Android invalidateDrawable() 不工作

Android invalidateDrawable() not working

我在自定义视图中有一堆可绘制对象。我希望用户能够按下一个或多个可绘制对象并改变颜色。目前,每个可绘制对象只是一个具有两种状态的 StateListDrawablestate_pressed 和未按下。每次我按下可绘制对象时,setState returns true 所以我假设它实际上已更改,但我没有看到可绘制图像发生变化。 invalidateDrawable 什么都没做吗?我究竟做错了什么?如何在按下时重绘一个可绘制对象而不需要调用 customView.invalidate() 并每次都重绘整个对象?我最初是这样做的,但发现我的应用 运行 非常 slowly/inefficiently。谢谢!

流量:

Custom View (contains set of our custom class - TouchKey)
- Custom class TouchKey containing drawable and info
- Upon press or release, custom class finds which drawable to change

这是 TouchKey class 中的按钮触摸代码(MyTouch 是自定义 class 跟踪 android 设备上的所有触摸):

public void pressed(MyTouch touch) {
    boolean successfulStateChange = this.drawable.setState(new int[]{android.
                                                           R.attr.state_pressed});
    this.customView.invalidateDrawable(drawable);
}

public void released(MyTouch touch) {
    boolean successfulStateChange = this.drawable.setState(new int[]{-android.
                                                           R.attr.state_pressed});
    this.customView.invalidateDrawable(drawable);
}

如何在我的自定义视图中绘制我的 StateListDrawable

public class CustomView extends View {

    private TreeMap<Integer, TouchKey> keymap;

    /* Initialization Code Stuff Here - call drawKey */

    // StateListDrawable Creation
    private StateListDrawable drawKey(Canvas canvas, int bounds_l, 
                                  int bounds_t, int bounds_r, int bounds_b) 
        throws Resources.NotFoundException, XmlPullParserException, IOException {

        StateListDrawable key = new StateListDrawable();
        key.addState(new int[]{android.R.attr.state_pressed}, 
                     ContextCompat.getDrawable(mContext, R.drawable.key_pressed));
        key.addState(new int[]{-android.R.attr.state_pressed}, 
                     ContextCompat.getDrawable(mContext, R.drawable.key_released));    

        key.setBounds(bound_l, bounds_t, bounds_r, bounds_b);
        key.draw(canvas);

        return key;
    }
}

I was doing that originally but found that my app ran very slowly/inefficiently

如果这样做,那么您在代码中的某些地方会有很大的优势,或者(我想)在绘制之前不缩放图像。因此,请尝试在您的代码中找到对系统具有巨大优势的逻辑。因为View.invalidate()这么快的方法。

其他 0,02$ :

我想你会开发类似键盘的东西。对于这种情况,您需要使 canvas 的区域无效。

View.invalidate(new Rect(0, 0, 49, 49));

我也遇到了这个问题,不过最后还是解决了。这个问题的原因是你在上下文中使用的 Drawable 对象没有通过调用 setBounds(Rect) 设置它是 Bounds,所以它的 BoundsRect(0,0,0,0) 默认情况下。这导致 Drawable 附加的 ViewinvalidateDrawable() 不工作。

查看 View.invalidateDrawable():

@Override
public void invalidateDrawable(@NonNull Drawable drawable) {
    if (verifyDrawable(drawable)) {
        final Rect dirty = drawable.getDirtyBounds();
        final int scrollX = mScrollX;
        final int scrollY = mScrollY;

        invalidate(dirty.left + scrollX, dirty.top + scrollY,
                dirty.right + scrollX, dirty.bottom + scrollY);
        rebuildOutline();
    }
}

查看Drawable.getDirtyBounds():

  /**
 * Return the drawable's dirty bounds Rect. Note: for efficiency, the
 * returned object may be the same object stored in the drawable (though
 * this is not guaranteed).
 * <p>
 * By default, this returns the full drawable bounds. Custom drawables may
 * override this method to perform more precise invalidation.
 *
 * @return The dirty bounds of this drawable
 */
@NonNull
public Rect getDirtyBounds() {
    return getBounds();
}

所以 Rect dirtyRect(0,0,0,0),如果你没有设置 Drawable.Bounds。因此 View.invalidate() 不起作用。

所以你要做的就是在代码的某个地方设置Drawable.Bounds,比如:

@Override
public void draw(@NonNull Canvas canvas) {
    Rect localRect = canvas.getClipBounds();
    this.setBounds(localRect);
    ...
}