SlidingPaneLayout：没有平滑动画的滑动？

Question

我正在使用最新支持库中提供的新SlidingPaneLayout，它提供了openPane() 和closePane() 方法来平滑打开和关闭面板。不幸的是，没有动画没有公共方法可以做到这一点。

还有办法做到这一点吗？我觉得可能需要反思。

附：该文件位于sdk/extras/android/support/v4/src/java/android/support/v4/widget/。

Answer 1

我最终编写了一个提供两种方法的子类，openPaneNoAnimation() 和 closePaneNoAnimation()。是的，它是一种反射，并且可能会停止使用未来的支持库，但现在它可以完成这项工作。在最坏的情况下，这些方法会退回到使用 openPane() 和 closePane()。

import java.lang.reflect.Field;
import java.lang.reflect.Method;

import android.content.Context;
import android.support.v4.widget.SlidingPaneLayout;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;

public class AnimationlessSlidingPaneLayout extends SlidingPaneLayout {
    private boolean mSlideEnabled = true;
    private Field mSlideOffsetField = null;
    private Field mSlideableViewField = null;
    private Method updateObscuredViewsVisibilityMethod = null;
    private Method dispatchOnPanelOpenedMethod = null;
    private Method dispatchOnPanelClosedMethod = null;
    private Field mPreservedOpenStateField = null;
    private Method parallaxOtherViewsMethod = null;

    public AnimationlessSlidingPaneLayout(Context context) {
        this(context, null, 0);
    }

    public AnimationlessSlidingPaneLayout(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }

    public AnimationlessSlidingPaneLayout(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        try {
            mSlideOffsetField = SlidingPaneLayout.class.getDeclaredField("mSlideOffset");
            mSlideableViewField = SlidingPaneLayout.class.getDeclaredField("mSlideableView");
            updateObscuredViewsVisibilityMethod = SlidingPaneLayout.class.getDeclaredMethod("updateObscuredViewsVisibility",
                                                                                            View.class);
            dispatchOnPanelClosedMethod = SlidingPaneLayout.class.getDeclaredMethod("dispatchOnPanelClosed", View.class);
            dispatchOnPanelOpenedMethod = SlidingPaneLayout.class.getDeclaredMethod("dispatchOnPanelOpened", View.class);
            mPreservedOpenStateField = SlidingPaneLayout.class.getDeclaredField("mPreservedOpenState");
            parallaxOtherViewsMethod = SlidingPaneLayout.class.getDeclaredMethod("parallaxOtherViews", float.class);

            mSlideOffsetField.setAccessible(true);
            mSlideableViewField.setAccessible(true);
            updateObscuredViewsVisibilityMethod.setAccessible(true);
            dispatchOnPanelOpenedMethod.setAccessible(true);
            dispatchOnPanelClosedMethod.setAccessible(true);
            mPreservedOpenStateField.setAccessible(true);
            parallaxOtherViewsMethod.setAccessible(true);
        } catch (Exception e) {
            Log.w("ASPL", "Failed to set up animation-less sliding layout.");
        }
    }

    public void openPaneNoAnimation() {
        try {
            View slideableView = (View) mSlideableViewField.get(this);
            mSlideOffsetField.set(this, 1.0f);
            parallaxOtherViewsMethod.invoke(this, 1.0f);
            requestLayout();
            invalidate();
            dispatchOnPanelOpenedMethod.invoke(this, slideableView);
            mPreservedOpenStateField.set(this, true);
        } catch (Exception e) {
            openPane();
        }
    }

    public void closePaneNoAnimation() {
        try {
            View slideableView = (View) mSlideableViewField.get(this);
            mSlideOffsetField.set(this, 0.0f);
            parallaxOtherViewsMethod.invoke(this, 0.0f);
            requestLayout();
            invalidate();
            updateObscuredViewsVisibilityMethod.invoke(this, slideableView);
            dispatchOnPanelClosedMethod.invoke(this, slideableView);
            mPreservedOpenStateField.set(this, false);
        } catch (Exception e) {
            closePane();
        }
    }

}