPoint设置为false,正如我在第2点中所说的那样.
这是我的touch_move的样子：
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,(x + mX)/2,(y + mY)/2);
mX = x;
mY = y;
mDrawPoint = false;
}
}
