android图像视图渐变背景

Question

所以，我不想更新ImageView来根据手机陀螺仪和光传感器的一些事件来改变梯度。然而，此刻我正在尝试点击事件。

我想设置一个以单击事件为中心的径向渐变。我第一次尝试设置布局背景时考虑到了这一点，一切都很好。然后，我尝试将其更改为布局中的ImageView（在大小和位置上是所需的视觉元素），梯度中心向下向右移动。

这是代码：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_seeker);
    RelativeLayout layout = (RelativeLayout) findViewById(R.id.seeker_layout);
    layout.setOnTouchListener(new View.OnTouchListener() {
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            if (event.getAction() == MotionEvent.ACTION_DOWN) {
                int location[] = new int[2];
                //measuring location of Image View to try and find correlation to shift
                findViewById(R.id.gradient_indicator).getLocationOnScreen(location);
                int grad_height = findViewById(R.id.gradient_indicator).getMeasuredHeight();
                int grad_width = findViewById(R.id.gradient_indicator).getMeasuredWidth();
                final float pos_x = event.getX();
                final float pos_y = event.getY();
                Toast position = Toast.makeText(getApplicationContext(), "Event Position (" + String.valueOf(pos_x) + "x" + String.valueOf(pos_y) + ")n Window Dimensions(" + grad_width + "x" + grad_height + ")n Window Position(" + location[0] + "x" + location[1] + ")", Toast.LENGTH_LONG);
                position.show();
                ShapeDrawable.ShaderFactory shader_factory = new ShapeDrawable.ShaderFactory() {
                    @Override
                    public Shader resize(int width, int height) {
                        RadialGradient radialGradient = new RadialGradient(pos_x, pos_y, 350, 0xff0000ff, 0, Shader.TileMode.MIRROR);
                        return radialGradient;
                    }
                };
                //Set curve radius to equal values in dp as specified in loaded xml shape
                float dp_radius = 5;
                int curve = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,dp_radius, getResources().getDisplayMetrics());
                float[] r_radii = new float[8];
                Arrays.fill(r_radii,curve);
                //create shape programatically that matches xml one
                RoundRectShape rs = new RoundRectShape(r_radii, null, null);
                ShapeDrawable sd = new ShapeDrawable(rs);
                sd.setShaderFactory(shader_factory);
                ImageView gradient_indicator = (ImageView) findViewById(R.id.gradient_indicator);
                if (Build.VERSION.SDK_INT >= 15) {
                    setBackgroundV15Plus(gradient_indicator, sd);
                } else {
                    setBackgroundV15Minus(gradient_indicator, sd);
                }

            }
            return true;
        }
    });
}
@TargetApi(15)
private void setBackgroundV15Plus(View view, ShapeDrawable sd) {
    view.setBackground(sd);
}
@SuppressWarnings("deprecation")
private void setBackgroundV15Minus(View view, ShapeDrawable sd) {
    view.setBackgroundDrawable(sd);
}

这是我得到的结果的图像，我用红圈标记了光标的位置。位移梯度

Answer 1

Nanoc建议的工作解决方案（它不是超级优雅，但它很有效）：
我计算它的方法是在xml ImageView声明中添加边距。然后，您可以从Java访问边距，而无需转换dp像素单位。从事件位置中减去所有
访问边距的代码：
ImageView gradient_indicator=（ImageView）findViewById（R.id.gradient_indicator）；RelativeLayout.LayoutParams lp=（RelativeLLayout.LayoutParams）gradient_indicator.getLayoutParams（）；int grad_margin_top=lp.topMargin；int grad_margin_left=lp.leftMargin；