在此代碼中,我想在兩個ImageView的頂部之間畫一條線。但是,在運行應用程序時,在調用invalidate()
之後,自定義視圖顯示爲純黑色。Android自定義視圖在調用無效後顯示純黑色
這裏是我的代碼:
public class ArrowView extends RelativeLayout {
public Paint paint;
public Bitmap eraser;
public Canvas cacheCanvas;
public float leftX;
public float leftY;
public float rightX;
public float rightY;
public boolean update = false;
public ImageView iv_leftArrow;
public ImageView iv_rightArrow;
private int w;
private int h;
LayoutInflater mInflater;
public ArrowView(Context context) {
super(context);
this.setWillNotDraw(false);
mInflater = LayoutInflater.from(context);
init();
}
public ArrowView(Context context, AttributeSet attrs) {
super(context, attrs);
this.setWillNotDraw(false);
mInflater = LayoutInflater.from(context);
init();
}
public ArrowView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
this.setWillNotDraw(false);
mInflater = LayoutInflater.from(context);
init();
}
@Override
public void onSizeChanged(int w, int h, int oldW, int oldH) {
this.w = w;
this.h = h;
super.onSizeChanged(w, h, oldW, oldH);
}
public void init() {
View v = mInflater.inflate(R.layout.arrow_view, this, true);
paint = new Paint(Paint.ANTI_ALIAS_FLAG);
paint.setColor(Color.BLACK);
paint.setStrokeWidth(5);
v.setBackgroundColor(Color.TRANSPARENT);
eraser = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
iv_leftArrow = (ImageView) v.findViewById(R.id.iv_leftarrow);
iv_rightArrow = (ImageView) v.findViewById(R.id.iv_rightArrow);
cacheCanvas = new Canvas();
cacheCanvas.setBitmap(eraser);
}
public void setCoordinates(float leftX, float leftY, float rightX, float rightY) {
this.leftX = leftX;
this.leftY = leftY;
this.rightX = rightX;
this.rightY = rightY;
}
@Override
public void onDraw(Canvas c) {
super.onDraw(c);
setCoordinates(iv_leftArrow.getX() + iv_leftArrow.getWidth()/2, iv_leftArrow.getY(), iv_rightArrow.getX() + iv_rightArrow.getWidth()/2, iv_rightArrow.getY());
if (update) {
c.drawLine(leftX, leftY, rightX, rightY, paint);
update = false;
}
cacheCanvas.drawPath(p, paint);
}
}
有什麼理由自定義視圖顯示調用invalidate()
後爲純黑色?
你在哪裏設置「更新」爲true? –
在調用'invalidate()'之前,我從我的'CollectingDetail'活動中設置了它。也許我會在調用CollectingDetail中的setArrow()之前調用它。 –
在最後一行:'cacheCanvas.drawPath(p,paint);'你怎麼能找到** p **的值? –